Radiographic and clinical outcome of syringomyelia in patients treated for tethered cord syndrome without other significant imaging abnormalities

Filum Terminale: A Comprehensive Review with Anatomical, Pathological, and Surgical Considerations

The conus medullaris is the distal tapering end of the spinal cord, and the filum terminale (FT) is regarded as a bundle of non-functional fibrous tissue; therefore, some scholars call it the spinal ligament, while others describe the human FT as "remnants of the spinal cord." It was later found that in the human spinal cord, the FT is composed of an intradural segment and an epidural segment, and the end of the FT is connected to the coccyx periosteum. Because some nerve tissue is also found in the FT, as research progresses, FT may have the potential for transplantation. A lack of exhaustive overviews on the FT in the present literature prompted us to conduct this review. Considering that a current comprehensive review seemed to be the need of the hour, herein, we attempted to summarize previous research and theories on the FT, elucidate its anatomy, and understand its pathological involvement in various diseases.

A critical analysis of surgery for occult tethered cord syndrome

INTRODUCTION

Tethered cord syndrome (TCS) is an amalgamation of neurological, urological, orthopedic, and dermatologic signs and symptoms with radiographic evidence of a thickened filum and low-lying conus. Surgical sectioning of the filum and disconnection of any tethering entities such as dermal sinus tracts or lipomas has been shown to improve outcomes. The manifestation of TCS symptoms in the absence of a low-lying conus has been referred to as occult tethered cord syndrome (OTCS) and is much less well reviewed in the literature. To date, there has only been one randomized controlled trial examining the effect of intervention in OTCS; therefore, contemporary data is often elicited from limited cohorts.

OBJECTIVE

To perform a comprehensive literature review of management in OTCS and evaluate treatment response rates to sectioning of the filum terminale.

RESULTS

Seventeen papers met inclusion criteria for our review. Sample sizes ranged from 8 to 60 children, and results were mixed, often dependent on study design, definition of typical OTCS symptoms, and follow-up intervals. Symptomatic improvement was observed in > 50% of patients for all but one study; however, the recurrence rates were highly variable.

CONCLUSION

The data regarding the efficacy of surgical treatment in OTCS is mixed and merits more rigorous scientific examination with strict and clear parameters regarding symptomatic operationalization and follow-up time points to monitor for TCS recurrence.

Surgical outcomes by sectioning a filum terminale in patients with terminal syringomyelia

BACKGROUND

Although terminal syringomyelia suggests a tethered spinal cord, a consensus has still not been established for surgical indications, when there are no associated abnormalities or only minor associated abnormalities. We analyzed surgical outcomes of sectioning a filum terminale in patients with terminal syringomyelia to elucidate the significance of untethering surgery.

METHODS

Fifty-seven pediatric patients with terminal syringomyelia who underwent untethering via sectioning the filum terminale between 2007 and 2018 were retrospectively analyzed. Postoperative outcomes of symptoms and MRI findings were evaluated.

RESULTS

Of 57 patients, 40 had other associated abnormalities (25 with filar lipoma and 29 with low conus medullaris) that could be responsible for tethered cord. Nineteen patients had symptoms. The mean age at the time of surgery was 18 months (3-96 months). The mean follow-up period was 3.3 years (1-9 years). Preoperative symptoms improved in 9 patients (47%) after surgery. At 1 year after the surgery, the size of syringomyelia decreased in 19 (33%), increased in 4 (8%), and did not change in 34 (69%) patients. Of 28 patients who were followed up for more than 3 years, the size decreased in 17 (61%), increased in 1 (4%), and did not change in 10 (35%).

CONCLUSION

When untethering was performed by sectioning a filum terminale, the size of terminal syringomyelia decreased in more than half of patients in the long term. Sectioning the filum terminale demonstrated the possibility of radiological and clinical improvement in patients with terminal syringomyelia.

Is detethering necessary before deformity correction in congenital scoliosis associated with tethered cord syndrome: a meta-analysis of current evidence

PURPOSE

To compare the clinical and radiological outcomes in patients with congenital scoliosis (CS) and tethered cord syndrome (TCS) undergoing deformity correction with (NI group) versus without (NNI group) prior neurosurgical intervention aimed at detethering the cord.

