Fetal surgery for open neural tube defect with severe ventriculomegaly.

OBJECTIVE: Prenatal open neural tube defect (ONTD) repair is performed to decrease the risk of needing treatment for hydrocephalus after birth and to preserve motor function. Some centers may not consider patients to be candidates for surgery if severe ventriculomegaly is present and there is no expected benefit in risk for hydrocephalus treatment. This study sought to compare the postnatal outcome of fetuses with ONTD and severe ventriculomegaly (ventricular width ≥ 15 mm) that underwent prenatal repair with the outcome of fetuses with severe ventriculomegaly that underwent postnatal repair and fetuses without severe ventriculomegaly (< 15 mm) that underwent prenatal repair. METHODS: This was a retrospective study of fetuses with ONTD that underwent prenatal or postnatal repair between 2012 and 2021 at a single institution. The cohort was divided into two groups based on preoperative fetal ventricular size: those with severe ventriculomegaly (ventricular width ≥ 15 mm) and those without severe ventriculomegaly (< 15 mm). Fetal ventricular size was measured by magnetic resonance imaging before surgery using the standardized approach and the mean size of the left and right ventricles was used for analysis. Motor function of the lower extremities was assessed at the time of referral by ultrasound and if flexion-extension movements of the ankle were seen it was considered as preserved S1 motor function. Postnatal outcomes, including motor function of the lower extremities at birth and the need for a diversion procedure for hydrocephalus treatment during the first year after birth, were collected and compared between groups. Multivariate regression analysis was used to adjust for potential confounders. RESULTS: In this study, 154 patients were included: 145 underwent fetal surgery (101 fetoscopic and 44 open hysterotomy) and nine with severe ventriculomegaly underwent postnatal repair. Among the 145 patients who underwent fetal surgery, 22 presented with severe ventriculomegaly. Fetuses with severe ventriculomegaly at referral that underwent prenatal repair were significantly more likely to need hydrocephalus treatment by 12 months after birth than those without severe ventriculomegaly (61.9% vs 28.9%, P < 0.01). However, motor function assessment at birth was similar between both prenatal repair groups (odds ratio, 0.92 (95% CI, 0.33-2.59), P = 0.88), adjusted for the anatomical level of the lesion. The prenatal repair group with severe ventriculomegaly had better preserved motor function at birth compared to the postnatal repair group with severe ventriculomegaly (median level, S1 vs L3, P < 0.01; proportion with S1 motor function, 68.2% vs 11.1%, P < 0.01). Fetuses with severe ventriculomegaly that underwent prenatal repair had an 18.9 (95% CI, 1.2-290.1)-times higher chance of having intact motor function at birth, adjusted for ethnicity, presence of club foot at referral and gestational age at delivery, compared with the postnatal repair group. There was no significant difference in the need for hydrocephalus treatment in the first year after birth between prenatal and postnatal repair groups with severe ventriculomegaly (61.9% vs 87.5%, P = 0.18). CONCLUSIONS: Although fetuses with ONTD and severe ventriculomegaly do not seem to benefit from fetal surgery in terms of postnatal hydrocephalus treatment, there is an increased chance of preserved motor function at birth. Results from this study highlight the benefit of prenatal ONTD repair for cases with severe ventriculomegaly at referral to preserve motor function. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

lVentral tethering-is the prognosis worse than in dorsal tethering in the dysraphic spine?

OBJECTIVE: To compare cases of dysraphism with ventral tethering of cord with those with dorsal tethering and to find out any differences in the outcome of surgery in them. METHODS: We collected the data of 188 consecutively operated tethered cord patients at our institute in the past 7 years and divided them into ventral tethering and dorsal tethering groups. Those that we felt had both dorsal and ventral tethering were excluded. Their preoperative clinical, radiological, and baseline neurophysiological parameters as well as postoperative clinical and radiological parameters were analyzed in a retrospective study. RESULTS: Among the 188 tethered cord patients, 52 (28%) had ventral tethering and 136 (72%) had posterior tethering. Preoperative neurodeficit and cord signal changes as well as absent baseline MEP (of any one muscle) were significantly more associated with ventral tethered cord than the dorsal tethered cord. The neurological deterioration after surgery occurred significantly in the ventral tethered cord group than in the dorsal tethered cord group. Also, the postoperative MRI had more incomplete detethering cases in the ventral group than in the dorsal tethered cord group. CONCLUSION: Ventral tethered cord is more likely to present with preoperatively neurological deficits. It should be carefully identified in the preoperative MRI, so that the intraoperative difficulties in complete detethering and postoperative deterioration can be anticipated.

