Late post-operative paraparesis after rib penetration of the spinal canal in a patient with neurofibromatous scoliosis

Myelopathy Associated with Rapid Progression of a Dystrophic Neurofibromatosis-1 Curve - A Case Report and Review of Literature

Introduction

Thoracic myelopathy in neuro fibromatosis-1 (NF-1) is most commonly due to intra-spinal neurofibromas/dumb-bell tumors/intra-canal rib head penetration (RHP) causing cord compression. However, acute thoracic myelopathy due to rapid progression of the kyphoscoliotic curve alone in NF-1 without a significant spinal cord compression occurs very rarely. This case report discusses our experience with one such patient and we also discuss intraoperative and post-operative challenges encountered with this patient and a rare complication of hemothorax postoperatively.

Case Report

A 15-year-old male presented to the clinic after being lost to follow-up for 4 years with a rapid acute deterioration of dystrophic curve and no myelopathic symptoms (Scoliosis - 65°, Kyphosis - 77°). His subsequent examination in 6 weeks showed acute development of myelopathic gait with right ankle and extensor hallucis longus weakness. He was admitted for halo gravity traction for 6 weeks and a single-stage posterior instrumentation with excision of rib heads at the apex was planned. Postoperatively, the patient developed massive left hemothorax and loss of power in both lower limbs at day 2. He subsequently regained full power and complete resolution of myelopathic symptoms at the end of 9- month follow-up with a satisfactory alignment of spine in the follow-up X-rays.

Conclusion

Acute onset of myelopathy is a rare and uncommon finding with a rapid deterioration of dystrophic curve alone without any major spinal cord compromise. Early detection of dysplastic changes with early aggressive surgical management and deformity correction is necessary with dystrophic NF-1 curves to prevent pre-operative and post-operative morbidities.

Management of NF-1 dystrophic scoliosis associated with rib heads dislocation into the spinal canal in neurological intact patients: a systematic literature review

PURPOSE

The management of scoliosis and kyphoscoliosis in patients with Type 1 Neurofibromatosis (NF-1) among spinal surgeons is still challenging due to the severity of the deformity especially in dystrophic deformity types. This rapid and progressive condition is likely to be associated with dislocated rib heads into the spinal canal, hence representing a real dilemma on the decision making between its resection versus not resection during the corrective surgery, especially in patients with normal neurological status. The objective of this publication is to discuss the management options in this patient population through a literature review.

METHODS

A comprehensive systematic literature search was performed for relevant studies using PubMed, Web of Science, and Scopus databases. Previous publications depicting neurologically intact patients with NF-1 and rib dislocation into the canal were reviewed. Articles reporting individual cases or case series/cohorts with patient-discriminated findings were included.

RESULTS

The data collection retrieved a total of 55 neurologically intact patients with NF-1 dystrophic scoliosis and rib penetration into the canal who underwent spinal surgery. Among them, 37 patients underwent surgery without head rib resection and 18 patients with rib excision. No patient presented postoperative neurological deficit except for one case of late postoperative neurological deterioration reported in a patient within situ fusion in which the surgeons ignored the presence of previous spinal cord compression.

CONCLUSION

Corrective surgery for patients with NF-1 and rib penetration into the canal in neurologically intact patients can be safely performed without the resection of the dislocated rib heads without a higher risk of neurological compromise.

Surgical Treatment of the Intraspinal Rib Head Dislocation in Children With Dystrophic Scoliosis Secondary to Type 1 Neurofibromatosis

BACKGROUND

The purpose of this study was to explore the surgical treatment of intraspinal rib head dislocation (IRH) in children with dystrophic scoliosis secondary to type 1 neurofibromatosis (NF1-DS).

METHODS

From 2006 to 2019, 32 of 128 patients with NF1-DS were found to have IRH and enrolled in this study. There were 19 boys and 13 girls with an average age of 8.8±2.6 years. Patients were divided into 2 groups: group A (n=25) without IRH resection and group B (n=7) with IRH resection. The intraspinal rib proportion (IRP), apical vertebra rotation, apical vertebral translation, main thoracic curve Cobb angle, trunk shift and thoracic kyphosis, lumbar lordosis, and sagittal vertebral axis were measured before and after the operation. Spinal injury was graded based on the American Spinal Injury Association (ASIA) Impairment Scale.

