Head or neck injury increases the risk of chronic daily headache: A population-based study

OBJECTIVE: To evaluate the extent to which head and neck injury (HANI) contributes to chronic daily headache (CDH). BACKGROUND: In prospective studies, head injury is associated with headache (HA) that remains a problem at 12 to 24 months post-head injury in 20 to 30% of patients. Of these, up to 30 to 50% manifest CDH. The degree to which head injury contributes to CDH has not been evaluated in a non-clinical population. We evaluate the relationship between lifetime occurrence of HANI and CDH in a randomly chosen population sample. METHODS: Study participants are from the Frequent Headache Epidemiology Study. Cases with CDH (≥180 HA/year) and a comparison group with episodic headache (EH, 2 to 102 HA/year) were identified from the general population. Subjects were asked about lifetime occurrence of HANI. HANI were further classified as potentially precipitating injuries (PPI) if they occurred within 2 years of CDH onset for cases or in an equivalent 2-year period for EH controls. RESULTS: Lifetime occurrence of HANI was more frequent in cases than controls for men (adjusted OR = 3.1 [1.3 to 7.2]), women (OR = 1.5 [0.97 to 2.3]), and overall (OR = 1.7 [1.1 to 2.4]). The attributable risk was 15% (36% men, 11% women). Results were similar for PPI. The odds of CDH increased with the number of lifetime HANI in all groups (p < 0.05 trend). CONCLUSIONS: Results suggest that head and neck injury (HANI) accounts for approximately 15% of chronic daily headache (CDH) cases in this non-clinical population. The relationship between HANI and CDH was not limited to injuries proximate to CDH onset. The lifetime risk of CDH increases with increasing number of HANI.