Prospective study of selective peripheral denervation for botulinum-toxin resistant patients with cervical dystonia

We have carried out a prospective study of selective peripheral denervation (SPD) in cervical dystonia (CD) patients with primary or secondary botulin um toxin (BT) treatment failure using independent standardized assessment. Patients referred for surgery had a standardized clinical examination, neck muscle EMG, videofluoroscopic swallow and CT of the cervical spine, and we re selected for surgery on the basis of the results of these investigations . CD severity, disability and pain were assessed preoperatively and at 3, 6 , 9, 12 and 18 months postoperatively using the Toronto Western Spasmodic T orticollis Rating Scale (TWSTRS). Severity of head tremor and dysphagia wer e scored using established rating scales. Additionally, psychosocial functi on was assessed in a representative subsample of patients (n = 12) using se veral established questionnaires. Of the 62 patients who were assessed, 22 (35.5%) were not offered surgery, most commonly because of widespread dysto nia. Of the remaining 40 patients, 37 have so far had surgery, 31 of whom h ave been followed up for at least 1 year, and 15 for 18 months after surger y (mean follow-up duration 16.7 months). Using the TWSTRS global outcome sc ore, 68% of patients derived functionally relevant improvement at 12 months after surgery. In the entire operated group, total TWSTRS scores were redu ced by 30% at 6 and 12 months after surgery (P < 0.0001). The subscores for severity, disability and pain were reduced by 20, 30 and 40%, respectively , at 6 months (P <less than or equal to> 0.01) and 20, 40 and 30%, respecti vely, at 12 months (P ( 0.01). Pain increased over time, which appeared to result from muscle reinnervation. TWSTRS scores were not significantly impr oved in the six patients with primary BT treatment failure. Head tremor did not change. There was a significant improvement of body concept, perceived disfigurement, stigma, and quality of life in the 12 patients whose psycho social function was assessed. Preoperative disability and restriction of he ad movement were negatively correlated and the initial response to BT treat ment positively correlated with global outcome score. Spread or deteriorati on of dystonia elsewhere in the body occurred in three patients, with unple asant sensory symptoms in denervated posterior cervical segments occurring in 14. Ten patients developed mild to moderate dysphagia, and two developed severe dysphagia. We conclude that SPD is an effective treatment for patie nts with secondary, but probably not for those with primary, BT treatment f ailure. Reinnervation is not infrequent and can compromise outcome. Postope rative morbidity is low, but there is a risk of dysphagia.