2 The procedure
2.1.1 Cervical dystonia is a condition in which the muscles of the neck contract painfully and cause twisting of the head. The head may be pulled backwards (retrocollis), forwards (anterocollis) or to the side (torticollis), depending on which muscle groups are affected. This muscle spasm may occur intermittently or continuously. The cause of cervical dystonia is not known. In children, it is sometimes associated with congenital abnormalities of the shape of the head or of the spine, but it may occur at any age. Cervical dystonia may persist for several years, or sometimes for life. Some patients recover spontaneously.
2.1.2 Standard treatment for cervical dystonia includes physiotherapy, drugs to reduce spasm, injections of botulinum toxin, and brain surgery. Selective peripheral denervation may be an alternative, especially for people who have not responded to other treatments.
2.2.1 Selective peripheral denervation is a surgical procedure that varies according to the muscle groups affected. It is performed under general anaesthetic and involves cutting, through a skin incision, the nerves that supply the affected muscles. Sometimes the muscles themselves may be divided.
2.3.1 The evidence was limited to one systematic review and several case series studies. The review found no controlled studies and no reliable evidence to compare the procedure with other treatments. Two of the larger case series studies found 'very good to excellent' results in 88% (228/260 and 182/207) of patients at follow-up. However, the time to follow-up and how these outcomes were assessed were not specified in either of these two studies. For more details, refer to the Sources of evidence section.
2.3.2 One Specialist Advisor noted that careful patient selection should improve the efficacy of the procedure.
2.4.1 The largest case series study identified reported the following complications: occasional tic-like pain (1%, 3/260); tonsillar abscess (0.4%, 1/260); transient swelling of the neck in a few patients (number not specified); and pins and needles or sensation of tightness or fullness in a few patients (number not specified). For more details, refer to the Sources of evidence section.
2.4.2 The Specialist Advisors listed potential adverse events as difficulty in swallowing, as well as the usual potential complications of surgery, such as infection and haemorrhage.