Title : Bilateral thalamic infarction from a single rare artery: A case of Percheron infarction with hemorrhagic transformation
Abstract:
Background: The artery of Percheron (AoP) is a rare anatomical variant in which a single perforating trunk arising from one P1 segment of the posterior cerebral artery supplies both paramedian thalami bilaterally. AoP occlusion accounts for approximately 0.1–2% of all ischaemic strokes and classically presents with altered consciousness, vertical gaze palsy, and memory impairment. Early CT findings are frequently non-specific, leading to diagnostic delay. Haemorrhagic transformation is a recognised but infrequently reported complication that may worsen prognosis and complicate anticoagulation decisions when a cardioembolic source is identified.
Case Presentation: A 63-year-old man with known hypertension and previously undiagnosed atrial fibrillation was found unresponsive at home and presented to our centre after an 11-hour delay. Despite initial profound unresponsiveness, his admission NIHSS was 3/42 and GCS was 15/15 with preserved orientation; however, upward vertical gaze palsy, anisocoria, and left ptosis were noted. Non-contrast CT revealed bilateral thalamic hypodensities. MRI demonstrated bilateral paramedian thalamic infarcts with restricted diffusion and blooming artefacts on susceptibility-weighted imaging consistent with haemorrhagic transformation. A concurrent left occipital infarct supported a cardioembolic mechanism. Haemorrhagic transformation precluded anticoagulation, and the patient was managed with antiplatelets, high-intensity statins, and blood pressure control. On day three, the patient’s neurological status deteriorated rapidly, requiring intubation. He was discharged against medical advice on day four and died the following day.
Conclusion: This fatal case illustrates the treacherous trajectory of AoP infarction, in which a deceptively low NIHSS score reflecting the well-documented insensitivity of this scale to posterior circulation deficits may mask the severity of bilateral thalamic injury. Haemorrhagic transformation complicated management by precluding anticoagulation for newly diagnosed atrial fibrillation. Clinicians should maintain a high index of suspicion for AoP infarction when bilateral thalamic lesions are encountered and recognise that the NIHSS alone is insufficient to gauge severity in thalamic and brainstem strokes.