Junctional Neural Tube Defect (JNTD): A Rare and Relatively New Spinal Dysraphic Malformation.

Junctional neurulation completes the sequential embryological processes of primary and secondary neurulation as the intermediary step linking the end of primary neurulation and the beginning of secondary neurulation. Its exact molecular process is a matter of ongoing scientific debate. Abnormality of junctional neurulation-junctional neural tube defect (JNTD)-was first described in 2017 based on a series of three patients who displayed a well-formed secondary neural tube, the conus, that is physically separated by a fair distance from its companion primary neural tube and functionally disconnected from rostral corticospinal control. Several other cases conforming to this bizarre neural tube arrangement have since appeared in the literature, reinforcing the validity of this entity. The clinical, neuroimaging, and electrophysiological features of JNTD, as well as the hypothesis of its embryogenetic mechanism, will be described in this chapter.

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.

Prevalence of neural tube defects among pregnant women in Addis Ababa: a community-based study using prenatal ultrasound examination.

PURPOSE: The primary aim of this study was to estimate the prevalence of NTDs at ultrasound examination in communities of Addis Ababa and secondarily to provide a description of the dysmorphology of the NTD cases. METHODS: We enrolled 958 pregnant women from 20 randomly selected health centers in Addis Ababa during the period from October 1, 2018, to April 30, 2019. Of these 958 women, 891 had an ultrasound examination after enrollment, with a special focus on NTDs. We estimated the prevalence of NTDs and compared it with previously reported hospital-based birth prevalence estimates from Addis Ababa. RESULTS: Among 891 women, 13 had twin pregnancies. We identified 15 NTD cases among 904 fetuses, corresponding to an ultrasound-based prevalence of 166 per 10,000 (95% CI: 100-274). There were no NTD cases among the 26 twins. Eleven had spina bifida (122 per 10,000, 95% CI: 67-219). Among the 11 fetuses with spina bifida, three had a cervical and one had a thoracolumbar defect while the anatomical site for 7 was not registered. Seven of the 11 spina bifida defects had skin covering, while two of the cervical lesions were uncovered. CONCLUSION: We report a high prevalence of NTDs among pregnancies in communities of Addis Ababa based on screening by ultrasound. The prevalence was higher than in previous hospital-based studies in Addis, and the prevalence of spina bifida was particularly high.

Syndrome of anterior neural stalk, vertebral abnormality, enteric duplication cyst, and diaphragmatic hernia related to persistent ventral neurenteric canal: report of two cases.

PURPOSE: Abnormalities in notochordal development can cause a range of developmental malformations, including the split notochord syndrome and split cord malformations. We describe two cases that appear related to unusual notochordal malformations, in a female and a male infant diagnosed in the early postnatal and prenatal periods, which were treated at our institution. These cases were unusual from prior cases given a shared constellation of an anterior cervicothoracic meningocele with a prominent "neural stalk," which coursed ventrally from the spinal cord into the thorax in proximity to a foregut duplication cyst. METHODS: Two patients with this unusual spinal cord anomaly were assessed clinically, and with neuroimaging and genetics studies. RESULTS: We describe common anatomical features (anterior neural stalk arising from the spinal cord, vertebral abnormality, enteric duplication cyst, and diaphragmatic hernia) that support a common etiopathogenesis and distinguish these cases. In both cases, we opted for conservative neurosurgical management in regards to the spinal cord anomaly. We proposed a preliminary theory of the embryogenesis that explains these findings related to a persistence of the ventral portion of the neurenteric canal. CONCLUSION: These cases may represent a form of spinal cord malformation due to a persistent neurenteric canal and affecting notochord development that has rarely been described. Over more than 1 year of follow-up while managed conservatively, there was no evidence of neurologic dysfunction, so far supporting a treatment strategy of observation.

Dorsal bony spur in pediatric split cord malformations: eight-year experience from a tertiary care hospital.

