Abstract text (incl. figure legends and references)

Background: Idiopathic intracranial hypertension (IIH) is an increasingly prevalent disease bearing the risk of visual impairment and affecting quality of life. Clinical presentation and outcome are heterogeneous. Large, well-characterized cohorts are scarce.

Objective: To describe the Vienna-Idiopathic-Intracranial-Hypertension (VIIH) database aiming to characterize the clinical spectrum, diagnostic findings, therapeutic management and outcome of IIH.

Methods: Applying the modified Dandy criteria we identified 113 IIH-patients treated at our center between 2014 and 2021.

Results: Of 113 patients, 89% were female (mean age 32.3 years). Median body mass index (BMI) was 31.8, with 85% overweight (BMI>25). Papilledema was found in 95% with 5% classified as IIH without papilledema. Headache was present in 84% and showed migrainous features in 36%. Median opening pressure in lumbar puncture was 31cmH2O.

Pharmacotherapy (predominantly acetazolamide) was established in 99%, 56% required at least one therapeutic lumbar puncture and 13% surgical intervention.

After a median follow-up of 3.7 years, 43% had not achieved significant weight loss, papilledema was present in 49% and headache in 76% (58% improved).

Comparing initial presentation to follow-up, perimetry was abnormal in 67% vs. 50% (8% worsened, 24% improved) and transorbital sonography in 87% vs 65% with a median optic-nerve-sheath-diameter of 5.4mm vs. 4.9mm. Medianperipapillary-retinal-nerve-fiber-layer thickness had decreased from 199µm to 94µm and ganglion-cell-layer thickness from 40µm to 36µm.

Conclusions: The VIIH database constitutes a large representative and well-characterized cohort and emphasizes substantial long-term sequelae of IIH. Future analyses will aim to refine phenotyping and identify factors predicting outcome.