Whiplash headache is transitory worsening of a pre-existing primary headache.

Acute and chronic whiplash headache are new diagnostic entities in the ICHD-2 (5.3, 5.4). In a prospective cohort study, 210 rear-end collision victims were identified consecutively from police records and asked about head and neck pain in questionnaires after 2 weeks, 3 months and 1 year. The results were compared with those of matched controls who were also followed for 1 year. Of 210 accident victims, 75 developed headache within 7 days. Of these, 37 had also neck pain and complied with the criteria for acute whiplash headache. These 37 had the same headache diagnoses, headache features, accompanying symptoms and long-term prognosis as the 38 without initial neck pain who therefore did not comply with the acute whiplash headache diagnosis. Previous headache was a major risk factor for headache both in the acute and chronic stage. Compared with the non-traumatized controls, headache in the whiplash group had the same prevalence, the same diagnoses and characteristic features, and the same prognosis. Both acute and chronic whiplash headache lack specificity compared with the headache in a control group, and have the same long-term prognosis, indicating that such headaches are primary headaches, probably elicited by the stress of the situation.