Abstracts

Rationale: Myoclonus is characterized by sudden brief jerks, either associated with muscle activity (positive myoclonus) or quiescence of muscle activity (negative myoclonus). The causes of myoclonus are variable, and can be seen in normal physiologic circumstances such as with hypnic jerking or with a variety of epileptic phenomenon, neurodegenerative disorders, or post-anoxic injuries. Treatment is also variable, and generally involves the use of anti-seizure medications. Commonly used medications include benzodiazepines, most often clonazepam, as well as levetiracetam. Some studies recommend treatment based on neurophysiological classification, such as botulism toxin for segmental myoclonus. We describe three cases of acquired pathologic myoclonus refractory to multiple traditionally employed medication therapies, with improved and rapid response with the addition of brivaracetam as adjunct drug therapy. Methods: We reviewed three patients that presented to our institution with refractory myoclonus in whom brivaracetam was ultimately started. The cause of myoclonus was post-anoxic and presumed cortical in two (one with acute myoclonic status epilepticus related to an anoxic brain injury from asthma-induced cardiopulmonary arrest and one remote anoxic injury related to a brown recluse bite, with progression to Lance Adams syndrome) and one with possible segmental myoclonus. Two out of the three patients had an electroencephalogram (EEG) correlate seen with the clinical jerking (the two with anoxic injury), while the patient with suspected segmental myoclonus did not show any EEG changes associated with the clinical jerking of the left abdomen and leg. All patients were on multiple anti-seizure medications, including benzodiazepines and levetiracetam prior to the addition of brivaracetam. Clinical and EEG improvement were evaluated. Results: All patients were on an average of five anti-seizure medications (range 3-6). In addition to levetiracetam and benzodiazepines (typically, clonazepam, but also diazepam and clobazam), the other agents used included valproic acid, fosphenytoin and lamotrigine as well as anesthetic agents. All patients continued to have notable myoclonus in spite of the polytherapy. Brivaracetam was added to the regimen at 50mg-100mg twice daily. One of the three patients was loaded with 100mg prior to maintenance treatment. Patient 1 (50-year-old man with Lance Adams syndrome) showed improvement in clinical myoclonus and EEG findings at day two, and patient 2 (20 year old with acute post-anoxic injury) showed resolution of stimulus induced myoclonus with only rare spontaneous myoclonus as well as diminished spike wave activity on the EEG at day three. Patient 3 (80-year-old man with presumed segmental myoclonus) did not show as rapid clinical improvement as the other patients, but did have resolution of myoclonus noted at day nine without further medication changes. Conclusions: Brivaracetam may be a useful treatment in cases of refractory myoclonus from acquired etiologies. Our patient series provides an interesting observation that patients with cortical myoclonus, and possibly segmental myoclonus, may benefit with the addition of brivaracetam when refractory to the current accepted treatment. This may suggest the potential of an additive benefit in spite of a similar mechanism of action between levetiracetam and brivaracetam. It is unclear if this effect would be similar in the absence of levetiracetam. Funding: No funding