Spinal deformity in neurofibromatosis type-1: diagnosis and treatment

Recent Developments in Surgical Treatment of Spinal Deformity in Pediatric Patients: Experience from a Single-Center Series of 42 Neurofibromatosis Type 1 Patients

BACKGROUND

The management of spinal deformities in patients with NF-1 is challenging. The study aimed to assess the outcomes of the surgical treatment of spine deformities in children with neurofibromatosis type 1 with our treatment approach.

METHODS

A retrospective single-center study on pediatric patients with spinal deformities associated with NF-1 who received surgical treatment between 2006 and 2024.

RESULTS

The study group comprised 42 patients with a mean age at surgery of 9.8 years. Twenty-five patients (60%) were treated by means of growth-preserving techniques and 17 patients (40%) by means of definitive fusion. Preoperative halo-gravity traction was used in 14 (33%) cases. In the group treated with a growth-preserving technique, a 54.1% mean curve correction was observed at the latest follow-up, and growth of the thoracic spine was maintained at a physiological rate; however, 25 unplanned revision surgeries (mostly due to mechanical complications) were necessary. In the group treated by definitive fusion, a 66% curve correction was achieved at initial surgery, which remained unchanged at latest follow-up, and revision surgery was performed in three cases for augmentation of the fusion mass. There was one neurological complication (2%). Another patient developed a deep wound infection (2%).

CONCLUSIONS

Good and sustainable surgical correction of spinal deformities can be achieved in pediatric patients with NF-1. Due to the bony dystrophic changes, surgical treatment is challenging and the complication rate is higher than in spinal deformities of other etiologies.

Basilar invagination and atlantoaxial dislocation as a complication of severe dystrophic cervical kyphosis correction in neurofibromatosis type 1: Report of a rare case and review of literature

INTRODUCTION AND IMPORTANCE

Neurofibromatosis type 1 (NF1) affects the musculoskeletal system as well as the cervical spine. It is associated with severe, progressive cervical kyphosis. Surgical intervention is the treatment of choice to avoid neurological impairment and malalignment.

CASE PRESENTATION

We herein report an 11-year-old NF-1 patient with severe cervical kyphosis and intact neurological status. We applied five days of cervical traction followed by surgery utilizing the combined cervical approach (posterior release, anterior corpectomy and reconstruction, and posterior cervicothoracic instrumentation). In one-year follow-up, atlantoaxial dislocation (AAD) and basilar invagination (BI) were detected in neuroimagings. The complication was corrected by adding C1 to the previous construct via unilateral C1 lateral mass screw, contralateral C1 sublaminar hook, unilateral C3 and contralateral C4 sublaminar hook insertion, fixed with contoured rods medial to previous rods. This led to the correction of the AAD and the BI and the patients remained neurologically intact.

CLINICAL DISCUSSION

Severe cervical kyphosis in the setting of NF-1 is progressive and carries a considerable risk of neurologic compromise. Surgical intervention is thus necessary.

CONCLUSION

The combined approach with complete spinal column reconstruction is the surgical approach of choice. However, complete curve correction to near-normal lordosis carries the risk of proximal junctional failure (PJF).

Vertebral Column Subluxation in Neurofibromatosis Type 1-Associated Dystrophic Scoliosis: A Report of Two Cases and Narrative Review

BACKGROUND AND OBJECTIVE

Neurofibromatosis-1 (NF1) dystrophic scoliosis is a challenging disease to manage surgically, with multiplanar curves progressing rapidly and unpredictably. Conservative management with bracing is often unsuccessful, and many patients necessitate instrumented fusion to halt progression of their curves. In rare cases, patients can present with spontaneous vertebral subluxation, significantly complicating the surgical management of this already complex disease process. The objective here was to describe 2 cases of vertebral subluxation in NF1-associated dystrophic scoliosis along with their surgical corrections and clinical courses.

METHODS

A retrospective review of 2 cases at the authors' institution was performed to describe their preoperative symptom complexes, surgical corrections, and postoperative courses. A narrative review of the literature surrounding NF1-associated dystrophic scoliosis and subluxation is also presented.

RESULTS

Two cases of vertebral subluxation at T4-5 and C7-T1 are presented. Both patients had significant dystrophic features throughout their spines, and halo-gravity traction was unsuccessful in 1 patient and led to vertebral and subclavian artery injuries in the other. One patient underwent an uncomplicated deformity correction with partial vertebral column resection to facilitate his deformity correction. The other patient, after her vascular injuries, ultimately suffered a spinal cord injury after a fall and underwent emergent instrumentation, decompression, and partial vertebral column resection at the site of subluxation, with improvement in her neurological function afterward.

CONCLUSION

Dystrophic scoliosis in NF1 remains a difficult disease to treat, and deformity correction in patients with subluxation is particularly complex. These cases here highlight the unpredictability and possible complications of halo-gravity traction, need for good fixation to facilitate subluxation reduction, high chance of hardware complications and proximal or distal failure, and importance of cooperative management of these patients in conjunction with other surgical services.

Incidence of Tethered Cord Syndrome in Pediatric Patients With Neurofibromatosis Type 1

OBJECTIVE

The link between tethered cord syndrome (TCS) and neurofibromatosis type 1 (NF1) remains unclear. To date, only 2 studies have indicated a high occurrence of TCS in the pediatric NF1 patient population. Our study aims to ascertain the incidence of TCS among Chinese pediatric patients with NF1.

METHODS

A single-institution, 8-year retrospective analysis at a tertiary-level children's hospital was conducted for patients with NF1 who underwent surgery for TCS. The clinical features, imaging characteristics, genetic testing outcomes, and histopathological findings of pediatric NF1 patients with TCS were analyzed.

RESULTS

During the study period, a total of 115 pediatric patients were diagnosed with NF1. Among these 115 NF1 patients, 11 individuals, accounting for 9.6% of the sample, were confirmed to have TCS. This rate of occurrence is significantly higher than the incidence rate of TCS in the general population, which stands at 0.17%. All 11 of the pediatric NF1 patients underwent surgery for TCS. Out of the 11 patients who were advised to have tethered cord release surgery, 4 (36.4%) were girls, and the average age of these 11 patients was 8.6 years, with ages ranging from 2 to 17 years. The conus medullaris position of the 11 pediatric NF1 patients ranged from L1 to L2, and 10 of them (91%) had a filum terminale lipoma, characterized by high signal intensity on T1-weighted magnetic resonance images. Another patient was diagnosed with occult TCS. All 11 pediatric NF1 patients exhibited symptoms associated with TCS, such as neuromotor dysfunction, abnormalities in urination, defecation, skeletal system abnormalities, or pain. Eight of the 11 pediatric NF1 patients had undergone genetic testing, which is a crucial part of the diagnostic process for NF1. The histopathological examination of the 11 pediatric NF1 patients who underwent surgery revealed that 10 patients had fatty infiltration of the filum terminale, while the remaining patient exhibited fibrosis of the filum terminale.

CONCLUSIONS

In the group of pediatric patients with NF1, the incidence of TCS, presenting to the pediatric neurosurgery clinic for any reason, is significantly higher than that of the general population. However, the pathophysiological relationship between NF1 and TCS is still not clear. It is essential to provide counseling to NF1 patients and their families about the symptoms of TCS to make sure they are aware and can seek the necessary care when needed. This underscores the importance of not only diagnosing NF1 but also staying alert for related conditions like TCS, which may have a higher occurrence in this demographic.

Clinical features and surgical treatments of scoliosis in neurofibromatosis type 1: a systemic review and meta-analysis

BACKGROUND

Neurofibromatosis type 1 (NF 1) is an autosomal-dominant tumor predisposition genetic disease affecting approximately 1 in 3000 live births. The condition could present various manifestations ranging from skin abnormalities to neurological tumors. The musculoskeletal system could also be frequently affected, and scoliosis is the most common orthopedic manifestation. Characterized by the early-onset and rapid progression tendency, NF 1-related dystrophic scoliosis presented discrepancies from idiopathic scoliosis in terms of natural history, clinical features, and management outcomes and thus required special attention. In the current study, the authors conducted a systemic review to outline the body of evidence of the natural history, clinical characteristics, surgical outcomes, and surgical complications of NF 1-induced scoliosis, aiming to provide an elucidative insight into this condition.

METHOD

Systemic review and meta-analysis were conducted according to the latest Preferred Reporting Items for Systematic Reviews Meta-Analyses (PRISMA) guidelines. The search was performed in Medline, Embase, and Web of Science Core Collection up to December 27, 2022, using related keywords. Clinical features such as frequencies, segmental involvement, and hereditary information were summarized and described qualitatively. Meta-analysis was conducted using R software and the 'meta' package to yield an overall outcome of efficacy and safety of surgical management, precisely, spinal fusion procedure and growing rods procedure. Corrective rate of Cobb angle, sagittal kyphosis angle, and T1-S1 length post-operative and at the last follow-up was used to evaluate the efficacy, and the occurrence of surgery-related complications was used to evaluate the safety.

RESULT

A total of 37 articles involving 1023 patients were included. Approximately 26.6% of the NF 1 patients would present with scoliosis. Patients tend to develop scoliosis at an earlier age. The thoracic part turned out to be the most affected segment. No obvious correlation between scoliosis and genotype or hereditary type was observed. Both spinal fusion and growing rod surgery have shown acceptable treatment outcomes, with spinal fusion demonstrating better performance in terms of effectiveness and safety. The growing rods technique seemed to allow a better lengthening of the spine. The mainstay post-operative complications were implant-related complications but could be managed with limited revision surgery. Severe neurological deficits were rarely reported.

