Occult Tethered Cord Syndrome Research Articles

P.153 Utility of neurophysiology in the diagnosis of tethered cord syndrome (TCS)

Background: Tethered cord syndrome, a condition in which the spinal cord stretches as a child grows, can cause various clinical symptoms. Occult TCS (OTCS) is a condition where a child displays some or many clinical symptoms of TCS, but no radiographic abnormality confirms the presence of a tethered cord (1-4). Diagnosis of OTCS in children is invasive and multi-factorial. The current diagnostic approach involves three main factors- clinical signs and symptoms, radiographic evidence, and motor evoked potentials (MEPs) tested under general anesthesia. Transcranial magnetic stimulation (TMS) is a non-invasive testing method for OTCS. It can replace MEPs, which are conducted under general anesthesia. Methods: We will conduct a case-control series of children at our center who have undergone TMS. We will characterize the children who have TCS and suspected OTCS and detail the children’s current diagnosis methods and outcomes in a technical note. We will then compare their pre-operative and post-operative data. Results: So far, we have conducted TMS on 10 children to help diagnose occult TCS. Conclusions: This approach is a novel and effective way to improve the accuracy of diagnosis in children, potentially preventing unnecessary surgery, or detecting patients who would otherwise suffer from the condition.

Clinical criteria for filum terminale resection in occult tethered cord syndrome.

Tethered cord syndrome (TCS) comprises three symptom categories: back/leg pain, bowel/bladder, and neurological complaints. MRI typically reveals a low-lying conus medullaris, filum terminale (FT) pathology, or lumbosacral abnormalities. FT resection is established in TCS but not in radiologically occult TCS (OTCS). This study aims to identify patients with OTCS who are likely to benefit from FT resection. The authors recruited 149 patients with OTCS (31 pediatric, 118 adult) treated with FT resection-including only cases with progressive TCS, negative spine MRI, and no concurrent neurological/urological conditions. A comprehensive questionnaire collected patient self-reported symptoms and clinical findings at the preoperative and at 3- and 12-month follow-up examinations. Based on questionnaire data, the authors extracted a 15-item symptoms and findings scale to represent the three TCS symptom categories, assigning 1 point for each item present. OTCS presents without radicular/segmental sensorimotor findings, but with leg/back pain and conus dysfunction, in addition to leg fatigue and spasticity; the latter indicating an upper motoneuron pathology. The 15-item scale showed clinical improvement in 89% of patients at the 3-month follow-up and 68% at the 12-month follow-up. Multivariate analysis of the scale revealed that it accurately predicts outcome of FT resection in 82% of cases. Patients with a preoperative score exceeding 6 points are most likely to benefit from surgery. By applying the study's inclusion criteria and incorporating the novel 15-item scale, surgeons can effectively select candidates for FT resection in patients with OTCS. The observed outcomes in these selected patients are comparable to those achieved in degenerative spine surgery.

Sectioning of the Filum Terminale in Patients with Chiari Malformation Type 1 Associated with Occult Tethered Cord Syndrome: Literature Review

AbstractApproximately 125 years ago, a group of pathologies now known as Chiari malformations was described for the first time. However, some mechanisms of its formation still remain unknown. A bibliographic survey was performed through a search in PubMed. In 1938, it was already theorized that an increase in spinal cord tension could be the cause of Chiari malformation type 1 (CM1) tonsillar herniation. In 1953, a condition known for the anchoring of the filum terminale to the vertebral canal was described for the first time and would later be known as tethered cord syndrome (TCS). Some studies have shown that it is associated with increased tension in the spinal cord, and this formed the basis for a possible pathophysiological explanation of tonsillar herniation. Case series emerged reporting that treatment for TCS with the sectioning of the filum terminale (SFT) could provide clinical improvement of patients with CM1. A new pathological entity emerged when it was realized that patients with the clinical picture of TCS could have the medullary cone in its normal position, differing from the caudal migration expected for the TCS. This condition became known as occult tethered cord syndrome (OTCS). Case series attempted to demonstrate its association with the origin of CM1, a non-intuitive association, since the cone in the normal position contradicts traction as a source of tonsillar herniation. To this day, the absence of randomized control trials limits any conclusions regarding the effectiveness of SFT for the treatment of patients with CM1.