METHODS

A systematic review and meta-analysis were performed. The databases PubMed, Embase and Google Scholar were searched until March 2020. Inclusion criteria was studied describing performance of deformity correction and fusion surgery for congenital scoliosis with tethered cord syndrome with or without prior detethering procedure. Studies describing growth sparing procedures or congenital scoliosis associated with non-tethering pathologies such as syrinx were excluded. Case reports and series with less than 10 subjects were also excluded. NIH quality assessment tool was used for assessing quality of individual study.

RESULTS

Sixteen studies were included for analysis of which eight were found to be retrospective case series (level IV evidence) and retrospective case-control studies (level III evidence) each. Overall proportional meta-analysis found no significant difference in correction rate, operative duration, blood loss or complication rate between the NI and NNI groups. However, subgroup analysis performed after inclusion of only level III evidence studies revealed significantly lesser operative duration and blood loss with comparable correction and complication rate in NNI group.

CONCLUSION

Deformity correction and fusion surgery may be performed safely and effectively in CS with TCS patients without the need of a prior detethering procedure.

Posterior-Only Surgical Correction with Heavy Halo-Femoral Traction for the Treatment of Severe and Rigid Congenital Scoliosis Associated with Tethered Spinal Cord and Type II Split Cord Malformation

OBJECTIVE

To evaluate the safety and efficacy of posterior-only surgical correction with heavy halo-femoral traction for the treatment of severe and rigid congenital scoliosis (SRCS) associated with tethered spinal cord (TSC) and type II split cord malformation (SCM).

METHODS

Thirteen patients with SRCS associated with TSC and type II SCM underwent posterior-only surgical correction with heavy halo-femoral traction. The preoperative mean coronal Cobb angle was 88.87° ± 12.15°; the mean flexibility was 15.28% ± 3.88%; and the mean angle of thoracic kyphosis and lumbar lordosis was 39.63° ± 18.47° and 56.99° ± 10.02°, respectively.

RESULTS

The mean duration of surgery was 320 ± 43.64 minutes and the mean blood loss was 1422.31 ± 457.59 mL. The mean follow-up period was 24.46 ± 7.53 months. After heavy halo-femoral traction, the mean coronal Cobb angle was reduced to 59.14° ± 8.75°. After posterior-only surgical correction, postoperative mean coronal Cobb angle was further reduced to 33.85° ± 8.77°. The postoperative mean correction rate was 62.46% ± 5.04%. The postoperative mean angle of thoracic kyphosis and lumbar lordosis was 29.31° ± 6.75° and 47.79° ± 3.68°, respectively. At the final follow-up, the corrective loss rate of Cobb angle was only 0.69%. There were no significant differences between final follow-up and preoperative modified Japanese Orthopaedic Association total scores. The Scoliosis Research Society-22 total score improved at the final follow-up evaluation compared with the preoperative total score.

CONCLUSIONS

Without prophylactic neurosurgical intervention and spine-shortening osteotomy, posterior-only surgical correction with heavy halo-femoral traction could be safe and effective for the treatment of SRCS associated with TSC and type II SCM.

Syringomyelia in children with closed spinal dysraphism: long-term outcomes after surgical intervention

OBJECTIVE

The nature of the relationship between spinal cord syrinx and tethered cord is not well known. It is unclear if surgical cord untethering results in resolution or improvement of an associated syrinx. The objective of this study was to report the response of spinal cord syrinx to surgical cord untethering.

METHODS

The authors retrospectively reviewed all patients with a syrinx and tethered cord who presented to a single institution over an 11-year interval. Patients with open neural tube defects were excluded. Thirty-one patients were identified, 25 of whom had both clinical and imaging follow-up after surgery. Patients were grouped according to etiology of the tethered cord. Clinical outcomes and syrinx characteristics were recorded.

