Benztropine for the relief of acute non-traumatic neck pain – a randomised trial

Patients present to the Emergency department with acute cervical muscle spasm and pain, which may be spontaneous in onset or related to non-traumatic twisting events. In lay speech this may be referred to as a ‘wry neck’. Conventional analgesics such as paracetamol, NSAIDs and oral opoids are the mainstay of treatment for wry neck, but often provide inadequate pain relief. Centrally acting anti-cholinergic drugs are used for the relief of pain/spasm from the chronic condition of idiopathic cervical dystonia and from drug induced dystonic reactions. The use of these drugs for acute spasmodic neck pain has been poorly studied. There is a single study in the literature assessing the centrally-acting anti-cholinergic drug benztropine (trade name cogentin) in the relief of pain and spasm from this condition. This is a case series of 5 patients with acute pain and spasm of the neck and demonstrated remarkable relief of pain and improvement in range of motion in all patients following an intra-muscular injection of benztropine. Our hypothesis is that IM benztropine will provide relief of neck pain and improve range of neck movement in patients presenting with wry neck. We aim to compare the effect of 2mg IM benztropine with placebo on pain scores and range of motion in patients presenting to the ED with wry neck.