A systematic review and meta-analysis of minimally invasive surgery in children with occult tethered cord syndrome.

BackgroundAt present, the surgical treatment of occult tethered cord syndrome (OTCS) in children is mostly two types of minimally invasive surgery: filum terminalis laxity or filum terminalectomy. The clinical efficacy and safety of minimally invasive treatment and conservative treatment are still unclear. Therefore, this study will use the advantages of systematic review and meta-analysis to evaluate the objectivity, and explore the effect of minimally invasive surgery on children with occult tethered cord syndrome.MethodsA computer search was used to search PubMed, Embase, CNKI, Wanfang Database and other literature search websites about the randomized controlled trials (RCTs) of minimally invasive surgery in children with occult tethered cord syndrome and spinal lipoma. Professional journals were manually searched to avoid omissions. The search keywords were: occult myelolipoma, occult tethered cord syndrome, surgical treatment of tethered cord syndrome, occult tethered cord syndrome.ResultsA total of 6 relevant literatures that could be used for meta-analysis were selected. A total of 425 subjects were included in the article, of which 132 were treated conservatively and 293 were treated surgically. The heterogeneity detection test statistics of the included studies were Chi2 (Chi-squared test) =8.18, df (degree of freedom) =5, I2=39%<50%, Z=2.53, and the homogeneity of the included studies was good. The number of unimproved cases under conservative treatment was 40, accounting for 30.30%; the number of unimproved cases under surgical treatment was 33, accounting for 11.26%, and the total unimproved rate of the two groups accounted for 17.17%. The unimproved rate of the experimental group was significantly lower than that of the control group, and the difference was statistically significant (P=0.01). The results of bias analysis showed that there was no significant bias in the literature included in this study.DiscussionMeta-analysis results confirmed that minimally invasive surgery has a significant effect on the treatment of occult children with tethered cord syndrome. However, due to the small sample size of the included literature, further evaluation of the treatment risk is required.

TETHERED CORD SYNDROME IN CHILDREN WITH DAYTIME INCONTINENCE

(Introduction) In tethered cord syndrome, the lower end of the spinal cord is moored to the caudal tissue, causing various neuropathies. Bladder dysfunction often appears early. We herein evaluated children with daytime urinary incontinence in whom tethered cord syndrome was eventually diagnosed. (Method) Eighteen children (9 males and 9 females) with daytime urinary incontinence were enrolled between March 2011 and October 2017. The causes of their urinary incontinence were investigated using spinal MRI and changes in clinical symptoms before and after untethering surgery. (Results) The average age at the first visit was 6.3 years (range: 4-9 years). Urodynamic testing and a voiding cystourethrogram (VCUG) were performed in all cases of refractory daytime incontinence, and all patients with abnormal findings on either test underwent spinal MRI. The diagnosis based on spinal MRI findings was filum lipoma in eight, occult tethered cord syndrome in four, low set conus in four, conus lipoma in one, and sacral meningeal cyst in one, patient. The average observation period after untethering surgery was 66.3 months (range: 22-116 months). All the patients achieved a cure postoperatively. Four patients were treated for nocturnal enuresis by oral medication, and three patients required urological management via clean, intermittent catheterization. (Conclusions) When treating children with daytime continence, one should consider the possibility of tethered cord syndrome, the diagnosis of which can be aided by urodynamic assessment of bladder function.

A critical analysis of surgery for occult tethered cord syndrome.

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

Spinal Dysraphism in the Last Two Decades : What I Have Seen during the Era of Dynamic Advancement.

Compared to any other decade, the last two decades have been the most dynamic period in terms of advances in the knowledge on spinal dysraphism. Among the several factors of rapid advancement, such as embryology during secondary neurulation and intraoperative neurophysiological monitoring, there is no doubt that Professor Dachling Pang stood high amidst the period. I review here the last two decades from my personal point of view on what has been achieved in the field of spinal dysraphism, focusing on occult tethered cord syndrome, lumbosacral lipomatous malformation, terminal myelocystocele, retained medullary cord, limited dorsal myeloschisis and junctional neural tube defect. There are still many issues to revise, add and extend. Profound knowledge of basic science is critical, as well as refined clinical analysis. I expect that young scholars who follow the footsteps of precedent giants will shed bright light on this topic in the future.

