Brain imaging factors associated with progression of subcortical hyperintensities in CADASIL over 2-year follow-up

BACKGROUND AND PURPOSE

Mutations in the NOTCH3 gene cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a cerebral small vessel disease manifesting with stroke, migraine and dementia in adults. The disease displays significant phenotypic variability that is incompletely explained. Early abnormalities in vascular function have been shown in animal models. We postulated that studying changes in vascular function may offer insights into disease progression.

METHODS

Twenty-two subjects with CADASIL [50% female, 50 (±11) years] from 19 pedigrees were included in a longitudinal multimodality study using brain magnetic resonance imaging (MRI), clinical measures, neuropsychology and measures of peripheral vascular function. MRI studies included measurement of structural brain changes, cerebral blood flow (CBF) and cerebrovascular reactivity by arterial spin labelling and a CO₂ respiratory challenge.

RESULTS

Over 2 years, new stroke or transient ischaemic attack (TIA) occurred in five (23%) subjects and new significant disability in one (5%). There were significant increases in number of lacunes, subcortical hyperintensity volume and microbleeds, and a decrease in brain volume. CBF declined by 3.2 (±4.5) ml/100 g/min over 2 years. CBF and carotid-femoral pulse wave velocity at baseline predicted change in subcortical hyperintensity volume at follow-up. Carotid intima-media thickness and age predicted brain atrophy. Baseline CBF was lower in subjects who showed a decline in attention and working memory.

CONCLUSIONS

Cerebral blood flow predicts radiological progression of hyperintensities and thus is a potential biomarker of disease progression in CADASIL. Over 2 years, there were changes in several relevant imaging biomarkers (CBF, brain volume, lacunes, microbleeds and hyperintensity volume). Future studies in CADASIL should consider assessment of CBF as prognostic factor.

Changing clinical patterns and increasing prevalence in CADASIL

OBJECTIVES

CADASIL is a monogenic small vessel vasculopathy causing recurrent stroke. Early descriptions suggested dementia and disability were common from the 5th decade but there is evidence of marked phenotypic variability. We investigated the prevalence and clinical features of CADASIL in the west of Scotland.

METHODS

We undertook a retrospective review of clinical records of patients with confirmed CADASIL identified through a specialist clinic. Patients were divided to examine the effect of date of diagnosis on clinical outcomes and the characteristics at different ages. The location of pedigree members was used to estimate prevalence.

RESULTS

Twenty-one different CADASIL-causing NOTCH3 mutations were identified in 49 pedigrees (61% in exon 4). Disease prevalence in Glasgow was 4.6/100,000 adults. Mutation prevalence was estimated at 10.7/100,000 population. Median age at first stroke in women (57 years) was higher than previous estimates, and stroke age in men was higher in patients diagnosed more recently (pre 2006 46 years, post 2006 56 years, P=0.034). In patients over 58 years of age, 13/34 (38%) were living independently and 17/28 (61%) were mobile without aids when last seen.

CONCLUSIONS

CADASIL prevalence is at least 4.6 per 100,000 adults. Median age of first stroke may be older than previously thought. Clinicians should consider CADASIL in the differential diagnosis even in older patients with stroke.