http://www.aetna.com/cpb/medical/data/400_499/0401.html

Selective peripheral denervation was performed in 111 patients with total or marked relief of symptoms in 97 (87%). There have been no complications and the only sequelae have been atrophy of the denervated muscles and anesthesia in the territory of the occipital nerves.

http://www.anesthesia-analgesia.org/...3/551.full.pdf

The purpose of selective peripheral denervation in torticollis is to release the abnormal contracture of the muscles involved while preserving the function of other muscles. The procedure alleviates abnormal posture and symptoms yet maintains normal neck movement (1,2)