Surgical Outcomes in Patients Exhibiting Muscular Weakness Postadolescence Due to Tight Filum Terminale.

INTRODUCTION: Tight filum terminale is a neurological condition marked by various symptoms, including muscle weakness. There is a notable lack of literature addressing muscle weakness, particularly in cases emerging during adolescence and beyond. The diagnosis is challenging due to a lack of radiological abnormalities, and the literature on its treatment, especially untethering, in adults is limited. This study aims to evaluate the effectiveness of untethering in improving muscle weakness and other symptoms in postadolescent patients diagnosed with tight filum terminale. METHODS: A retrospective analysis was conducted on seven postadolescent patients diagnosed with tight filum terminale and presenting muscle weakness who underwent untethering at our institution between January 2018 and August 2022. Patients were monitored for muscle strength improvement, lumbar and lower extremity pain, and bowel and bladder dysfunction (BBD) after untethering. RESULTS: Muscle weakness improved in all cases after untethering, with a mean duration of 9.1 weeks for the improvement. Patients unable to walk independently regained mobility in an average of 22.3 weeks. Lumbar and lower limb pain improved in all cases within an average of 8.1 weeks, while BBD improved in six of the seven cases within an average of 1.9 weeks. CONCLUSIONS: Our findings suggest that untethering is an effective surgical intervention for postadolescent patients diagnosed with tight filum terminale and presenting muscle weakness.

Comparison of the inter-laminar approach and laminotomy open approach for filum terminale lipoma: A retrospective analysis.

PURPOSE: Filum terminale lipoma (FTL) causes spinal-cord tethering and is associated with tethered-cord syndrome, which is treated by dissection of the entrapment. The conventional treatment for FTL involves dissection of the spinal cord through a laminotomy open approach (LOA). However, in recent years, the interlaminar approach (ILA) has gained popularity as a minimally invasive surgery. This study compares the effectiveness of the minimally invasive ILA with the conventional LOA in treating FTL. METHODS: We retrospectively evaluated data on the ILA and LOA for FTL at our center. In total, 103 participants were enrolled, including 55 in the ILA group and 48 in the LOA group. RESULTS: The ILA required significantly less surgical time and resulted in less blood loss. The improvement rate of symptoms in symptomatic patients was 84%, and for urinary symptoms and abnormal urodynamic study findings, it was 77%. The postoperative maintenance rate for asymptomatic patients was 100%. Postoperative complications of ILA included delayed wound healing in two patients (3.6%). CONCLUSION: Compared with LOA, ILA offers advantages in terms of shorter operative time and less blood loss, with no significant difference in long-term symptom-improvement rates between the groups.

Utility of Multimodal Intraoperative Neuromonitoring for Excision of Filum Terminale Ependymoma in Close Proximity to Conus.

Myxopapillary ependymoma are well circumscribed tumours arising mainly from conus medullaris (CM) and filum terminale (FT), typically presenting at median age of 39 years.1 Owing to its aggressive clinical behaviour including cerebrospinal fluid dissemination and local recurrence, it is classified as grade 2 in World Health Organisation Central Nervous System 5 Classification.2 Gross total resection without capsular violation is critical, as subtotal resection is associated with local recurrence.3 The FT comprises intradural filum terminale (iFT) and extradural filum terminalecomponents with iFT extending from the inferior tip of the CM to coccyx.4 The iFT-CM junction is a transitional zone; with neural tissue being incrementally replaced by fibrous tissue of filum, gradually converging to a pure nonneural FT.5 Achieving gross total resection is challenging for intramedullary FT myxopapillary ependymoma in proximity to conus, necessitating neuromonitoring to preserve vital CM functions. We present a case of 33-year-old male with 6 months of nocturnal back pain and bilateral lower limb without neurological deficits. Preoperative MRI revealed a T2 hyperintense, heterogeneously contrast enhancing intradural extramedullary mass at L1 vertebral level.

Diagnosis and Management of Tethered Cord Syndrome.

