[A case of bilateral thalamic infarction with the characteristic MRI finding].

A 62-year-old Japanese man with a history of smoking, hypertension and paroxysmal atrial fibrillation presented sudden-onset disturbance of consciousness. He had a fluctuating consciousness, transient apnea, and vertical gaze palsy. Brain diffusion-weighted MRI showed hyperintense signals in the rostral midbrain and bilateral paramedian thalami, and the diagnosis of midbrain and bilateral thalamic infarction was made. The midbrain lesion corresponded with midbrain V sign, a characteristic finding of this infarction. Although there are several other deseases causing bilateral thalamic lesion, this sign is very helpful in distinguishing the disease from others. On the other hand, CT angiography visualized another variant of thalamoperforating arteries instead of Artery of Percheron (AOP), the common variant in bilateral thalamic infarction. This case indicates that other anatomical variants of thalamoperforating arteris besides AOP could cause this infarction.