Specific Imaging Findings

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) has a characteristic imaging appearance with involvement of the bilateral anterior temporal lobe white matter and the external capsules on both CT and MR imaging. The involved white matter is diffusely hypodense on CT, of low T1 signal and T2 hyperintense. There is no associated mass effect or contrast enhancement and the involved areas have increased diffusivity with increased signal on ADC maps. The lesions start to appear in the subcortical white matter at around 20 years of age and subsequently extend into the deep gray matter and brainstem. Lacunar infarctions are very common and usually appear by 30 years of age in the subcortical white matter, internal capsule, deep gray matter, and brainstem. The number of lacunar infarctions increases with age. Microbleeds, best seen as areas of “blooming” signal loss on T2 imaging, are frequently present. While these findings, primarily in the external capsules and even more so in the anterior temporal white matter, are highly characteristic for CADASIL, none of them are pathognomonic and may be seen with the much more common sporadic microangiopathy. However, the combination of typical findings in a young adult is highly suggestive of this disorder.

Pertinent Clinical Information

The main clinical manifestations are recurrent ischemic stroke, migraine, psychiatric symptoms (mostly mood disorders), and progressive cognitive impairment. Migraine, very commonly with aura, is the most common initial symptom. The long clinical course (several decades) and variable onset of symptoms even within families can result in many CADASIL patients being initially misdiagnosed with multiple sclerosis, dementia, or CNS vasculitis. The diagnosis is confirmed by the presence of granular osmiophilic material (GOM) in skin biopsies, which is 100% specific.