Tethered cord syndrome is a condition in which the spinal cord is tethered by pathological structures such as a tight filum terminale, intradural lipomas with or without a connecting extradural component, intradural fibrous adhesions, diastematomyelia, and neural placode adhesions following closure of a myelomeningocele.It usually occurs in childhood and adolescence as the spine grows in length, but it can also develop in adulthood. Symptoms of tethered cord syndrome are slowly progressive and varied. Incorrect diagnosis and inappropriate treatment may be provided if the physician lacks knowledge and understanding of this disease.This chapter aims to describe the pathophysiology, syndromes, diagnostic imaging, surgical treatment, and prognosis of tethered cord syndrome to enhance the understanding of this condition.

Use of ultrasound to estimate the prevalence of occult spinal dysraphism in children undergoing urogenital and anorectal surgeries: A cross-sectional study.

Background and Aim: The use of ultrasound has immensely increased the safety toward regional blocks and central venous access and has been considered as the standard of care for securing central access. The aim of this study is to estimate the prevalence of occult spinal dysraphism using ultrasound in children less than 2 years of age undergoing elective urogenital or anorectal surgery. Material and Methods: The lumbosacral region of 159 American Society of Anesthesiologists (ASA) category I/II patients, posted for elective urogenital and anorectal surgery was scanned with ultrasound, prior to giving caudal block. Results: The prevalence of occult spina bifida was 3% in our study. There was no statistically significant association of cutaneous marker with abnormal scan. Conclusion: Prevalence of occult spina bifida was ten-times higher in our study than in the general population. Perioperative ultrasound screening of the lower spinal anatomy by anesthesiologist done prior to performing neuraxial block is worthwhile in ruling out occult spinal anomalies in high-risk children of occult spinal dysraphism.

Surgical management of tethered spinal cord syndrome through biportal endoscopic approach: a novel technical note.

This video article explores a case of tethered cord release through a minimally invasive biportal endoscopic approach. A 24-year-old female with chronic back pain and thigh numbness underwent surgery. The chosen approach involved biportal endoscopic technique, demonstrating precision with minimal bone excision. Preoperative imaging revealed a midline fusion defect at L5 and abnormal conus medullaris termination. The surgical procedure involved one-sided hemilaminectomy, durotomy, and careful filum terminale separation. Postoperatively, radiological exams confirmed success with minimal bone defect. Emphasizing minimal invasiveness, reduced bone excision, and muscle sparing, this technique showcased successful outcomes, enabling the patient's rapid postoperative recovery without complications. The video can be found here: https://stream.cadmore.media/r10.3171/2024.1.FOCVID23228.

Preliminary Experience with 3-Dimensional-Exoscopic Untethering of a Type II Diastematomyelia: Technical Note and Review of the Literature.

OBJECTIVE: To describe the use of a high-definition 3-dimensional (3D) exoscope (VITOM 3D exoscope; KARL STORZ GmbH) for the neurosurgical treatment of a rare pediatric disease, type II diastematomyelia with associated tethered cord. METHODS: A 13-year-old girl who presented with diastematomyelia type II with a tethered cord was surgically treated with the aid of a high-definition 3D exoscope, with a third operator moving and pivoting its arm. Intraoperative monitoring and mapping were arranged. The surgery required a bilateral access to address both the split cord malformation and the tethering of the filum terminale. The filum terminale was identified and cut, and the connective fibrovascular tissue separating the 2 medullary halves was unraveled. These steps were performed with no changes of intraoperative monitoring. Pertinent literature was addressed carefully. RESULTS: The surgery was successful, and the patient was discharged home on the eleventh postoperative day without any complications. The 3-month postoperative magnetic resonance imaging scan demonstrated regular surgical outcomes; no dynamic motor disturbances were reported. To our knowledge, this is the first spinal congenital malformation treated with the use of a 3D exoscope. CONCLUSIONS: The use of 3D exoscope is advancing in spinal surgery, as it provides magnification, stereopsis, lighting, and definition comparable with the operating microscope; the addition of a third operator simplified the operations of moving around the arm, releasing these burdens for the surgeons. Our preliminary experience proved that the use of a 3D exoscope is feasible and safe for the surgical management of a type II diastematomyelia with tethered cord.

Convolutional neural network-based magnetic resonance image differentiation of filum terminale ependymomas from schwannomas.