CONCLUSION

Scoliosis, especially the subtype characterized by dystrophic bony changes, is a significant orthopedic manifestation of NF1. It has an early onset, a tendency to persistently and rapidly progress, and is challenging to deal with. The current review outlines the available evidence from the perspective of natural history, clinical features, and the treatment efficacy and safety of the mainstay surgical options. Patients with NF1 scoliosis will benefit from a better understanding of the disease and evidence based treatment strategies.

The management of neurofibromatosis type 1 (NF1) in children and adolescents

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a rare neurogenetic disorder characterized by multiple organ system involvement and a predisposition to benign and malignant tumor development. With revised NF1 clinical criteria and the availability of germline genetic testing, there is now an opportunity to render an early diagnosis, expedite medical surveillance, and initiate treatment in a prompt and targeted manner.

AREAS COVERED

The authors review the spectrum of medical problems associated with NF1, focusing specifically on children and young adults. The age-dependent appearance of NF1-associated features is highlighted, and the currently accepted medical treatments are discussed. Additionally, future directions for optimizing the care of this unique population of children are outlined.

EXPERT OPINION

The appearance of NF1-related medical problems is age dependent, requiring surveillance for those features most likely to occur at any given age during childhood. As such, we advocate a life stage-focused screening approach beginning in infancy and continuing through the transition to adult care. With early detection, it becomes possible to promptly institute therapies and reduce patient morbidity. Importantly, with continued advancement in our understanding of disease pathogenesis, future improvements in the care of children with NF1 might incorporate improved risk assessments and more personalized molecularly targeted treatments.

Functional and Radiological Outcomes of All-Posterior Surgical Correction of Dystrophic Curves in Patients with Neurofibromatosis Type 1

STUDY DESIGN

A retrospective cohort study.

PURPOSE

To determine outcomes following all-posterior surgery using computed tomography navigation, hybrid stabilization, and multiple anchor point techniques in patients with neurofibromatosis type 1 (NF-1) and dystrophic scoliosis.

OVERVIEW OF LITERATURE

Previous studies favored antero-posterior fusion as the most reliable method; however, approaching the spine anteriorly was fraught with significant complications. With the advent of computer assisted navigation and multiple anchor point method, posterior only approach is reporting successful outcomes.

METHODS

This study included patients who underwent all-posterior surgical deformity correction for dystrophic NF-1 curves. Coronal and sagittal Cobbs angles, apical rotation, and the presence of dystrophic features were evaluated before surgery. Postoperatively, sagittal, coronal, and axial correction, implant position, and implant densities were evaluated. The decline in curve correction and implant-related complications were evaluated at follow-up. Clinical outcomes were evaluated using the Scoliosis Research Society-22 revised index.

RESULTS

This study involved 50 patients with a mean age of 13.6 years and a mean follow-up duration of 5.52 years. With a mean coronal flexibility of 18.7%, the mean apical vertebral rotation (AVR), preoperative coronal Cobb angle, and sagittal kyphosis were 27.4°, 64.01°, and 47.70°, respectively. The postoperative mean coronal Cobb angle was 30.17° (p <0.05), and the sagittal kyphosis angle was 25.4° (p <0.05). The average AVR correction rate was 41.3%. The correction remained significant at the final mean follow-up, with a coronal Cobb angle of 34.14° and sagittal kyphosis of 25.02° (p <0.05). The average implant density was 1.41, with 46% of patients having a high implant density (HID). The HID had a markedly higher mean curve correction (29.30° vs. 38.05°, p <0.05) and a lower mean loss of correction (5.7° vs. 3.8°, p <0.05).

CONCLUSIONS

Utilizing computer-assisted navigation, hybrid instrumentation, and multiple anchor point technique and attaining high implant densities, this study demonstrates successful outcomes following posterior-only surgical correction of dystrophic scoliosis in patients with NF-1.

The role of scoliosis on the comorbidity and demographics of neurofibromatosis type 1 patients: A retrospective analysis of the National Inpatient Sample database

Neurofibromatosis type 1 (NF1) is the most common neurocutaneous syndrome in the United States, affecting every 1 in 3000 individuals. NF1 occurs due to non-functional mutations in the NF1 gene, which expresses neurofibromin, a protein involved in tumour suppression. As a result, NF1 typically presents with non-cancerous neoplasm masses called neurofibromas across the body. Out of all NF1 abnormalities, the most common skeletal abnormality seen in around 10%-30% of NF1 patients is scoliosis, an improver curvature of the spine. However, there is a lack of research on the effects of scoliosis on demographics and morbidities of NF1 patients. We performed a national analysis to investigate the complex relationship between NF1 and scoliosis on patients' demographics and comorbidities. We conducted a retrospective cross-sectional analysis of the 2017 US National Inpatient Sample database using univariable Chi-square analysis and multivariable binary logistic regression analysis to determine the interplay of NF1 and scoliosis on patients' demographics and comorbidities. Our query resulted in 4635 total NF1 patients, of which 475 (10.25%) had scoliosis and 4160 (89.75%) did not. Demographic analysis showed that NF1 patients with scoliosis were typically younger, female and white compared to NF1 patients without scoliosis. Comorbidity analysis showed that NF1 patients with scoliosis were more likely to develop malignant brain neoplasms, epilepsy, hydrocephalus, pigmentation disorders, hypothyroidism, diabetes with chronic complications and coagulopathy disorders. NF1 patients with scoliosis were less likely to develop congestive heart failure, pulmonary circulation disease, peripheral vascular disease, paralysis, chronic pulmonary disease, lymphoma and psychosis. NF1 patients with scoliosis were predominantly younger, female, white patients. The presence of scoliosis in NF1 patients increases the risks for certain brain neoplasms and disorders but serves a protective effect against some pulmonary and cardiac complications.

Surgical Management of Intraosseous Neurofibroma in Cervical Spine: A Case Report

CASE

A 30-year-old man had cervical radiculomyelopathy and neck pain caused by a massive intraosseous neurofibroma (IONF) originating from the C6 vertebrae. We performed posterior tumor resection with spinal instrumentation and fusion from C3 to T2 and a follow-up resection procedure of the remaining C6 anterior tumor, sacrificing the affected vertebral artery (VA), which accordingly required bypass surgery at 2 months recovery. Reconstruction using a titanium mesh cage was successfully performed. There were no local recurrences at 2 years postoperatively.

CONCLUSIONS

Total tumor resection split into 2 stages with sacrifice of the affected VA is a feasible option for treatment of IONF.

Tumors and infections of the growing spine

The growing spine differs from the adult spine in several ways. Although tumors and infections cause only a small percentage of pediatric back pain incidences, delayed proper diagnosis and treatment may be disastrous. Benign lesions, such as osteoid osteoma, osteoblastoma, and aneurysmal bone cyst in the spine, are predominant during the first two decades of life, whereas malignant bony spinal tumors are rare. In the pediatric population, malignant spine tumors include osteosarcoma, Ewing's sarcoma, lymphoma, and metastatic neuroblastoma. Infections of the growing spine are rare, with the incidence of discitis peaking in patients under the age of 5 years and that of vertebral osteomyelitis peaking in older children. Spondylodiscitis is often a benign, self-limiting condition with low potential for bone destruction. Conservative treatments, including bedrest, immobilization, and antibiotics, are usually sufficient. Spinal tuberculosis is a frequently observed form of skeletal tuberculosis, especially in developing countries. Indications for surgical treatment include neurologic deficit, spinal instability, progressive kyphosis, late-onset paraplegia, and advanced disease unresponsive to nonoperative treatment. Spinal tumors and infections should be considered potential diagnoses in cases with spinal pain unrelated to the child's activity, accompanied by fever, malaise, and weight loss. In spinal tumors, early diagnosis, fast and adequate multidisciplinary management, appropriate en bloc resection, and reconstruction improve local control, survival, and quality of life. Pyogenic, hematogenous spondylodiscitis is the most common spinal infection; however, tuberculosis-induced spondylodiscitis should also be considered. Level of evidence: level 4.

Determining the risk of spinal pathology progression in neurofibromatosis type 1 patients - a national tertiary neurofibromatosis type 1 centre study

BACKGROUND

Neurofibromatosis type 1 (NF1) gives rise to a variety of spinal pathologies that include dural ectasia (DE), vertebral malalignments (VMA), spinal deformities (SD), syrinx, meningoceles, spinal nerve root tumours (SNRT), and spinal plexiform tumours (SPT). The relationship between these and the progression of these pathologies has not been explored before in detail and this paper aims to address this.

METHODS

Data was retrospectively collected from adult NF1 multi-disciplinary team meetings from 2016 to 2022 involving a total of 593 patients with 20 distinct predictor variables. Data were analyzed utilizing; Chi-Square tests, binary logistic regression, and Kaplan-Meier analysis.

RESULTS

SNRT (19.9%), SD (18.6%), and (17.7%) of VMA had the highest rates of progression. SD was significantly associated (p < 0.02) with the presence and progression of all spinal pathologies except for SPT. Statistically significant predictors of SD progression included the presence of DVA, VMA, syrinx, meningocele, and SNRT. Kaplan-Meier analysis revealed no statistically significant difference between the times to progression for SD (85 days), SNRT (1196 days), and VMA (2243 days).

CONCLUSION

This paper explores for the first time in detail, the progression of various spinal pathologies in NF1. The presence and progression of SD is a key factor that correlated with the progression of different spinal pathologies. Early identification of SD may help support clinical decision-making and guide radiological follow-up protocols and treatment.