RESULTS

The study group had a total of 42 IRH. The mean follow-up duration was 46.1±28.7 months. The preoperative IRP in both groups was similar (35.5±14.3% vs. 31.2±15.3%, P=0.522). The postoperative IRP was lower in group B (18.5±11.2% vs. 0%, P=0.002). The IRP in group A decreased from preoperative (31.2±15.3%) to postoperative (18.5±11.2%) (P<0.05). There was no significant difference in the apical vertebra rotation, apical vertebral translation, main thoracic curve Cobb angle, trunk shift, thoracic kyphosis, lumbar lordosis, and sagittal vertebral axis between the 2 groups before surgery and after surgery. Four patients with nerve injury caused by the IRH had full neurological recovery postoperatively. All patients were ASIA grade E at the last follow-up.

CONCLUSIONS

The surgical treatment of IRH in children with NF1-DS should be determined on the basis of the presence of preoperative neurological symptoms. This study supports the practice of correcting spinal deformities only in patients with mild or no spinal cord injury. If there are obvious neurological symptoms, IRH resection is necessary to relieve spinal cord compression to recover nerve function.

LEVEL OF EVIDENCE

Level III.

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.

Traumatic rib head subluxation through the intervertebral foramen causing spinal cord contusive injury in a cat

Case summary

A 4-year-old cat involved in a road traffic accident presented with paraparesis, which was worse on the right-hand side. Neurolocalisation was to the T3–L3 spinal cord segments. Survey radiographs showed rib fractures but no definitive diagnosis for the paraparesis. CT revealed fracture of the dorsal rim and a T9 rib subluxation through the intervertebral foramen at T8–T9. This caused a contusive spinal injury. Treatment consisted of rest and analgesia. The cat recovered well, with the owner reporting no abnormalities 5 months following the injury.

Relevance and novel information

Road traffic accidents are a common cause of injury in the cat population, with a significant number having thoracic injuries. These include rib injures such as fractures. This is the first reported case of a traumatic rib subluxation causing a contusive injury in the spinal cord of any species. Previously reported rib subluxations have been seen in humans with spinal deformities. Conservative management in this case was sufficient.

Sublaminar fixation versus hooks and pedicle screws in scoliosis surgery for Marfan syndrome

Background:

In patients with Marfan syndrome (MFS), surgical correction of spinal deformities with hooks and/or pedicle screws involves a higher rate of complications than in patients with adolescent idiopathic scoliosis. Therefore, sublaminar instrumentation is often a last resort option. This study wants to assess the ability of sublaminar fixation to achieve three-dimensional scoliosis correction and spine stabilization compared with hook and/or pedicle screw systems.

Methods:

Twenty-one MFS patients who underwent posterior spinal fusion at a highly specialized medical center in 1995–2017 were divided into two different groups retrospectively evaluated at a minimum follow-up of 2 years. Group 1 (8 patients) was composed by hooks and screws instrumentation, while Group 2 (13 patients) was composed by hook or pedicle screw system associated to sublaminar wires/bands. Radiological (correction and long-term stability) and general endpoints (mean blood loss, surgery time, and complications) were compared between the groups.

Results:

The degree of correction compared with the preoperative status was satisfactory with both approaches, although the difference between them was not significant. No significant differences were found for general endpoints between groups.

Conclusion:

Our data suggest that scoliosis correction with sublaminar fixation is not inferior to treatment with hooks and/or pedicle screws.

Level of Evidence:

III.

Surgical treatment of spinal deformities in Marfan syndrome: Long-term follow-up results using different instrumentations

Background:

Scoliosis is the most frequent spinal deformity related to Marfan syndrome (MFS). Treatment with a brace is often ineffective, and surgical treatment is very challenging; many instrumentations were used along the years. Our retrospective study has the purpose of identifying the reliability of different devices in three-dimensional correction of the spine deformities in MFS.

