Studies on Headache: Mechanisms of Chronic Posttraumatic Headache*

Abstract

The majority of patients with headaches that persist or recur for long periods after head injuries have no intracranial abnormalities. Sixty-three patients with the complaint of headache following injury to the head were studied in an attempt to find the causative factors of the pain where intracranial damage is not present. Electromyographic studies showed that excessive muscle potentials were present at or near sites of disagreeable head sensations and that, in general, the amount of muscle potential varied directly with the intensity of the pain. It was found that existing headaches were eliminated when 1% procaine hydrochloride was injected into zones of deep tenderness of the scalp. Certain head movements accentuated headaches when present while others diminished their intensity. A corresponding increase or decrease in muscle action potentials accompanied these variations in intensity. Previous studies indicate that there is little likelihood that noxious stimuli arising intracranially are factors of major significance in the causation of chronic post-traumatic headache. All patients in the present study exhibited emotional disturbances. It is thought that they over-react to minimal head sensations. The chronic post-traumatic headache closely resembles in mechanism and symptomatology those headaches accompanying and following stressful and unpleasant life situations but which are unrelated to head trauma. Vertigo, listing, pallor, sweating, nausea and pulse changes which accompanied the post-traumatic headache were experimentally studied. These symptomatic accompaniments are thought to result from the spread of excitation within the brain stem caused by noxious stimuli arising in the skeletal muscles and their attachments at the base of the skull.