Approaches to Incidental Intradural Tumors of the Spine in the Pediatric Population

BACKGROUND

Incidental intradural tumors of the spine in the pediatric population are rare lesions whose management remains unclear. Surgeons must balance the risks of iatrogenic deficits and complications after surgical resection against the risks from progressive growth of the tumor. Moreover, the natural history of an incidental finding can be difficult to predict. Here, we review the literature on incidental intradural tumors of the spine and present considerations for their management.

SUMMARY

Growth of the tumor or changes in radiographic features are usually indications for resection. Asymptomatic lesions can be found in patients with genetic syndromes that predispose to tumor formation, such as neurofibromatosis type 1 and 2, schwannomatosis, and Von-Hippel-Lindau syndrome, and careful workup of a genetic cause is warranted in any patient presenting with multiple tumors and/or cutaneous features. Close follow-up is generally favored given the heavy tumor burden; however, some recommend pre-emptive resection to prevent permanent neurological deficits. Incidental intradural tumors can also occur in association with hydrocephalus, significant syringomyelia, and cord compression, and surgical treatment is usually warranted. Tumors may also be discovered as part of the workup for scoliosis, where they are not truly incidental to the scoliosis but rather are contributing to curve deformation.

KEY MESSAGES

Thorough workup of patients for associated genetic syndromes or comorbidities should be undertaken in pediatric patients with incidental intradural tumors. Further research is needed into the natural history of these incidental lesions. Incidental tumors can often be managed conservatively with close follow-up, with surgical intervention warranted for expanding tumors or new-onset symptoms.

A Nationwide Study Characterizing the Risk and Outcome Profiles of Multilevel Fusion Procedures in Neuromuscular Scoliosis Patients with Neurofibromatosis Type 1

BACKGROUND

Spine abnormalities are a common manifestation of Neurofibromatosis Type 1 (NF1); however, the outcomes of surgical treatment for NF1-associated spinal deformity are not well explored. The purpose of this study was to investigate the outcome and risk profiles of multilevel fusion surgery for NF1 patients.

METHODS

The National Inpatient Sample was queried for NF1 and non-NF1 patient populations with neuromuscular scoliosis who underwent multilevel fusion surgery involving eight or more vertebral levels between 2004 and 2017. Multivariate regression modeling was used to explore the relationship between perioperative variables and pertinent outcomes.

RESULTS

Of the 55,485 patients with scoliosis, 533 patients (0.96%) had NF1. Patients with NF1 were more likely to have comorbid solid tumors (P < 0.0001), clinical depression (P < 0.0001), peripheral vascular disease (P < 0.0001), and hypertension (P < 0.001). Following surgery, NF1 patients had a higher incidence of hydrocephalus (0.6% vs. 1.9% P = 0.002), seizures (4.9% vs. 5.7% P = 0.006), and accidental vessel laceration (0.3% vs.1.9% P = 0.011). Although there were no differences in overall complication rates or in-hospital mortality, multivariate regression revealed NF1 patients had an increased probability of pulmonary (OR 0.5, 95%CI 0.3-0.8, P = 0.004) complications. There were no significant differences in utilization, including nonhome discharge or extended hospitalization; however, patients with NF1 had higher total hospital charges (mean -$18739, SE 3384, P < 0.0001).

CONCLUSIONS

These findings indicate that NF1 is associated with certain complications following multilevel fusion surgery but does not appear to be associated with differences in quality or cost outcomes. These results provide some guidance to surgeons and other healthcare professionals in their perioperative decision making by raising awareness about risk factors for NF1 patients undergoing multilevel fusion surgery. We intend for this study to set the national baseline for complications after multilevel fusion in the NF1 population.

How to select the lowest instrumented vertebra in NF-1 non-dystrophic scoliosis

PURPOSE

To investigate lowest instrumented vertebra (LIV) selection strategy for neurofibromatosis type 1 (NF-1) non-dystrophic scoliosis.

METHODS

Consecutive eligible subjects with NF-1 non-dystrophic scoliosis were included. All patients were followed up at least for 24 months. Enrolled patients with LIV in stable vertebra were divided into stable vertebra group (SV group), and the other patients with LIV above the stable vertebra were divided into above stable vertebra group (ASV group). Demographic data, operative data, preoperative and postoperative radiographic data, and clinical outcome were collected and analyzed.

RESULTS

There were 14 patients in SV group (ten males and four females, mean age 13.9 ± 4.1 years) and 14 patients in ASV group (nine males and five females, mean age 12.9 ± 3.5 years). The mean follow-up period was 31.7 ± 17.4 months for patients in SV group and 33.6 ± 17.4 months for patients in ASV group, respectively. No significant differences were found in demographic data between two groups. The coronal Cobb angle, C7-CSVL, AVT, LIVDA, LIV tilt and SRS-22 questionnaire outcome significantly improved at the final follow-up in both groups. However, significantly higher loss of correction rate and increasement of LIVDA were found in ASV group. Two patients (14.3%) in ASV group but none in SV group suffered adding-on phenomenon.

CONCLUSIONS

Although patients in both SV and ASV groups obtained improved therapeutic efficacy at final follow-up, the radiographic and clinical outcome seemed more likely to deteriorate in ASV group after surgery. The stable vertebra should be recommended as LIV for NF-1 non-dystrophic scoliosis.

A Review of Spinal Lesions in Neurofibromatosis Type 1 in a Large Neurofibromatosis Type 1 Center

BACKGROUND

Spinal lesions are a known manifestation of neurofibromatosis type 1 (NF1). The aim of this retrospective review was to analyze and report the prevalence of spinal lesions on imaging in a large NF1 center.

METHODS

The data were collected from a period of 62 months from a cohort of 514 patients. Data were collected from multidisciplinary team meeting reports that included radiologic reports of each patient investigating 20 distinct variables. The prevalence of each of these lesions was calculated, and any statistically significant associations were investigated using the χ² test.

RESULTS

Four-hundred forty-seven patients had classic NF1, and 67 patients had spinal NF1. Many of the patients had spinal abnormalities; 25.7% of these patients were found to have dural ectasia, whereas 44.9% of patients had a spinal deformity. A statistically significant association between dural ectasia and spinal neurofibromatosis was established (P < 0.05). An additional statically significant association was established between dural ectasia and spinal deformity (P < 0.00001). The patients with spinal nerve root tumors were identified, and it was found that 49.8% of patients possessed these tumors, whereas 56.3% of these tumors were intraspinal tumors. The most common region affected was the cervical spine, and the most common spinal level was C2.

CONCLUSIONS

This high prevalence of spinal tumours in mobile areas of the spine is possibly the result of a combination of genetic predisposition and repeated microtraumas resulting in tumor formation. This is the largest reported study of spinal lesions in NF1 based on imaging and offers insights into the etiology and relationships between lesions.

Orthopaedic Manifestations of Neurofibromatosis Type I

Neurofibromatosis type 1 (NF1) is a congenital disease which is caused by mutations in the NF1 gene on chromosome 17, resulting in an altered function of the neurofibromin protein. Owing to the ubiquitous expression of this protein, this syndrome is associated with pathology in many organ systems of the body, especially the central and peripheral nervous, musculoskeletal, and integumentary systems. This review outlines the common sequelae related to a diagnosis of NF1 and the common treatment approach to each.

Vertebral column resection (VCR) at the subapical vertebra for correction of angular kyphosis associated with neurofibromatosis type 1(NF1): a case report

PURPOSE

To describe the process and outcome of vertebral column resection (VCR) at the subapical vertebra for correction of angular kyphosis associated with neurofibromatosis type 1(NF1).

METHODS

A review and summary of the medical history, radiographs, operative procedure, and complications of a 16-year-old male presenting with severe angular kyphosis associated with NF1 with dyspnea.

RESULTS

A 16-year-old male presented with severe angular kyphosis associated with NF1 with dyspnea. Preoperative radiographs demonstrated multiple vertebrae were rotated in the vicinity of the apical vertebra, with a wedge-shaped deformity, dysplasia, T10-T12 kyphotic angle of 160°, and T2-L2 kyphotic angle of 95°. VCR at the L1 vertebra (distal end of the apical vertebra) with bone grafting and internal fixation was performed. Postoperative imaging revealed that the T2-L2 Cobb angle was 20°, denoting a correction rate of 79%. The patient's height increased from 130 to 150 cm. The position of internal fixation was not displaced, and the correction angle was maintained at 2-year follow-up.

CONCLUSIONS

The novel strategy of performing VCR at the subapical vertebra, with posterior displacement of the distal end, and remodeling of the spinal canal is potentially a safe and efficacious option to correct sharp angular kyphosis.

Neurofibromatosis type 1, severe cervical spinal kyphotic deformity, and vertebral arteriovenous fistula presenting with tetraplegia: case report and literature review

INTRODUCTION

Neurofibromatosis type 1 (NF-1) is an autosomal-dominant disorder affecting 1 in 3000 individuals worldwide. NF-1 is characterized by café-au-lait macules and peripheral nerve sheath tumors. Patients with NF-1 frequently exhibit bony dysplasia, including spinal deformities such as scoliosis or kyphosis, pseudarthrosis of the tibia, and soft tissue tumors. Some patients with NF-1 exhibit spinal changes, including acutely angled cervical kyphosis. Prior studies have also described arteriovenous (AV) fistulas in individuals with NF-1, as well as a predisposition to cervical fistulas which display symptoms secondary to mass effect, rather than hemorrhage. Sometimes, fistulas are incidentally detected during evaluations for cervical kyphotic deformities.

