treatment in myoclonus

Q: All of the following are found to be helpful in myoclonus EXCEPT? 

A) Levetiracetam 

B) Phenytoin 

C) Clonazepam 

D) Valproic acid 

E) Zonisamide

Answer: B

Physicians tend to reflexly use anti-seizure meds to treat myoclonus. Only a few drugs found to be effective in myoclonus. The most rigorously tested and found to be an effective drug is Levitractam. Other drugs found to be helpful include Piracetam, Brivaracetam, Clonazepam, and Zonisamide. Many other drugs have been described with limited effectiveness like Baclofen, Benztropine, Carbamazepine, Diazepam, Lamotrigine, Phenobarbital, Primidone, Sumatriptan, Tetrabenazine, Topiramate and Trihexyphenidyl. Besides pharmacology treatment stimulation and surgical interventions have also been used, where the most widely used is Deep Brain Stimulator (DBS).

 The response to treatment in myoclonus can be assessed by the Unified Myoclonus Rating Scale (UMRS). 

 Phenytoin (choice B) so far has not shown any role in the treatment of myoclonus. In fact, in many cases, it is found to worsen myoclonus.

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References:

1. Eldridge R, Iivanainen M, Stern R, et al. "Baltic" myoclonus epilepsy: hereditary disorder of childhood made worse by phenytoin. Lancet 1983; 2:838.

2. Genton P, Gélisse P. Antimyoclonic effect of levetiracetam. Epileptic Disord 2000; 2:209.

3. Roze E, Vidailhet M, Hubsch C, et al. Pallidal stimulation for myoclonus-dystonia: Ten years' outcome in two patients. Mov Disord 2015; 30:871.