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.

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.

Treating difficult-to-diagnose tight filum terminale: our experience with four patients

Tight filum terminale (TFT) is a general term for pathological conditions that result in abnormal tension on the spinal cord, pulling the conus medullaris caudally. Because symptoms can vary, we aim to review the usefulness of Komagata’s criteria in our experience with four patients who had TFT that was missed in prior workups. We performed a retrospective review of the medical records of four patients who underwent resection of the filum terminale for TFT. A total of four patients underwent surgery. The patients’ chief complaints were lower back pain, lower limb pain and numbness. All patients met the Komagata diagnostic criteria for TFT and also had neurological abnormalities of the upper limbs, such as numbness and pathological reflexes. We resected the filum terminale in all patients, and achieved resolution of their preoperative symptoms. Komagata’s diagnostic criteria are seemingly useful for the diagnosis of TFT.

Real spinal cord injury without radiologic abnormality in pediatric patient with tight filum terminale following minor trauma: a case report

Background Spinal cord injury without radiographic abnormality (SCIWORA) is defined as having “clinical symptoms of traumatic myelopathy with no radiographic or computed tomographic features of spinal fracture or instability”. The mechanism of pediatric SCIWORA following minor trauma is still unclear. Tight filum terminale (TFT) has been studied in the literature, but the information regarding the predisposing factor for SCIWORA is still being defined. Case presentation We report three cases of thoracic and lumber SCIWORA with TFT. The trauma was potentially mild in all cases but resulted in catastrophic damage of the cord. All patients had no signs or symptoms of tethered cord syndrome prior to the minor trauma. TFT was found during operation. Conclusions We suggest that TFT might be a predisposing factor for SCIWORA and chronic spinal cord traction play an important role in the mechanism of pediatric thoracic and lumber SCIWORA following minor trauma. Patients who never undergo treatment for TFT likely have an elevated risk of developing SCIWORA following minor trauma.