RESULTS

Of the 25 patients with tethered cord, 68% (n = 17) were male. The average age at presentation was 2.5 years (0-10.1 years) and age at surgery was 3.7 years (range 1 day to 17 years). Etiologies of tethered cord were lipomyelomeningocele (n = 8), thickened/fatty filum (n = 7), intradural lipoma (n = 5), myelocystocele (n = 2), meningocele (n = 2), and diastematomyelia (n = 1). Twenty-three of the patients underwent primary untethering, whereas 2 patients had received untethering previously at another institution. The average syrinx length and width prior to surgery were 4.81 vertebral levels (SD 4.35) and 5.19 mm (SD 2.55 mm), respectively. Conus level ranged from L1 to S3. Patients were followed for an average of 8.4 years (1.35-15.85 years). Overall there was no significant change in syrinx length or width postoperatively; the average syrinx length increased by 0.86 vertebral levels (SD 4.36) and width decreased by 0.72 mm (SD 2.94 mm). Seven of 25 patients had improvement in at least one presenting symptom, including scoliosis, weakness, bowel/bladder dysfunction, and pain. Eight patients had stable presenting symptoms. Six patients were asymptomatic and 5 patients had new or worsening symptoms, which included scoliosis, pain, or sensory changes.

CONCLUSIONS

Although some syrinxes improved after surgery for tethered cord, radiological improvement was not consistent and did not appear to be associated with change in clinical symptoms. The decision to surgically untether a cord should be focused on the clinical symptoms and not the presence of a syrinx alone. Further studies are needed to confirm this finding.

Management of concomitant scoliosis and tethered cord syndrome in non-spina bifida pediatric population

BACKGROUND

The management of concomitant scoliosis and tethered cord syndrome in the non-spina bifida pediatric population is challenging. In the present study, we evaluate the efficacy of different treatment modalities and propose a treatment plan for the management of affected patients.

METHODS

A systematic literature review was conducted by querying the MEDLINE, PubMed, Cochrane, EMBASE, Scopus, and Web of Science databases for papers published between January 1996 and June 2016 and reporting on concomitant scoliosis and tethered cord. We excluded animal studies, non-English papers as well as papers reporting on patients with multiple concomitant intraspinal anomalies such as spina bifida.

RESULTS

Out of 1993 articles, only 13 met our inclusion criteria. These 13 articles described six main management approaches: Observation, cord untethering only, cord untethering followed by deformity correction, simultaneous cord untethering and deformity correction, and deformity correction without untethering. Selection of the best approach is a function of the patient's symptomatology and Cobb angle.

CONCLUSION

We propose treatment plan for the management of patients with concomitant tethered cord syndrome and spinal deformity. Asymptomatic patients can be followed conservatively and managed as scoliosis patients with no need for untethering. Surgical management in a staged fashion seems appropriate in symptomatic patients with a Cobb angle less than 35°. In these patients, deformity can improve following untethering, thus sparing the patient the risks of surgical correction of scoliosis. Staged or non-staged cord untethering and curve correction seem to be adequate in symptomatic patients with Cobb angle >35° as these patients are likely to require both untethering and deformity correction.

Evaluation and management of tethered cord syndrome in occult spinal dysraphism: Recommendations from the international children's continence society

AIMS

As awareness and frequency of tethered spinal cord (TSC) related to occult spinal dysraphism (OSD) has increased with magnetic resonance imaging (MRI), variability exists in its evaluation and management. Due to no published level I data, we summarize the current International Children's Continence Society (ICCS) recommendations for diagnosis and treatment of OSD.

METHODS

Guidelines were formulated based on analysis of pertinent literature and consensus among authors. This document was vetted by the multidisciplinary members of the ICCS via its website before submission for peer review publication.

RESULTS

The more frequent diagnosis of OSD is associated with increased operative intervention. Spinal cord untethering (SCU) has a highly variable risk profile, largely dependent on the specific form of OSD. Progressive neurological deterioration attributed to "tethered cord" may occur, with or without surgery, in selected forms of OSD whereas other cohorts do well.

CONCLUSION

Infants with classic cutaneous markers of OSD, with progressive neurologic, skeletal, and/or urologic findings, present no diagnostic or therapeutic dilemma: they routinely undergo MRI and SCU. Conversely, in asymptomatic patients or those with fixed, minor abnormalities, the risk profile of these OSD cohorts should be carefully considered before SCU is performed. Irrespective of whether or not SCU is performed, patients at risk for progression should be followed carefully throughout childhood and adolescence by a multidisciplinary team.

