Somatosensory evoked potentials and headache: a further examination of the central theory.

The central theory of headache was investigated by examining the amplitude of the somatosensory evoked potential (SSEP) in headache sufferers and headache-free controls. The P1-N1 amplitude was found to be greater, and to increase more rapidly with increasing stimulus intensity, for headache subjects than for controls. The N1-P2 amplitude was also found to be larger for headache subjects than for controls, but there was no significant difference between groups on the rate at which this component increased with stimulus intensity. When the P1-N1 and N1-P2 amplitudes were assessed in headache subjects, during and between attacks, no significant differences between conditions were observed. No significant differences between tension and migraine sufferers were observed on either component. It was concluded that the central nervous systems of headache sufferers may be more reactive to somatosensory input than those of headache-free persons and that this might be an important factor in the pathophysiology of headache.