PURPOSE: Preoperative diagnosis of filum terminale ependymomas (FTEs) versus schwannomas is difficult but essential for surgical planning and prognostic assessment. With the advancement of deep-learning approaches based on convolutional neural networks (CNNs), the aim of this study was to determine whether CNN-based interpretation of magnetic resonance (MR) images of these two tumours could be achieved. METHODS: Contrast-enhanced MRI data from 50 patients with primary FTE and 50 schwannomas in the lumbosacral spinal canal were retrospectively collected and used as training and internal validation datasets. The diagnostic accuracy of MRI was determined by consistency with postoperative histopathological examination. T1-weighted (T1-WI), T2-weighted (T2-WI) and contrast-enhanced T1-weighted (CE-T1) MR images of the sagittal plane containing the tumour mass were selected for analysis. For each sequence, patient MRI data were randomly allocated to 5 groups that further underwent fivefold cross-validation to evaluate the diagnostic efficacy of the CNN models. An additional 34 pairs of cases were used as an external test dataset to validate the CNN classifiers. RESULTS: After comparing multiple backbone CNN models, we developed a diagnostic system using Inception-v3. In the external test dataset, the per-examination combined sensitivities were 0.78 (0.71-0.84, 95% CI) based on T1-weighted images, 0.79 (0.72-0.84, 95% CI) for T2-weighted images, 0.88 (0.83-0.92, 95% CI) for CE-T1 images, and 0.88 (0.83-0.92, 95% CI) for all weighted images. The combined specificities were 0.72 based on T1-WI (0.66-0.78, 95% CI), 0.84 (0.78-0.89, 95% CI) based on T2-WI, 0.74 (0.67-0.80, 95% CI) for CE-T1, and 0.81 (0.76-0.86, 95% CI) for all weighted images. After all three MRI modalities were merged, the receiver operating characteristic (ROC) curve was calculated, and the area under the curve (AUC) was 0.93, with an accuracy of 0.87. CONCLUSIONS: CNN based MRI analysis has the potential to accurately differentiate ependymomas from schwannomas in the lumbar segment.

Atypical presentation of tight filum terminale with thoracic disc herniation: a case report.

BACKGROUND: Tight filum terminale is a rare and challenging condition to diagnose because it presents with nonspecific symptoms and unclear imaging findings. This report documents an atypical case of tight filum terminale. CASE PRESENTATION: The patient was a previously healthy Asian 18-year-old male presenting with recurrent upper extremity and back pain, initially treated as nonspecific musculoskeletal pain. Notably, the patient's symptoms were inconsistent with the dermatome, showing no correlation with his skin's sensory innervation areas. In contrast to typical tight filum terminale presentations focused on lower extremity and lumbar region disturbances, this patient experienced pain and weakness predominantly in the upper extremities and back, hypothesized to result from traction myelopathy exacerbated by thoracic disc herniation. Investigations including blood and nerve function tests were inconclusive. However, a magnetic resonance imaging scan revealed a combination of tight filum terminale and tiny thoracic disc herniation. A diagnosis of tethered spinal cord syndrome was confirmed following further tests and imaging. The filum terminale was surgically removed, resolving the symptoms at a 7-month follow-up. CONCLUSIONS: This case underlines the importance of including tight filum terminale as a differential diagnosis in cases of unexplained upper or lower extremity pain. Primary care practitioners, particularly those managing undefined symptoms, should consider tight filum terminale in their diagnostic approach.

The discrepancy in triggered electromyography responses between fatty filum and normal filum terminale.

BACKGROUND: Functional role of filum terminale (FT) was not well studied though it contains structure basis for nerve impulse conduction. We aimed to explore the possible functions of the FT from the perspective of triggered electromyography (EMG) during surgery. METHODS: We retrospectively reviewed intraoperative neurophysiological monitoring data from pediatric patients who underwent intradural surgeries at the lumbar level in Shanghai Children's. Hospital from January 2018 to March 2023. Altogether 168 cases with complete intraoperative neurophysiological recordings of the FT were selected for further analysis. Triggered EMG recordings of the filum originated from two main types of surgeries: selective dorsal rhizotomy (SDR) and fatty filum transection. RESULTS: 96 cases underwent SDR and 72 cases underwent fatty filum transection. Electrical stimulation of the FT with fatty infiltration did not elicit electromyographic activity in the monitored muscles with the maximum stimulus intensity of 4.0 mA, while the average threshold for FT with normal appearance was 0.68 mA, and 89 out of 91 FT could elicit electromyographic responses in monitored channels. The threshold ratio of filum to motor nerve roots at the same surgical segment was significantly higher in patients with fatty filum, and a cut-off point of 21.03 yielded an area under curve of 0.943, with 100% sensitivity and 85.71% specificity. CONCLUSION: Filum with normal appearance can elicit electromyographic activity in the lower limbs/anal sphincter similar to the performance of the cauda equina nerve roots. The threshold of fatty filum is different from that of normal appearing FT. Triggered EMG plays an important role in untethering surgeries.

