A multiparametric MEG study of the effect of medications on neuronal oscillations in generalized or cervical dystonia

Objective: To better understand the mechanism of action of anti-dystonia medications by comparing cerebral oscillations at network level, pre and post administration of medications, using MEG in patients with generalized or cervical dystonia. Background: The underlying mechanisms of dystonia remain poorly understood and etiologic treatments are lacking. Reduced intracortical inhibition and distorted somatotropic cortical representation in the somatosensory cortex are thought to play a critical role. Methods: MEG data on generalized or cervical dystonia patients (N=5) between the ages of 16-70 years old, recruited from Henry Ford WB Hospital was collected. Subjects were scheduled for a MEG scan, with two 20- minute studies spaced an hour apart in each treatment condition (OFF medications, ON meds-1 hour after ingestion). For each cortical model site, coherence is defined as the oscillations of neural activity and their synchronization with all other active network sources, and further averaged over frequencies. Coherence imaging was performed to quantify default mode network connectivity of subjects. MEG Tools uses a nonlinear volumetric transformation of the patient\u27s brain to transform MEG coordinates to these standard brain coordinates. Results: Pre and Post medication MEG data was available on three dystonia patients. One patient each could not complete their pre and post medication scan. 1. In all 3 patients with pre and post data, the overall coherence increased after treatment. 2. In both patients on either Botox or Valium, there was an increased beta and gamma band coherence activity post treatment. 3. This increased activity was absent in the patient on carbidopa/ levodopa. Conclusions: Our exploratory pilot study while limited by our sample size and use of a cortical model, did generate some potentially interesting findings. 1. The overall coherence increased after treatment could be a sign of increased neuronal synchrony. 2. The absence of beta and gamma coherence peaks with Sinemet suggests an alternate mechanism to increase coherence. 3. The increased gamma band coherence activity may be a reflection of restoration of GABAergic activity and cortical inhibition. These findings need to be replicated in a larger sample size. This will give us a better indication of the mechanism of action of medications which offer symptomatic relief in dystonia patient, perhaps offering insight in to the mechanism of the disease process. (Figure presented)