Application of IHS criteria to headache attributed to spontaneous intracranial hypotension in a large population

We applied the recent International Headache Society (IHS) criteria for headache related to spontaneous intracranial hypotension (SIH) to 90 consecutive patients with a final diagnosis of SIH confirmed by cerebral magnetic resonance imaging with contrast. Orthostatic headache (developing within 2 h of standing or sitting up) was present in 67 patients (75%) but appeared within 15 min after standing or sitting - as required by point A of the criteria - in only 53 (59%). Forty-four (49%) patients did not satisfy point A, including 22 (24%) with non-orthostatic headache and 14 (16%) with headache developing ≥ 15 min after standing or sitting up; 80 (89%) did not satisfy point D. Only three (3%) patients had headache fully satisfying the IHS criteria. These findings indicate that the current IHS criteria do not capture most patients with SIH-associated headache. Excluding the requirement for response to epidural blood patch (criterion D) and considering headaches appearing within 2 h of sitting or standing up would capture more patients.