INTRODUCTION: Dorsal spurs in Type I split cord malformations (SCM-I) are infrequent findings. The pathogenesis of the same is debatable. The objective of this study is to analyze our experience with SCM-I patients having dorsal bony spurs. METHODOLOGY: Retrospective analysis of SCM patients operated from 2010 to 2017 was performed. Their demographic profile, clinic-radiological features, operative findings, and outcome following surgery were recorded. RESULTS: Twenty-four cases of Type I SCM harboring dorsal bony spurs were identified with mean age of 4.96 years. The commonest split site was lumbar, documented in 62.5%. Scoliosis was observed in 58.3%. Pre-operative neurological deficits were seen in 66.6% cases with asymmetric weakness of limbs seen in 16.6%. There was no new neurological deficit observed post-operatively. CONCLUSIONS: This is the largest series of dorsal spurs occurring in SCM, reported in literature so far. Meticulous pre-operative evaluation and imaging are important to identify dorsal spurs for appropriate management and good clinical outcome. Differentiating dorsal spur from ventral spur is important as it has a bearing on surgical approach.

Ventral anchoring of the conus medullaris: a new surgical technique preventing the radiographic recurrence of retethering after surgery for tethered spinal cord.

OBJECTIVE: Retethering is not an unusual operation for a congenital lumbosacral dysraphic spinal lesion. The present study aimed to assess a new surgical technique for preventing retethering. SURGICAL TECHNIQUE: After untethering the spinal cord, the pia mater or scar tissue at the caudal end of the conus medullaris is anchored to the ventral dura mater loosely using 8-0 thread, and the dura mater is closed directly. This technique is called ventral anchoring. RESULTS: Ventral anchoring was performed in 15 patients (aged 5 to 37 years old, average age: 12.1 years old) between 2014 and 2021. All but one patient showed improvement or stabilization of the preoperative symptoms. No complication directly related to the procedure was observed. Postoperative MRI demonstrated that the dorsal subarachnoid space was restored in 14 patients but was undetectable or absent in three patients on follow-up MRI. No patients have experienced a recurrence of the tethered cord syndrome during the follow-up period. CONCLUSION: Ventral anchoring is effective for restoring the dorsal subarachnoid space after untethering the spinal cord. This preliminary study suggested that ventral anchoring has the potential to prevent the postoperative radiographic recurrence of tethered spinal cord in patients with a congenital lumbosacral dysraphic spinal lesion.

A clinical clue toward recognition of split cord malformation type-I resembling meningocele in neonates.

This is a letter to share the clinical experience we had with neonates born with a specific feature of spina bifida. The lesion is like a meningocele containing skim amount of fluid, with a tiny dimple around the center of the cutaneous lesion which causes inward retraction of the dysplastic coverage. This feature is in favor of accompanied split cord malformation (SCM) type I, and the central nidus is in continuous with the dural sleeve around the bony septum of SCM. By recognition of this clinical clue, surgical repair can be planned to perform with appropriate provision, particularly foreseeing the amount of intraoperative bleeding and duration of anesthesia in the newborn patients.

Prenatal diagnosis of acrania/exencephaly/anencephaly sequence (AEAS): additional structural and genetic anomalies.

OBJECTIVES: To analyse additional structural and genetic anomalies in fetuses with acrania/exencephaly/anencephaly sequence (AEAS). METHODS: A retrospective analysis of 139 fetuses with AEAS diagnosed between 2006 and 2020 in a single tertiary referral ultrasound department. RESULTS: The median gestational age at diagnosis decreased from 15 weeks in 2006 to 13 weeks in 2020 (- 0.21 per each year; p = 0.009). In 103 fetuses, the defects were limited to the neural tube (NTD) (74.1%), in 36 fetuses (25.9%), there were additional structural non-NTD anomalies. The most common were ventral body wall defects present in 17.8% (23/139), followed by anomalies of the limbs (7.2%; 10/139), face (6.5%; 9/139) and heart (6.5%; 9/139). Genetic anomalies were diagnosed in 7 of the 74 conclusive results (9.5%; 7/74; trisomy 18, n = 5; triploidy, n = 1; duplication of Xq, n = 1). In univariate logistic regression models, male sex, limb anomalies and ventral body wall defects significantly increased the risk of genetic anomalies (OR 12.3; p = 0.024; OR 16.5; p = 0.002 and OR 10.4; p = 0.009, respectively). CONCLUSIONS: A significant number of fetuses with AEAS have additional structural non-NTD anomalies, which are mostly consistent with limb body wall complex. Genetic abnormalities are diagnosed in almost 10% of affected fetuses and trisomy 18 is the most common aberration. Factors that significantly increased the odds of genetic anomalies in fetuses with AEAS comprise male sex, limb anomalies and ventral body wall defects.

