SYNOPSISElectromyographic examinations of neck and temporal muscles were performed in 132 patients with various types of headaches and in 51 controls. No muscle action potentials were found provided control subjects were voluntarily relaxed. The majority of headache patients though voluntarily relaxed showed continous electrical activity in muscles resulting from sustained spasm. This phenomenon seems to be characteristic for headache patients. It is named “cephalgic” spasm of head and neck muscles. “Cephalgic” spasm is thought to be a consequence rather than the cause of h