CASE PRESENTATION

The case herein describes a patient with NF-1 who exhibited a severe cervical spinal kyphotic deformity and a vertebral AV fistula. The patient initially presented with neck pain that radiated to all four limbs and resulted in limb weakness.

DISCUSSION

Spinal kyphosis is common in patients with NF-1, and if dystrophic changes are noted on plain radiographs, MRI should be considered for the further survey of potential spinal vascular lesions.

Genotype-Phenotype Correlations in Neurofibromatosis Type 1: Identification of Novel and Recurrent NF1 Gene Variants and Correlations with Neurocognitive Phenotype

Neurofibromatosis type 1 (NF1) is one of the most common genetic tumor predisposition syndrome, caused by mutations in the NF1. To date, few genotype-phenotype correlations have been discerned in NF1, due to a highly variable clinical presentation. We aimed to study the molecular spectrum of NF1 and genotype-phenotype correlations in a monocentric study cohort of 85 NF1 patients (20 relatives, 65 sporadic cases). Clinical data were collected at the time of the mutation analysis and reviewed for accuracy in this investigation. An internal phenotypic categorization was applied. The 94% of the patients enrolled showed a severe phenotype with at least one systemic complication and a wide range of associated malignancies. Spine deformities were the most common complications in this cohort. We also reported 66 different NF1 mutations, of which 7 are novel mutations. Correlation analysis identified a slight significant inverse correlation between age at diagnosis and delayed acquisition of psychomotor skills with residual multi-domain cognitive impairment. Odds ratio with 95% confidence interval showed a higher prevalence of learning disabilities in patients carrying frameshift mutations. Overall, our results aim to offer an interesting contribution to studies on the genotype–phenotype of NF1 and in genetic management and counselling.

Management and surgical outcomes of dystrophic scoliosis in neurofibromatosis type 1: a systematic review

OBJECTIVE

Neurofibromatosis type 1 (NF1) dystrophic scoliosis is an early-onset, rapidly progressive multiplanar deformity. There are few studies on the surgical management of this patient population. Specifically, perioperative morbidity, instrument-related complications, and quality-of-life outcomes associated with surgical management have not been systematically evaluated. In this study, the authors aimed to perform a systematic review on the natural history, management options, and surgical outcomes in patients who underwent NF1 dystrophic scoliosis surgery.

METHODS

A PubMed search for articles with “neurofibromatosis” and either “dystrophic” or “scoliosis” in the title or abstract was performed. Articles with 10 or more patients undergoing surgery for NF1 dystrophic scoliosis were included. Data regarding indications, treatment details, morbidity, and outcomes were summarized and analyzed with descriptive statistics.

RESULTS

A total of 310 articles were identified, 48 of which were selected for full-text review; 30 studies describing 761 patients met the inclusion criteria. The mean age ranged from 7 to 22 years, and 99.7% of patients were younger than 18 years. The mean preoperative coronal Cobb angle was 75.2°, and the average correction achieved was 40.3°. The mean clinical follow-up in each study was at least 2 years (range 2.2–19 years). All patients underwent surgery with the intent of deformity correction. The scoliosis regions addressed were thoracic curves (69.6%) and thoracolumbar (11.1%) and lumbar (14.3%) regions. The authors reported on a variety of approaches: posterior-only, combined anterior-posterior, and growth-friendly surgery. For fixation techniques, 42.5% of patients were treated with hybrid constructs, 51.5% with pedicle screw–only constructs, and 6.0% with hook-based constructs. Only 0.9% of patients underwent a vertebral column resection. The nonneurological complication rate was 14.0%, primarily dural tears and wound infections. The immediate postoperative neurological deficit rate was 2.1%, and the permanent neurological deficit rate was 1.2%. Ultimately, 21.5% required revision surgery, most commonly for implant-related complications. Loss of correction in both the sagittal and coronal planes commonly occurred at follow-up. Five papers supplied validated patient-reported outcome measures, showing improvement in the mental health, self-image, and activity domains.

CONCLUSIONS

Data on the surgical outcomes of dystrophic scoliosis correction are heterogeneous and sparse. The perioperative complication rate appears to be high, although reported rates of neurological deficits appear to be lower than clinically observed and may be underreported. The incidence of implant-related failures requiring revision surgery is high. There is a great need for multicenter prospective studies of this complex type of deformity.

Surgical challenges and functional outcomes in dystrophic cervical kyphosis in Neurofibromatosis -1: an institutional experience

OBJECTIVE

Dystrophic cervical kyphosis secondary to neurofibromatosis 1 (NF1) is rarely reported. The primary objective is to highlight the clinical presentation and surgical outcomes based on clinical and biomechanical parameters. The secondary objective is to highlight the early and late complications of these surgeries.

METHODS

The hospital records of six patients operated between 2008 and 2018 were retrospectively reviewed with a minimum follow-up of 24 months. Besides demographics information, radiological findings and operative details, the outcome measures reported were neurological (MJOA score, Nurick scale), pain (VAS score) and operative complications.

RESULTS

The mean age of patients was 15.1 years (8-32 years). The average kyphotic vertebra involved-3.6 bodies (range 2-5 bodies) with four patients showing intraspinal anomaly-neurofibromas, dural ectasia. Clinically, patients improved postoperatively with-VAS (pre vs. post-: 6.6 vs. 2.6, p - < 0.05), MJOA score (pre vs. post: 10.3 vs. 13.3, p - < 0.05), Nurick grade (pre vs. post: 3.5 vs. 2.1, p - < 0.05). There was significant deformity correction from 66.8° to 20.7° (p value < 0.031), mean T1 Slope (pre vs. post - 1.8 ± 20.4 to 0.6 ± 12.8, p value - < 0.43). Mean blood loss encountered was 1800 ± 434.6 cc; however, patients with paraspinal neurofibromas reported greater blood loss. Late complications included pseudoarthrosis (1), C5 palsy (1) and junctional kyphosis (1). Vertebral dysplasia and erosions continued in all patients post-operatively.

CONCLUSIONS

Antero-posterior approach provides circumferential decompression and better sagittal balance correction. Cervical spine must be screened in all NF-1 patients and followed up regularly to assess for dystrophic changes.

Scoliosis in Neurofibromatosis Type 1 on Whole-Body Magnetic Resonance Imaging: Frequency and Association With Intraspinal and Paraspinal Tumors

OBJECTIVES

Scoliosis is a common orthopedic problem in patients with neurofibromatosis 1 (NF1). Spinal deformities are found in 77% of all NF1 cases, with no widely accepted etiology. This study aimed to evaluate the frequency and types of scoliosis in NF1 patients using whole-body magnetic resonance imaging and to assess the association of intraspinal and paraspinal tumors with the imaging findings of scoliosis.

METHODS

A total of 122 NF1 patients with whole-body magnetic resonance imaging were found from the electronic medical records. Ninety-seven cases that met the inclusion criteria were identified. All patients underwent 3-T magnetic resonance imaging with automated software fusion of the 3 sets of short TI inversion recovery and 3-dimensional T1-weighted coronal images. Frequency and location of scoliosis and intraspinal and paraspinal tumors were recorded. Patients with severe dystrophic-type scoliosis were separately identified, and Cobb angles were measured for all such cases. Association analysis was performed. A P value less than 0.05 was considered statistically significant.

RESULTS

Ninety-seven patients with NF1 were evaluated. Two had prior spinal surgery and were excluded. The final sample of 95 patients included 33 (35%) men and 62 (65%) women with a mean ± SD body mass index of 25.82 (4.96) kg/m2. Of the 95 patients, 43 (45.3%) had scoliosis, 13 of 43 (30.2%) of which were severely angled. Of the 95 patients, 25 (26.3%) had locoregional tumor presence. Intraclass correlation for Cobb angles measured 0.99 (confidence interval, 0.98-1.0). Fisher exact test determined no association between scoliosis and presence of either paraspinal or intraspinal tumors (P = 0.485). There was also no association between the tumors and severe dystrophic scoliosis (P = 1.0).

CONCLUSIONS

This study found no association between the presence of locoregional spinal tumors and scoliosis in NF1 patients. This work adds to the body of knowledge of scoliosis in NF1 patients and infers that presence of scoliosis should not mandate immediate search for locoregional spinal tumors.

The prognosis and recovery of major postoperative neurological deficits after corrective surgery for scoliosis : an analysis of 65 cases at a single institution

AIMS

The outcome following the development of neurological complications after corrective surgery for scoliosis varies from full recovery to a permanent deficit. This study aimed to assess the prognosis and recovery of major neurological deficits in these patients, and to determine the risk factors for non-recovery, at a minimum follow-up of two years.

METHODS

A major neurological deficit was identified in 65 of 8,870 patients who underwent corrective surgery for scoliosis, including eight with complete paraplegia and 57 with incomplete paraplegia. There were 23 male and 42 female patients. Their mean age was 25.0 years (SD 16.3). The aetiology of the scoliosis was idiopathic (n = 6), congenital (n = 23), neuromuscular (n = 11), neurofibromatosis type 1 (n = 6), and others (n = 19). Neurological function was determined by the American Spinal Injury Association (ASIA) impairment scale at a mean follow-up of 45.4 months (SD 17.2). the patients were divided into those with recovery and those with no recovery according to the ASIA scale during follow-up.

