A Prospective Multicenter Study on the Evaluation of Frequency of Idiopathic Intracranial Hypertension in Korea

Background: Idiopathic intracranial hypertension (IIH) is a complex neurological disorder that primarily affects obese women of reproductive age. Epidemiological data on IIH in Asia are scarce, and previous small retrospective studies in Asia have reported a significantly different patient profile from what is known for this disorder. We aimed to prospectively examine the frequency of IIH in headache clinics and to assess the presence of red flag signs in patients with IIH. Methods: We prospectively collected data on consecutive first-visit patients with IIH who visited the headache clinics of 11 hospitals in Korea between January 2022 and March 2024. Data on clinical characteristics, lumbar puncture opening pressure, and neuroimaging were collected. The SNNOOP10 list was administered to patients with IIH to assess the presence of red flags. Results: Among the 13,028 new headache patients, 22 were diagnosed with IIH (frequency, 0.17%; 95% confidence interval [CI], 0.11–0.25%; women, 0.19%; 95% CI, 0.12–0.30%; men, 0.11%; 95% CI, 0.04–0.28%). The median age of the patients was 33 years (interquartile range, 27–44 years), and 18 patients (81.8%) were women. Sixteen (72.7%) patients were obese (≥ 25 kg/m²) according to the Asian-Pacific classification, with only 11 (50%) having a body mass index ≥ 30 kg/m². All patients with IIH reported one or more red flags in the SNNOOP10 list, with papilledema being the most common (n = 14; 63.6%). When patients with papilledema and red flags irrelevant to IIH were excluded, 10 patients (45.5%) had no red flags. Among the headache-related red flags, pattern change or new-onset headache (n = 6; 27.3%) were the most common. Positional headache (n = 2; 9.1%) and precipitation due to sneezing, coughing, or exercise (n = 1; 4.5%) were uncommon. Conclusion: The frequency of IIH in headache clinics in Korea was low. Typical obesity profiles, clinical characteristics, and papilledema are less common in Korean patients with IIH. Although the SNNOOP10 list seems to be feasible, clinical suspicion alone may not be sufficient to screen for IIH, particularly in Asians.