EVALUATION OF MYOBLOC (BOTULINUM TOXIN TYPE B) IN PATIENTS WITH POST‐WHIPLASH HEADACHES

Ciceron L. Opida, MD, Bon Secour Holy Family Hospital of Altoona Altoona, PA Myobloc (botulinum toxin type B; BoNT‐B) is a new botulinum toxin serotype antigenically distinct from the type A toxin. It acts to block the release of acetylcholine at the neuromuscular junction, resulting in a localized paralysis when minute doses are injected. Studies in patients with cervical dystonia have shown that BoNT‐B effectively reduces symptoms including pain associated with this disorder, and suggest that it may be effective in alleviating other painful syndromes, such as chronic headaches. The purpose of this open‐label study was to evaluate the efficacy of BoNT‐B in the treatment of patients with post‐whiplash headaches. Thirty‐one patients were enrolled in the study. These patients were status post‐whiplash after 6 months, had headaches that were disabling after 4 weeks of injury, and were complaining of deep head pain that was radiating from the occipital to the orbital and lasting for more than 5‐months duration. Patients had restriction of head flexion, rotation, and/or side bending at the top of the neck. The numeric rating scale (0–10) was used to rate the severity of symptoms. Pre‐injection, most patients were at 10 on the NRS; none were below 8. Patients were injected with 1 cc BoNT‐B (5000 U) divided among the suboccipital muscles (Recti capitis posteriors major and minor, obliqui capitis inferior and superior). Of the 31 patients, 22 (71%) reported improvements in their headache intensity and severity, and neck motion. Most patients were at 0–2 on the NRS post‐injection. Adverse effects were minor, consisting mainly of dry mouth (40%) and pain at the injection site lasting for only a few days. The results of our study suggest that BoNT‐B may be an effective agent for the treatment of post‐whiplash headaches; further studies are warranted. Support of Elan Pharmaceuticals is gratefully acknowledged.