Radiological signs supporting idiopathic intracranial hypertension in symptomatic patients with lumbar puncture opening pressure < 250 mm

Lumbar puncture opening pressure (LPOP) exceeding 250mmH₂O is key in diagnosing idiopathic intracranial hypertension (IIH), per revised Friedman's criteria. Some patients do not meet LPOP criteria (with or without papilledema), despite having IIH-related symptoms and neuroimaging findings. This study aimed to investigate the radiological findings and clinical symptoms in patients suspected of having IIH without meeting the LPOP criteria. We retrospectively evaluated cerebral venous sinus stenosis using the conduit Farb score (CFS) and other radiological findings suggestive of IIH by computed tomography venography and magnetic resonance venography in females ≥ 18 years-old with chronic headaches, suspected IIH, and LPOP < 250 mm. Eighty-eight women (56 with LPOP < 200 mm H₂O and 32 with LPOP ranging between 200 and 250mmH₂O) were included. Among patients with LPOP 200-250mmH₂O, 40% (12) exhibited three or more radiological findings supporting IIH, compared to 17% (8) in the LPOP < 200 mmH₂O group (p = 0.048). Cerebral venous stenosis (CFS ≤ 5) was observed in 80% (24) of those with LPOP 200-250 mmH₂O, contrasting with 40% (19) of those with LPOP < 200 mmH₂O (p < 0.001). Cerebral venous stenosis was significantly more common in patients with LPOP 200-250 mmH₂O than < 200 mmH₂O, suggesting that they may benefit from IIH treatment.