Beyond Epileptic Seizures: Myoclonus as a Gateway to the Diagnosis of Anti-NMDAR Encephalitis
DOI:
https://doi.org/10.61997/bjm.v15i1.492Keywords:
Encephalitis, NMDA receptor, Autoantibodies, Myoclonus, RituximabAbstract
Background: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) autoimmune encephalitis may initially present with motor symptoms. We describe a case with facial myoclonus and clonic movements of the right upper limb, accompanied by language impairment. Case presentation: A man in his third decade of life, with a history of type 2 diabetes mellitus, presented with behavioral changes, difficulty writing, and focal motor seizures of the right upper limb, some with secondary generalization. Neurological examination revealed mild dysarthria, right facial and brachial myoclonus, and bilateral Babinski sign. Brain magnetic resonance imaging showed a left parietal hyperintense lesion with diffusion restriction; electroencephalography demonstrated focal irritative activity in the left parietal region. Cerebrospinal fluid studies revealed mild pleocytosis and positive anti-NMDAR antibodies. He was treated with steroid pulses and rituximab, resulting in seizure resolution, improvement of motor deficits, and progressive recovery of verbal language. Conclusion: Focal myoclonus can be an initial presentation of anti-NMDAR encephalitis; clinical, imaging, and immunological correlation enables timely diagnosis.
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