Incidence:

The incidence is about 10% of all cerebrovascular malformations and about 75% of them are supratentorial and 50% of the patients harbors multiple lesions. 

It has been reported that a sex imbalance exists for extracerebral cavernomas of the middle fossa, which occur mainly in oriental female patients. Familial occurrence and multiplicity (10%) are more frequent in patients of Mexican descent. It has been recently suggested that the familial form of cavernomas is a dynamic disease requiring careful monitoring in view of de novo formation of vascular malformations.
Male patients seem to present with lesions earlier in life than do female patients . Female patients seem to be more predisposed to hemorrhage and typically hemorrhage in the middle decades of life.

Pathology:

These lesions are low flow malformations and consist of ectatic, largely thrombosed groups of tightly packed, abnormally thin-walled, small blood vessels that displace normal neurological tissue in the brain or spinal cord. The vessels are filled with slow-moving or stagnant blood that is usually clotted or in a state of decomposition. 

There is no definite sex preponderance; however the incidence of overt hemorrhage is significantly higher in females. Pregnancy constitutes a well-known risk factor of hemorrhage; moreover, a major role of endocrine substances in influencing bleeding and growth of cavernomas has been suggested.  

Although cavernous malformations usually do not hemorrhage as severely as AVMs do, they sometimes leak blood into surrounding neurological tissues because the walls of the involved blood vessels are extremely fragile. They are unencapsulated and surrounded by gliotic brain. They may contain cysts. This non neoplastic lesion may increase in size due to increase in surrounding gliosis, hemorrhage into cysts or dilated vascular channels. Calcifications are common.

Like AVMs, cavernous malformations can range in size from a few fractions of an inch to several inches in diameter, depending on the number of blood vessels involved. Supratentorial ones are more frequent. 

Some people develop multiple lesions, more so in the familial variety. 

Natural history:

There is no consensus about the natural history as of now.

It has been suggested that some familial, sexual, and racial factors may play a role in the natural behavior of cavernomas.

The studies suggest that a subset of lesions bleeds and bleeds again more frequently and at shorter intervals than would be expected from the average hemorrhagic risk; however, the biological profile of these lesions is not completely defined..

It has been suggested that location may play some role in the natural behavior of cavernous angiomas. It is not rare for cavernomas of the third ventricle or in an eloquent area to demonstrate rapid and extensive growth;  hormonal influence may be the factor or could be related only to the high sensitivity of these areas even to small bleedings.

The issue of de novo lesion genesis remains difficult. Some cavernomas  probably continue to remain cryptic, despite the great sensitivity of MR imaging in detecting these vascular malformations.

The risk of significant bleed is only about 0.2 % per year. Risk of rebleed is probably similar to that of AVMs.

Clinical features:

Although they are often not as symptomatic as AVMs, cavernous malformations can cause seizures in some people. In fact seizures are the commonest presenting symptom; subclinical bleed is the rule. It has been suggested that subclinical bleeding is the reason for poor seizure control and that valproic acid may induce bleeding and should be avoided.

Transient neurological deficit is attributed to subclinical haemorrhages.

In a recent series, the presenting symptoms included overt hemorrhage in 18%, slowly progressive or transient neurological deficits in 20.7%, seizures in 46.9%, and headache in 10.3%; 6 patients (4.1%) were asymptomatic. 

Investigations:

CT scans may reveal a nonenhancing hyperdense lesion with no perilesional edema or mass effect, and appears to fill a void, unless associated with significant haemorrhage.

MRI is more sensitive and specific. A mixed signal mass because of islands of haematomas of different ages is very specific. T2 images show a low intensity rim of haemosiderin described as the ‘target sign’. It has been suggested to be the flow void caused by tiny draining veins.

frontal cavernoma-MRI	cerebellar cavernoma	hemorrhage due to cerebellar cavernoma	giant cavernoma

GRE images are more sensitive than SE images.

Some MR characteristics of the cavernous angiomas may help in planning the therapeutic approach; an increasing hypointense ring around the malformation denotes repeated microhemorrhages, probably labeling active malformations. Otherwise, hyperintense lesions on spin-echo MR images denoting subacute bleeding show a tendency to recurrent hemorrhages. 

Angiography may not reveal the lesion as a rule; however a delayed venous phase may suggest a faint blush in about 20%.

Management:

After AVMs, cavernous malformations are the type of vascular lesion most likely to require treatment. The indications in patients for the surgical treatment of cavernous angiomas include intractable seizures, progressive neurological deficits, and previous gross hemorrhage. Surgical excision of a symptomatic and easily accessible lesion is advised by most of the surgeons.  There is no consensus on management of incidental, asymptomatic ones as of now.

cav.angioma at surgery

The choice is between a straight-line approach through a stereotactic craniotomy or careful microsurgery.

The role of radiosurgery is still being debated. It has been postulated that the immature endothelium may not be radiosensitive.The inherent thin-walled structure of the cavernous angioma probably does not lend itself to the obliterating effects of radiosurgery on the abnormal vessel of an arteriovenous malformation.