Endoscopic spinal cord untethering using a 1 cm skin incision technique in pediatrics: a technical case report.

BACKGROUND: Spinal cord untethering by sectioning the filum terminale is commonly performed in tethered cord syndrome patients with minor abnormalities such as filar lipoma, thickened filum terminale, and low conus medullaris. Our endoscopic surgical technique, using the interlaminar approach, allows for sectioning the filum terminale through a very small skin incision. To our knowledge, this procedure has not been previously reported. This is the first case report involving a 1 cm skin incision. CASE PRESENTATION: A 9-month-old male patient was referred to our neurosurgical department due to a coccygeal dimple. MRI revealed a thickened fatty filum. After considering the treatment options for this patient, the parents agreed to spinal cord untethering. A midline 1 cm skin incision was made at the L4/5 vertebral level. Untethering by sectioning the filum terminale was performed by full endoscopic surgery using the interlaminar approach. The procedure was uneventful and there were no postoperative complications. CONCLUSIONS: In terms of visibility and minimizing invasiveness, our surgical technique of using the interlaminar approach with endoscopy allows for untethering by sectioning the filum terminale through a very small skin incision.

Sacral terminal filar cyst: a distinct variant of spinal meningeal cyst and midterm clinical outcome following combination resection surgery.

Objective: Spinal meningeal cysts (SMCs) are currently classified into three types: extradural cysts without nerve root fibers (Type I), extradural cysts with nerve root fibers (Type II), and intradural cysts (Type III). However, the sacral terminal filar cyst is a distinct subtype with the filum terminale rather than nerve roots within the cyst. This study aimed to investigate the clinicoradiological characteristics and surgical outcomes of sacral terminal filar cysts. Methods: A total of 32 patients with sacral terminal filar cysts were enrolled. Clinical and radiological profiles were collected. All patients were surgically treated, and preoperative and follow-up neurological functions were evaluated. Results: Chronic lumbosacral pain and sphincter dysfunctions were the most common symptoms. On MRI, the filum terminale could be identified within the cyst in all cases, and low-lying conus medullaris was found in 23 (71.9%) cases. The filum terminale was dissociated and cut off in all cases, and the cyst wall was completely resected in 23 (71.9%) cases. After a median follow-up period of 26.5 ± 15.5 months, the pain and sphincter dysfunctions were significantly improved (both P < 0.0001). The cyst recurrence was noted in only 1 (3.1%) case. Conclusions: Sacral terminal filar cysts are rare, representing a distinct variant of SMCs. Typical MRI features, including filum terminale within the cyst and low-lying conus medullaris, may suggest the diagnosis. Although the optimal surgical strategy remains unclear, we recommend a combination of resection of the cyst wall and dissociation of the filum terminale. The clinical outcomes can be favorable.

Tethered Cord Syndrome: Role of Imaging Findings in Surgical Decision-Making.

For infants presenting with urinary problems or lower extremity weakness, imaging is ordered to investigate spinal pathology. Tethered cord syndrome (TCS) often manifests without conclusive anatomic evidence. In our case, a premature infant presented with urosepsis and was found to have an asymmetric gluteal crease and a sacral dimple. Renal ultrasound showed mild hydronephrosis, and a cystourethrogram revealed bilateral high-grade vesicoureteral reflux. Ultrasound and magnetic resonance imaging demonstrated a borderline low-lying spinal cord at the mid-L3 vertebral level. Urodynamic testing to confirm neurogenic bladder could not be completed on the first attempt due to urinary tract infection and on the second attempt due to instrument intolerance. Despite the lack of conclusive imaging evidence of a tethered cord, enough supportive clinical data was present to proceed with surgical intervention with the goal of preventing the progression of neurological dysfunction. Because TCS is ultimately a clinical diagnosis, appropriate management should not be discouraged by inconclusive or borderline imaging findings.

