Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology
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Reported prevalence of idiopathic intracranial hypertension without papilledema (IIHWOP) in series of patients with chronic or transformed migraine is significantly higher than expected; yet, IIHWOP is not included among the risk factors for migraine progression. However, several studies provided evidences suggesting that IIHWOP could represent a possible, largely underestimated, risk factor for progression of pain in migraine and, possibly, in other primary headaches. Data from two recent studies, albeit aimed to different end-points, strongly support this hypothesis. ⋯ Moreover, after the diagnostic lumbar puncture, a transient improvement of headache frequency has been observed in the majority of intracranial hypertensive chronic headache subjects. Taken together, the data of these two recent papers rise the following hypothesis: (1) asymptomatic IIHWOP is much more prevalent than expected in general population; (2) IIHWOP is a powerful and largely unrecognized risk factor for progression of pain in primary headache patients; (3) sinus venous stenosis at MRV is a reliable predictor of raised intracranial hypertension also in asymptomatic patients; (4) sinus venous stenosis has a causative role in IIH pathophysiology. These assumptions share a potential high clinical impact and need to be urgently tested in adequately designed controlled studies.