Efficacy of Segmental Muscle Vibration on Pain Modulation in Patients With Primary Cervical Dystonia: a Randomized Controlled Study

This study aims to evaluate the effectiveness of Vibration Muscle Stimulation (VMS) in reducing pain and improving quality of life in patients with primary cervical dystonia (CD), a focal dystonia characterized by involuntary and often painful muscle contractions in the neck. The study will involve patients who have been treated with botulinum toxin and are candidates for an integrated rehabilitation program, which includes physiotherapy and occupational therapy. Participants will be randomized into two groups: an experimental group receiving therapeutic VMS (80 Hz frequency, 0.5 mm vibration amplitude) and a control group receiving sham VMS. Both groups will undergo a 10-session rehabilitation program combining 45 minutes of physiotherapy and 15 minutes of VMS (or sham), followed by 30 minutes of occupational therapy. The primary outcome measure will be pain and disability as assessed by the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and the McGill Pain Questionnaire. Secondary outcomes will include improvements in quality of life and clinical severity of dystonia. The results are expected to provide insights into the potential role of VMS in enhancing rehabilitation outcomes for patients with cervical dystonia.

Detailed Description This study aims to evaluate the efficacy of Segmental Muscle Vibration (SMV) on pain reduction and quality of life improvement in patients with primary cervical dystonia (CD). The study is conducted on patients undergoing botulinum toxin treatment and eligible for a standardized integrated rehabilitation protocol, including physiotherapy and occupational therapy. Cervical dystonia is a neurological disorder characterized by involuntary contractions of neck muscles, leading to abnormal movements, postures, and significant pain. Current treatment often involves botulinum toxin injections, but additional therapeutic strategies are required to address persistent symptoms such as pain and impaired quality of life. SMV, a non-invasive intervention, applies mechanical vibration to specific muscles to modulate pain perception, improve proprioception, and enhance motor function. This study seeks to determine the translational potential of SMV as a component of integrated rehabilitation in CD patients.

The study is a single-center, randomized controlled trial with parallel arms. Patients in the experimental group will receive 10 sessions of integrated rehabilitation, including 45 minutes of physiotherapy, 15 minutes of therapeutic SMV, and 30 minutes of occupational therapy. Patients in the control group will follow an identical protocol, but the SMV will be sham (the vibration device produces sound but no actual vibration). Participants are recruited from the Spasticity Outpatient Clinic at Fondazione Don Gnocchi, Rovato (BS), Italy, where they are treated for painful cervical dystonia with botulinum toxin. After receiving the toxin, patients meeting inclusion criteria are briefed on the study's purpose and procedures. Upon signing informed consent, participants undergo an initial evaluation (T0) by a physiatrist, who assigns them randomly to either the experimental or control group using a pre-sealed envelope system.

The rehabilitation program consists of 10 outpatient sessions. Each session includes physiotherapy for 60 minutes, which involves active strengthening of antagonist muscles, mobilization, stretching of cervical-thoracic kinetic chains, proprioceptive control, postural exercises, and body schema modulation. Occupational therapy follows for 30 minutes, focusing on improving proprioceptive, praxis, and spatial control of movements. SMV is administered during the last part of each physiotherapy session. In the experimental group, SMV is applied to the trapezius (middle/descending fibers) and quadratus lumborum bilaterally at 80 Hz with an amplitude of 0.5 mm. In the control group, sham SMV is applied using disconnected terminals that produce sound but no vibration, ensuring blinding.

Participants will be evaluated at baseline (T0), after five sessions (T1), and after completing the program (T2) using standardized scales. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) will assess clinical severity, disability, and pain. The McGill Pain Questionnaire will evaluate pain perception and subjective experience. The Tsui Score will measure the clinical severity of dystonia, including amplitude and duration of dystonic movements, tremor, and shoulder elevation. Randomization is performed using sequentially numbered, sealed envelopes containing group allocation. Both patients and therapists are blinded to the group assignment, and sham SMV mimics the sound of active SMV without delivering vibration.