RESULTS

The incidence of major deficit was 0.73%. At six-month follow-up, 39 patients (60%) had complete recovery and ten (15.4%) had incomplete recovery; these percentages improved to 70.8% (46) and 16.9% (11) at follow-up of two years, respectively. Eight patients showed no recovery at the final follow-up. The cause of injury was mechanical in 39 patients and ischaemic in five. For 11 patients with misplaced implants and haematoma formation, nine had complete recovery. Fisher's exact test showed a significant difference in the aetiology of the scoliosis (p = 0.007) and preoperative deficit (p = 0.016) between the recovery and non-recovery groups. A preoperative deficit was found to be significantly associated with non-recovery (odds ratio 8.5 (95% confidence interval 1.676 to 43.109); p = 0.010) in a multivariate regression model.

CONCLUSION

For patients with scoliosis who develop a major neurological deficit after corrective surgery, recovery (complete and incomplete) can be expected in 87.7%. The first three to six months is the time window for recovery. In patients with misplaced implants and haematoma formation, the prognosis is satisfactory with appropriate early intervention. Patients with a preoperative neurological deficit are at a significant risk of having a permanent deficit. Cite this article: Bone Joint J 2022;104-B(1):103-111.

Anatomical changes in vertebra in dystrophic scoliosis due to neurofibromatosis and its implications on surgical safety

STUDY DESIGN

Detailed radiological analysis by multimodality imaging.

OBJECTIVE

To document anatomical changes jeopardizing instrumentation safety in Neurofibromatosis deformity correction surgeries.

MATERIALS AND METHODS

The apical and 3 adjacent vertebral segments above and below amounting to 70 segments in 10 NF scoliosis were studied by radiographs, CT and MRI. The changes in lamina, pedicle and vertebral body that could jeopardize pedicle screw and sublaminar wire placement were documented and changes were appropriately classified.

RESULTS

Extensive anatomical changes were noted. These changes were more severe at the apex and independent of the curve severity. Both laminae were normal in only 36 (Type 1), rest had either gross asymmetry in length and shape (Type 2; 21) or also in sloping (Type 3; 13). Of the 140 pedicles, normal pedicles were found only in 48 (Type 1); while they were divergent (Type 2; 4) or abnormally elongated with only thinning (Type 3a; 26); or with sclerosis (3b; 34); or very curved and wavy (3c; 23) and even fractured or indistinct (Type 4; 5). It was notable that 92 of the 140 pedicles were unsuitable for pedicle screws. A unique phenomenon of body drift was identified in 29 segments which could jeopardize screw placement and rib dislocation into the canal was found in 18 segments.

CONCLUSION

Gross anatomical changes jeopardizing both sublaminar wire strength and trajectory of pedicle screws were common in NF and independent of curve severity. Therefore, detailed preoperative assessment and planning by a 3D CT are essential.

Pre-operative Halo-Pelvic Traction for Neurofibromatosis Patients with Severe Proximal Thoracic Spinal Deformity: Indications and Early Treatment Outcome

Introduction:

To report the indications and early treatment outcomes of pre-operative halo-pelvic traction in patients with neurofibromatosis associated with severe proximal thoracic (PT) spinal deformity.

Materials and methods:

We reviewed four patients with neurofibromatosis with severe PT spinal deformity. Case 1, a 16-year-old male presented with severe PT kyphoscoliosis (scoliosis: 89°, kyphosis: 124°) and thoracic myelopathy. Case 2 was a 14-year-old, skeletally immature male who presented with a PT lordoscoliosis (scoliosis: 85°). Case 3, a 13-year-old male, presented with severe PT kyphoscoliosis (scoliosis: 100°, kyphosis: 95°). Case 4, a 35-year-old gentleman, presented with severe PT kyphoscoliosis (scoliosis: 113°, kyphosis: 103°) and thoracic myelopathy. All patients underwent pre-operative halo-pelvic traction. After a period of traction, all patients underwent posterior spinal fusion (PSF) with autologous bone grafts (local and fibula bone grafts) and recombinant human bone morphogenetic protein-2 (rhBMP-2).

Results:

Both patients with thoracic myelopathy regained near normal neurological status after halo-pelvic traction. Following traction, the scoliosis correction rate (CR) ranged from 18.0% to 38.9%, while the kyphosis CR ranged from 14.6% to 37.1%. Following PSF, the scoliosis CR ranged from 24.0% to 58.8%, while the kyphosis CR ranged from 29.1% to 47.4%. The total distraction ranged from 50-70mm. Duration of distraction ranged from 26-95 days. The most common complication encountered during halo-pelvic traction was pin-related e.g. pin tract infection, pin loosening and migration, osteomyelitis, and halo-pelvic strut breakage. No patients had cranial nerve palsies or neurological worsening.

Conclusion:

Pre-operative correction of severe PT spinal deformities could be performed safely and effectively with the halo-pelvic device prior to definitive surgery.

Halo traction combined with posterior-only approach correction for cervical kyphosis with Neurofibromatosis-1: minimum 2 years follow-up

Background

Surgical management of cervical kyphosis in patients with NF-1 is a challenging task. Presently, anterior-only (AO), posterior-only (PO) and combined anterior-posterior (AP) spinal fusion are common surgical strategies. However, the choice of surgical strategy and application of Halo traction remain controversial. Few studies have shown and recommended posterior-only approach for cervical kyphosis correction in patients with NF-1. The aim of this study is to evaluate the safety and the effectiveness of halo Traction combined with posterior-only approach correction for treatment of cervical kyphosis with NF-1.

Methods

Twenty-six patients with severe cervical kyphosis due to NF-1 were reviewed retrospectively between January 2010 and April 2018. All the cases underwent halo traction combined with posterior instrumentation and fusion surgery. Correction result, neurologic status and complications were analyzed.

Results

In this study, cervical kyphosis Cobb angle decreased from initial 61.3 ± 19.7 degrees to postoperative 10.6 ± 3.7 degrees (P<0.01), with total correction rate of 82.7%, which consist of 45.8% from halo traction and 36.9% from surgical correction. JOA scores were improved from preoperative 13.3 ± 1.6 to postoperative 16.2 ± 0.7 (P<0.01). Neurological status was also improved. There was no correction loss and the neurological status was stable in mean 43 months follow-up. Three patients experienced minor complications and one patient underwent a second surgery.

Conclusion

Halo traction combined with PO approach surgery is safe and effective method for cervical kyphosis correction in patients with NF-1. A satisfied correction result, and successful bone fusion can be achieved via this procedure, even improvement of neurological deficits can also be obtained. Our study suggested that halo traction combined with PO approach surgery is another consideration for cervical kyphosis correction in patients with NF-1.

Multidisciplinary approach for repair of a large ventral thoracic meningocele in neurofibromatosis-1; a systematic review of the literature and case report

Thoracic meningoceles and dural ectasia are less commonly recognized manifestations of neurofibromatosis 1 (NF1). Rarely, large thoracic meningoceles may become compressive and lead to respiratory compromise secondary to lung compression. Surgical goals aim to increase lung aeration through decreasing the size of the meningocele through shunting, excision or repair of the meningocele, and varying degrees of dural tube reconstruction. There is no agreement on the best approach for large, symptomatic meningoceles. Here, we discuss the case of a 41-year-old woman with NF1 who presented with dyspnea and enlargement of a large, 19 cm thoracic meningocele. A multidisciplinary team of thoracic, plastic, and neurological surgery participated in the operation to excise the meningocele and reconstruct the dural tube without the need for subsequent shunting of spinal fluid. We also systematically review the literature on thoracic meningoceles in NF1 to understand the optimal treatment of this pathology.

The Haleem-Marks-Botchu classification: a novel CT-based classification for intracanal rib head penetration

PURPOSE

Intracanal rib head penetration is a well-known entity in dystrophic scoliotic curves in neurofibromatosis type 1. There is potential for spinal cord injury if this is not recognised and managed appropriately. No current CT-based classification system is currently in use to quantify rib head penetration. This article aims to propose and evaluate a novel CT-based classification for rib head penetration primarily for neurofibromatosis but which can also be utilised in other conditions of rib head penetration.

MATERIALS AND METHODS

The grading was developed as four grades: normal rib head (RH) position-Grade 0, subluxed extracanal RH position-Grade 1, RH at pedicle-Grade 2, intracanal RH-Grade 3. Grade 3 was further classified depending on the head position in the canal divided into thirds. Rib head penetration into proximal third (from ipsilateral side)-Grade 3A, into the middle third-Grade 3B and into the distal third-Grade 3C. Seventy-five axial CT images of Neurofibromatosis Type 1 patients in the paediatric age group were reviewed by a radiologist and a spinal surgeon independently to assess interobserver and intraobserver agreement of the novel CT classification. Agreement analysis was performed using the weighted Kappa statistic.

RESULTS

There was substantial interobserver correlation with mean Kappa score (k = 0.8, 95% CI 0.7-0.9) and near perfect intraobserver Kappa of 1.0 (95% CI 0.9-1.0) and 0.9 (95% CI 0.9-1.0) for the two readers.

CONCLUSION

The novel CT-based classification quantifies rib head penetration which aids in management planning.

Multiple Intraspinal Gangliogliomas in a Child With Neurofibromatosis Type 1: Case Report and Literature Review

Neurofibromatosis type 1 (NF1)-associated primary intramedullary spinal cord ganglioglioma has only rarely been reported. Because of frequent nonresectability, they pose significant management challenges despite clinical indolence. This report describes a 4-year-old girl with NF1 who was found to have multiple discrete, infiltrative intramedullary cord masses, and biopsy demonstrated World Health Organization grade I ganglioglioma. Panel-based next-generation sequencing showed her previously identified germline NF1 mutation and a second somatic NF1 mutation. This represents the first report of multiple primary intramedullary gangliogliomas in a child with NF1 and demonstrates how biopsy with panel-based next-generation sequencing provides potential targets for MAPK/MEK/BRAF pathway inhibitor therapy.