More preoperative flexibility implies adequate neural pliability for curve correction without prophylactic untethering in scoliosis patients with asymptomatic tethered spinal cord, a retrospective study

Background

Tethered spinal cord is frequently associated with scoliosis. It is still controversial whether a prophylactic untethering is necessary before correction procedure in scoliosis patients with tethered spinal cord. In this study we determined the clinical outcome of a one-stage posterior scoliosis correction without a prophylactic untethering for treating scoliosis with an asymptomatic tethered spinal cord.

Methods

Seventeen (5 males and 12 females) scoliosis patients with tethered spinal cords were retrospectively reviewed. All patients underwent a one-stage posterior scoliosis correction without preventive untethering. Parameters of radiograph were used to assess correction result. The Scoliosis Research Society (SRS)-22 questionnaire was analyzed pre- and post-operatively to evaluate the clinical outcomes. The modified Japanese Orthopaedic Association (mJOA) score was used to assess the pre- and post-operative spinal cord function.

Results

The post-operative coronal Cobb angle was significantly decreased compared with preoperative. (23.8 ± 6.4° vs. 58.4 ± 12.6°, P < 0.01). The coronal Cobb angle was 22.4 ± 6.8° at the final follow-up evaluation. The apical vertebral translation (AVT) was also decreased significantly. (27.5 mm vs. 60.9 mm, P < 0.01). The SRS-22 total score was improved at the 1-year follow-up evaluation compared with the pre-operative SRS-22 total score (87 ± 4 vs. 70 ± 5, p < 0.05). The functional activities, pain, self-image, mental health, and surgery satisfactory scores at the final follow-up evaluation were all improved compared with the corresponding pre-operative scores, especially the self-image and mental health scores (p < 0.05). The spinal cord function was stable and there was no new neurological symptoms after scoliosis correction. No difference existed between the pre- and post-operative total mJOA score (26 ± 2 vs. 27 ± 2, p = 0.39), which including subjective symptom (p = 0.07), clinical symptom (p = 0.33), daily activities (p = 0.44) and bladder function (p = 0.67).

Conclusion

One-stage posterior scoliosis correction is a safe and effective surgical procedure for scoliosis patients combined with asymptomatic tethered spinal cord who have adequate spinal cord function reserve.

The natural history and management of patients with congenital deficits associated with lumbosacral lipomas

INTRODUCTION

Many patients with lumbosacral lipoma are asymptomatic; however, a significant proportion will have neurological deficits present at birth. Implication of these deficits with respect to natural history and management are not well understood.

METHODS

A retrospective review of all infants with lumbosacral lipoma seen at BCCH between 1997 and 2013 was carried out. The study population was stratified on the presence of a congenital, non-progressive deficit and subdivided on treatment approach. The subsequent developments of deficits resulting in untethering procedures were recorded.

RESULTS

Of the 44 infants in this study, 24 patients had no neurologic deficit while 20 patients had a fixed, non-progressive deficit evident at birth. Ten of 24 patients without a neurological deficit at birth underwent a prophylactic untethering with 3 eventually requiring repeat untethering after, on average, 62.7 months. Eleven of 14 asymptomatic, monitored patients required untethering for clinical deterioration. Two required a second untethering procedure after 48.7 months. Ten of 20 infants with congenital deficits present at birth underwent prophylactic untethering, and 4 required further surgery after 124 months. Ten patients underwent observation with 8 eventually requiring surgery. Two required repeat untethered after 154 months. The complication rates and operative burden for patients are similar whether prophylactic or delayed surgery is performed.

CONCLUSION

The presence of congenital neurologic deficit does not affect the likelihood of deterioration in patients managed expectantly; prophylactic detethering of these patients did not prevent delayed neurologic deterioration. Comparing the need for repeat surgery in prophylactically untethered patients with initial untethering of patients operated upon at the time of deterioration, prophylactic untethering may confer a benefit with respect to subsequent symptomatic tethering if complication rates are low. However, in a setting with multidisciplinary follow-up, a period of observation for patients and intervention when patients become symptomatic is an acceptable approach for patients with or without congenital deficits.

