The immediate effect of peripheral stimulation on cervical dystonia disease outcomes: single-case experimental design.

Only 15 people were analysed. With no untreated or sham group and no blinding, the improvements could be placebo or the natural ups and downs of dystonia, which the authors acknowledge. Sessions were booked for when the last botulinum injection was assumed to have worn off. That timing is an assumption, not a measurement. Everything was measured immediately after a single session and 10 minutes later, so the paper says nothing about whether any change lasts or alters the condition over time. The 3D camera system used to measure neck movement has not been shown to be valid and reliable in adults with cervical dystonia. There is no agreed figure for how large a change in neck range or pain matters to people with cervical dystonia, so it is unclear whether the changes seen were meaningful to patients. The reported numbers do not always match: the results sections report improvement in 8 of 15 (53.3%) after muscle stimulation and 7 of 15 (46.67%) after vibration, while the paper's own summary paragraph reports 8 (42.1%) for both. Only people who had pain or restricted neck movement at the start were analysed, so the results describe a subgroup of those enrolled.

The authors declared no competing interests and stated that the research received no specific grant from public, commercial or not-for-profit funding agencies. No involvement of a company in designing, running or writing up the study is described.

Do not read this as evidence that TENS, muscle stimulation or vibration works for cervical dystonia. There were only 15 people, no control group and no blinding, effects were measured only straight after a single session, and several participants got worse rather than better. The authors themselves say the small numbers and the absence of blinding mean placebo and the natural course of the condition cannot be ruled out.