Phenotyping spinal abnormalities in patients with Neurofibromatosis type 1 using whole-body MRI

Neurofibromatosis Type 1 (NF1) has been reported to be associated with a variety of spinal abnormalities. The purpose of this study was to quantify the prevalence of spinal abnormalities in a collective of NF1 patients that is representative for the general NF1 population, to associate the co-appearance of spinal abnormalities with both NF1 and clinical symptoms and to investigate if different mutations of the NF1 gene affect the prevalence of these abnormalities. Retrospectively, 275 patients with NF1 and an age- and sex-matched collective of 262 patients were analyzed. The prevalence of spinal abnormalities was recorded. Mutational analysis of the NF1 gene was obtained in 235 NF1 patients. Associations between spinal abnormalities, clinical symptoms and genotype were investigated by binary logistic regression analysis. Prevalence of all spinal abnormalities was higher in NF1 patients than in the control group. Six characteristics of spinal abnormalities were significantly associated with NF1 (all p < 0.05). An influence of scalloping on scoliosis (OR 3.01; p = 0.002); of meningoceles (OR 7.63) and neuroforaminal tumors (OR 2.96) on scalloping, and of dural ectasia on neuroforaminal tumors (OR 1.93) was identified. Backpain and loss of motor function were associated with neuroforaminal tumors, spinal tumors and scalloping of vertebral bodies (all p < 0.05). Specific mutations of the NF1 gene were not relevantly associated with the development of spinal abnormalities. These findings can aid clinicians to improve clinical care of NF1 patients by creating awareness for co-appearences of specific spinal abnormalities and associated symptoms.

Early-Onset Spinal Deformity in Neurofibromatosis Type 1: Natural History, Treatment, and Imaging Surveillance

»

Early-onset scoliosis (EOS) or kyphosis is common in patients with neurofibromatosis (NF) and is characterized by rapid progression of deformity.

»

Traditional growing rods provide good functional and deformity outcomes in patients with NF and EOS; magnetically controlled growing rods (MCGRs) also provide good deformity correction, although high rates of revision have been reported after their use.

»

Among patients with NF type 1 (NF1), morphologic characteristics of the spinal deformity are different in those with paraspinal neurofibromas than in those without paraspinal tumors.

»

Patients with NF1 are at low risk for developing malignant peripheral nerve sheath tumors during childhood (<1%) and their lifetime (8% to 12%), and routine imaging surveillance for malignancy in the absence of symptoms should be clinically directed.

»

Further investigation is needed to standardize screening for EOS in children with NF1 and to develop guidelines for ideal imaging modalities, including their frequency and a timeline.

Natural History of Scoliosis in Children with NF1: An Observation Study

(1) Background. Scoliosis is the most common musculoskeletal manifestation of Neurofibromatosis type 1 (NF1), and it might be dystrophic (D) or non-dystrophic (ND) depending on the presence of dysplastic changes of the spine. The aim of our study was to describe the characteristics and natural history of patients with NF1 and scoliosis. (2) Methods. We retrospectively reviewed records from patients with NF1 and scoliosis. Scoliosis was classified as D if at least two dystrophic changes were documented at imaging. (3) Results. Of the 438 patients reviewed, 43 fulfilled inclusion criteria; 17 were classified in D group and 26 in ND. The groups did not differ in age and localization of scoliosis curvature. Surgery was needed more often in D group, but the between-group difference was not significant. Male-to-female ratios of 3:1 and 4:1 were reported in surgically treated NF1 patients with ND and D scoliosis, respectively. (4) Conclusions. Our data suggests independently by the presence of dysplastic changes affecting the spine that males with NF1 are more often affected by scoliosis that requires surgery.

Modulation of spine fusion with BMP-2, MEK inhibitor (PD0325901), and zoledronic acid in a murine model of NF1 double inactivation

BACKGROUND

Spine fusion is a common procedure for the treatment of severe scoliosis, a frequent and challenging deformity associated with Neurofibromatosis type 1 (NF1). Moreover, deficiencies in NF1-Ras-MEK signaling affect bone formation and resorption that in turn impacts on spine fusion outcomes.

METHODS

In this study we describe a new model for AdCre virus induction of Nf1 deficiency in the spines of Nf1^flox/flox mice. The virus is delivered locally to the mouse spine in a fusion procedure induced using BMP-2. Systemic adjunctive treatment with the MEK inhibitor (MEKi) PD0325901 and the bisphosphonate zoledronic acid (ZA) were next trialed in this model.

RESULTS

AdCre delivery resulted in abundant fibrous tissue (Nf1^null +393%, P < 0.001) and decreased marrow space (Nf1^null -67%, P < 0.001) compared to controls. While this did not significantly impact on the bone volume of the fusion mass (Nf1^null -14%, P = 0.999 n.s.), the presence of fibrous tissue was anticipated to impact on the quality of spine fusion. Multinucleated TRAP + cells were observed in the fibrous tissues seen in Nf1^null spines. In Nf1^null spines, MEKi increased bone volume (+194%, P < 0.001) whereas ZA increased bone density (+10%, P < 0.002) versus BMP-2 alone. Both MEKi and ZA decreased TRAP + cells in the fibrous tissue (MEKi -62%, P < 0.01; ZA -43%, P = 0.054). No adverse effects were seen with either MEKi or ZA treatment including weight loss or signs of illness or distress that led to premature euthanasia.

CONCLUSIONS

These data not only support the utility of an AdCre-virus induced knockout spine model, but also support further investigation of MEKi and ZA as adjunctive therapies for improving BMP-2 induced spine fusion in the context of NF1.

Non-Oncological Neuroradiological Manifestations in NF1 and Their Clinical Implications

Simple Summary

Central nervous system involvement (CNS) is a common finding in Neurofibromatosis type 1 (NF1). Beside tumor-related manifestations, NF1 is also characterized by a wide spectrum of CNS alterations with variable impacts on functioning and life quality. Here, we propose an overview of non-oncological neuroradiological findings in NF1, with an insight on pathophysiological and embryological clues for a better understanding of the development of these specific alterations.

Abstract

Neurofibromatosis type 1 (NF1), the most frequent phakomatosis and one of the most common inherited tumor predisposition syndromes, is characterized by several manifestations that pervasively involve central and peripheral nervous system structures. The disorder is due to mutations in the NF1 gene, which encodes for the ubiquitous tumor suppressor protein neurofibromin; neurofibromin is highly expressed in neural crest derived tissues, where it plays a crucial role in regulating cell proliferation, differentiation, and structural organization. This review article aims to provide an overview on NF1 non-neoplastic manifestations of neuroradiological interest, involving both the central nervous system and spine. We also briefly review the most recent MRI functional findings in NF1.

Comparison of Early Definitive Fusion and Traditional Growing Rods in Early-onset Dystrophic Scoliosis in Neurofibromatosis Type 1: A Preliminary Report

BACKGROUND

Early definitive spinal fusion (EF) has been widely recommended to avoid spinal deformity progression for early-onset scoliosis (EOS) with neurofibromatosis type 1 (NF-1). In contrast, growing rod (GR) procedure has recently been recommended for EOS associated with the dystrophic type NF-1. However, no studies have compared the surgical outcomes between EF and GR procedure for EOS with NF-1. The purpose of this study was to compare the surgical outcomes of EF versus GR for early onset and dystrophic scoliosis with NF-1.

METHODS

This was a retrospective multicenter study; 26 EOS patients with dystrophic type of NF-1 who underwent EF (16 patients) or GR (10 patients) were investigated. We compared age at first surgery, fused levels, total number of surgeries, coronal major curve, complication rates, spinal height (T1-T12 and T1-S1 length), and forced vital capacity between the 2 groups.

RESULTS

The mean age at first surgery was 7.3 years in the EF and 5.8 years in the GR (P<0.05). The mean follow-up period was 12.8 and 10.5 years, respectively. The 2 groups did not show significant differences in preoperative major Cobb angle (75.1 vs. 83.1 degrees), complication rate (53% vs. 60%), and increase rate of T1-T12 (20.0% vs. 30.4%). However, significant differences (P<0.05) were recognized in fusion segments (13.9 vs. 15.8), total numbers of surgery (2.6 vs. 10.1), correction rate of major curve (59.0% vs. 40.6%), increase rate of T1-S1 (19.0% vs. 33.9%), body height at final follow-up (151 vs. 142 cm), and forced vital capacity at final follow-up (2.23 vs. 1.46 L).

CONCLUSIONS

Early fusion is still a viable option for progressive EOS with dystrophic type of NF-1 even in the growth-friendly era. Surgeons should consider the best procedure for each patient taking into account the severity of dystrophic change when treating EOS with NF-1.

LEVEL OF EVIDENCE

Level IV.

Assessing the unique characteristics associated with surgical treatment of dystrophic lumbar scoliosis secondary to neurofibromatosis type 1: a single-center experience of more than 10 years

OBJECTIVE

Dystrophic lumbar scoliosis secondary to neurofibromatosis type 1 (DLS-NF1) may present an atypical, unique curve pattern associated with a high incidence of coronal imbalance and regional kyphosis. Early surgical intervention is complicated and risky but necessary. The present study aimed to assess the unique characteristics associated with the surgical treatment of DLS-NF1.

