Molding the sensory cortex: Spatial acuity improves after botulinum toxin treatment for cervical dystonia

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Abstract
Disorganization of sensory cortical somatotopy has been described in adult onset primary torsion dystonia (AOPTD). Although botulinum toxin type A (BTX‐A) acts peripherally, some studies have suggested a central effect. Our primary hypothesis was that sensory cortical reorganization occurs after BTX‐A treatment of AOPTD. Twenty patients with cervical dystonia and 18 healthy age‐matched control patients had spatial discrimination thresholds (SDTs) measured at baseline and monthly for 3 months. Mean baseline SDT (±SD) was 1.75 ±0.76 mm in the dystonia group, greater than the control group mean of 1.323 ± 0.45 mm (P = 0.05). Mean control group SDT did not vary significantly over time. A transient improvement of 23% from baseline (P = 0.005) occurred in the dystonia group 1 month after injection, which did not positively correlate with changes in physician and patient ratings of torticollis severity. The presumed mechanism of SDT improvement is a modulation of afferent cortical inputs from muscle spindles. © 2007 Movement Disorder Society