A randomized study of botulinum toxin versus botulinum toxin plus physical therapy for treatment of cervical dystonia

Background: Physical therapy (PT) for cervical dystonia is not well studied, and the underlying physiological effects are not known. Methods: We enrolled 26 subjects comprising of 16 cervical dystonia and 10 healthy controls for normative physiological data. We randomized cervical dystonia patients who reported suboptimal benefits on botulinum toxin (BoNT) injections to BoNT alone (BoNT arm) or BoNT plus PT (PT-BoNT arm). PT-BoNT arm received manual PT on the injection day followed by six weeks of home-exercise program. Home-exercise program comprised of stretching, range-of-motion and isometric exercises. The primary outcome was change from baseline in Toronto Western spasmodic torticollis rating scale (TWSTRS) that was recorded six weeks after exercise program. TWSTRS was video evaluated by blinded raters. We probed sensorimotor plasticity with transcranial magnetic stimulation (TMS) using a paired associative stimulation (PAS) paradigm. Results: TWSTRS score improved (severity 31%, p = 0.002; pain 28%, p = 0.01) and PAS plasticity decreased (p = 0.01) in PT-BoNT arm compared to BoNT arm. PAS values for PT-BoNT arm were found to approach values of healthy control values. Change in PAS measure correlated significantly with TWSTRS change (severity, r = 0.56, p = 0.04; pain, r = 0.61, p = 0.03. TWSTRS disability score only approached significance (p = 0.14) when comparing the two treatment arms. Conclusion: PT is a potential adjunct in patients with cervical dystonia who report suboptimal benefits with BoNT therapy. PT related benefits in cervical dystonia are likely mediated through modulation of sensorimotor plasticity.