METHODS

Thirty-nine consecutive patients with DLS-NF1 treated surgically at a mean age of 14.4 ± 3.9 years were retrospectively reviewed. Patients were stratified into three types according to the coronal balance classification: type A (C7 translation < 30 mm), 22 patients; type B (concave C7 translation ≥ 30 mm), 0 patients; and type C (convex C7 translation ≥ 30 mm), 17 patients. Types B and C were considered to be coronal imbalance. The diversity of surgical strategies, the outcomes, and the related complications were analyzed.

RESULTS

The posterior-only approach accounted for 79.5% in total; the remaining 20.5% of patients received either additional anterior supplemental bone grafting (12.8%) to strengthen the fixation or convex growth arrest (7.7%) to reduce growth asymmetry. The lower instrumented vertebra (LIV) being L5 accounted for the largest share (41%), followed by L4 and above (35.9%), the sacrum (15.4%), and the pelvis (7.7%). Type C coronal imbalance was found in 23 patients (59%) postoperatively, and the incidence was significantly higher in the preoperative type C group (14/17 type C vs 9/22 type A, p = 0.020). All the patients with postoperative coronal imbalance showed ameliorative transition to type A at the last visit. The rate of screw malposition was 30.5%, including 9.9% breached medially and 20.6% breached laterally, although no serious neurological impairment occurred. The incidence of rod breakage was 16.1% (5/31) and 0% in patients with the posterior-only and combined approaches, respectively. Four revisions with satellite rods and 1 revision with removal of iliac screw for penetration into the hip joint were performed.

CONCLUSIONS

Surgical strategies for DLS-NF1 were diverse across a range of arthrodesis and surgical approaches, being crucially determined by the location and the severity of dystrophic changes. The LIV being L5 or lower involving the lumbosacral region and pelvis was not rare. Additional posterior satellite rods or supplementary anterior fusion is necessary in cases with insufficient apical screw density. Despite a high incidence of postoperative coronal imbalance, improvement of coronal balance was frequently confirmed during follow-up. Neurological impairment was scarce despite the higher rate of screw malposition.

Neurofibromatosis Type 1 with Severe Dystrophic Kyphosis: Surgical Treatment and Prognostic Analysis of 27 Patients

OBJECTIVE

The aim of the present study was to explore the surgical treatment and prognosis of 27 cases of neurofibromatosis type 1 with severe dystrophic kyphosis.

METHODS

We performed surgical treatment for scoliosis and kyphosis caused by dystrophic curves at Peking Union Medical College Hospital, Beijing, China from December 2015 to December 2017. The study included 21 patients with moderate to severe kyphosis, 12 males and 9 females, with an average age of 14.95 ± 6.05 years. All patients had kyphosis angles greater than 70° and had more than four skeletal developmental defects. A total of 6 patients with severe kyphosis, 2 males and 4 females, with an average age of 12.5 years, had more than five skeletal developmental defects with a kyphosis angle greater than 90° or a lumbar kyphosis angle greater than 40°. According to the patient's own situation, we adopted a low-grade surgery scheme (grades 1 or 2) or a high-grade surgery scheme (grades 3-6). The low-grade surgery was mainly lower articular surface resection or pontodestomy, and the high-grade surgery was mainly apical vertebral body or upper discectomy. All patients were followed up to determine their prognosis.

RESULTS

Statistical analysis showed that there was a significant difference in preoperative and postoperative scores between the two groups (P < 0.05), and scoliosis correction showed that surgical treatment had a significant effect on scoliosis kyphosis. The mean follow-up time was 66.7 months. Follow-up results showed that 50% of complications after internal fixation were related to high-level surgery. Complications included displacement of the titanium cage, removal of the lamina hook, formation of pseudoarthrosis, and internal fixation failure (with a rate of 7.7%-14.3%). In contrast, there were no associated symptoms for low-grade surgery. In addition, the results showed that gender, age, extent of resection, height, and body mass index had no significant effect on preoperative, postoperative, and prognostic indicators of patients (P > 0.05).

CONCLUSION

Early identification of dysplastic scoliosis-related deformities plays an important role in surgical planning and prognosis, and low-level surgical procedures are more favorable for patients' prognosis.

Spinal Deformities after Childhood Tumors

Simple Summary

A significant number of children surviving intra- or juxta-spinal tumors develop secondary spinal deformities and disabilities. This retrospective non-comparative study focuses on deformity analysis, age, and skeletal maturity dependent treatment options and results. Patients who developed severe scoliosis, pathological kyphosis, and/or lordosis were either treated conservatively or surgically by using growth-friendly spinal implants in younger children or definite spinal fusion during puberty. Despite severe spinal deformity, some patients were not surgically corrected in order to preserve mobility through trunk motion or malignant tumor progression. Growth-friendly spinal implants and spinal fusions were able to significantly reduce pathological curves. The first method, with bilateral rib-to-pelvis fixation, still allows spinal magnetic resonance imaging or neurosurgical intervention if needed. Severe ad hoc curve correction enhances the risk of neurological deterioration because of prior spinal cord impairment. The data of this study may help to improve the individual patient care.

Abstract

Childhood tumors of the central nervous system (CNS) and other entities affecting the spine are rare. Treatment options vary from surgical biopsy to partial, subtotal, and total resection, to radiation, to chemotherapy. The aim of this study is to investigate spinal deformity and subsequent surgical interventions in this patient cohort. A retrospective review at our institution identified children with CNS tumors, spinal tumors, and juxta-spinal tumors, as well as spinal deformities. Tumor entity, treatment, mobilization, and radiographic images were analyzed relative to the spinal deformity, using curve angles in two planes. Conservative or surgical interventions such as orthotic braces, growth-friendly spinal implants, and spinal fusions were evaluated and analyzed with respect to treatment results. Tumor entities in the 76 patients of this study included CNS tumors (n = 41), neurofibromatosis with spinal or paraspinal tumors (n = 14), bone tumors (n = 12), embryonal tumors (n = 7), and others (n = 2). The initial treatment consisted of surgical biopsy (n = 5), partial, subtotal, or total surgical resection (n = 59), or none (n = 12), followed by chemotherapy, radiotherapy, or both (n = 40). Out of 65 evaluated patients, 25 revealed a moderate or severe scoliotic deformity of 71° (range 21–116°), pathological thoracic kyphosis of 66° (range 50–130°), and lordosis of 61° (range 41–97°). Surgical treatment was performed on 21 patients with implantation of growth-friendly spinal implants (n = 9) as well as twelve dorsal spinal fusions (two with prior halo distraction). Surgical interventions significantly improved spinal deformities without additional neurological impairment. With the increasing number of children surviving rare tumors, attention should be focused on long-term problems such as spinal deformities and consequent disabilities. A significant number of children with CNS tumors, spinal tumors or juxta-spinal tumors required surgical intervention. Early information about spinal deformities and a close follow-up are mandatory for this patient group.

Pragmatic approach to neuraxial anesthesia in obstetric patients with disorders of the vertebral column, spinal cord and neuromuscular system

Neuraxial anesthesia provides optimal labor analgesia and cesarean delivery anesthesia. Obstetric patients with disorders of the vertebral column, spinal cord and neuromuscular system present unique challenges to the anesthesiologist. Potential concerns include mechanical interference, patient injury and the need for imaging. Unfortunately, the existing literature regarding neuraxial anesthesia in these patients is largely limited to case series and rare retrospective studies. The lack of practice guidance may lead to unwarranted fear of patient harm and subsequent avoidance of neuraxial anesthesia for cesarean delivery or neuraxial analgesia for labor, with additional risks of exposure to general anesthesia. In this narrative review, we use available evidence to recommend a framework when considering neuraxial anesthesia for an obstetrical patient with neuraxial pathology.

Spinal manifestations of Neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) patients may present a wide spectrum of spinal pathologies. Osseous changes may lead to severe deformities with significant implications on growth and quality of life. Neurogenic tumors and soft tissue abnormalities may cause neuropathic pain and dysfunction ranging from minor paresthesias to profound motor and sensory deficits. Advanced imaging such as whole-body MRI, and volumetric tumor burden assessment have an evolving role in the evaluation and follow-up of patients with high spinal tumor load. Novel biological agents that target the hyperactivated ras pathway are currently under investigation and are reshaping current and future treatment paradigms. Surgical interventions for benign and malignant tumors, as well as deformity correction remain pivotal in treatment frameworks and require careful assessment by a dedicated multidisciplinary team.

PURPOSE

In this manuscript we review the various spinal manifestations of NF1 patients, indication for surgical intervention and oncological treatments.

Comparison of Effectiveness between Cobalt Chromium Rods versus Titanium Rods for Treatment of Patients with Spinal Deformity: A Systematic Review and Meta-Analysis

Background

Biomechanical properties of rods determine their ability to correct spinal deformity and prevention of postoperative sagittal and coronal changes. The selection of a proper rod material is crucial due to their specific mechanical properties that influence the surgical outcome. The purpose of this study is to compare the effectiveness of cobalt chromium rods versus titanium rods for the treatment of spinal deformity by a systematic review and meta-analysis.

Methods

PubMed, EMBASE, and the Cochrane library were searched for observational and biomechanical studies comparing cobalt chromium and titanium rods in terms of correction rate, thoracic kyphosis, lumbar lordosis, incidence of rod fracture, fatigue life of contoured rod, bending stiffness of rods, and occurrence of proximal junctional kyphosis. The demographic data and mean values of outcomes of interest were extracted from each group and compared by their mean difference as an overall outcome measure. The Review Manager software (RevMan 5.3) was utilized at a 95% significance level.

