Botulinum toxin therapy for cervical dystonia: review of the clinical evidence and ongoing studies

Cervical dystonia, also referred to as spasmodic torticollis, is the most frequent form of adult-onset focal dystonia seen in neurological practice. It is characterized by involuntary contractions in a specific set of muscles causing abnormal, sustained and frequently painful postures of the head, neck and shoulders. Intramuscular injection of botulinum toxin (BoNT) into selected muscles is currently considered the treatment of first choice. This has been confirmed by numerous short- and long-term clinical studies, which have established high-quality class I and II evidence (level A recommendation by the American Academy of Neurology) that both BoNT-A and BoNT-B are safe and effective treatment options for cervical dystonia. This review summarizes the clinical evidence currently available and attempts to provide an overview of ongoing clinical studies in this field.