Altered Mental Status at High Altitude: Obstructive Hydrocephalus Mimicking High-Altitude Cerebral Edema (HACE)

Barg, Taylor, Jaclyn Walker, Samara Levine, David Ryan Ormond, and James P Maloney. Altered Mental Status at High Altitude: Obstructive Hydrocephalus Mimicking High Altitude Cerebral Edema (HACE). <i>High Alt Med Biol.</i> 00:00-00, 2025.-A 29-year-old female presented to a Colorado emergency department with amnesia, headache, confusion, and dysarthria after rapidly ascending a 4,404 m (14,267 ft) peak. Head CT revealed cerebral edema and hydrocephalus. She was hypotensive and required vasopressors prior to evacuation to a lower-altitude intensive care unit and received initial treatment for high-altitude cerebral edema (HACE) with dexamethasone. Imaging and clinical workup revealed obstructive hydrocephalus due to a colloid cyst with minimal radiographical evidence of cerebral edema except due to the compressive effects of hydrocephalus. She transiently developed stress-induced cardiomyopathy and mixed neurocardiogenic shock. This case emphasizes the importance of considering HACE mimics at high altitude triggered by hypoxia-mediated increases in intracranial pressure.