Results

Eleven eligible studies with 641 participants for 7 observational studies and 35 samples for 4 biomechanical studies were identified. There were no significant differences between cobalt chromium and titanium rods in the correction rate of spinal deformity. Postoperative thoracic kyphosis was well restored in the cobalt chromium group with statistical significance (p value = 0.009). The incidence of rod fracture was high in titanium rods compared to cobalt chromium rods with significant difference (p value = 0.0001). Proximal junctional kyphosis occurs more in the cobalt chromium group with a significant difference (p value = 0.0009). No statistical significance between two materials in terms of lumbar lordosis, fatigue of life, and bending stiffness of rods.

Conclusion

The cobalt chromium rod is better than titanium rod for effective correction of spinal deformity and postoperative stability of the spine. However, the use of cobalt chromium rods is associated with increased risk of proximal junctional kyphosis.

Surgical treatment of scoliosis in neurofibromatosis type I: A retrospective study on posterior-only correction with third-generation instrumentation

Background:

Scoliosis is the most common orthopedic complication of neurofibromatosis type I. Scoliosis can be occurred with two patterns: dystrophic or idiopathic-like. In adolescence, in consideration of bone dystrophy, osteopenia, and often associated hyperkyphosis, most of the authors recommend an anterior-posterior approach. According to other authors, modern instrumentations could be sufficient to sustain a solid posterior arthrodesis.

Materials and Methods:

Ten patients were diagnosed with scoliosis in neurofibromatosis type I aged between 8 and 25 years, Cobb angle of the thoracic curve >45°, and minimum follow-up (FU) of 1 year and treated with posterior-only approach with third-generation high-density instrumentations. Radiographic measurements were performed on the coronal and sagittal planes. Nonparametric tests (Friedman test and Wilcoxon test) were applied to evaluate the reducibility of the preoperative curve (T0), the postoperative surgical correction (T1), and its maintenance on FU.

Results:

Statistics showed results compared to those evaluated in the literature with a combined approach regarding surgical correction and its maintenance on FU. On T1, a median correction of 53.5% of the scoliotic curve and of 33.7% of the thoracic hyperkyphosis was observed. On FU, the correction was maintained. A global improvement in balance was appreciated. The curves, despite rigid, showed a relative reducibility to bending tests and traction. No significant complications occurred.

Conclusions:

The posterior-only approach produces a satisfactory correction of the dystrophic neurofibromatosis scoliosis if associated with the use of high-density third-generation instrumentations. We are confident in recommending posterior-only approach in dystrophic neurofibromatosis scoliosis with coronal curves till 110° and coexisting thoracic kyphosis till 80°

Comparison between surgical fusion and the growing-rod technique for early-onset neurofibromatosis type-1 dystrophic scoliosis

Background

Spinal deformities constitute one of the most common types of manifestations of neurofibromatosis type-1 (NF-1), which can lead to either dystrophic or non-dystrophic early-onset scoliosis (EOS). Surgical treatment for EOS with NF-1 is challenging, and the outcomes have rarely been reported. The anterior-posterior procedure is widely used, but posterior-only fusion is theoretically easier and safer to perform. Is it possible that a new surgery that accommodates growth is a better choice? A direct comparison between posterior fusion and growth-friendly surgery in terms of surgical outcomes has not yet been conducted in dystrophic EOS with NF-1 patients.

Methods

Baseline information was extracted from the NF-1 database at our institute with approval from the local ethics committee. All enrolled patients were diagnosed with NF-1. Clinical and radiographic data were recorded preoperatively, after the initial surgery, and at the final follow-up. Implant-related, alignment, neurological complication and unplanned revision surgery data were recorded. We compared the outcomes of these two groups in terms of curve correction, growth parameters, complications and unplanned revision surgeries.

Results

There were eight patients in the PF group and eight patients in the GR group, with a mean follow-up of 51.0 ± 17.5 months. The main curve size was similar (PF 67.38° ± 17.43° versus GR 75.1° ± 26.43°, P = 0.501), and there were no significant differences in the initial surgery correction rate or the rate of correction. However, the patients in the GR group exhibited more T1-S1 growth during the follow-up overall and per year than did those in the PF group. The operative time was significantly longer for the PF group than for the GR group (PF, 4.39 ± 1.38 vs. GR, 3.00 ± 0.42 h; p = 0.008). Significantly fewer segments were involved in the PF group (8.25 ± 3.20) than in the GR group (13.00 ± 1.60).

Conclusion

For the initial treatment of dystrophic EOS in patients with NF-1, the GR technique is possibly a more appropriate treatment than is the PF technique in terms of trunk growth. However, the repeated procedures required for GR may be a considerable disadvantage. More studies with direct measurement of pulmonary function must be conducted to determine the effect of GR on pulmonary development. More studies with larger sample sizes and longer follow-up periods are needed to fully assess the treatment strategies.

Management of Proximal Thoracic Kyphoscoliosis with Early Myelopathy in a Young Adult with Neurofibromatosis Type 1: A Case Report and Review of Literature

INTRODUCTION

Neurofibromatosis (NF) 1 is associated with skeletal deformities. Scoliosis is seen in about 10-64% of NF-1 patients. NF-1 may be associated with dystrophic or non-dystrophic type of curve. There are technical difficulties in treating large dystrophic curve with proximal thoracic kyphoscoliosis in NF-1. This case report and subsequent review of literature attempts to provide a line of management for such difficult lesions.

MATERIALS AND METHODS

We present a case of 22-year-old male with NF-1 who came to us with gradually progressive upper back deformity and signs of early myelopathy for 2-3 months. The patient had a 100° proximal thoracic kyphosis and 100° scoliosis with no neurological deficit and brisk reflexes. A single stage posterior fixation with three column osteotomy at the apex of the curve was performed.

RESULTS

The kyphosis was corrected to 65° from 100, the scoliosis was corrected to 60° from 100. Clinically, the hump in the upper back was visibly reduced. At 1-year follow-up, the patient remained asymptomatic with no loss of correction and implant breakage on X-ray.

CONCLUSION

Large dystrophic proximal thoracic kyphoscoliosis is a difficult lesion to treat and can be managed with an all posterior approach, achieving good cosmetic and neurological outcomes, as demonstrated by this case.

Surgical Outcomes and Complications Following All Posterior Approach for Spinal Deformity Associated with Neurofibromatosis Type-1

Objectives

The purpose of this study was to evaluate surgical outcomes and complications of spinal deformity associated with neurofibromatosis type-1 (NF-1).

Methods

From 2012 to 2018, patients suffering from spinal deformity associated with NF-1 who underwent surgical correction were identified. Demographic data and radiographic measures were retrospectively reviewed. Pre- and postoperative whole spine radiograph images were used to determine both coronal and sagittal Cobb angles. All of patients underwent 3-dimentional computed tomographic scan and magnetic resonance imaging scan to confirm dystrophic features. For evaluation of clinical outcomes, we surveyed the pre- and postoperative scoliosis research society-22r (SRS-22r) score.

Results

Seven patients with spinal deformity associated with NF-1 were enrolled in this study. The mean age of patients was 29.5±1.2 years old. The mean follow-up period was 2.8±1.4 years. The apex of the deformity was located in cervicothoracic (n=1), thoracic (n=4), and lumbar region (n=2). Most patients have poor bone quality and decreased bone mineral density with average T-score of -3.5±1.0. All patients underwent surgical correction via posterior approach. The pre- and postoperative mean coronal and sagittal Cobb angle was 61.6±22.6° and 34.6±38.1°, 56.8±18.5° and 40.2±9.1°, respectively. Mean correction rate of coronal and sagittal angle was 44.7% and 23.1%. Ultimate follow-up SRS-22r score (average score, 3.9±0.4) improved comparing to preoperative score (average score, 3.3±0.9). Only one patient received revision surgery due to rod fracture. No serious complication occurred, such as neurological deficit, and viscerovascular injury.

Conclusion

The surgical correction of patients having spinal deformity associated with NF-1 is challenging, however the radiographic and clinical outcomes are satisfactory. The all posterior approach can be a safe and effective surgical option for patients having dystrophic curves associated with NF-1.

Clinical and neuroradiological characterisation of spinal lesions in adults with Neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) manifests itself in many ways in the spine. This study aims to report the types of spinal lesions, clinical and demographic data in a large cohort from a complex NF1 centre. The characteristics of those with spinal neurofibromatosis, where neurofibromas are present on every spinal nerve root, were sought for comparison with the wider group of NF1 patients. This is a retrospective review of MDT minutes of 303 patients from a UK NF1 centre and the largest reported series of NF1 patients based on radiological data. Prevalence of each symptom and lesion was calculated and statistically significant associations were established. The most reported findings were cutaneous lesions (44.9%) and neurological deficit (27.4%). 28.4% had dural ectasia, 52.5% had some form of spinal deformity. 57.8% had spinal nerve root tumours, the most common of which were at C2. The most progressive lesions were spinal nerve root tumours (29.1%). The only statistically significant association found was between dural ectasia and spinal deformity (P < 0.003), where dural ectasia is associated with a 32.6% increase in spinal deformity incidence. This is the largest descriptive study of spinal lesions in NF1. Spinal tumours and spinal deformity are prevalent in NF1. The predilection of spinal tumours for flexible spinal regions suggests that repetitive movement might be an important factor in pathogenesis. Physicians and patients should be alert to the observation that although many spinal neurofibromatosis patients display no neurological deficit, they often have significant lesions which require monitoring and sometimes surgery.