The relationship between the incidence of post-traumatic headache and the severity of head injury has been a controversial issue. The milder the head injury, the more frequently severe headache is noted as a symptom. To investigate this relationship, 121 civilians were investigated using simplified classifications of the grade of headache, type of injury (mild or severe), cervical X-ray and head CT findings, and clinical history. All the subjects were claiming compensation for work-related injuries.

In the mildly injured group, 46/64 patients complained of severe headache, while only 19/57 had severe headache in the severely injured group. Abnormal findings on the cervical X-ray films including degenerative changes were more frequent in the severe headache group. CT abnormalities correlated positively with the severity of head injury, but showed an inverse relationship with the incidence of headache. Mentally impaired patients also complained of headache less frequently. On the basis of these results, possible organic mechanisms related to the pathogenesis of post-traumatic headache are discussed.