The hyperdense basilar artery sign: a case of locked-in syndrome

BACKGROUND: Locked-in syndrome, although a notoriously famous clinical entity, the rarity of the condition coupled with the variability of clinical features on acute presentation represents a potential diagnostic pitfall for the emergency physician. CASE: A previously healthy 25-year-old female was brought to our Emergency Department after being found unresponsive. On examination, she was conscious and alert with a Glasgow Coma Score of 9; on neurological examination, the patient was quadriplegic and unable to speak but was able to move her eyes and blink. Non-contrast brain computed tomography (CT) revealed a hyperdense basilar artery, and CT cerebral angiography confirmed basilar artery thrombosis. CONCLUSION: This case highlights the need for a high index of suspicion to make a diagnosis of locked-in syndrome in the Emergency Department, especially in young patients with no apparent risk factors for an ischemic stroke. The hyperdense basilar artery sign is one of the earliest signs on non-contrast CT imaging and may be the only clue to guide further management in a patient with basilar artery occlusion.