Materials and Methods:

We reviewed retrospectively the records of patients surgically treated, in a single institution between 1999 and 2016, for spinal deformities in MFS. X-rays were reviewed for analyzing the magnitude of the curves in preoperative time (T0), the amount of correction in the immediate after surgery period (T1), and it's stability at follow-up (FU) (T2). The clinical outcomes were also evaluated with the Scoliosis Research Society 24.

Results:

A total of 21 patients with a mean age at surgery of 16 years met inclusion and exclusion criteria. Four different construct types were identified: hooks with sublaminar wires (G1), hooks and pedicle screws (G2), pedicle screws (G3), and pedicle screws with sublaminar wires (G4). The mean FU time was 8 years. The average major scoliosis curve had a mean value of 63.48° at T0 and was corrected to 28.81° at T2. Furthermore, minor curve, thoracic lordosis, and lumbar kyphosis (when associated to scoliosis) were also corrected. Student t-test showed significative differences (P < 0.05) for all curves between T0–T1 and T0–T2 while between T1 and T2, no differences were found. We also evaluated separately the results of each instrumentation, and G3 obtained the best performances.

Conclusions:

Our results shows that screws may guarantee a better correction of the deformities.

Level of Evidence:

III

Posterior Correction Without Rib-head Resection for Patients With Neurofibromatosis Type 1, Dystrophic Scoliosis, and Rib-head Protrusion Into the Spinal Canal

STUDY DESIGN

A retrospective study.

OBJECTIVE

The objective of this study is to report the result of patients with neurofibromatosis type 1(NF-1), dystrophic scoliosis, and rib-head protrusion into the spinal canal who received posterior scoliosis correction surgery without rib-head resection.

SUMMARY OF BACKGROUND DATA

A total of 124 patients with NF-1 and dystrophic scoliosis were treated at our institution during the study period. Eight patients with a median age of 12 years had rib-head protrusion into the spinal canal and received surgery and were included in the analysis.

METHODS

All 8 patients (6 male, 2 female) were treated from 2003 to 2013 and received posterior correction with a pedicle screw-rod 3-dimensional correction system or screw-hook hybrid system. Scoliosis correction rate and percentage of spinal canal occupied by the rib head were analyzed.

RESULTS

The median patient age, number of segments fused, and follow-up duration were 12 years, 10.5, and 22.5 months, respectively. There were no surgery-related complications, and symptoms in all patients improved after surgery. The median postoperative and 1-year follow-up sagittal kyphotic angles were significantly smaller as compared with the preoperative value (28.5 and 31 vs. 62.5 degrees, P=0.012). The median postoperative coronal Cobb angle of the main thoracic curve was significantly smaller compared with the preoperative value (29 vs. 64.5 degrees, P=0.012). The median percentage of the spinal canal occupied by the intraspinal rib was significantly lower at 1-year follow-up compared with the preoperative value (23.1% vs. 28.6%, P=0.018).

CONCLUSIONS

Posterior correction without rib-head excision can provide good outcomes for patients with NF-1 and dystrophic scoliosis and rib-head protrusion into the spinal canal.

Thoracic compression myelopathy due to the progression of dystrophic scoliosis, the presence of a paraspinal tumor, and high and excessive amplitude movement of the shoulder

The authors present a case of 45-year-old man with neurofibromatosis type 1 (NF-1) and thoracic scoliosis, previously undergoing fusion surgery, who developed myelopathy. This patient further complained of lightning pain when he extended and horizontally abducted the convex-side shoulder. Radiological examination revealed the progression of dystrophic scoliosis with opened spinal canals and the presence of a neurofibroma behind the spinal cord at the apical levels. Delayed development of spinal instability can occur due to dystrophy even postoperatively in patients with NF-1. After tumor resection, he had rapid recovery from myelopathy and no recurrence of radiating pain despite shoulder movement. These findings provide a speculation that high, intense amplitude movement of the shoulder toward the spinal canal causes the impingement on the neurofibroma, resulting in indirect compression of the exposed spinal cord. This is the first report describing thoracic compression myelopathy associated with paraspinal displacement of the scapula.

