Elevated local field potential power characterizes choreic storms identified by deep brain stimulator event capture

Some patients with hyperkinetic movement disorders may present with a severe and prolonged state of uncontrolled chorea and/or ballism, termed 'choreic storm', causing distress and prompting intervention. These events may be more frequent and severe in patients with childhood-onset movement disorders. Deep brain stimulation (DBS) can be effective for medically refractory dyskinesias including chorea, and the availability of event-based local field potential (LFP) sensing in clinically available devices present an opportunity to better understand the underlying neurophysiology of these episodic phenomena. We analyzed clinical, electrophysiological, and corroborating video data from a patient with a de novo CEP85L mutation (NM_001042475.2, c.2381A>G, p.Y794C) presenting with chorea-predominant dyskinetic cerebral palsy, microcephaly, and intellectual disability. The patient underwent bilateral pallidal DBS for medically refractory symptoms and showed improvement in her baseline chorea. However, choreic storms continued multiple times per week, requiring frequent rescue medications and/or emergency medical intervention. These episodes were associated with autonomic features and variable triggers. Family-initiated LFP event recording supplemented by concurrent video facilitated side-by-side analysis of clinical episodes, revealing elevated LFP power in the theta to low gamma frequencies during choreic storms compared to baseline event recordings. Episode-associated increases in LFP power captured during choreic storms may represent a putative within-patient electrophysiological correlate of these severe episodic exacerbations. Although requiring confirmation and extension in larger series, these observations suggest that adaptive stimulation paradigms could be useful for patients experiencing choreic storms.