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 (p<0.001). Abnormal findings on the cervical X-ray films including degenerative changes were more frequent in the severe headache group (p<0.02). CT abnormalities correlated positively with the severity of head injury (p<0.001), but showed an inverse relationship with the incidence of headache (p<0.01). Mentally impaired patients also complained of headache less frequently (p<0.01). On the basis of these results, possible organic mechanisms related to the pathogenesis of post-traumatic headache are discussed.