The effect of filum terminale sectioning for Chiari 1 malformation treatment: systematic review.

Symptomatic Chiari type I malformation (CM) is treated with posterior fossa decompression with/ without duroplasty. Few authors suggested cerebellar tonsil caudal migration due to a supposed "caudal traction" of cranial nerve structures in a so-called occult tethered cord syndrome. For these authors, filum terminale (FT) sectioning may improve CM symptoms. The objective of this review is to evaluate the effect of FT sectioning on the treatment of CM. Using the PRISMA guidelines for systematic reviews, we reviewed studies to evaluate patient's outcomes with CM who underwent FT sectioning. The MINORS instrument was used for methodological quality assessment. The included studies' levels of evidence (LOE) were classified according to the Oxford Centre of Evidence-Based Medicine. Two studies from the same group of authors were included. We cannot assure if the cited cases in the first study were also included in their latter published study. The described results suggest that outcomes were not collected in a standardized fashion. Outcomes are described vaguely as a percentage of improvement. Case series samples were small and included not only patients with CM but also patients with scoliosis and syringomyelia. The MINORS score reported that both studies had low methodological quality. Both included studies were classified as level 4 of evidence. There is no scientific support for filum terminale sectioning in patients with CM without evidence of tethered cord. This procedure may be considered experimental and should be validated in a strict criterion of inclusion clinical trial comparing outcomes in posterior fossa decompression.

Oculo-Auriculo-Vertebral Dysplasia With Craniocervical Instability and Occult Tethered Cord Syndrome. An Addition to the Spectrum? First Case Report and Review of the Literature.

Oculo-auriculo-vertebral spectrum (OAVS) is an uncommon congenital disorder of abnormal development of the first and second pharyngeal arches. This spectrum is characterized by craniofacial microsomia, epibulbar dermoids, ear abnormalities, renal and cardiac defects, and a wide range of vertebral segmentation and formation disorders. Frequently, the cervicothoracic spine is involved. Only recently, the morbidity attributed to the spinal abnormalities has gained attention. Strategy and timing of spine surgery has become increasingly important in patients with OAVS. Here, we report a case of OAVS with characteristic vertebral cervical and thoracic involvement and its sequelae requiring multiple spinal procedures, further complexed by an unprecedented occult tethered cord syndrome, which was successfully treated by surgical detethering. In this context, the recent literature on spinal anomalies is reviewed.

A review of the disagreements in the prevalence and treatment of the tethered cord syndromes with chiari-1 malformations

Background:The tethered cord syndrome (TCS) accompanying Chiari-1 (CM-1) malformations and the occult tethered cord syndrome (OTCS) syndrome accompanying the low lying cerebellar tonsil (LLCT) syndrome may be treated with sectioning of the filum terminale (SFT).Methods:Utilizing PubMed, we reviewed the neurosurgical literature to determine how frequently spinal neurosurgeons diagnosed the TCS (e.g., conus terminating below the normal L1-L2 disc level) on lumbar magnetic resonance (MR) studies in patients with CM-1 malformations [e.g. tonsils >5–12 mm below the foramen magnum (FM) warranting SFT]. In addition, we assessed how frequently spinal neurosurgeons encountered the OTCS (e.g., conus normally located at L1-L2 on MR) accompanying the LLCT (e.g., tonsils herniated <5 mm below the FM) also requiring SFT.Results:According to the neurosurgical literature, the incidence of TCS accompanying CM-1 requiring SFT ranged from 2.2% to < 6%, and up to 14%. Few studies additionally highly correlated the OCTS accompanying the LLCT syndrome warranting SFT.Conclusions:Given the differences in the literature, more studies are needed to assess the risks (complications) vs. benefits (improved neurological outcomes) of SFT surgery for TCS with CM-1 and SFT for OCTS with LLCT.

