The impact of a biocellulose-based repair of fetal open spina bifida on the need to untether the cord: is it time to unify techniques for prenatal repair?

OBJECTIVE: To report the need for cord untethering after prenatal repair of open spina bifida using a unique biocellulose-based technique performed at a later gestational age. METHODS: An observational cohort study was conducted to determine the incidence of tethered cord syndrome. Between May 2013 and May 2022, we performed 172 procedures using the percutaneous fetoscopic approach in fetuses at 26-28 weeks of gestation. After placode dissection, a biocellulose patch was placed to cover the placode, a myofascial flap (when possible) was dissected, and the skin was closed. Owing to death or loss to follow-up, 23 cases were excluded. Cord tethering syndrome was defined as symptoms of medullary stretching, and the infants were evaluated and operated on by local neurosurgeons after an magnetic resonance imaging examination. Infants over 30-month had ambulation and neurodevelopment evaluations (PEDI scale). RESULTS: Among 172 cases operated at a median gestational age of 26.7 weeks and delivered at 33.2 weeks, 149 cases were available for postnatal follow-up, and cord untethering was needed in 4.4% of cases (6/136; excluding 13 cases younger than 12 months). Cerebrospinal fluid diversion and bladder catheterization were needed in 38% and 36% of cases, respectively. Of the 78 cases evaluated at 30 months, 49% were ambulating independently, and 94% had normal social function. CONCLUSION: The biocellulose-based technique was associated with a low rate of cord tethering, wich may be attributed to the lack of the duramater suture during prenatal repair, the formation of a neoduramater and/or later gestational age of surgery.

Use of a machine learning algorithm with a focus on spinopelvic parameters to predict development of symptomatic tethered cord after initial untethering surgery.

OBJECTIVE: Among patients with a history of prior lipomyelomeningocele repair, an association between increased lumbosacral angle (LSA) and cord retethering has been described. The authors sought to build a predictive algorithm to determine which complex tethered cord patients will develop the symptoms of spinal cord retethering after initial surgical repair with a focus on spinopelvic parameters. METHODS: An electronic medical record database was reviewed to identify patients with complex tethered cord (e.g., lipomyelomeningocele, lipomyeloschisis, myelocystocele) who underwent detethering before 12 months of age between January 1, 2008, and June 30, 2022. Descriptive statistics were used to characterize the patient population. The Caret package in R was used to develop a machine learning model that predicted symptom development by using spinopelvic parameters. RESULTS: A total of 72 patients were identified (28/72 [38.9%] were male). The most commonly observed dysraphism was lipomyelomeningocele (41/72 [56.9%]). The mean ± SD age at index MRI was 2.1 ± 2.2 months, at which time 87.5% of patients (63/72) were asymptomatic. The mean ± SD lumbar lordosis at the time of index MRI was 23.8° ± 11.1°, LSA was 36.5° ± 12.3°, sacral inclination was 30.4° ± 11.3°, and sacral slope was 23.0° ± 10.5°. Overall, 39.6% (25/63) of previously asymptomatic patients developed new symptoms during the mean ± SD follow-up period of 44.9 ± 47.2 months. In the recursive partitioning model, patients whose LSA increased at a rate ≥ 5.84°/year remained asymptomatic, whereas those with slower rates of LSA change experienced neurological decline (sensitivity 77.5%, specificity 84.9%, positive predictive value 88.9%, and negative predictive value 70.9%). CONCLUSIONS: This is the first study to build a machine learning algorithm to predict symptom development of spinal cord retethering after initial surgical repair. The authors found that, after initial surgery, patients who demonstrate a slower rate of LSA change per year may be at risk of developing neurological symptoms.

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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

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.

Total spine MRI for the preoperative evaluation of adolescent idiopathic scoliosis: Part 2 - spinal cord tumors, dysraphisms, diastematomyelia, and vertebral anomalies.

Adolescent idiopathic scoliosis is a commonly encountered condition often diagnosed on screening examination. Underlying, asymptomatic neural axis abnormalities may be present at the time of diagnosis. At certain institutions, total spine MRI is obtained preoperatively to identify these abnormalities. We provide a framework for the radiologist to follow while interpreting these studies. In part 1, we discuss Arnold Chiari malformations, syringomyelia, and the tethered cord. In part 2, we focus on spinal cord tumors, dysraphisms, to include diastematomyelia, and vertebral anomalies.

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.

Surgical technique of spine-shortening vertebral osteotomy for adult tethered cord syndrome: a case report and review of the literature.

