Role of electromyography and ultrasonography in the diagnosis of double crush lumbar radiculopathy and common fibular injury: illustrative cases.

BACKGROUND: Double crush syndrome consists of two compression sites along a peripheral nerve and is rare in the lower extremities. Electrodiagnostic and ultrasound (US) studies may be helpful in evaluating foot drop involving overlapping pathologies. OBSERVATIONS: Case 1 involved a man who presented with left dorsiflexor weakness and left foot numbness. Electromyography (EMG) revealed a left common fibular nerve entrapment neuropathy and left L5 radiculopathy. US and magnetic resonance imaging (MRI) revealed a large cystic lesion of the left common fibular nerve treated by cyst removal. The left foot drop persisted postoperatively. Lumbar computed tomography myelography revealed severe left foraminal stenosis at L5-S1. Multilevel lumbar laminectomies and facetectomies with an L5-S1 fusion were performed. Within 1 month postoperatively, the left foot drop had improved. Case 2 involved a man who developed a right foot drop caused by right lumbar foraminal stenosis at L4-5 and L5-S1. EMG and US of the right common fibular neuropathy showed large fascicles involving the right common fibular nerve. MRI revealed a hyperintense signal of the right common fibular nerve. Spontaneous improvement occurred within 6 months without surgery. LESSONS: Spine surgeons should recognize double crush in the lower extremities. EMG and US are valuable in detecting peripheral nerve abnormalities, especially in cases with overlapping lumbar pathology.

Intradural, extramedullary hemangioblastoma at the level of the conus medullaris: illustrative case.

BACKGROUND: Hemangioblastomas are rare, slow-growing, and highly vascularized tumors that typically occur in the cerebellum and spinal cord. The cervical and thoracic regions are the most common spinal sites, and the tumors are usually intramedullary. OBSERVATIONS: The authors report the case of a man whose chest computed tomography performed for managing coronavirus disease 2019 incidentally revealed an enhancing area in the spinal canal at T12-L1. The patient reported low back pain as well as leg numbness and tingling. Magnetic resonance imaging of the lumbar region with and without gadolinium contrast demonstrated an intradural, extramedullary lesion with displacement of the conus medullaris. The differential diagnosis included a schwannoma and myxopapillary ependymoma. Bilateral T12-L1 laminectomies were performed with resection of the mass. The general pathologist rendered the frozen section diagnosis of a spindle cell neoplasm, suggesting the differential diagnosis of schwannoma or myxopapillary ependymoma. Immunohistochemistry was positive for inhibin, GFAP, reticulin, CD31, SOX-10, S100, and EMA. A World Health Organization grade 1 hemangioblastoma was confirmed. LESSONS: Spinal surgeons should be cognizant of the presenting symptoms and differential diagnosis of hemangioblastomas at the level of the conus medullaris, especially when the tumor is diagnosed incidentally. Additional investigations should be performed to determine whether von Hippel-Lindau syndrome is associated with the hemangioblastoma, as this combination portends a different clinical presentation, multiple tumor locations, and tumor recurrence following resection.