Filum Section for Urinary Incontinence in Children with Occult Tethered Cord Syndrome: A Randomized, Controlled Pilot Study

Occult tethered cord syndrome, in which there is normal neuroanatomic imaging despite clinical and urodynamic evidence of neuropathic bladder behavior, is controversial. Several uncontrolled series describe improvement in bladder function following section of the filum terminale. We performed a pilot randomized, controlled study comparing medical treatment to surgical section of the filum plus medical treatment in children with occult tethered cord syndrome. Children refractory to standard medical management for 1 year or more with normal conus position on magnetic resonance imaging and abnormal urodynamics were randomized. Exclusion criteria included any neurological conditions, spinal dysraphism, bladder outlet obstruction and an atonic bladder. Patients were assessed at randomization and 1 year later with a standardized urodynamic score, the validated PEMQOL (Pediatric Enuresis Module on Quality of Life™) scale, and a validated bowel and bladder dysfunction score. After 8 years we accrued 21 patients. The bowel and bladder dysfunction score improved in the surgical and medical arms (20% and 24%) and the urodynamic score improved slightly (6% and 4%, respectively). The PEMQOL Child and Family Impact Scales improved modestly in both groups. All differences were nonsignificant. Interim analysis indicated that more than 700 patients in each arm would be required to demonstrate a statistical difference with respect to urodynamic score based on our preliminary data. There appears to be no objective difference in urological outcome between medical management plus or minus filum section for patients with occult tethered cord syndrome. These data challenge the existence of the concept of occult tethered cord syndrome, in which bowel and bladder dysfunction score is attributed to tethering by the filum despite a normally located conus.

Occult tethered cord syndrome: a review

Tethered cord syndrome is a well-defined condition, the management of which is fairly uniform. In contrast, occult tethered cord syndrome is a recently defined entity, where the management is still controversial. The pathophysiology is unclear and may be conceptually incongruent with current understanding of typical tethered cord syndrome. Presentation, investigation, and management of this condition are reviewed, and current understanding is presented. The aim of this study is to review the presentation, pathophysiology, investigation, and management of occult tethered cord syndrome. Literature review. Patients with occult tethered cord syndrome presents predominantly with urologic symptoms. Adult and pediatric patients vary slightly in their presentation with a higher incidence of pain in the former and incontinence in the latter. Operative management for these patients is associated with consistent improvement in urologic function in particular, although surgery is also associated with risk of worsening symptoms. The natural history of untreated patients is unknown. As occult tethered cord syndrome becomes increasingly recognized, it is important to be aware of the potential benefits of operative intervention for appropriately selected patients. Given that the natural history of this entity remains unknown, a clinical trial is currently underway that may assist in defining the role for operative management in treating this condition.

Use of prone position magnetic resonance imaging for detecting the terminal filum in patients with occult tethered cord syndrome

The pathophysiology of occult tethered cord syndrome (OTCS) with no anatomical evidence of a caudally shifted conus and a normal terminal filum is hard to understand. Therefore, the diagnosis of OTCS is often difficult. The authors hypothesized that the posterior displacement of the terminal filum may become prominent in patients with OCTS who are in a prone position if filum inelasticity exists, and they investigated prone-position MRI findings. Fourteen patients with OTCS and 12 control individuals were examined using T2-weighted axial MRI with the patients in a prone position on a flat table. On each axial view, the distance between the posterior and anterior ends of the subarachnoid space (A), the distance between the posterior end of the subarachnoid space and the terminal filum (B), the distance between the posterior end of the subarachnoid space and the dorsal-most nerve among the cauda equina (C), and the distance between the posterior end of the subarachnoid space and the ventral-most nerve (D) were measured. The location ratios of the terminal filum, the dorsal-most nerve, and the ventral-most nerve were calculated by the ratio of A to B (defined as TF = B/A), A to C (defined as DN = C/A), and A to D (defined as VN = D/A), respectively. Patients underwent sectioning of the terminal filum with the aid of a surgical microscope. The low-back pain Japanese Orthopaedic Association score was obtained before surgery and at the final follow-up visit. On prone-position axial MRI, the terminal filum was separated from the cauda equina and was shifted caudally to posterior in the subarachnoid space in all patients with OTCS. The locations of the caudal cauda equina shifted to ventral in the subarachnoid space. The TF values in the OTCS group were significantly lower than those in the control group at the L3-4 (p = 0.023), L-4 (p = 0.030), L4-5 (p = 0.002), and L-5 (p < 0.001) levels. In contrast, the DN values in the OTCS group were significantly higher than those of the control group at the L-2 (p = 0.003), L2-3 (p = 0.002), L-3 (p < 0.001), L3-4 (p < 0.001), L-4 (p = 0.007), L4-5 (p = 0.003), and S-1 (p = 0.014) levels, and the VN values in the OTCS group were also significantly higher than those of the control group at the L2-3 (p = 0.022), L-3 (p = 0.027), L3-4 (p = 0.002), L-4 (p = 0.011), L4-5 (p = 0.019), and L5-S1 (p = 0.040) levels. Sections were collected during surgery for histological evaluation, and a decreased elasticity within the terminal filum was suggested. Improvements in the Japanese Orthopaedic Association score were observed at the final follow-up in all patients. The authors' new method of using the prone position for MRI shows that the terminal filum is located significantly posterior and the cauda equina is located anterior in patients with OTCS, suggesting a difference in elasticity between the terminal filum and cauda equina.