Resection of a large multisegmental filum terminale ependymoma through a multisegmental hemilaminectomy.

This video demonstrates a gross-total resection of a multisegmental intradural extramedullary tumor using only multisegmental hemilaminectomy. The patient is a 21-year-old woman presenting with only backache. MRI of the lumbar spine demonstrates a large multisegmental heterogeneously enhancing intradural extramedullary tumor extending down from the eleventh dorsal vertebrae down to the fifth lumbar vertebrae. The surgical video demonstrates the technique of multisegmental hemilaminectomy and microsurgical resection of the tumor without posterior spinal instrumentation. Postoperatively, the patient had no neurological deficit and was discharged on postoperative day 5. Three-month postoperative MRI shows no residual disease or spinal deformity.

Anatomical considerations regarding a high-flow arteriovenous fistula below the conus medullaris in a patient with hereditary hemorrhagic telangiectasia: Case report.

BACKGROUND AND IMPORTANCE: Cauda equina radicular arteriovenous fistulas are rare "low flow" shunting lesions characterized by direct communication between the radicular artery and vein of a cauda equina nerve root. None have been associated with hereditary hemorrhagic telangiectasia and a high-flow cauda equina radicular arteriovenous fistula has never been reported. We present a unique case of a high-flow cauda equina radicular arteriovenous fistula in a patient with hereditary hemorrhagic telangiectasia. Marked flow-induced vascular remodeling posed significant diagnostic and therapeutic challenges which will be highlighted in this report. CLINICAL PRESENTATION: A 39-year-old female with genetically confirmed hereditary hemorrhagic telangiectasia presented with progressive thoracic myelopathy secondary to a high-flow single-hole arteriovenous fistula below the conus. The feeding artery, arising from the anterior spinal artery, and draining vein had a paramedian course, favoring the diagnosis of a cauda equina radicular arteriovenous fistula (supplied by a proximal radicular artery) over a filum terminale arteriovenous fistula. Transarterial embolization was attempted but significant elongation and tortuosity of the anterior spinal artery precluded microcatheter access to the fistulous point. Surgical disconnection was successfully performed. The intraoperative findings supported the diagnosis of cauda equina radicular arteriovenous fistula. Delayed neurologic deterioration secondary to overshooting venous thrombosis was observed. She recovered after the initiation of therapeutic anticoagulation. CONCLUSION: To the best of our knowledge, we hereby report the first high-flow cauda equina radicular arteriovenous fistula. The accurate differentiation of cauda equina radicular arteriovenous fistula from filum terminale arteriovenous fistulas, while challenging, is important to avoid treatment-related complications. Careful preoperative planning, the use of specialized endovascular and surgical techniques, and meticulous postoperative care can ensure the safe and complete disconnection of high-flow cauda equina radicular arteriovenous fistulas.

[Classification and microsurgical treatment of primary tethered cord syndrome in adults].

OBJECTIVE: To summarize the clinical manifestation, classification, and experience of surgical treatment of primary tethered cord syndrome (TCS) in adults. METHODS: The authors retrospectively analyzed a series of 171 adult patients with primary TCS who were surgically treated under microscope from March 2007 to October 2019. There were 61 males and 110 females whose ages were 18-65 years, with an average age of (39.02±11.81) years. Clinically, the patients presented with various neurological symptoms and signs including lower back and legs pain, reflex changes, sensory disturbances, muscle weakness, and sphincter problems. They were divided into 5 types by clinical manifestations and neuro-imaging features: (1) filum terminale traction in 69 cases, (2) split cord malformation in 21 cases, (3) myelomeningocele in 20 cases, (4) lipomyelomeningocele in 36 cases, and (5) dermal sinus traction in 25 cases. All the patients underwent microsurgery to untether the spinal cord. The patients kept prone position 7 days postoperatively. The Kirollos grading was used to evaluate the outcome of intraoperative untethering. The visual analogue scale (VAS) was used to evaluate the pain, the score of critical muscle strength was used to evaluate the lower extremity motor function, and the Japanese Orthopaedic Association (JOA) sphincter function score was used to evaluate the bladder function. RESULTS: All of the 171 patients were treated with microsurgery to release the adhesion and cut off the filum terminalis. 61 cases of them received resection of the lesions according to the etiology. All the tethered spinal cord reached Kirollos grade Ⅰ untethering and the dural sac was reconstructed. Other than 5 patients had cerebrospinal fluid leakage and incision laceration and underwent re-suture, there was no surgical complication. The local pain was relieved, the lower limbs weakness or bowel and bladder dysfunction gradually recovered postoperatively. The period of follow-up ranged from 6 months to 12.5 years with an average of (5.62±2.31) years. The neurological function was improved in 153 cases and stable in 18 cases. There was no recurrence of tethered cord be found during the follow-up period. CONCLUSION: The primary TCS in adulthood could be classified into 5 types by clinical manifestations and neuro-imaging features and surgical treatment should be undertaken in regard to the classifications including dissection and resection of the lesion detethering the spinal cord and reconstruction of the dura sac under microscope. The outcome of surgical treatment is satisfactory.

