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.

Asymptomatic pontine myelinolysis.

A 43-year-old lady presented with bilateral foot drop due to alcohol-related peripheral neuropathy. There was no history of electrolyte disturbance or altered consciousness. Cranial nerve, bulbar and pyramidal symptoms and signs were absent. Nerve conduction studies confirmed the neuropathy. Inadvertently requested neuroimaging of brain demonstrated signal change typical of central pontine myelinolysis. Asymptomatic pontine myelinolysis occurs rarely in alcoholics in the absence of bulbar dysfunction. It is important for physicians to be aware of the clinical entity of asymptomatic pontine myelinolysis to avoid misinterpretation of abnormalities detected on cerebral imaging in alcoholic individuals.

Is inadequate family history a barrier to diagnosis in CADASIL?

OBJECTIVES: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) has typical clinical features that include stroke, migraine, mood disturbances and cognitive decline. However, misdiagnosis is common. We hypothesized that family history is poorly elicited in individuals presenting with features of CADASIL and that enquiry into family history of all four cardinal manifestations of CADASIL is superior to elicitation of family history of premature stroke alone in raising the diagnostic possibility of CADASIL. MATERIALS AND METHODS: Retrospective review of family histories at presentation in 40 individuals with confirmed CADASIL was performed through structured interview in a Neurovascular Genetics clinic (182 first-degree and 242 second-degree relatives identified). Family history obtained from structured interview was compared to family history initially documented at presentation. RESULTS: At initial presentation, 30% of individuals were inaccurately documented to have no family history of significant neurological illness. Thirty-five per cent of patients had an initial alternative diagnosis. Initial inaccurate documentation of negative family history was more frequent in individuals with an initial alternative diagnosis. After structured interviews, 34% of 182 first-degree and 35% of 242 second-degree relatives of CADASIL patients had history of stroke (16% of first-degree relatives had stroke before the age of 50 years). Forty-three per cent of first-degree and 28% of second-degree relatives had migraine, mood disturbance or cognitive decline. CONCLUSIONS: A false-negative family history was commonly documented in individuals presenting with features of CADASIL and was associated with initial misdiagnosis. Restriction of family history to premature stroke alone is probably inadequate to identify affected CADASIL pedigrees.

The prevalence of cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) in the west of Scotland.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is caused by mutations of the Notch3 gene on 19p13. Varying phenotypic expression leads to under recognition and misdiagnosis. Prevalence therefore remains uncertain. We sought to estimate the prevalence of CADASIL in the west of Scotland. METHODS: A register for CADASIL was established at a regional neurosciences centre in 2002. All patients with genetically (exons 3, 4, 5, and 6) or histologically confirmed CADASIL residing in two defined administrative health areas were identified. Pedigree members at varying risk of carrying the mutation were also identified and the number of probable Notch3 mutation carriers in the defined population was predicted. Prevalence was calculated for definite CADASIL cases, with and without probable carrier numbers, based upon adult population figures from the 2002 national census. RESULTS: Twenty two individuals from seven pedigrees with confirmed CADASIL and resident in the defined geographical area were identified, yielding a prevalence of 1.98 (95% confidence interval 1.24-3.00) per 100 000 adults. An additional 37 individuals were predicted to be carriers of the Notch3 mutation, yielding a probable mutation prevalence of 4.14 (3.04-5.53) per 100,000 adults. CONCLUSIONS: The prevalence of genetically proven CADASIL was 1.98 per 100,000 adults in the defined population. This figure underestimates disease burden.

Tilt table testing in patients referred from an epilepsy clinic.

OBJECTIVE: To assess the role of head up tilt testing (HUT) in diagnosing probable or possible vasovagal syncope (VVS) in patients referred from an epilepsy clinic. METHODS: One hundred thirty two patients underwent HUT over 36 months. Complete data were available on 128 patients (52 male) aged 14-80 (mean 36.7) years. The main indication for HUT (head up tilt at 70 degrees for 45 minutes) was recurrent undiagnosed blackouts, likely to be VVS. Patients were divided, prior to knowledge of the HUT results, into probable VVS, possible VVS, or probable/possible VVS associated with definite epilepsy. RESULTS: HUT was positive in 72 patients (56%), and led to an alternative definite diagnosis in 31 (24%). Diagnostic change was more likely in those provisionally labelled either as possible VVS (15 of 34; 44%) or as a combination of epilepsy with possible or probable VVS (12 of 19; 63%) compared to those with probable VVS (4 of 75; 5%; P<0.01).Of the 45 patients previously treated with antiepileptic medications 27 did not have epilepsy. CONCLUSION: HUT has an important role in confirming or refuting the diagnosis of VVS in patients presenting with undiagnosed blackouts to an epilepsy clinic, and particularly so in patients with possible rather than probable VVS, and in those thought to have a combination of epilepsy and possible or probable VVS.