(Kiosk 1) Ballistic Arm Movements Due to Cortical Myoclonus Following Stroke Triggered by Contralateral Limb Movement Improved with Chemodenervation of Contralateral Spastic Dystonic Muscles: A Case Report

Case Diagnosis: Patient with multifocal stroke presenting with ipsilateral ballistic arm movements due to cortical myoclonus triggered by stretching contralateral spastic muscles and successfully treated with chemodenervation of the contralateral spasticity.

Case Description or Program Description: 51-year-old right-handed man with prior left cerebellar infarct and more recent infarcts to the left caudate, putamen, corona radiata, anterior temporal lobe and insular cortex resulting in bilateral involvement. Presented with right wrist, hand and ankle stiffness and pain. He had difficulty using his cane due to uncontrolled ballistic left shoulder movements causing loss of balance and falls. On examination he had spastic right wrist flexors (Modified Ashworth 1+) as well as impaired range of motion of right ankle in both dorsiflexion and plantarflexion with stiffness of the hallux and severe extensor posturing of the lesser toes (Modified Ashworth 3). He demonstrated uncontrolled ballistic jerking movements of the left shoulder due to cortical myoclonus which were triggered with extension of the right wrist and opening of the hand. Baclofen and clonazepam did not provide significant improvement. Chemodenervation with Onabotulinumtoxin A injections were performed to the right upper and lower extremity (flexor carpi radialis, flexor hallucis longus, extensor digitorum brevis, and extensor hallucis longus).

Setting: Outpatient Clinic

Assessment/Results: At one-month follow-up he was able to actively extend the right wrist and open the hand without eliciting left shoulder myoclonic jerks. At three-month follow-up there was recurrence of right wrist spastic dystonia and left shoulder myoclonus which again resolved with repeat chemodenervation.

Discussion (relevance): Cortical myoclonus can occur after stroke and can be stimulus sensitive, typically to touch. However, in this patient jerks were triggered by stretch and active movement of the contralateral limb. Proximal involvement mimics hemiballism.

Conclusions: Targeted focal chemodenervation of antagonistic spastic and dystonic muscles may be used to treat cortical myoclonus if they are ultimately found to be the stimulus and conservative measures fail.