The oldest presenting neurenteric cyst of the spinal cord.

We describe an 81-year-old gentleman presenting with mild myelopathic symptoms in the upper limbs. Imaging showed a C1-3 intradural extramedullary lesion initially thought to be an arachnoid cyst. A C1 + 2 hemilaminectomy and partial excision was performed with histology revealing a neurenteric cyst (NC). NCs are congenital tumours that usually present within the third decade of life, they account for 1% of all spinal tumours. A literature search was conducted and we found that the age of presentation might actually be earlier than previously described. We also found that there has never before been a case described in the eighth decade of life, making this the oldest known symptomatic presentation of this rare condition.

Complex spinal dysraphism: myelomenigocele associated with dorsal bony spur, split cord malformation type I, syringomyelia, lipoma and tethered cord.

Variations in split cord malformation (SCM) are known. However, association of SCM type I with myelomeningocele along with same level dorsal bony spur has not been described previously. We report a 1-year old male child who presented with these findings with associated syringomyelia, lipoma and tethered cord.

Identifying biomarkers for prenatal diagnosis of neural tube defects based on "omics".

Neural tube defects (NTDs) are the most severe birth defects and the main cause of newborn death; posing a great challenge to the affected children, families, and societies. Presently, the clinical diagnosis of NTDs mainly relies on ultrasound images combined with certain indices, such as alpha-fetoprotein levels in the maternal serum and amniotic fluid. Recently, the discovery of additional biomarkers in maternal tissue has presented new possibilities for prenatal diagnosis. Over the past 20 years, "omics" techniques have provided the premise for the study of biomarkers. This review summarizes recent advances in candidate biomarkers for the prenatal diagnosis of fetal NTDs based on omics techniques using maternal biological specimens of different origins, including amniotic fluid, blood, and urine, which may provide a foundation for the early prenatal diagnosis of NTDs.

Assessment of MRI and Ultrasound Screening for Tethered Cord Syndrome in Patients Diagnosed With Esophageal Atresia/Tracheoesophageal Fistula.

INTRODUCTION: Infants with esophageal atresia and/or tracheoesophageal fistula (EA/TEF) undergo screening for tethered cord syndrome (TCS) via ultrasound and magnetic resonance imaging. Existing literature lacks data to guide optimal timing of screening and magnetic resonance imaging (MRI) is often delayed until 3-6 mo of age, when it is frequently forgotten. Detethering surgery has a high rate of success in patients with TCS and is often performed prophylactically due to potential irreversible deficits. This study aims to improve screening procedure for infants with EA/TEF. METHODS: A retrospective chart review was done of all EA/TEF patients treated over 6 y (n = 79). The study examined how often each imaging modality was performed and identified a TCS lesion, as well as age of screening/surgical intervention. RESULTS: Screening for TCS was done with MRI 58% of the time and US 15% of the time. However, 38% of patients did not undergo any screening. Out of the patients with TCS on MRI (n = 19, 41.3%), 73.7% had neurosurgery. Of patients who underwent ultrasound (US) (n = 12), nine patients also had MRI later: two reported TCS lesions and subsequently had neurosurgery. Surgical infection rates and complications were 0/14. CONCLUSIONS: MRI demonstrated a higher rate of detecting TCS lesions than US, and patients with TCS frequently had detethering. Patients with ≥3 VACTERL or vertebral anomalies had a higher incidence of TCS on MRI. Patients with vertebral anomalies reported false negative ultrasounds in two cases, suggesting the potential superiority of MRI screening in this subgroup. A third of children did not undergo any imaging and this will require a process improvement.

Meningeal carcinomatosis secondary to neurenteric cysts with malignant transformation: a case report.

