[A case of midbrain and thalamic infarction showing Collier's sign in one side and blepharoptosis in the other side].

A 68-year-old man was admitted to the hospital complaining of aphasia and right hemiparesis. Neurological examination revealed aphasia, right hemiparesis and ataxia in the left upper extremity. He showed striking ocular symptoms: intense retraction of the right eyelid (Collier's sign), complete ptosis of the left eyelid which might conceal Collier's sign, marked upward gaze palsy and slight downward gaze palsy. Vertebral angiography and MRI revealed an infarction in the left medial area and the left crus cerebri in the upper midbrain, the left subthalamic area inferomedially extending from the adjacent area to the posterior commissure and the medial area in the left thalamus resulting from occlusion of the left mesencephalic artery. From these MRI findings and the reports on pathological findings of patients with Collier's sign, we suggest that damage in the posterior commissure or its adjacent area may be responsible for the sign. Upward gaze palsy is often associated with Collier's sign because fibers mediating upward gaze may decussate in the posterior commissure. Third nerve palsy is also associated with the Collier's sign in some patients. The mechanism creating Collier's sign may be a disturbance of inhibitory fibers leading to the motoneuron pool of the levator muscle in the posterior commissure or its adjacent area.