Neurosarcoidosis of the Cauda Equina: Clinical Course, Radiographic and Electrodiagnostic Findings, Response to Treatment, and Outcomes

Abstract

Background and objectives: Sarcoidosis is a multisystem granulomatous disease affecting the nervous system in 3%-5% of cases. It can affect almost any component of the nervous system. Involvement of the cauda equina is an understudied phenotype, and questions remain regarding its natural history and optimal approach to management. This study aims to study the long-term clinical evolution of neurosarcoidosis affecting the cauda equina, response to treatment, and clinical and radiographic outcomes.

Methods: Patients with neurosarcoidosis treated at Emory University between January 1, 2011, and December 8, 2021, were retrospectively evaluated for manifestations of cauda equina disease and included if disease of the cauda equina could be substantiated by MRI or EMG.

Results: Of 216 cases, 14 (6.5%) involved the cauda equina. The median age was 49.5 years, and most were female (85.7%) and African American (64.3%). Chronic (>28 days) presentations were most common (78.6%), but acute (<7 days, 14.3%) and subacute (7-28 days, 7.1%) were also seen. The median modified Rankin Scale (mRS) score at nadir was 3 (range 2-4). Symptoms were asymmetric in 78.6% and included leg numbness (85.7%), leg weakness (64.3%), perineal numbness (35.7%), pain (42.3%), and incontinence (21.4%). On MRI, the cauda equina enhanced in 100%, appeared nodular in 78.6%, and was diffusely involved in 71.4%. Coexisting myelitis was common (cervical 28.6%, thoracic 35.7%, and conus medullaris 28.6%). Intracranial inflammation included leptomeningitis (71.4%) and cranial neuropathies (57.1%). Electrodiagnostic studies were conducted in 3 with only one showing features consistent with a radicular process. Serum and CSF angiotensin-converting enzyme levels were elevated in 38.5% and 0.0%, respectively. CSF white blood cell and protein were elevated in 92.9%. Corticosteroids were tried in all patients with durable stabilization or improvement in only 3 (21.4%). Second-line agents associated with improvement included methotrexate/infliximab (3/4, 75%), methotrexate (3/4, 75.0%), and azathioprine (1/1, 100%). During a median follow-up of 22.5 months, the final median mRS score was 3. Relapses occurred at a median of 6 months in 21.4%. In 9 patients with MRI follow-up, 6 improved (66.7%), 1 stabilized (11.1%), and 2 worsened (22.2%).

Discussion: Characteristic features of cauda equina involvement by neurosarcoidosis include chronically delayed presentations, nodular enhancement on MRI, poor response to corticosteroids, and substantial resultant neurologic disability.