BACKGROUND: Meningeal carcinomatosis is mainly associated with breast cancer, lung cancer, and melanoma. However, meningeal carcinomatosis secondary to a neurenteric cyst with malignant features is extremely rare. CASE PRESENTATION: We report the case of a 35-year-old woman who was admitted to the hospital with a 10-month history of headache, 6-month history of diplopia, 4-month history of hearing loss, and 1-month history of back pain, suggesting a diagnosis of chronic meningitis. Notably, enhanced brain and spinal cord magnetic resonance imaging (MRI) revealed extensive lesions with enhancement signals in the pia mater of the pons and cervical, thoracic, and lumbar spinal cord. The cerebral spinal fluid profile showed that pressure was significantly elevated, with a slight increase in leukocytes that mostly comprised mononuclear cells and decreased glucose concentration. Cytology evaluation showed a small cluster of atypical nuclei, which were suspected to be tumor cells arising from the epithelium. However, no primary tumor was found through comprehensive body and skin screening. After a histopathological biopsy of subarachnoid meninx of the thoracic spinal canal, the cause of meningeal carcinomatosis of this patient was determined as neurenteric cysts with malignant features, which is extremely rare. CONCLUSION: This is the first case to ever report neurenteric cysts as a cause of leptomeningeal carcinomatosis and the first ever report of neurenteric cysts presenting as leptomeningeal carcinomatosis without typical cyst visible on brain MRI. This extremely rare case provided a novel view on the pathogenesis of meningeal carcinomatosis and clinical presentation of neurenteric cysts, highlighting the value of meningeal biopsy in chronic meningitis of unknown causes.

Occult tethered cord syndrome: a rare, treatable condition.

PURPOSE: Occult tethered cord syndrome (OTCS) is an entity that shows tethered cord syndrome (TCS) with normal spinal MRI findings. The definition and treatment of OTCS have been controversial since first proposal. The purpose of this study was to evaluate the existence, prevalence, histological characteristics, and surgical outcomes of OTCS. METHODS: We retrospectively analyzed patients who underwent untethering surgery for OTCS from January 2010 to December 2019. Inclusion criteria were (1) clinical manifestation of TCS; (2) supported by urodynamic study (UDS) or electromyography/nerve conduction study; (3) no structural lesions in the urological tract or spinal cord, and no developmental delay; and (4) postoperative follow-up for > 6 months. Sectioned fila from OTCS patients were histologically compared with those from cases of thickened filum or low-lying conus. RESULTS: Five (four female, one male) of 439 patients (1.1%) who underwent untethering surgeries for occult spinal dysraphism corresponded to OTCS. Mean age at the time of surgery was 16 years (7-22 years). Mean postoperative follow-up duration was 45 months (15-114 months). The main symptom was urinary dysfunction in four patients and leg pain in one. All patients had detrusor-sphincter dyssynergia. Fila from OTCS patients revealed increased fibrous tissue as in TCS patients. Four patients showed postoperative improvement and one with preoperative static course had no improvement. CONCLUSIONS: This study suggests that OTCS is a definitely existing entity although rare. OTCS is curable when timely treatment is given. Sudden onset with rapid progression of symptom seems the best indication for surgery.

Limited dorsal myeloschisis involving one hemicord of a split cord malformation - a "hemi-LDM".

This is a case report of an exceedingly rare case of a limited dorsal myeloschisis (LDM) with its stalk inserted on the midline dorsal surface of one of a pair of hemicords in a type II split cord malformation. This entity, literally a "hemi-LDM," has been seen only once by the senior author in his catalogue of over 200 cases of LDM (Pang et al., 2020), nor has it been reported elsewhere before. We postulate that here the mechanism of focal nondisjunction of the hemi-neural plate during primary neurulation, which produces LDMs, occurs at the cusp of the consecutive developmental stages of gastrulation and primary neurulation, right after the appearance of the hemi-neural plates and hemi-notochords caused by the endomesenchymal tract. This child also had a terminal lipoma attached to the end of the conus, indicating that disruption of all three tandem stages of neural tube formation, namely, gastrulation, primary neurulation, and secondary neurulation, can occur in the same individual.

Treatment of spinal deformity with diastematomyelia type I: one-stage, two-stage surgery and new technique (vertebral column resection through wide bony septum).