Surgical Management of Intracanal Rib Head Dislocation in Neurofibromatosis Type 1 Dystrophic Kyphoscoliosis: Report of Two Cases and Literature Review

There is still no consensus on the management of severe intracanal RH dislocation in neurofibromatosis type 1 dystrophic kyphoscoliosis. This study notes the early cord function impairment signs, reports a serious complication in a susceptible cord, identifies possible mechanisms of injury, and discusses the management of intracanal RH dislocation presented in the literature. First report is as follows: a 12-year-old female with cord compromise and preoperative neurology that underwent thoracotomy and anterior release. The RH was left in situ following a rib excision. During the posterior stage of the procedure she presented with complete loss of all IOM traces prior to any correction manoeuvres. The neurology recovered 72 h postop and the final correction and instrumented fusion were uneventfully completed 15 days postop. Second report is as follows: a 10-year-old male, whose only neurology was a provoked shock-like sensation to the lower limbs following direct pressure on the rib cage. He underwent an uneventful posterior RH excision and instrumented correction and posterior spinal fusion. In conclusion, any possible cord dysfunction sign should be sought during examination. Decompression of the spinal cord by resecting the impinging bony part, even in the absence of neurological symptoms, is advised before any attempt to release or correct the deformity.

Posterior-only spinal fusion without rib head resection for treating type I neurofibromatosis with intra-canal rib head dislocation

OBJECTIVES

Patients with Type I neurofibromatosis scoliosis with intra-canal rib head protrusion are extremely rare. Current knowledge regarding the diagnosis and treatment for this situation are insufficient. The purpose of this study is to share our experience in the diagnosis and surgical treatments for such unique deformities.

METHODS

Six patients with Type I neurofibromatosis scoliosis with rib head dislocation into the spinal canal were diagnosed at our institution. Posterior instrumentation and spinal fusion without intra-canal rib head resection via a posterior-only approach was performed for deformity correction and rib head extraction. The efficacy and outcomes of the surgery were evaluated by measurements before, immediately and 24 months after the surgery using the following parameters: coronal spinal Cobb angle, apex rotation and kyphosis of the spine and the intra-canal rib head position. Post-operative complications, surgery time and blood loss were also evaluated.

RESULTS

Patients were followed up for at least 24 months post-operatively. The three dimensional spinal deformity was significantly improved and the intra-canal rib head was significantly extracted from the canal immediately after the surgery. At follow-up 24 months after surgery, solid fusions were achieved along the fusion segments, and the deformity corrections and rib head positions were well maintained. There were no surgery-related complications any time after the surgery.

CONCLUSIONS

Systematic examinations are needed to identify patients with Type I neurofibromatosis scoliosis with rib head dislocation into the canal who can be treated by posterior-only spinal fusion without rib head resection.

The rib head as a landmark in the anterolateral approach to the thoracic spine: a computed tomography-based morphometric study

OBJECT

The rib head is an important landmark in the anterolateral approach to the thoracic spine. Resection of the rib head is typically the first step in gaining access to the underlying pedicle and ultimately the spinal canal. The goal of this work is to quantify the relationship of the rib head to the spinal canal and adjacent aorta at each thoracic level using CT-based morphometric measurements.

METHODS

One hundred thoracic spine CT scans (obtained in 50 male and 50 female subjects) were evaluated in this study. The width and depth of each vertebra body were measured from T-1 to T-12. In addition, the distance of each rib head to the spinal canal was determined by drawing a line connecting the rib heads bilaterally and measuring the distance to this line from the most ventral aspect of the spinal canal. Finally, the distance of the left rib head to the thoracic aorta was measured at each thoracic level below the aortic arch.

RESULTS

The vertebral body depth progressively increased in a rostral to caudal direction. The vertebral body width was at its minimum at T-4 and progressively increased to T-12. The rib head extended beyond the spinal canal maximally at T-1. This distance incrementally decreased toward the caudal levels, with the tip of the rib head lying approximately even with the ventral canal at T-11 and T-12. The distance between the aorta and the left rib head increased in a rostral to caudal direction as well.

