European Reference Network for Rare Vascular Diseases (VASCERN) position statement on cerebral screening in adults and children with hereditary haemorrhagic telangiectasia (HHT)

Table 2 Cerebrovascular lesions in HHT patients

Lesion type	Subcategory	Haemorrhage rate (per year)	Prevalence in HHT patients	Prevalence in general population	Screening in general population?^a
Cerebral AVMs	Nidal type	General population estimate 2.2% (95% CI 1.7–2.7%) [13]. Ruptured = 10% in 10% the first year after haemorrhage, then goes back to usual rate of unruptured AVMs [7, 13, 24]	~ 6.2% [8]	650/100,000 [13, 25, 26]	No
Cerebral AVMs	Fistula type	Much higher risk than nidal type AVM [12, 15]	~ 1.1% but uncommon in adults [8]	< 2% of AVMs [27]	No
Capillary malformations (telangiectases)^b		0% or exceedingly rare	2.4–61% [14, 15]	0.70% [13]	No
Cavernous malformations		<< 1%, but higher in deep localization [13, 28]	3.50% [8]	0.6/100,000 [29]	No
Developmental venous anomalies		0% or exceedingly rare [30]	12% [8, 14]	3% [31]	No
Cerebral aneurysm		< 1% [21]	2.1–6.8% [8, 19, 20]	Likely double reported rates of 2–3.2% (95% CI 1.9–5.2) [21, 32]^c	No

^aScreening does not include investigation of symptomatic patients
^bHave been included as micro-AVMs in some studies, see text
^cBecause most meta-analysis use papers that were published before CT or MR angiography became popular and able to detect smaller lesions, the prevalence of incidental aneurysms in the general population should be higher than the reported literature rates of 2–3.2%

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