Cavernous Malformations Of The Brain / Cavernomas
A cavernoma or cavernous malformation is a vascular abnormality of the central nervous system. It consists of a cluster of abnormal, dilated vessels. Pathologically, it is red to purple in colour, about the size of a raspberry. Cavernomas contain blood products at various stages of evolution and are usually less than 3 centimetres in size.
Causes of Cavernous Malformation
Some individuals are born with a tendency to develop cavernous malformations. They are not a cancer, meaning they cannot spread to other parts of the body. Occasionally, people can have multiple cavernomas.
Cavernous malformations occur in people of all races and sexes. The male-female ratio is about equal. Family history may be a factor especially in patients of Hispanic descent. Recent work has linked pre-disposition to cavernous malformation to errors in the development of the seventh human chromosome. Cavernomas can be found in any region of the brain and be of varying sizes. They are found in 5% of the population, although many are asymptomatic.
Symptoms of a Cavernous Malformation
- Progressive or transient neurological deficits
It is important to know that a cavernous malformation can be present and not produce any symptoms. In fact, approximately 12% of patients with cavernomas are asymptomatic.
Headaches and Cavernous Malformations
Headaches accompany cavernous malformations in many patients and may even be the driving factor for the diagnostic evaluation that uncovers the lesion. 6-10% of patients with a cavernoma will report headaches as an accompanying symptom.
Progressive or Transient Neurological Deficits
Patients may present with double vision, unsteadiness, sensory disturbances, and weakness or paralysis on one side of the body. These complaints are closely related to where lesion is located. 20% of patients will complain of these when they present to the physician.
Seizures and Cavernous Malformations
Sometimes patients present to emergency with a seizure and upon investigation of the seizure a cavernous malformations is found. 36% of patients with a cavernous malformation will present seizures.
Bleeding from Cavernous Malformations
Up to 25% of patients will present with a haemorrhage. This is the most serious complication of a cavernoma. If the cavernoma does bleed, it usually, but not always, starts with a headache. The headache starts suddenly and may be followed by nausea, vomiting, neurological problems or a decreasing level of consciousness. Sometimes a bleed may be very small and produce very mild or no symptoms at all.
Why Do Cavernous Malformations Bleed?
We do not know of any specific activity that provokes haemorrhaging. There are no special precautions that can be taken to avoid bleeding.
What is The Risk That A Cavernous Malformation Will Bleed?
The risk depends on where the malformation is located. Deep lesions in the brainstem bleed and cause problems in 10% of people per year with cavernomas. Symptomatic haemorrhages from superficial lesions are very uncommon (less than 1% year).
There are two main tests that are used to diagnose cavernomas. They are:
- Computerized Axial Tomography (CAT Scan)
- Magnetic Resonance Imaging (MRI)
MRI has provided the ability to image and localize otherwise hidden lesions of the brain and provide accuracy of diagnosis preoperatively. Both the MRI and CAT scans produce images of slices through the brain. These tests help the doctors to see exactly where the cavernoma is located. Cavernomas cannot be seen on a cerebral angiogram.
The following are indications to consider treatment of a cavernous malformation:
- Neurological dysfunction
- An episode of bleeding
- Intolerable symptoms
- Uncontrolled seizures
There are two options available for patients who are found to have cavernous malformations:
- No treatment
Note: Alternatives may exist to these two options and your doctor will be happy to discuss options with you.
When a cavernous malformation is deemed to have bled or be causing neurological dysfunction, it may be surgically removed under general anaesthesia. Since it does not grow back, the cure is immediate. The risk of surgery will depend on where the cavernous malformation is located.
The doctor will recommend the best treatment, determined by the symptoms and by the location of the cavernoma. Many cavernomas do not require treatment and will be followed conservatively with clinical evaluation and/or an MRI on a yearly basis.