Comparison of The Electrophysiological Characteristics of Tight Filum Terminale And Tethered Cord Syndrome

This study aims to characterize tight filum terminale (TFT) in motor evoked potential (MEP) testing by comparing TFT patients with both tether cord syndrome (TCS) patients and healthy subjects. Fifty TFT patients, 18 TCS patients, and 35 healthy volunteers participated in this study. We recorded MEPs following transcranial magnetic stimulation from the bilateral abductor hallucis muscles as well as compound muscle action potentials and F-waves evoked by electrical stimulation of the tibial nerve from the bilateral abductor pollicis brevis muscles. The peripheral conduction time (PCT) was calculated from the latency of the compound action potential and F-wave. Furthermore, the central motor conduction time (CMCT) was calculated by subtracting PCT from MEP latency. TFT and TCS patients had a significantly longer MEP latency than healthy subjects. PCT in TFT patients were significantly longer than those in TCS patients or healthy subjects. Using the cut-off values for PCT, we were able to diagnose patients with TFT patients with a sensitivity of 72.0% and a specificity of 91.4%. Prolonged PCT in the MEP test may be a useful indicator for TFT and suggests that MEP may be used as an adjunct diagnostic tool for TFT.

Anatomy of the Spinal Cord

The spinal cord begins as the cervical cord immediately below the medulla and extends through the spinal canal, where it becomes the thoracic, lumbar, sacral, and coccygeal parts of the cord. In most persons, the spinal cord proper ends at the lower portion of the first lumbar vertebral body, where it forms the conus medullaris and, finally, the filum terminale. A cervical enlargement contains the innervation pathways of the upper limbs; a lumbar enlargement contains the pathways of the lower limbs. This chapter reviews ascending and descending pathways in the spinal cord.

International survey on the management of lumbosacral cutaneous stigmata in infants with suspected occult spinal dysraphism

OBJECTIVE Occult spinal dysraphism (OSD) is a common pediatric neurosurgical diagnosis rife with controversy surrounding both the screening of asymptomatic infants and the threshold to offer a prophylactic detethering operation. The authors sought to clarify international practice patterns with a survey of pediatric neurosurgeons. METHODS A survey asked pediatric neurosurgeons whether they would perform imaging in patients with a variety of cutaneous stigmata associated with OSD and whether they would offer prophylactic detethering surgery for asymptomatic patients with a variety of imaging findings on the OSD spectrum. RESULTS Completed surveys were received from 141 pediatric neurosurgeons. Broad consensus was demonstrated on the need for obtaining images in sample patients with more severe stigmata ranging from large lipoma with a skin appendage to focal dysplastic skin in the lumbar midline. Ninety percent of respondents would perform MRI for these patients. In contrast, for patients with a low-sacral dimple, flat hemangioma, and symmetric (Y-shaped) splaying of the intergluteal cleft, opinion on the need for imaging varied considerably (between 57% and 89% recommended imaging). Respondents differed on the type of imaging that they would perform, with 31% to 38% recommending ultrasound screening. The responses reflected less consensus on when to offer surgery to patients with simple spinal tethering (low-lying conus medullaris and fatty filum terminale). Both a lower level of the conus and increased thickness of the filum terminale affected decision-making. CONCLUSIONS The results of this survey showed significant consensus on the recommendation for screening imaging in patients with more dramatic cutaneous stigmata, although these stigmata are the rarest. A significant variance in opinions was reflected in the recommendation for imaging of the most common cutaneous stigmata. Consensus was also lacking on which lesions deserve prophylactic detethering surgery. Significant equipoise exists for future study of screening imaging and of surgical decision-making in patients with asymptomatic OSD and associated cutaneous stigmata.

Dural splitting reconstruction in retethering after lipomeningocele repair: Technical note

Background: Tethered spinal cord syndrome (TCS) can occur after the surgical repair of lipomeningoceles (LMCs). In these cases, the tethering results from postoperative adhesions between the spinal cord and the overlying repaired dura. A watertight dural closure using the residual dura and/or the surrounding tissues does not always provide enough space for the spinal cord and risks retethering. Here, we report a 16-year-old patient with secondary TCS following lipomeningocele repair who successfully underwent release of the tethered filum terminale utilizing a novel dural splitting reconstructive technique to attain a water-tight closure without the need for a duroplasty. Methods: A 16-year-old patient had a LMC repaired at birth. She now presented with progressive low back pain, and gait disturbances. The MRI documented secondary spinal cord tethering at the prior spinal dysraphism repair site. Results: A secondary release of the filum terminale utilizing a novel dural splitting technique to avoid the need for a duroplasty was performed. Conclusion: Here, in a 16-year-old patient with a recurrent tethered cord syndrome following repair of a LMC at birth, we utilized a novel dural splitting reconstruction technique and averted the need for a duroplasty.

Surgical histopathology of a filar anomaly as an additional tethering element associated with closed spinal dysraphism of primary neurulation failure

Background: Closed spinal dysraphism of primary neurulation failure could be associated with filar anomalies, such as filar lipoma or thickened and tight filum terminale (TFT), resulting from impaired secondary neurulation. Retained medullary cord (RMC) is a remnant of the cavitary medullary cord originating from the secondary neurulation failure. Some filar lipomas are known to contain a central canal-like ependyma-lined lumen with surrounding neuroglial tissues (E-LC w/NGT), that is, a characteristic histopathology of RMC. To clarify the embryological background of these filar anomalies, we evaluated the histopathological findings. Methods: Among 41 patients with lesions of primary neurulation failure who underwent initial untethering surgery, the filum including cord-like structure (C-LS) was additionally resected in 10 patients (five dorsal and transitional lipomas; five limited dorsal myeloschisis). We retrospectively analyzed the clinical, neuroradiological, intraoperative, and histopathological findings. Results: Among 10 patients, two patients were diagnosed with RMC based on morphological features and intraoperative neurophysiological monitoring. The diagnosis of filar lipoma was made in six patients, since various amounts of fibroadipose tissue were histopathologically noted in the filum. Two patients were diagnosed with TFT, since the filum was composed solely of fibrocollagenous tissue. E-LC w/NGT was noted not only in both C-LSs of RMCs but also in two out of six fila both with filar lipomas and fila with TFTs. Conclusion: These findings provide further evidence for the idea that entities, such as filar lipoma, TFT, and RMC, can be considered consequences of a continuum of regression failure occurring during late secondary neurulation.

Tetrad of Split Cord Malformation I with Neuroenteric Cyst, Dermoid Cyst, and Thickened Filum Terminale in a 2-Year-Old Child: A Case Report

<b><i>Introduction:</i></b> Split cord malformations (SCMs) are developmental anomalies that are associated with a number of congenital defects. However, a combination of SCM I with a neuroenteric cyst (NEC) is extremely rare, and only 11 cases have been described in the literature. To the best of authors’ knowledge, the combination of the above two with dermoid cyst and thickened filum terminale has never been reported in the literature. <b><i>Case Presentation:</i></b> We present a case of the above combination in a 2-year-old child who underwent microsurgical excision of all 4 pathologies and complete recovery. <b><i>Conclusion:</i></b> NEC and dermoid should be considered in the differential diagnosis when imaging reveals cystic pathology along with SCM. Expeditious surgical repair resulted in an outstanding functional outcome at 1-year follow-up.