[Lateral thalamic infarction. 22 cases].
Isolated lateral thalamic infarcts (LThl) are rare. They often produce lacunar syndromes, and their main cause is thought to be an hypertensive arteriolopathy. To verify these data, we reviewed 639 cerebral infarcts demonstrated by CT and/or MRI and included in a hospital stroke registry over a 4-year period. We identified 22 cases (3.5 p. 100) of isolated LThl (right LThl: 15; left LThl: 7). Nineteen had MRI study. There were 13 men and 9 women of mean age 65 years. None had the complete Dejerine-Roussy syndrome: sensory disturbances 21 cases, hemiparesis 7, hemiataxia 5, involuntary movements 4. They were divided in group 1 (14 cases) with prominent sensory symptomatology and group 2 (8 cases) with prominent motor symptomatology. The pulvinar and the ventral posterior thalamic nucleus were affected in both groups while adjacent nuclei such as ventral lateral or lateral posterior were more often affected in group 2. All patients but one had good recovery but 13 developed thalamic pain severely interfering with social activities in 5 cases. Several findings suggested that rather an arteriolopathy than large vessels disease or cardiogenic embolism had been a major cause in this series: 1) all patients but one (including 2 with a potential cardiac source of embolism) were hypertensive or diabetic, 2) lesions were small infarcts in the territory of perforators, 3) patients did not experience premonitory as well as subsequent cerebral events suggestive of vertebrobasilar atherosclerosis while 2 experienced deep cerebral hypertensive hemorrhage, and 4) neuro-imaging found additional asymptomatic lacunes in numerous patients. However, in the absence of angiography in most patients, these results do not preclude a potential role of artery-to-artery microembolism.