A 24-year-old female, with a body mass index (BMI) of 37.3, presented with headaches, transient visual obscurations (TVOs), pulsatile tinnitus, Frisén 5 papilledema, and scotomas. She was diagnosed with idiopathic IH after a normal magnetic resonance imaging and venogram (MRI/V) of her brain, an elevated opening pressure of 27 cm. water, and normal CSF. Her IIH resolved with acetazolamide 4 g/day and an optic nerve sheath fenestration (ONSF) on the left. He then started testosterone therapy for female-to-male reassignment and was on this for 20 months when his headaches, pulsatile tinnitus, TVOs, and Frisén 3 papilledema recurred, at BMI of 31. Brain MRI/V were normal. Opening pressure was elevated at 31 cm. water. Free testosterone level was 177.8 picogram/ml (range 0.2-5), bioavailable testosterone 334.8 picogram/ml (range 0.5-8.5), total testosterone 511 picogram/ml (range 2-45). Acetazolamide 4 g/day did not improve the papilledema, thus a left ONSF was repeated. As of writing this abstract, 2 weeks after the repeat fenestration, there was no improvement in his papilledema, but the headaches and other symptoms have resolved. He has decided to continue testosterone therapy. 

We acknowledge that IIH may recur, but given his testosterone therapy for his gender reassignment, recurrent IH due to testosterone therapy should be strongly considered. This supports the theory that IIH may be due to hyper-androgenism and increased CSF testosterone. In-vitro studies in rats showed that testosterone increased CSF production. Thus, IIH patients undergoing hormonal therapy for gender reassignment should proceed with caution.