Objective: To correlate local filed potential (LFP) spectral data with clinical improvement of the Unified Myoclonus Rating Scale (UMRS) in post-hypoxic myoclonus (PHM) syndrome treated with deep brain stimulation (DBS).

Background: We present a 56year old patient (pt) who suffered anoxic brain injury secondary to suicide attempt. Subsequently, the pt developed generalized seizures, with rest and action myoclonic jerks affecting all extremities. The pt was wheelchair bound and treatment was refractory to multiple medications. As a result, the pt was implanted with bilateral Globus Pallidus (GPi) DBS.

Method: LFP survey was conducted bilaterally for each available DBS contact following IPG implantation, showing high spectral power at 10-12 and 25Hz. Chronic recording was initiated post implantation at 10Hz to allow the clinician to observe changes in LFP activity until initial programming four weeks later. LFP streaming was performed during each clinic visit. These recordings were analyzed at 11Hz (highest spectral power) and 50Hz (gamma LFP to assess overall broadband activity) by counting LFP peaks that crossed frequency threshold. UMRS were analyzed at pre-DBS, 1, 3, and 6 months post-DBS and were correlated with LFPs.

Results: The highest observed LFP activity was used to determine initial contact selection (contact 2 and 9). Myoclonus at Rest section of the UMRS were highly correlated to LFP activity at 11Hz and 50Hz (Pearson r=0.778 and 0.882, respectively [Figure1]. Over the course of 6 months, patient showed marked improvement in myoclonic jerks at rest, with further reduction in action and negative myoclonus. Patient was able to walk with the help of one person assistance and eat without assistance. At 6 months post DBS, pt showed 33% improvement in the myoclonus at rest, and 50% improvement in the global disability score based on the UMRS [Table1].

Conclusion: Our case demonstrates improvement in UMRS with bilateral GPi-DBS in a patient with PHM. Changes in rest myoclonus highly correlated with LFP suppression activity at both beta and gamma frequency peaks suggesting that LFP activity may help understand stimulation parameters and may provide insights into the disease.

Spike correlation with Myoclonus at rest 11-50Hz

Pre and post op assessment based on UMRS

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