Isolated neurosarcoidosis with a primary lesion in the cauda equina.

A man in his late 50s without notable medical background was admitted with subacute onset of bilateral lower extremity weakness. Blood and physiological examinations revealed no significant abnormalities. Cerebrospinal fluid (CSF) examination revealed elevated cell count and protein levels and an immunoglobulin G index of 2.01. T1-weighted MRI showed swelling and enhancement of the cauda equina. After admission, the patient developed bowel and bladder incontinence, deteriorated to manual muscle test 0 and developed right trochlear, trigeminal and facial nerve palsy. He underwent a cauda equina biopsy and was diagnosed with neurosarcoidosis. After methylprednisolone pulse therapy and corticosteroid treatment, cauda equina syndrome including lower extremity weakness and cerebral nerve palsy improved. The patient's daily activities improved to the baseline level over 2 months after discharge. Serum and CSF soluble interleukin-2 receptor levels were within the reference range and decreased with the improvement of neurological and imaging findings.