Polymyography combined with time-locked video recording (video EMG) for presurgical assessment of patients with cervical dystonia

We assessed 26 patients with cervical dystonia, in whom botulinum toxin (BT ) injections had failed, before selective peripheral denervation. We decide d to base the decision which muscle should be denervated on both clinical i nformation and EMG data and focussed on the following features: activity at onset or during 'dystonic spasms' (according to the concept of the 'leadin g' dystonic muscle), paradoxical activity during voluntary head movements c ausing restriction of head movements opposite the side of head turn or tilt and activity when symptoms deteriorated during walking. To identify these muscles we developed a new recording system that integrates simultaneous vi deo-taping and polymyography (video EMG) by means of a digital counter, dri ven by the recording software (resolution 0.1 s), that was fixed in view of the video camera. This system time-locked clinical signs with relevant EMG activity thus allowing demonstration of the above features. These were fou nd in 68% of dystonic muscles with each of them being present in approximat ely 40%. Video EMG allows an integrated approach to identify overactive nec k muscles in patients with cervical dystonia taking into account both relev ant clinical findings and EMG data. Copyright (C) 2001 S. Karger AG, Basel.