STUDY DESIGN: Case series, literature review, and technical note. OBJECTIVES: To compare two different approaches to treat the spinal deformity with split cord malformation type I (SCM I). To present a new method of one-stage surgical treatment of congenital spinal deformity with wide bony septum (SCM I). METHODS: Analysis of the literature on the different types of combined surgical treatment of spinal deformities with SCM I was performed. We have provided our own data on 27 patients treated for congenital spinal deformity and SCM I, one of which underwent Schwab IV type osteotomy at the apex of the deformity through the bony septum and pedicles. Inclusion criteria were presence of spinal deformity in combination with SCM 1, performed surgery to correct spinal deformity, and follow-up period of at least 2 years. RESULTS: The result of the literature review was controversial and requires additional research. The average age of patients was 8.8 ± 6.6 years old. One-stage treatment of SCM I and spinal deformity was performed in 10 patients (group I) and two-stage in 14 patients (group II). Three patients with severe myelodysplasia, SCM I, and congenital kyphoscoliosis underwent correction of spinal deformity without SCM I removing (group III). The group I had the longest surgery duration (mean 289 ± 75 min) and largest blood loss (mean 560 ± 386 ml), a high percentage of deformity correction (mean 69.6%), and the highest rate of complications (60%). The most optimal was the two-stage treatment with the mean surgery duration 191 ± 137 min, mean blood loss 339 ± 436 ml, mean correction rate 63%, and frequency of complications 21%. The average follow-up time was 6.0 ± 2.6 years. CONCLUSIONS: One stage surgery associated with a large surgical invasion and a large number of complications. It can be used in some cases, for example when the wide bony septum (SCM I) is localized at the apex of the congenital scoliosis or kyphosis. In all other cases, it is worth adhering to a two-stage treatment. Many new works demonstrate the relative safety and effectiveness of deformity correction without removing the SCM. In our opinion, indications for treatment of spinal deformity without SCM I removing can be the need to perform a shortening ostetomy outside the SCM zone. The remaining cases require a thorough assessment and a balanced decision.

Myelomeningocele as an anomaly of secondary neurulation.

PURPOSE: Myelomeningocele (MMC) is the representative entity of open neural tube defects resulting from an error during primary neurulation. However, cases of MMC in the region of the secondary neural tube (below the junction of S1 and S2 vertebrae) are sometimes encountered. We aimed to analyze the clinical features of atypical "low-lying" MMC in comparison to the typical MMC and suggest possible pathoembryogenesis. METHODS: From 1986 to 2020, 95 MMC patients were treated in our institute. A retrospective review of the radiological and clinical information was performed. We defined "low-lying" MMCs as those with fascia or lamina defects below the S1-2 interspinous ligament. RESULTS: Thirty-one out of the 95 MMC patients were identified as having low-lying MMC. The percentage of low-lying MMC within the entire MMC group increased dramatically (19% from 1990 to 1999 and 48% from 2000 to 2020). Thirty-nine percent of the low-lying MMCs were associated with hydrocephalus, and 36% showed the Chiari malformation. Clean intermittent catheterization was being performed by 52% of the patients and 46% had a motor weakness. The proportions of hydrocephalus, neurological symptoms, and the number of related procedures in the low-lying MMC were substantially lower than the typical MMC in our cohort and the literature. CONCLUSIONS: We present cases of atypical MMC occurring in the region of secondary neurulation. These cases provide clues that secondary neurulation may lead to open neural defects. Future experiments with animal models supporting what we have seen in the clinics will greatly enhance the understanding of the developmental process of neurulation and the corresponding anomalies.

Filum terminale transection in pediatric tethered cord syndrome: a single center, population-based, cohort study of 95 cases.

PURPOSE: The purpose of this study was to evaluate outcome following surgical transection of filum terminale (FT) in symptomatic and asymptomatic pediatric patients with radiological findings consistent with tethered cord syndrome (TCS). METHODS: Patients < 17 years who underwent untethering surgery between 2007 and 2018 were screened for eligibility. Those who had undergone primary transection of the FT, and had preoperative radiological findings of fatty filum, thickened FT, or low-lying conus, below the pedicles of L2, were included. The cohort was divided into symptomatic and asymptomatic depending on clinical presentation. Surgical complications and functional outcome was recorded. RESULTS: In total, 95 patients were included, of whom 62 were symptomatic. In symptomatic patients, the main indications for radiological evaluation were scoliosis (29%) and motor symptoms (19%). In asymptomatic patients, skin stigmata (76%) were the most common finding. Fatty or thick FT was the most common radiographic finding, seen in 61% of symptomatic and 79% of asymptomatic cases. All patients underwent transection of the FT and were followed for a median of 1.8 years. A postoperative complication occurred in 12%, all Ibanez type Ib and managed without invasive treatment. For the symptomatic cohort, significant improvement was seen for both urodynamic assessment (48% improved, p = 0.002) and sensorimotor function (42% improved, p < 0.001). CONCLUSIONS: Neurological improvement or halted deterioration was seen in the majority of symptomatic cases. Asymptomatic patients did not experience any severe complications. Filum transection should be offered to symptomatic and asymptomatic patients upon diagnosis of fatty filum, thickened FT, or low-lying conus.