Supplementary Material for: Torticollis under Cyclobenzaprine

The muscle-relaxing 5-HT₂ receptor antagonist cyclobenzaprine is structurally closely related to amitriptyline. It is widely used to treat patients presenting with back pain and fibromyalgia. Very rarely cyclobenzaprine toxicity can result in extrapyramidal symptoms, but occurrence of torticollis has not been reported so far. We report on a patient presenting with torticollis and myoclonic movements after treatment with cyclobenzaprine, who was successfully treated with intravenous biperiden. This case might be additional evidence for the necessity of appropriate dosage in case of liver impairment. Secondly there are possibly consequences as regards the therapy of motor side effects.