Objective: To report the case of a patient who developed generalized myoclonus revealing ischemic lesions of the brainstem

Background: Myoclonus is a movement disorder defined by brief, shock-like movements with no specific pattern (positive myoclonus) or a sudden interruption of muscular activity (negative myoclonus). It can be classified into cortical, subcortical, peripheral, segmental and non-segmental which includes brainstem reticular reflex.

Method: A 64-year-old male developed anoxic encephalopathy causing coma five months ago. This happened following a prostatic biopsy performed under general anesthesia, during which he suffered from cardio-respiratory arrest. After coma recovery two weeks later, he presented generalized myoclonus involving all four limbs, trunk, lips, tongue and palate. It worsens when he is startled and diminishes during sleep without disappearing. At clinical examination, five months after onset of symptoms, lower limb weakness rated at 3/5 is also observed. Cerebral MRI reveals an ischemic lesion of the brainstem. EEG shows multiple spike and polyspike waves that are typically associated with generalized cortical myoclonus. The patient was first treated with levetiracetam in association with clobazam with initial clinical amelioration shortly followed by the recurrence of the myoclonus after 15 days of treatment. He continued to present jerks of the same amplitude. The treatment is then adjusted with the replacement of levetiracetam by sodium valproate and the addition of piracetam. The therapeutic molecule change permitted a regression of the amplitude of the myoclonus and the movements spacing in time, the dosage was later optimized until the movement was only slightly noticeable.

Results: We consider this to be a rare complication of an anoxic encephalopathy. In our patient, generalized myoclonus was observed associated with jerks on the lips and palatal veil. The only brain anomaly that could explain this movement was an ischemic lesion located in the brainstem while EEG observes anomalies that are typically seen with cortical myoclonus. The patient was treated according to the electrophysiological findings, and still required many treatment adjustments.

Conclusion: We can speculate that the brainstem lesion was initially responsible for a reticular reflex myoclonus which was secondarily generalized. We can also speculate that the origin of the myoclonus can influence treatment response.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/secondary-generalized-myoclonus-resulting-from-brainstem-ischemic-lesion/