Role of Magnetic Resonance Imaging in the Screening of Closed Spinal Dysraphism.

Closed spinal dysraphism (CSD) encompasses a heterogeneous group of spinal cord deformities, which can be accompanied by several types of skin stigmata. These skin stigmata may include inconspicuous features, such as sacral dimples and deformed gluteal clefts, but the association between such mild skin stigmata and CSD is uncertain. This study aimed to reevaluate the indication for magnetic resonance imaging (MRI) in patients with skin stigmata while considering the indication for surgery. A retrospective analysis was conducted on magnetic resonance images of 1255 asymptomatic children with skin stigmata between 2003 and 2015. Skin stigmata classification was based on medical chart data. All subtypes of CSDs except for filum terminale lipomas (FTL), FTL thicker than 2 mm or with low conus medullaris, were considered to meet the surgical indication. CSD prevalence was estimated while considering the surgical indications and assessed after excluding all FTL cases. Skin stigmata were classified into seven types, dimple, deformed gluteal cleft, hair, subcutaneous mass, appendage, discoloration, and protruding bone, and included 1056 isolated and 199 complex ones. The prevalence of CSD was 19.5%, 6.8%, and 0.5% among patients with isolated dimples (n = 881) and 13.9%, 5.8%, and 0.7% among those with isolated deformed gluteal clefts (n = 136) for all cases, surgical indications, and patients without FTL, respectively. Dimples and deformed gluteal clefts had a low prevalence of CSD requiring surgical intervention, and cases without FTL were rare. Asymptomatic patients with mild skin stigmata may not require immediate MRI.

MRI characteristics of lumbosacral dural arteriovenous fistulas.

Background and purpose: Spinal dural arteriovenous fistulas located in the lumbosacral region are rare and present with nonspecific clinical signs. The purpose of this study was to find out the specific radiologic features of these fistulas. Methods: We retrospectively reviewed the clinical and radiological data of 38 patients diagnosed with lumbosacral spinal dural arteriovenous fistulas in our institution from September 2016 to September 2021. All patients underwent time-resolved contrast-enhanced three-dimensional MRA and DSA examinations, and were treated with either endovascular or neurosurgical strategies. Results: Most of the patients (89.5%) had motor or sensory disorders in both lower limbs as the first symptoms. On MRA, the dilated filum terminale vein or radicular vein was seen in 23/30 (76.7%) patients with lumbar spinal dural arteriovenous fistulas and 8/8 (100%) patients with sacral spinal dural arteriovenous fistulas. T2W intramedullary abnormally high signal intensity areas were found in all lumbosacral spinal dural arteriovenous fistula patients, with involvement of the conus present in 35/38 (92.1%) patients. The "missing piece sign" in the intramedullary enhancement area was seen in 29/38 (76.3%) patients. Conclusion: Dilatation of the filum terminale vein or radicular vein is powerful evidence for diagnosis of lumbosacral spinal dural arteriovenous fistulas, especially for sacral spinal dural arteriovenous fistulas. T2W intramedullary hyperintensity in the thoracic spinal cord and conus, and the missing-piece sign could be indicative of lumbosacral spinal dural arteriovenous fistula.

Clinical utility and interrater reliability of video urodynamics in children with isolated fibrolipoma of filum terminale.

