Thalamic infarcts and hemorrhages.

The anatomy and supply of thalamic arteries are briefly described here. Thalamic infarcts and small-size hemorrhages are classified according to their sites: (1) posterolateral, (2) anterolateral, (3) medial, and (4) dorsal. (1) Posterolateral hemorrhages or lateral thalamic infarcts are usually characterized by severe motor impairment and sensory loss. Transient reduced consciousness, vertical-gaze abnormalities, and small fixed pupils may be evidenced. (2) Patients with anterolateral hemorrhages or tuberothalamic artery infarcts present frontal-type neuropsychological symptoms associated with mild hemiparesis and hemihypesthesia. (3) Medially located hemorrhages or paramedian artery infarcts have decreased levels of consciousness, vertical- and horizontal-gaze abnormalities, amnesia, and abulia. (4) Dorsal hemorrhages or posterior choroidal artery infarcts present with minimal transient hemiparesis and hemihypesthesia; apraxia, aphasia, and amnesia have also been described.