Pallidal physiology and predictors of successful deep brain stimulation in jerky dystonia, dystonia with tremor, and their combination.

OBJECTIVE

We investigated the physiological differences in pallidal neurons among patients with jerky dystonia, tremor with dystonia, and their combination (mixed dystonia), and identified whether neuronal physiology differs between pallidal regions where deep brain stimulation (DBS) improves dystonia and those where it not.

METHODS

Microelectrode registration was used to record pallidal single cell activity. Location of the active electrode and volume of activated tissue (VAT) was reconstructed with the Lead-DBS (Matlab extension).

RESULTS

VAT locations were distributed in 'Good Effect' and 'No Effect' groups according to their consequent clinical improvements. The neurons that were localized within the region of such VATs were analyzed for further comparison. The cells in the 'No Effect' group, neurons had similar characteristics across jerky dystonia, dystonia with tremor. In the Mixed subgroup significant differences were found in firing rate and preburst interval. The 'Good Effect' group showed more pronounced differences, with higher firing rates and lower preburst intervals in jerky dystonia compared to the remaining two types. Dystonia with tremor had higher burst spike percent and longer preburst intervals, while mixed dystonia had the highest preburst interval.

CONCLUSION

Differences in the neuronal subtypes and single unit physiology in pallidal regions that are responsive to DBS among patients with jerky dystonia, dystonia with tremor, and their mixed phenomenology suggest that each phenomenological variant involves distinct physiological processes. Mixed dystonia represents a unique physiological process, not merely a combination of the other two. The regions of the pallidum that improve jerky dystonia and tremor are anatomically similar.

SIGNIFICANCE: Pallidal neurons show distinct physiological profiles in jerky dystonia, dystonia with tremor, and mixed phenotypes. The neuromodulatory effect of DBS may vary by dystonia type.