Fibrous myopathy induced by intramuscular injections of cyclizine

A 63-year-old woman was referred to neurology with bilateral severe progressive pain and stiffness in her thighs. The patient had a 3-year history of injecting intramuscular cyclizine into the anterior thigh to treat nausea associated with a longstanding pan-enteric dysmotility syndrome. MRI of the thighs demonstrated fibrotic appearances. A biopsy of the left vastus lateralis and surrounding fascia identified pathology consistent with a fibrous myopathy. The patient was advised to stop intramuscular injections of cyclizine and undergo physiotherapy but she still remained in considerable pain. Although fibrous myopathy occurring as a consequence of recurrent intramuscular drug injections, particularly heroin, has been previously described, this is the first report of fibrous myopathy associated with the use of intramuscular cyclizine. We highlight this rare association and suggest that the long-term use of intramuscular cyclizine be avoided.