Unraveling the neural signatures: Distinct pallidal patterns in dystonia subtypes

Dystonia manifests as slow twisting movements (pure dystonia) or repetitive, jerky motions (jerky dystonia). Dystonia can coexist with myoclonus (myoclonus dystonia) or tremor (tremor dystonia). Each of these presentations can have distinct etiology, can involve discrete sensorimotor networks, and may have characteristic neurophysiological signature. This study reports distinct neurophysiological signatures corresponding to the phenomenological subcategories and associations of dystonia.

We studied 17 dystonia patients undergoing deep brain stimulation surgery. Video-based movement tracking classified them into four phenomenological subcategories: myoclonus dystonia, pure dystonia, jerky dystonia, and tremor dystonia. Microelectrode recordings from the globus pallidus interna (GPi) and externa (GPe) were analyzed to characterize single-neuron activity reflecting underlying physiology.

Analysis of 1038 neurons revealed distinct patterns of burst, pause, and tonic activity across subtypes. Myoclonus dystonia had the highest prevalence of burst neurons in the GPi, while tremor dystonia showed a balanced distribution of burst and pause neurons. Myoclonus and pure dystonia had higher firing rates compared to tremor and jerky dystonia. Tremor dystonia showed the most irregular and bursty firing patterns. Overall, myoclonus and tremor dystonia had higher burst rates and lower interburst intervals than pure and jerky dystonia, highlighting distinct neuronal activity patterns across the different dystonia types.

The differences in pallidal neuron activity across the phenoemenological subtypes and associations of dystonia depict distinct neural mechanisms. These findings offer crucial physiological insights into the diverse phenomenology of different dystonia types.