425 - Segmental Myoclonus as a Presenting Manifestation of Multiple Sclerosis (MS): A Case Report

Case Diagnosis: Segmental Myoclonus as a Presenting Manifestation of Multiple Sclerosis

Case Description: 26-year-old female with history of pseudotumor cerebri presented to Emergency Department for worsening frequent rhythmic jerking movements of her neck and arm, hearing loss, and lower extremity weakness. Neurosurgery, previously following the patient for pseudotumor cerebri, recommended MRI brain and spine. These were concerning for cerebral, cervical, and thoracic demyelination. Subsequent hospitalization included 14-hour EEG that yielded no epileptiform discharge. Segmental myoclonus responded favorably to valproate, but not levitiracetam. LP with CSF labs were eventually positive for oligoclonal bands, confirming a diagnosis of MS. She then completed a course of IV steroids prior to transfer for acute inpatient rehabilitation.

Discussions: Segmental myoclonus refers to brief, involuntary contractions of one or more muscles innervated by contiguous brain or spinal cord segments. Few reports describe segmental myoclonus as a presenting symptom of MS. Our literature search yielded only 2 case reports detailing similar presentations. MS more commonly presents with symptoms related to demyelinating plaques in the optic nerve, brainstem, or cerebrum. In this case, meaningful functional improvement coincided with better control of her segmental myoclonus, which was achieved with valproate and clobazam. While her segmental myoclonus improved, motor recovery was limited. In the absence of other classic symptoms of MS, presentation with segmental myoclonus may pose a challenge to recognition of MS.

Conclusions: Segmental myoclonus is a rare presenting manifestation of MS that may pose a diagnostic challenge when presenting at disease onset. We suggest that segmental myoclonus should prompt consideration for Multiple Sclerosis in a patient with progressive neurological symptoms.