Section of the filum terminale: is it worthwhile in Chiari type I malformation?

A section of the filum terminale (SFT) is used for the surgical treatment of isolated tethered cord or that resulting from neurulation disorders. More recently, it has been proposed for the management of the occult tethered cord syndrome (OTCS), though it is still under debate. Even more controversial appears to be the use of SFT in patients with Chiari type I malformation (CIM), which is based on the possible presence of OTCS. This review shows that: (1) there are issues both in favor and against the occurrence of OTCS, (2) there is no significant correlation between CIM and tethered cord, the old "caudal traction theory" being not supported by clinical or experimental evidences. On these grounds, a relationship between CIM and OTCS is hard to be demonstrated, (3) a subgroup of patients with CIM suffering from OTCS may exist and benefit from SFT.

Tethered cord syndrome: a review of the literature from embryology to adult presentation

Tethered cord syndrome (TCS) is a clinical condition of various origins that arises from tension on the spinal cord. Radiographic findings may include the conus medullaris in a lower than normal position, fatty infiltration of the filum terminale, lipomyelomeningocele, myelomeningocele, myelocystocele, meningocele, split cord malformations, dermal sinus, anorectal malformations, and intraspinal tumors. The clinical constellation of signs and symptoms associated with TCS may include dermatologic, urological, gastrointestinal, neurological, and orthopedic findings. The current review focuses on TCS by age group of the more common causes of the condition, including myelomeningocele, lipomyelomeningocele, as well as the adult presentation of occult TCS. Pertinent review of the neuroembryology and normal anatomical position of the conus medullaris is included.

Study of the effects of flexion on the position of the conus medullaris: follow-up study using MR imaging in non-human primates

Previous anatomical and radiological studies of conus position with flexion and extension of the spine have had conflicting results. We previously performed a human cadaveric study with direct visualization of the conus during flexion and extension to further study this question and to potentially determine if flexion and extension of the spine during MRI may prove to be a diagnostic tool in occult tethered cord syndrome. We found no movement of the conus during flexion or extension. The present is a follow-up study using MR imaging of Rhesus (Macaca mulatta) monkeys to see if the conus moves in flexion or extension of the spine. We placed three adult male Rhesus monkeys under general anesthesia into a 1.5 T Siemens MRI machine. Sagittal T2-weighted images were obtained through the lumbosacral spine during flexion and extension. The conus position was compared between studies. In all animals, the conus terminated between L6 and S1, and the conus did not move from its neutral position in either flexion or extension of the spine. Flexion and extension of the non-human primate's spine does not result in a change of position of the conus medullaris to change position. Therefore, it is unlikely that the conus would change position during flexion and extension MRI in an adult without a tethered spinal cord.

