Chronic whiplash symptoms are related to altered regional cerebral blood flow in the resting state.

The neural pathogenic mechanisms involved in mediating chronic pain and whiplash associated disorders (WAD) after rear impact car collisions are largely unknown. This study's first objective was to compare resting state regional cerebral blood flow (rCBF) by means of positron emission tomography with (15)O labelled water in 21 WAD patients with 18 healthy, pain-free controls. A second objective was to investigate the relations between brain areas with altered rCBF to pain experience, somatic symptoms, posttraumatic stress symptoms and personality traits in the patient group. Patients had heightened resting rCBF bilaterally in the posterior parahippocampal and the posterior cingulate gyri, in the right thalamus and the right medial prefrontal gyrus as well as lowered tempero-occipital blood flow compared with healthy controls. The altered rCBF in the patient group was correlated to neck disability ratings. We thus suggest an involvement of the posterior cingulate, parahippocampal and medial prefrontal gyri in WAD and speculate that alterations in the resting state are linked to an increased self-relevant evaluation of pain and stress.