We report a case of a 57-year-old man with a tumor arising from the cauda equina with spinal cord and intracranial metastases in the basal cisterns and along the cranial nerves. He presented with severe lower back pain and mild gait imbalance. His imaging revealed a large mass in the lumbosacral region with involvement of the cauda equina, intradural extramedullary enhancing metastases in the thoracic spinal canal, and intracranial metastases in the suprasellar cistern and along both trigeminal and facial/vestibulocochlear nerve complexes. Pathological examination of the resected thoracic spinal cord mass showed an atypical papillary proliferation with moderate nuclear pleomorphism and rare mitotic figures. While the morphologic and immunophenotypic features were consistent with the diagnosis of a choroid plexus tumor, the atypical location for this entity required the exclusion of other epithelioid tumors with papillary architecture. Additional immunohistochemical markers were used to exclude a metastatic adenocarcinoma, a papillary variant of a meningioma, and a papillary variant of an ependymoma. Ultimately, methylation-based tumor profiling determined that the methylation class was a match for \"plexus tumor\" resulting in the integrated diagnosis of the tumor with features of choroid plexus papilloma. This is a unique presentation for both the location and the metastatic spread. The methylation profile was instrumental in establishing this diagnosis.

BACKGROUND: Atypical teratoid/rhabdoid tumor (AT/RT) is an uncommon malignant neoplasm and rarely occurs in the spinal space, especially in the cauda equina. Only 8 cases of pediatric AT/RT of the cauda equina have been reported. Therefore, its clinical behavior and optimal treatment remain unclear.
METHODS: The authors describe the case of a 9-year-old boy who presented with progressive back and left leg pain. Initial magnetic resonance imaging showed an intradural extramedullary lesion at the L3-4 level, which progressed rapidly to the L2-5 level within a month. He underwent partial resection of the tumor with an L2-5 laminectomy. The histopathological diagnosis was AT/RT. He received adjuvant chemotherapy and radiotherapy, and his gait disturbance improved postoperatively. At 6 months\' follow-up, disease recurrence was not observed.
CONCLUSIONS: Although extremely rare, AT/RT should be included in the differential diagnosis for prompt therapeutic intervention. Safe resection with minimal functional impairment, followed by postoperative chemoradiation, can lead to tumor control and improve neurological function. https://thejns.org/doi/10.3171/CASE24219.

BACKGROUND: Cauda equina neuroendocrine tumors (CENETs), previously known as cauda equina paragangliomas, and multiple cerebral cavernous malformations (CCMs) are uncommon conditions affecting the central nervous system. To the authors\' knowledge, they have not been reported in the same patient.
METHODS: The authors present the case of a 45-year-old male with CENET and concurrent incidental MRI findings of multiple CCMs. Familial CCMs are associated with mutations in the KRIT1 (CCM1), MGC4607 (CCM2), and PDCD10 (CCM3) genes. Peripheral paragangliomas have been associated with mutations in succinate dehydrogenase (SDHx), RET (multiple endocrine neoplasia 2), VHL (von Hippel-Lindau syndrome), and NF1 (neurofibromatosis type 1) genes. Except for a single case, cauda equina paragangliomas have not been associated with any underlying genetic mutations.
CONCLUSIONS: It is unclear whether the co-occurrence of these two rare conditions in the same patient is coincidental or suggests a possible shared pathogenesis. https://thejns.org/doi/10.3171/CASE24102.

Lower motor neuron (LMN) damage results in denervation of the associated muscle targets and is a significant yet under-appreciated component of spinal cord injury (SCI). Denervated muscle undergoes a progressive degeneration and fibro-fatty infiltration that eventually renders the muscle non-viable unless reinnervated within a limited time window. The distal nerve deprived of axons also undergoes degeneration and fibrosis making it less receptive to axons. In this review, we describe the LMN injury associated with SCI and its clinical consequences. The process of degeneration of the muscle and nerve is broken down into the primary components of the neuromuscular circuit and reviewed, including the nerve and Schwann cells, the neuromuscular junction, and the muscle. Finally, we discuss three promising strategies to reverse denervation atrophy. These include providing surrogate axons from local sources; introducing stem cell-derived spinal motor neurons into the nerve to provide the missing axons; and finally, instituting a training program of high-energy electrical stimulation to directly rehabilitate these muscles. Successful interventions for denervation atrophy would significantly expand reconstructive options for cervical SCI and could be transformative for the predominantly LMN injuries of the conus medullaris and cauda equina.