Study of the effects of flexion on the position of the conus medullaris

Previous anatomic studies have shown the conus medullaris to terminate between T12 and L1 vertebral levels in adults with normal spinal anatomy. Prior anatomic and radiographic studies of conus position with flexion and extension of the spine have had conflicting results. We performed a cadaveric study with direct visualization of the conus during flexion and extension to further study this question and potentially determine if flexion and extension of the spine during magnetic resonance imaging may prove to be a diagnostic tool in such pathologies as occult tethered cord syndrome. We performed T12 to L3 laminectomies in five fresh adult cadavers and exposed the conus and cauda equina. Cadavers were fully flexed at the waist and neck and the conus position observed. In all specimens, the conus terminated between T12 and L1 in the prone position. During flexion, the conus position remained stable with no ascent. However, flexion produced stretching and medial displacement of the cauda equina. Flexion of the spine does not cause the conus medullaris to change position in fresh human cadavers; however, flexion does cause the cauda equina to stretch and displace medially over the conus. Therefore, it is unlikely that the conus would change position during spine flexion during imaging or procedures such as lumbar puncture.

COMPARISON OF SECTION OF FILUM TERMINALE AND NON-NEUROSURGICAL MANAGEMENT FOR URINARY INCONTINENCE IN PATIENTS WITH NORMAL CONUS POSITION AND POSSIBLE OCCULT TETHERED CORD SYNDROME

Patients with persistent urinary incontinence and a normal location of the conus on magnetic resonance imaging scans may have occult tethered cord syndrome (OTCS). We compare outcomes in such patients after filum section versus nonoperative treatment. We performed a retrospective analysis of a consecutive series of children with refractory urinary incontinence and normal location of the conus who were offered section of the filum for treatment of possible OTCS. Eight children, aged 4.4 to 9.8 years, underwent filum section, with one child undergoing two such operations. Clinical urological improvement occurred in seven children at a mean follow-up period of 3.1 years, with improved urodynamic findings in four of the seven children tested postoperatively. Other non-urological back or lower limb abnormalities improved in five out of six children with such findings. None of the patients underwent additional urological operations after filum section. Seven children, aged 3.1 to 13.5 years, all of whom had abnormal urodynamic findings, did not undergo filum section. At a mean follow-up period of 3.3 years, two patients had urological improvement and three patients had undergone bilateral ureteric reimplantations. Other non-urological back and/or lower limb abnormalities were present in five patients and did not improve. One patient had the filum cut after 8 years and improved thereafter. Section of the filum in children with refractory urinary incontinence and OTCS may produce better urological outcomes than continued medical management. A definitive answer to the question of whether section of the filum is better than non-neurosurgical medical management for children with OTCS awaits the conclusion of a randomized controlled trial.

Section of the terminal filum for occult tethered cord syndrome: toward a scientific answer

The concept of an occult tethered cord syndrome (OTCS), in which a normally located conus is tethered by the terminal filum, is controversial. Children with OTCS typically present with neurogenic urinary incontinence that has been refractory to medical management. Authors of a number of case series have suggested that section of the terminal filum may improve urinary symptoms, but the quality of the evidence supporting this treatment is not good. The literature related to OTCS is reviewed and the progress toward a randomized controlled trial to assess the value of filum section in OTCS is detailed. A scientific answer to the question of filum section for OTCS awaits the results of an ongoing pilot randomized controlled trial and a more definitive trial to follow.

Occult Tethered Cord

(N. R. Selden) Object Controversy exists regarding proper indications for surgical lysis of the terminal filum in children with voiding dysfunction and tethered spinal cord. Recently, surgery has been offered to children who have a normally positioned conus medullaris and no terminal filum abnormality visible on 1.5-tesla magnetic resonance images (referred to as minimal or occult tethered cord syndrome [TCS]). The author evaluates existing clinical and scientific evidence relevant to this controversy. Methods Five retrospective, observational, noncontrolled studies of surgical terminal filum lysis for occult TCS in children were identified. Two further studies in which the authors reported surgical results in children with a normal-level conus medullaris were also identified. Conclusions These studies document encouraging clinical outcomes following surgery. Clinicopathological evidence suggests that occult TCS may result from radiographically occult structural abnormalities of the terminal filum. Although a preponderance of Class III clinical evidence supports the use of surgical filum lysis to treat occult TCS, no Class I or II evidence exists. Clinical practice varies; therefore, performance of a prospective randomized clinical trial of surgical terminal filum lysis for the treatment of occult TCS is advocated.