Idiopathic intracranial hypertension with and without papilloedema in a consecutive series of patients with chronic migraine.

Chronic migraine (CM) has been associated with idiopathic intracranial hypertension without papilloedema (IIHWOP), a significant percentage of these cases occurring in obese patients with intractable headache. A prospective study from February 2005 to June 2006 was made of 62 CM patients who fulfilled International Headache Society diagnostic criteria and had cerebral magnetic resonance venography (MRV) and lumbar puncture (LP) done. Two patients were excluded, six (10%) with elevated cerebrospinal fluid (CSF) open pressure (OP), five with body mass index (BMI) > 25. None of the patients had papilloedema or abnormal MRV. BMI and CSF OP were significantly correlated (r = 0.476, P < 0.001, Pearson's correlation test). Obesity (defined as BMI > 30) was a predictor of increase in intracranial pressure (defined as OP > 200 mmH(2)O) (f = 17.26, 95% confidence interval 6.0, 8.6; P < 0.001). From our study we strongly recommend that not only intractable CM patients with high BMI, but also first diagnosed patients with BMI > 30 should be systematically evaluated by a LP to rule out IIHWOP.