BACKGROUND: The aetiology behind chronic post-traumatic headache (CPTH) after mild head injury is unclear and management is complicated. In order to optimize treatment strategies we aimed to characterize a CPTH population.

METHODS: Ninety patients with CPTH and 45 patients with chronic primary headaches were enrolled from the Danish Headache Center. All patients were interviewed about demographic and headache data. They completed the Harvard Trauma Questionnaire (HTQ), Rivermead Post Concussion Symptoms Questionnaire, SF-36 and a headache diary.

RESULTS: The CPTH group experienced more cognitive ( P < 0.001) and somatic symptoms ( P = 0.048) and rated their self-perceived health as more affected in terms of physical function ( P = 0.036), physical role function ( P = 0.012) and social function ( P = 0.012) than the control group. Surprisingly, 31% of the CPTH group had a score equal to or above the cut-off score for having post-traumatic stress disorder (PTSD) according to the HTQ. In terms of demographics and headache, the groups were comparable except the CPTH group were more often without affiliation to the labour market ( P < 0.001).

CONCLUSIONS: The loss of work capacity and high levels of disability for the CPTH patients suggests directions for further research into what important factors are embedded in the patients' PTSD symptoms and might explain their prolonged illness.