Cerebral cavernous venous malformation
Cerebral cavernous venous malformations, commonly known as cavernous haemangioma or cavernoma, are common cerebral vascular malformations, usually with characteristic appearances on MRI.
Cavernous malformations are found throughout the body. This article focuses on cerebral cavernous venous malformations. For a general discussion and links to cavernomas in other locations, please refer to the general article on cavernous venous malformation.
Many alternative terms have been used over the years including cavernous haemangioma, cerebral cavernous malformation or simply cavernoma. As these lesions are not neoplastic, it has been argued that the terms 'haemangioma' and 'cavernoma' should be avoided. Additionally, it is important to note that according to newer nomenclature (ISSVA classification of vascular anomalies) these lesions are merely known as slow flow venous malformations.
Having said all that, it is probably helpful in reports to include the word 'cavernous' as this term is ubiquitous in the literature and most familiar to many clinicians.
For brevity, the term cavernous malformation is used in the remainder of this article.
Most patients who present symptomatically do so at 40-60 years of age. Most patients have single lesions. Multiple lesions may be familial and screening of family members may be indicated (see familial multiple cavernous malformation syndrome). Additionally, cavernous malformations, along with capillary telangiectasias, are commonly seen following cerebral radiotherapy 3.
The majority of lesions remain asymptomatic throughout life and are found incidentally. Presentation due to haemorrhage may cause a seizure or focal neurological deficit. The risk of haemorrhage is 1% per year for familial cases and somewhat less for sporadic lesions.
Histologically cavernous malformations are composed of a "mulberry-like" cluster of dilated thin-walled capillaries, with surrounding hemosiderin 3. Unlike AVMs, there is no normal brain between the interstices of these lesions.
Cerebral cavernomas tend to be supratentorial (~80% cases) but can be found anywhere including the brainstem. They are usually solitary, although up to one-third of patients with sporadic lesions have more than one 2.
Unless large, these lesions are difficult to see on CT. They do not enhance. If large then a region of hyperdensity can be seen. If there has been a recent bleed then it is more conspicuous and may be surrounded by a mantle of oedema.
MRI is the modality of choice, demonstrating a characteristic “popcorn” or "berry" appearance with a rim of signal loss due to hemosiderin, which demonstrates prominent blooming on susceptibility weighted sequences.
T1 and T2 signal is varied internally depending on the age of the blood produces and small fluid-fluid levels may be evident.
Gradient echo or T2* sequences are able to delineate these lesions better than T1 or T2 weighted images. In patients with familial or multiple cavernous angiomas GRE T2* sequences are very important in identifying the number of lesions missed by conventional Spin echo sequences.
Susceptibility weighted imaging (SWI) may have sensitivity equal to that of GRE in detecting these capillary telangiectasias in the brain. SWI is also highly sensitive in detecting calcification as compared to T1 and T2 images 6.
If a recent bleed has occurred then surrounding oedema may be present.
The lesions generally do not enhance, although enhancement is possible 7.
Cavernous malformations can be grouped into four types based on MRI appearances using the Zabramski classification 11.
Cavernous malformations are angiographically occult and do not demonstrate arteriovenous shunting.
Treatment and prognosis
Many cavernous malformations are asymptomatic and can be treated conservatively. Symptoms can relate to mass effect, epileptic activity or repeated haemorrhage. Symptomatic lesions should, when possible, be resected and complete resection is curative 9.
The differential, when cavernous venous malformations are numerous, is that of other causes of cerebral microhaemorrhages, including 2:
- cerebral amyloid angiopathy: usually numerous small foci
- chronic hypertensive encephalopathy: more common in the basal ganglia
- diffuse axonal injury (DAI)
- cerebral vasculitis
- radiation-induced vasculopathy
- haemorrhagic metastases
- Parry-Romberg syndrome 2
Larger lesions can mimic:
Calcified lesions, such as old neurocysticercosis, or other infections (e.g. tuberculoma) should also be considered.
Vascular tumours and malformations
vascular malformations and tumours
- vascular tumours
- tufted angioma (with or without Kasabach Merritt syndrome)
- Kaposiform hemangioendothelioma (with or without Kasabach Merritt syndrome)
- spindle cell hemangioendothelioma
- other, rare hemangioendotheliomas
- dermatologic acquired vascular tumors
- slow flow vascular malformations
- capillary malformation (CM)
- venous malformation (VM)
- common sporadic venous malformation
cavernous venous malformation (cavernoma or cavernous haemangioma)
- cerebral cavernous venous malformation
- orbital cavernous venous malformation
- hepatic cavernous venous malformation (hepatic haemangioma)
- splenic cavernous venous malformation (splenic haemangioma)
- breast venous malformation (breast haemangioma)
- retroperitoneal venous malformation
- soft tissue venous malformation
- primary intraosseous venous malformation
- cardiac venous malformations
- cavernous venous malformation (cavernoma or cavernous haemangioma)
- Bean syndrome
- familial cutaneous and mucosal venous malformation
- glomuvenous malformation (glomangioma)
- Maffucci syndrome
- common sporadic venous malformation
- lymphatic malformation (LM)
- fast flow vascular malformations
- arterial malformation
- arterial malformation
- arteriovenous fistulae (with one or more shunts)
- arteriovenous malformations (with a nidus of multiple shunts)
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