Syrinx location and size according to etiology: identification of Chiari-associated syrinx

OBJECT Syrinx size and location within the spinal cord may differ based on etiology or associated conditions of the brain and spine. These differences have not been clearly defined. METHODS All patients with a syrinx were identified from 14,118 patients undergoing brain or cervical spine imaging at a single institution over an 11-year interval. Syrinx width, length, and location in the spinal cord were recorded. Patients were grouped according to associated brain and spine conditions including Chiari malformation Type I (CM-I), secondary CM (2°CM), Chiari malformation Type 0 (CM-0), tethered cord, other closed dysraphism, and spinal tumors. Syringes not associated with any known brain or spinal cord condition were considered idiopathic. Syrinx characteristics were compared between groups. RESULTS A total of 271 patients with a syrinx were identified. The most common associated condition was CM-I (occurring in 117 patients [43.2%]), followed by spinal dysraphism (20 [7.4%]), tumor (15 [5.5%]), and tethered cord (13 [4.8%]). Eighty-three patients (30.6%) did not have any associated condition of the brain or spinal cord and their syringes were considered idiopathic. Syringes in patients with CM-I were wide (7.8 ± 3.9 mm) compared with idiopathic syringes (3.9 ± 1.0, p < 0.0001) and those associated with tethered cord (4.2 ± 0.9, p < 0.01). When considering CM-I-associated and idiopathic syringes, the authors found that CM-I-associated syringes were more likely to have their cranial extent in the cervical spine (88%), compared with idiopathic syringes (43%; p < 0.0001). The combination of syrinx width greater than 5 mm and cranial extent in the cervical spine had 99% specificity (95% CI 0.92-0.99) for CM-I-associated syrinx. CONCLUSIONS Syrinx morphology differs according to syrinx etiology. The combination of width greater than 5 mm and cranial extent in the cervical spine is highly specific for CM-I-associated syringes. This may have relevance when determining the clinical significance of syringes in patients with low cerebellar tonsil position.

Spinal Cord Monitoring Data in Pediatric Spinal Deformity Patients With Spinal Cord Pathology

STUDY DESIGN

Retrospective.

OBJECTIVES

The purpose of this study is to review the efficacy of monitoring data and outcomes in pediatric patients with spinal cord pathology.

SUMMARY OF BACKGROUND DATA

The incidence of spinal cord pathology in pediatric patients with scoliosis has been reported between 3% and 20%. Previous studies demonstrated that intraoperative spinal cord monitoring (IOM) during scoliosis surgery can be reliable despite underlying pathology.

METHODS

A single-center retrospective review of 119 spinal surgery procedures in 82 patients with spinal cord pathology was performed. Diagnoses included Arnold-Chiari malformation, syringomyelia, myelomeningocele, spinal cord tumor, tethered cord, and diastematomyelia. Baseline neurologic function and history of prior neurosurgical intervention were identified. Outcome measures included ability to obtain reliable monitoring data during surgery and presence of postoperative neurologic deficits. Results were compared for 82 patients with adolescent idiopathic scoliosis (AIS).

RESULTS

Usable IOM data were obtained in 82% of cases (97/119). Twenty-two cases (18%) had no lower extremity data. Patients with Arnold-Chiari malformation or syringomyelia pathologies, in isolation or together, had a significantly higher rate of reliable data compared to other pathologies (p < .0001). Among study group cases with usable data, there were 1 false negative (1%) and 4 true positive (4%) outcomes. There were no permanent neurologic deficits. The spinal cord pathology group demonstrated 80% sensitivity and 92% specificity.

CONCLUSIONS

Spinal cord monitoring is a valuable tool in pediatric patients with spinal cord pathology undergoing spinal deformity surgeries. When obtained, data allow to detect changes in spinal cord function. Patients with a diagnosis of Arnold-Chiari or syringomyelia have monitoring data similar to those patients with AIS. Patients with other spinal cord pathologies have less reliable data, and surgeons should have a lower threshold for performing wake-up tests to assess spinal cord function intraoperatively.