Osler-Weber-Rendu syndrome [Neurosurgery Wiki]

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====== Osler-Weber-Rendu syndrome ======

{{ ::osler-weber-rendu_syndrome.jpg?300|}}

Capillary telangiectasias involve small, dilated capillaries that may not be connected to larger vessels. They are usually considered benign and may not cause symptoms. However, they can sometimes be associated with other vascular malformations.

The disease carries the names of Sir William Osler, Henri Jules Louis Marie Rendu, and Frederick Parkes Weber, who described it in the late 19th and early 20th centuries.

===== General information =====
AKA [[hereditary hemorrhagic telangiectasia]] (HHT), AKA [[capillary telangiectasia]]: slightly enlarged capillaries with low flow. It cannot be imaged in any radiographic study. Usually incidentally found at [[necropsy]] without clinical significance (risk of [[hemorrhage]] is very low, except possibly in [[brain stem]]). Has intervening neural tissue
((Steiger HJ, Tew JM. Hemorrhage and Epilepsy in Cryptic Cerebrovascular Malformations. Arch Neurol. 1984; 41:722–724))
(unlike [[cavernous malformation]]s). Usually solitary, but maybe multiple when seen as a part of a [[syndrome]]: Osler-Weber-Rendu, Louis -Barr ([[ataxia telangiectasia]]), [[Wyburn-Mason Syndrome]], [[Sturge-Weber syndrome]].
Associated [[cerebrovascular malformation]]s (CVM) include [[telangiectasia]]s, AVMs (the most common CVM, seen in 5–13% of HHT patients
((Willemse RB, Mager JJ, Westermann CJ, Overtoom TT, Mauser H, Wolbers JG. Bleeding risk of cerebrovascular malformations in hereditary hemorrhagic telangiectasia. J Neurosurg. 2000; 92:779–784))), venous angiomas and aneurysms. Patients are also prone to [[pulmonary arteriovenous fistula]]s with an associated risk of a  cerebral [[paradoxical embolism]] which predisposes to embolic stroke and [[cerebral abscess]] formation 

===== Epidemiology =====
Rare autosomal dominant genetic disorder of blood vessels affecting ≈ 1 in 5,000 people. 95% have recurrent [[epistaxis]].


===== Clinical features =====

It is an autosomal dominant genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain.

The occurrence of concomitant multiple [[cerebral arteriovenous malformation]]s (mAVMs) is often associated with hereditary hemorrhagic telangiectasia (HHT) or [[craniofacial arteriovenous metameric syndrome]] (CAMS) and frequently occurs in the pediatric population.

It may lead to nosebleeds, acute and chronic digestive tract bleeding, and various problems due to the involvement of other organs. 



===== Diagnosis =====

==== Imaging CT ====

May show a well-demarcated homogeneous or mottled high density
((Bitoh S, Hasegawa H, Fujiwara M, et al. Angio- graphically Occult Vascular Malformations Causing Intracranial Hemorrhage. Surg Neurol. 1982; 17:35–42))
(high density due to hematoma, [[calcification]], thrombosis, hemosiderin deposition, alterations in BBB, and/or increased blood volume
((Cohen HCM, Tucker WS, Humphreys RP, et al. Angiographically Cryptic Histologically Verified Cerebrovascular Malformations. Neurosurgery. 1982; 10:704–714))
with some form of [[contrast enhancement]] (around or within lesion) in 17 of 24 patients
((Bitoh S, Hasegawa H, Fujiwara M, et al. Angio- graphically Occult Vascular Malformations Causing Intracranial Hemorrhage. Surg Neurol. 1982; 17:35–42)).
Surrounding edema or [[mass effect]] is rare (except in cases that have recently hemorrhaged).

==== MRI ====

May demonstrate previous hemorrhage(s),
((Lemme-Plaghos L, Kucharczyk W, Brant-Zawalski M, et al. MRI of Angiographically Occult Vascular Malformations. AJNR. 1986; 7:217–222))
(may be important when the presence of multiple occurrences affects therapeutic choices). T2 weighted image finding: a reticulated core of increased and decreased intensity, a prominent surrounding rim of reduced-intensity may be present (due to hemosiderin-laden macrophages from previous hemorrhages). GRASS image demonstrates flow-related enhancement in ≈ 60%of cases, which allows signal dropout from flowing blood on other sequences to be differentiated from that due to calcium (and thus, bone) or air (limitations: hemosiderin causes signal dropout, and slow in-plane flow does not enhance)
((Needell WM, Maravilla KR. MR Flow Imaging in Vascular Malformations Using Gradient Recalled Acquisition. AJNR. 1988; 9:637–642)).

===== Complications =====
Patients diagnosed with hereditary hemorrhagic telangiectasia (HHT) are at risk of developing [[intracranial arteriovenous malformation]]s (AVM). 

HHT-related AVMs are smaller in size with lower [[Spetzler-Martin AVM grading system]] and less [[temporal lobe]] involvement than sporadic AVMs. Patients with HHT frequently present with multiple intracranial AVMs. Conservative management is generally recommended due to lesion multiplicity and relatively low hemorrhagic risk
((Yang W, Liu A, Hung A, Braileanu M, Wang JY, Caplan JM, Colby GP, Coon AL,
Tamargo RJ, Ahn ES, Huang J. Lower Risk of Intracranial Arteriovenous
Malformation Hemorrhage in Patients With Hereditary Hemorrhagic Telangiectasia.
Neurosurgery. 2015 Nov 3. [Epub ahead of print] PubMed PMID: 26540357.))

Vascular malformations in the lungs may cause a number of problems. The lungs normally "filter out" bacteria and blood clots from the bloodstream; AVMs bypass the capillary network of the lungs and allow these to migrate to the brain, where bacteria may cause a [[brain abscess]] in up to 5 % and blood clots may lead to stroke.

===== Treatment =====

[[Osler-Weber-Rendu syndrome treatment]].

===== References =====