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, appearing as a raspberry. Cavernomas contain blood products at various stages of evolution and are usually less than 3 centimetres in size.
What are the Causes of Cavernous Malformations?
Some individuals are born with a tendency to develop cavernous malformations. They are not a cancer, which means they cannot spread to other parts of the body. Occasionally, people can have multiple cavernomas.
Who Gets a Cavernous Malformation?
Cavernous malformations occur in people of all races and sexes. The male-female ratio is about equal. Family history may be positive especially in patients of Hispanic descent. Recent work has linked the predisposition to cavernous malformation to the seventh human chromosome. Cavernomas can be found in any region of the brain, be of varying size, and present with varying clinical disorders. In a general population of 1,000,000 – .5% or 5000 people may be found to have a cavernous malformation, although many are not symptomatic.
What are the Symptoms of a Cavernous Malformation?
It is important to know that a cavernous malformation can be present and not produce any symptoms. In fact, approximately 12% of patients at our clinic are asymptomatic.
Headaches and Cavernous Malformations:
Headaches accompany a cavernous malformation in many patients and may have even precipitated the diagnostic evaluation uncovering the lesion. 6-10% of patients with a cavernoma will report headaches as an accompanying symptom.
Progressive or Transient Neurologic 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 the 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 malformation is found. 36% of patients with a cavernous malformation will present with seizures.
Bleeding from a Cavernous Malformation:
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, 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?
It is not known of any specific activity that provokes haemorrhage. There are no restrictions for patients with a cavernoma.
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 at a rate of 10% per year, whereas symptomatic haemorrhage from a superficial lesion is very uncommon. The risk with a superficial lesion is much lower (less than 1% year).
Diagnosis of Cavernous Malformations
There are two main tests that are used to diagnose cavernomas. These are:
1. Computerised Axial Tomography (CAT Scan)
2. Magnetic Resonance Imaging (MRI)
MRI has provided the ability to image and localise 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.
Treatment of Cavernous Malformations:
The following are indications to consider treatment of a cavernous malformation:
There are three possible options available for patients who are found to have a cavernous malformation:
* The statistics for the above information were based on data obtained by the University of Toronto Brain Vascular Malformation Study Group and published in the paper Cerebral Cavernous Malformations: Natural History and Prognosis After Clinical Determination With or Without Hemorrhage by Philip J. Porter, MD, Robert A. Willinsky, MD, FRCSC, William Harper, MD and M. Christopher Wallace, MD, FRCSC. Accepted for publication, J. Neurosurgery, 1997.