An observational study to discover the common conditions affecting the lumbosacral region that may affect lumbosacral position and tension. All the patients, underwent MRI exaamination (magnetic resonance imaging) in the supine position, were examined by the same consultant radiologist. The article was revised by the institutional ethical approval committee. The position of the nerve roots was observed, and the number of nerve roots was calculated anterior to a line passing between the mid-transvers process of L3(third lumbar vertebra). The number of nerve roots ahead of this line was calculated by the radiologist at the level of the right intervertebral foramen and at the left one. This procedure was applied to the normal group, and 5 common pathological diseases were repeated including single-level lumbar disc prolapse, multiple-disc prolapse, multiple bulge, spinal stenosis and spondylolisthesis (at the level of L45 (fourth to fifth lumbar vertebrae) or L5S1 (fifth lumbar to first sacral vertebrae) being outside the study area, i.e., L3). We noticed significant difference in the number of the nerve roots between the cases with herniated discs, spinal stenosis, and spondylolisthesis with the normal group and the significance was in ascending increment in significance being the highest in cases with spondylolisthesis, and even in the groups of other pathologies which are statistically not significant, we noticed that the significance is proportional to the severity of the disease being the least in single level cases (p 0.427), to be more significant on cases with multiple prolapses(p 0.319) to be more in cases with multiple bulges to start to be statistically significant in herniated, higher significance in cases with spinal stenosis to be the highest in cases with spondylolisthesis.

Myxopapillary ependymomas (MPEs) are well-circumscribed tumors arising mainly from the caudal neuraxis, i.e., conus medullaris (CM) and filum terminale (FT), commonly seen in adults with median age at presentation of 39 years.1 Owing to its partially aggressive clinical behavior involving cerebrospinal fluid dissemination and local recurrence, MPE is classified as grade 2 in the fifth edition of the World Health Organization Classification of Tumors of the Central Nervous System.2 Gross total resection without capsular violation is key, with subtotal resection being directly associated with local recurrence.3The FT has an intradural and extradural component. The intradural FT extends from the inferior tip of the CM to the coccyx.4 The intradural FT-CM junction is not demarcated, but rather a zone of transition, with neural tissue being incrementally replaced by fibrous tissue of filum, gradually converging to a pure non-neural FT.5 In intramedullary FT MPE in close proximity to the lower end of conus, achieving gross total resection presents a great challenge. Neuromonitoring is crucial to ensure preservation of vital CM functions. We present the case of a 33-year-old man with focal nocturnal back pain of 6 months\' duration followed by bilateral lower limb deep boring pain. He had no neurological deficits. Preoperative magnetic resonance imaging revealed a T2 hyperintense, heterogeneous contrast-enhancing intradural extramedullary mass at L1. Video 1 highlights step-by-step en bloc excision of the FT MPE with technical nuances, including intraoperative neurophysiological monitoring. Triggered electromyography (EMG) was used to positively map the eloquent CM and identify the intradural FT-conus interface at the superior pole of the tumor, which was then carefully dissected under continuous bulbocavernosus reflex monitoring. Similarly, we confirmed non-neural intradural FT at the lower pole by negative mapping and resected the lesion en bloc with an adequate stump for clear margins. Free-run EMG monitored all the rootlets that adhered to or were in close proximity to the lesion, ensuring their integrity and an uneventful postoperative recovery. Figure 1 depicts the anatomical orientation of the lesion with surrounding neural structures. Histopathology confirmed MPE. En bloc resection with preservation of neurological function remains the mainstay of treatment for FT ependymoma. Understanding the transitional intradural FT-CM interface is essential, often precluding a clear filum stump superiorly while resecting MPE. Intraoperative neurophysiological monitoring is an indispensable adjunct to ensure safe en bloc resection. It is also theoretically possible to use tibial and pudendal sensory evoked potentials (SEPs) in this surgical procedure. However, the clinical utility of SEPs is limited in FT surgery compared with triggered EMG or transcranial motor evoked potentials because conventional SEPs from posterior tibial nerve of the lower extremity do not cover all the root levels at risk, and the change in SEPs cannot be immediately recognized (as SEPs are averaged responses, and there is always a time lag). We did not use pudendal SEPs in this study because SEPs may give information only on the sensory sacral pathway.6 Dermatomal SEPs may be helpful, but again, they provide only sensory information. Instead, we used triggered EMG for mapping the nerve roots and transcranial motor evoked potentials to monitor the motor tracts. Further, we used the bulbocavernosus reflex, an alternative and more precise technique to monitor both motor and sensory nervous pathways at the sacral root level. Moreover, SEPs are more difficult to monitor in very young children and are less relevant in guiding the surgical strategy. Thus, we used both mapping (triggered EMG) and monitoring (transcranial motor evoked potentials and bulbocavernosus reflex) techniques, which can preserve sensory and motor sacral roots in this surgical procedure.