Bilateral Lower Sternocleidomastoid Botulinum Toxin Injections to Address Refractory Anterocollis

Anterocollis is a type of cervical dystonia characterized by simultaneous and repetitive antagonist muscles contractions, resulting in abnormal neck flexion. It was described with a frequency of 6.8% from 399 patients with diagnosis of cervical dystonia and usually coexists with torticollis and/or laterocollis, as mixed cervical dystonia patterns. Botulinum toxin is usually a practical and effective treatment for cervical dystonia. The target muscles to inject in anterocollis are usually sternocleidomastoid and scalene muscles. There is also a case report suggesting longus collis involvement. Nevertheless, the dosage of the medication in anterocollis is limited by frequent side effects of dysphagia. We described 2 cases of refractory anterocollis. They did not benefit from conventional bilateral upper portion of sternocleidomastoid muscle injections with OnabotulinumtoxinA, but notably improved their symptoms and clinical global impression after switching to injections into bilateral lower portion of sternocleidomastoid muscles, without significant side effects.