Hyperekplexia in a patient with a brainstem vascular anomaly

Objectives - To describe a patient with a clinical picture suggestive of id iopathic hyperekplexia (IH), who was later found to harbour a subtle brains tem vascular anomaly. Patient - A 35-year-old man, 4 years earlier, develop ed sudden jumping and falling in response to unexpected sensory stimuli. Re sults - Neurological examination was normal. Electromyography showed an exc essively large and non-habituating motor startle response. There were no mu tations of the a, subunit of the inhibitory glycine receptor which cause he reditary hyperekplexia. Although all these findings were consistent with a diagnosis of IH, a blink reflex study showed an enhanced recovery curve sug gestive of a brainstem lesion. A detailed MRI study revealed a subtle vascu lar anomaly involving the lower brainstem. Conclusion - This is the first r eport of sporadic hyperekplexia related to a brainstem vascular anomaly. Su btle damage to the brainstem should always be excluded in patients with spo radic hyperekplexia, regardless of the coexistence of additional clear-cut neurological symptoms.