CEREBRAL BLOOD-FLOW IN CHRONIC POSTTRAUMATIC HEADACHE

Background and Purpose.-Headache is the most common neurologic symptom following minor closed head injury. There is often a lack of objectiv e evidence supporting an organic basis of cerebral pathology in these cases. This pilot study considers the possibility of alterations in ce rebral blood flow, indicating evidence of an organic disorder in postt raumatic headache. Methods.-Regional cerebral blood flow studies of 35 patients with chronic posttraumatic headache (PTH) (International Hea dache Society criteria), identified retrospectively from our cerebral blood flow data base, were compared with those of 49 nonheadache contr ols and 92 migraineurs (Ad Hoc Committee criteria). Regional cerebral blood flow (initial slope index method) was measured using the xenon X e 133 inhalation technique. Results.-Compared to migraineurs and contr ols, and after adjusting for differences (analysis of covariance) in b aseline variables such as blood pressure, hematocrit and Pco(2),, pati ents with PTH had: (1)significantly lower mean initial slope indices ( P<0.001, P=0.002, respectively); (2) regional interhemispheric flow di fferences (rIFD), with higher distribution of regional asymmetrical pr obe pairs (rIFD greater than or equal to 7%: P[PTH versus control]=0.0 06, P[PTH versus migraine]=0.016; rIFD greater than or equal to 10%: P [PTH versus control]=0.011, P[PTH versus migraine]=0.003); and (3) mor e hemispheric asymmetries (P[PTH versus control]=0.023. P[PTH versus m igraine]=0.57). Lower mean initial slope indices and hemispheric asymm etry (mean interhemispheric flow difference greater than or equal to 3 .2%) predicted PTH over control (P=0.023 and 0.002, respectively). Low er mean initial slope indices predicted PTH over migraine (P=0.002). C onclusions.-Patients with PTH have reduced regional cerebral blood flo w, and regional and hemispheric asymmetries. These cerebral hemodynami c alterations support an organic basis to chronic posttraumatic headac he.