MRI hyperintensities of the temporal lobe and external capsule in patients with CADASIL

Background: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited, autosomal dominant condition caused by mutations of the Notch3 gene. Affected individuals have migraine, mood disturbance, and recurrent strokes, often progressing to subcortical dementia and premature death. MRI findings include focal lacunar infarcts and diffuse T2-weighted hyperintensity, or leukoaraiosis. However, such findings are seen much more commonly in patients with cardiovascular risk factors, particularly hypertension, where they are believed to represent cerebral small vessel disease. No previous study has sought to identify specific radiologic markers of CADASIL. Methods: MRI scans from 20 consecutive patients with CADASIL and 20 patients with sporadic leukoaraiosis due to presumed small-vessel disease were compared using the previously validated semiquantitative MRI rating scale devised by Scheltens et al. Analysis was blinded to clinical category. Results: Scores for hyperintensities of the temporal white matter and external capsule–insula region were significantly higher in patients with CADASIL. Hyperintensity confined to the pole of the temporal lobe was a characteristic finding in CADASIL, occurring in 19 patients with CADASIL but no patients with ischemic leukoaraiosis. Involvement of the external capsule, though less specific, was seen early in the disease course. In a few patients with CADASIL, involvement of the corpus callosum was observed. Conclusions: Temporal pole hyperintensity is a radiologic marker of CADASIL. Involvement of the external capsule and corpus callosum are also characteristic findings that may help to distinguish the disease.