Prepulse inhibition and recovery of trigemino-cervical reflex in patients with cervical dystonia.

OBJECTIVE

We aimed to analyze the prepulse inhibition (PPI) and recovery rate (R) of the trigeminocervical reflex (TCR) in patients with cervical dystonia (CD).

METHODS

We enrolled 15 patients with CD and 16 healthy subjects. TCR was recorded over splenius capitis after infraorbital nerve stimulation. For TCR-PPI, we applied a prepulse stimulus to the left second finger 100 ms prior to the test stimulus and the percentage of change of response to test stimulus was calculated. For TCR-R, we applied paired infraorbital stimuli at interstimulus interval (ISIs) of 300 ms and the percentage of change of the second compared to the first response was calculated.

RESULTS

TCR-PPI and TCR-R values were higher (less inhibition and greater recovery) on both sides in the patient group compared to healthy subjects. There was high correlation between TCR-PPI and TCR-R on both sides in patients with dystonia (p < 0.005). We did not find any significant relationship between TCR-R or TCR-PPI and side of dystonic posture.

CONCLUSIONS

We showed disturbed modulation of TCR in CD patients. In CD, a general inhibition of the inhibitory pathways and facilitation of the excitatory pathways occur. Although TCR was recorded directly on the affected muscles in CD, symmetric abnormal TCR findings in CD suggest that these findings are probably secondary to altered function of higher order centers rather than being directly related to the pathophysiological process.