Headache from clinically confirmed hemicrania continua arising from the sternocleidomastoid muscle: a case report

BACKGROUND: A patient with a history of cluster headaches, now in remission, presented with confirmed hemicrania continua that resolved with a local anaesthetic injection into the Sternocleidomastoid (SCM) muscle. To the best of our knowledge, this is the first reported case of a trigeminal autonomic cephalalgia arising from a soft tissue source in the neck. CASE PRESENTATION: A 66-year-old man with a history of cluster headaches presented with a six-month history of a new constant right-sided headache. The new headaches were associated with tearing and redness of the right eye and responded to indomethacin, thus meeting the International Classification of Headache Disorders (ICHD-3) diagnostic criteria for hemicrania continua. The history and physical examination suggested a cervical source of the headache arising from the ipsilateral SCM muscle. Injection of the muscle with 1% lidocaine resulted in the elimination of the pain for 1 month without indomethacin. CONCLUSIONS: Due to the convergence of trigeminal, cervical and autonomic nerve fibres, various combinations of headache syndromes can result. This case report demonstrates how a meticulous examination is a crucial component of headache evaluation. Treatment directed to this muscle spared this patient further daily indomethacin and associated side effects.