Cavernous malformations (CMs) are clusters of abnormal, stretched-out, thin-walled blood vessels filled with blood, hence the name “cavernous”. These blood vessel malformations can occur in the brain or spinal cord.
CMs account for an estimated 8-15% of all intracranial and spinal vascular malformations, and have an incidence of one in 100-200 people . The exact cause is unknown, and least 20% of these lesions have the familial form, especially prominent in the Hispanic population. Genes associated with CM have been identified on chromosomes 3 and 7. Symptomatic lesion peak during third to fourth decade, and has no gender preference.
In most cases, CMs remain asymptomatic and are an incidental finding on brain imaging done for other reasons. When the lesion continues to expand, it causes direct compression on the surrounding neurological structure. Moreover, depending on the activity of the lesion, the risk of rupture and bleeding varies. Hereby, the clinical deficits of the bleeding, depends on location of the lesion. Any of the following symptoms may occur, including seizures, weakness in arms or legs, visual problems, balance problems, memory and attention problems, headaches. Fortunately, bleedings resulting from CMs, are relatively ‘low-pressure’-bleedings, compared to bleedings caused by aneurysms and AVMs. CMs tend to come closer to the surface each time they bleed. A majority of CMs are associated with an enlarged vein called Deep Venous Anomaly (DVA). DVAs drain normal brain and happen to be larger in the part of brain where large veins do not exist. Therefore, the acronym anomaly is used. As the DVAs drain normal brain and they are attached to the CM in many cases, the DVA should not be resected. Taking the DVA out would cause a venous infarction of the area of the brain that the DVA drains.
CMs are part of a group of lesions known as "angiographically occult vascular malformations." This means that they are not visible on an angiogram. Angiograms cannot visualize CMs because blood flow through these types of lesions is slow.
Magnetic resonance imaging (MRI), with and without contrast remains the best means of diagnosing Cms. MRI scans may need to be repeated to analyze a change in the size of a cavernous malformation, recent bleeding, or the appearance of new lesions.
Many CMs are quiet and unless not on easily accessible surface of the brain or spinal cord, should be left alone. If they show increase in size, or start bleeding, surgical resection needs to be considered. Surgical resection needs to take into consideration, the size, activity and location of the CM in the brain and the spinal cord to tailor the best possible therapy for the patient with least side effects.