BACKGROUND: Miyakoshi et al. reported three cases of tethered cord syndrome treated by spine-shortening vertebral osteotomy, which provided relief of the patients' symptoms with no complications. Although the details of these cases were described in a previous report, the surgical technique was not thoroughly explained. In the present report, we describe the details of our procedure with reference to a fourth case. CASE PRESENTATION: A 47-year-old Asian woman was admitted to our hospital with a 1-year history of worsening leg numbness and urinary dysfunction. Magnetic resonance imaging revealed a low-lying conus medullaris extending to the level of S2 and surrounded by fat tissue at that level. We diagnosed her condition as adult tethered cord syndrome, and spine-shortening vertebral osteotomy was planned. The target level for the osteotomy was L2. Bilateral pedicle screw implants were placed at L1 and L3 using an anterior-posterior image intensifier. In this procedure, it is essential to use monoaxial screws inserted exactly parallel to the rostral endplates of each vertebral body; this ensures appropriate alignment between the L1 caudal endplate and the L2 osteotomy surface. The upper one-third of the lamina of L2 was resected, and the bilateral two-thirds of the pedicle of L2 was removed with a surgical air drill. After exposure of the lateral side of the L1-2 disc, discectomy was performed with a knife and curette. Following complete discectomy of L1-2, the upper vertebral body of L2 was removed with a surgical air drill. After complete removal of the vertebral body, a straight rod was connected to two screws and applied pressure between the screws. Two polyethylene tapes were applied to the L2 lamina and bilateral rods. CONCLUSION: Spine-shortening osteotomy that preserves the caudal one-third of the pedicle and lamina with one-above and one-below instrumentation successfully reduced the spinal cord tension without causing neural damage.

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.

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.

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.

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.

Prenatal Diagnosis of Diastematomyelia: a Case Report and Literature Review.

Diastematomyelia is a type of closed spinal dysraphism in which there is splitting of the spinal cord. It is a rare entity that accounts for less than 3% of closed spinal dysraphisms and affects females 1.3 to 6 times more frequently than males. Lesions are usually found in the lower thoracic and upper lumbar regions. It is characterised by two hemicords separated by a bony or cartilaginous spur. In most cases, it is an isolated malformation with a favourable prognosis. However, it may be associated with other abnormalities and sonography is the imaging test par excellence for early prenatal diagnosis. We report a case of diastematomyelia diagnosed by prenatal sonography at 24 weeks' gestation. Amniotic fluid alpha-fetoprotein (AF-AFP) was normal, while amniotic fluid acetylcholinesterase (AF-AChE) was positive. After birth, the diagnosis was confirmed with magnetic resonance imaging (MRI). The anomaly was associated with a spinal lipoma, tethered cord and dermal sinus. A review of all the cases described in the literature to date is carried out.

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.

Demographics, referral patterns, and outcome of patients with neural tube defects in southwestern Uganda.

OBJECTIVE: In Uganda, the burden of neural tube defects (NTDs) poses a serious neurosurgical and public health challenge; however, published data on this patient population are lacking. The authors sought to characterize the population of patients with NTDs, maternal characteristics, and referral patterns of these patients, and to quantify the burden of NTDs in southwestern Uganda. METHODS: A retrospective neurosurgical database at a referral hospital was reviewed to identify all patients with NTDs treated between August 2016 and May 2022. Descriptive statistics were used to characterize the patient population and maternal risk factors. A Wilcoxon rank-sum test and chi-square test were used to determine the association between demographic variables and patient mortality. RESULTS: A total of 235 patients were identified (121 male, 52%). The median age at presentation was 2 days (IQR 1-8 days). A total of 87% of patients with NTDs presented with spina bifida (n = 204) and 31 presented with encephalocele (13%). The most common location of dysraphism was lumbosacral (n = 180, 88%). Of all patients, 80% were delivered vaginally (n = 188). Overall, 67% of patients were discharged (n = 156) and 10% died (n = 23). The median length of stay was 12 days (IQR 7-19 days). The median maternal age was 26 years (IQR 22-30 years). The majority of mothers received only primary education (n = 100, 43%). The majority of mothers reported prenatal folate use (n = 158, 67%) and regular antenatal care (n = 220, 94%), although only 23% underwent an antenatal ultrasound (n = 55). Mortality was associated with younger age at presentation (p = 0.01), need for blood transfusion (p = 0.016) and oxygen supplementation (p < 0.001), and maternal education level (p = 0.001). CONCLUSIONS: To the authors' knowledge, this is the first study to describe the population of patients with NTDs and their mothers in southwestern Uganda. A prospective case-control study is necessary to identify unique demographic and genetic risk factors associated with NTDs in this region.

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.