Acoustic neuroma presenting as a hypnic headache

Hypnic headache (HH) is a rare, primary headache syndrome that invariably occurs during sleep and wakes the patient. Acoustic neuroma (AN) is a benign tumour that uncommonly presents with isolated headache. Here, we describe a patient with AN that presented with an HH-like syndrome. A 40-year-old woman presented with 4 months of generalised, throbbing, nocturnal headaches that woke her from sleep. Neurological examination was unremarkable. Retrospectively, she reported a 4-year history of mild, bilateral tinnitus. Neuroimaging demonstrated a large, left-sided AN in the cerebellopontine angle without obstructive hydrocephalus. Gamma knife radiosurgery controlled tumour growth. One year after radiosurgery, she became nocturnal headache-free. AN has not previously been described as presenting with an HH-like syndrome. There are four previous reports of an HH-like syndrome secondary to intracranial masses. In all cases, patients became headache-free following surgery. This advocates for neuroimaging to exclude structural causes.