CONCLUSIONS

The rib head is an important landmark in the anterolateral approach to the thoracic spine. At more cephalad levels, a larger portion of rib head requires resection to gain access to the spinal canal. At more caudad levels, there is a safer working distance between the rib head and aorta.

Double rib penetration of the spinal canal in a patient with neurofibromatosis

BACKGROUND

Rib head penetration into the spinal canal in patients with severe kyphoscoliosis secondary to neurofibromatosis type-1 (NF-1) is extremely rare. Double rib head penetration has only been reported once earlier.

METHODS

We are reporting on an adolescent male with NF-1 and severe thoracic kyphoscoliosis with adjacent double rib head penetration into the spinal canal without neurological deficits. Only one was recognized on the initial radiographic imaging.

RESULTS

A 14-year-old with NF-1 and 74 degrees left thoracic scoliosis and 75 degrees kyphosis was treated at our institution. Preoperative computed tomography (CT) demonstrated protrusion of the left T6 rib head into the spinal canal on the convexity of the curve, compressing the spinal cord. Staged surgical procedures for resection of the rib head and correction of the spinal deformity were planned. After presumed successful resection of the penetrated rib head, a postoperative CT revealed the presence of a second adjacent left T7 rib head in the spinal canal. This was not initially recognized owing to the severe deformity and image obliquity of the CT gantry. Another procedure was performed to remove this rib head. He was then placed in halo traction until anterior and posterior spinal fusion and segmental spinal instrumentation were performed. He achieved good deformity correction and had no neurological deficits throughout his treatment.

CONCLUSIONS

Rib head protrusion into the spinal canal can occur with spine deformity in NF-1. If present, the imaging should be carefully reviewed for the possibility of an adjacent rib head penetration that may have been obscured by the limitations of CT in the context of a dysplastic spinal deformity.

LEVEL OF EVIDENCE

Level V. Case study.

Post-traumatic thoracic scoliosis with rib head dislocation and intrusion into the spinal canal: a case report and review of literature

The objective of the study was to report a rare occurrence of dislocation and intrusion of two rib heads into the spinal canal at the convex apex of a post-traumatic thoracic scoliosis in an adult in the absence of any neurological impairment. A 47-year-old male presented with a slowly progressive, post-traumatic thoracic scoliosis and a mild aching sensation over the posterior chest wall. The lower limb neurology and bowel and bladder function were normal. There was no clinical evidence of neurofibromatosis. CT scans showed that the 8th and 9th ribs on the convex apex of the scoliotic curve had intruded into the spinal canal and were lying adjacent to the dura and spinal cord. The MRI scan did not show any cord signal intensity changes. Although rib dislocation and intrusion into the spinal canal is uncommon, images should be carefully analysed to rule out this condition in sharp angular scoliotic curves.

Rib head protrusion into the central canal in type 1 neurofibromatosis

BACKGROUND

Intraspinal rib head dislocation is an important but under-recognized consequence of dystrophic scoliosis in patients with neurofibromatosis 1 (NF1).

OBJECTIVE

To present clinical and imaging findings of intraspinal rib head dislocation in NF1.

MATERIALS AND METHODS

We retrospectively reviewed clinical presentation, imaging, operative reports and post-operative courses in four NF1 patients with intraspinal rib head dislocation and dystrophic scoliosis. We also reviewed 17 cases from the English literature.

RESULTS

In each of our four cases of intraspinal rib head dislocation, a single rib head was dislocated on the convex apex of the curve, most often in the mid- to lower thoracic region. Cord compression occurred in half of these patients. Analysis of the literature yielded similar findings. Only three cases in the literature demonstrates the MRI appearance of this entity; most employ CT. All of our cases include both MRI and CT; we review the subtle findings on MRI.

CONCLUSION

Although intraspinal rib head dislocation is readily apparent on CT, sometimes MRI is the only cross-sectional imaging performed. It is essential that radiologists become familiar with this entity, as subtle findings have significant implications for surgical management.