INTRODUCTION: Children with an isolated fibrolipoma of filum terminale (IFFT) but otherwise normal spinal cord are often evaluated with video urodynamics (VUDS). VUDS interpretation is subjective and can be difficult in young children. These patients may undergo detethering surgery if there is concern for current or future symptomatic tethered cord. OBJECTIVE: We hypothesized that VUDS in children with IFFT would have limited clinical utility regarding decision for or against detethering surgery and VUDS interpretation would have poor interrater reliability. METHODS: Patients with IFFT who underwent VUDS for from 2009 to 2021 were retrospectively reviewed to evaluate clinical utility of VUDS. 6 pediatric urologists who were blinded to patient clinical characteristics reviewed the VUDS. Gwet's first order agreement coefficient (AC1) with 95% CI was used to assess interrater reliability. RESULTS: 47 patients (24F:23M) were identified. Median age at initial evaluation was 2.8yrs (IQR:1.5-6.8). 24 (51%) patients underwent detethering surgery (Table). VUDS at initial evaluation were interpreted by treating urologist as normal in 4 (8%), reassuring for normal in 39 (81%), or concerning for abnormal in 4 (9%). Based on neurosurgery clinic and operative notes for the 47 patients, VUDS made no change in management in 37 patients (79%), prompted detethering in 3 (6%), was given as reason for observation in 7 (15%), and was normal or reassuring for normal but not documented as a reason for observation in 16 (34%) (Table). Interrater reliability for VUDS interpretation had fair agreement (AC1 = 0.27) for overall categorization of VUDS and EMG interpretation (AC1 = 0.34). Moderate agreement was seen for detrusor overactivity interpretation (AC1 = 0.54) and bladder neck appearance (AC1 = 0.46). DISCUSSION: In our cohort, 90% of patients had a normal or reassuring for normal interpretation of VUDS. VUDS interpretation affected clinical course in a minority of patients. There was fair interrater reliability for overall VUDS interpretation and therefore clinical course regarding detethering surgery could vary depending upon interpreting urologist. This fair interrater variability appeared to be related to variability in EMG, bladder neck appearance, and detrusor overactivity interpretation. CONCLUSION: VUDS affected clinical management in about 20% of our cohort and supported the choice for observation in around 50% of patients. This suggests VUDS does have clinical utility in pediatric patients with IFFT. The overall VUDS interpretation had fair interrater reliability. This suggest VUDS interpretation has limitations in determining normal versus abnormal bladder function in children with IFFT. Neurosurgeons and urologists should be aware of VUDS limitations in this patient population.

Prevention of retethering in untethering surgery of a tight filum terminale.

OBJECTIVE: Untethering surgery for a tight filum terminale is a common treatment with considerable efficacy and safety. On the other hand, retethering has been reported to occur. One of the major mechanisms of retethering is adherence of the cut end of the sectioned filum to the midline dorsal dural surface. To prevent retethering, the authors sectioned a filum terminale at the rostral level to the dural incision to keep the distance between the cut end of the sectioned filum and the dural incision and investigated whether this procedure decreased the occurrence of retethering. METHODS: Among the patients who underwent untethering surgery for a tight filum terminale between 2012 and 2016, patients followed up more than 5 years were included in the study. Symptoms, comorbid malformations, preoperative imaging, surgical details, perioperative complications, and long-term outcomes were reviewed retrospectively. RESULTS: Retrospective data for a total of 342 cases were included. The median age at surgery was 11 months (range 3-156 months). Preoperative MRI revealed 254 patients (74.3%) had a low-set conus. There were 142 patients (41.5%) with filar lipoma and 42 patients (12.3%) with terminal cyst. Syringomyelia was found in 29 patients (8.5%). In total, 246 patients (71.9%) were symptomatic and 96 patients (28.1%) were asymptomatic. There were no perioperative complications that required surgical intervention or prolonged hospitalization. The mean postoperative follow-up was 88 months (range 60-127 months). There were 4 patients (1.2%) with retethering who presented with bladder and bowel dysfunction. The mean time from initial untethering to retethering was 54 months (range 36-80 months). All 4 patients underwent untethering surgery, and preoperative symptoms resolved in 3 patients. CONCLUSIONS: The retethering rate after untethering surgery for a tight filum terminale in our series was lower than those in previously reported studies. Sectioning the filum terminale at the rostral level to the dural incision was considered an effective way to prevent retethering.