Familial cerebral cavernous malformations (FCCMs) is a rare evolutive vascular malformation disorder appearing on the MRI as multiple lesions that are caused by vascular malformations composed of closely clustered irregular dilated capillaries. Clinical manifestations include seizures, non-specific headaches, progressive or transient focal neurologic deficits, and/or cerebral hemorrhages.
The prevalence of all CCMs has been estimated at 1/200 to 1/1,000 individuals overall and is thus not rare. FCCMs represents about 20% of the cases with an estimated prevalence of 1/5,000 -1/ 10, 000 and is therefore a rare disease. A strong founder effect has been found in Hispanic-American CCM families.
Close to 60 % of FCCMs patients are symptomatic. FCCMs manifest usually between 20 and 30 years of age, but clinical manifestations can occur at any age. Symptoms include seizures (40-70%), non-specific headaches (10-30%), progressive or transient focal neurologic deficits (35-50%), and/or cerebral hemorrhages (41%). FCCMs patients most often present with multiple lesions, ranging from a few millimeters to a few centimeters in size. FCCMs occur predominantly in the brain, but have also been reported in the spinal cord, retina (5% of FCCM patients) and skin.
To date, mutations in three genes have been demonstrated to cause familial CCM; KRIT1 (CCM1), CCM2 (Malcavernin) and PDCD10 (CCM3), respectively located on chromosome 7q11.2-21, 7p13, and 3q26.1 encode proteins that modulate junction formation between vascular endothelial cells.
Cerebral magnetic resonance imaging (MRI) revealing the CCM(s) is the gold standard investigation to diagnose CCM; and should include a T2 gradient echo sequence which is highly sensitive for hemosiderin. Molecular screening of CCM genes is sometimes useful to ascertain the diagnosis in patients showing atypical MRI lesions; however, in most cases, it is used for genetic counseling.
In some cases, presenting with atypical hemorrhagic MRI lesions, the differential diagnosis of multiple hemorrhagic metastases or hereditary, hereditary cerebral hemorrhage with amyloidosis (see this term) may be considered.
Prenatal diagnosis is possible. However, in practice, very few prenatal diagnoses are requested in this disease (mostly in families where several patients have been severely affected with CCMs in the basal ganglia or spinal cord or pons).
Familial CCM is transmitted as an autosomal dominant trait with incomplete penetrance. Genetic counseling should be offered to the affected families informing them of the 50% risk of inheriting the mutated gene. Other important considerations in evaluating the genetic predisposition of CCMs include the number of lesions on the MRI brain scan, family history of CCM clinical characteristics, and the age of onset.
Regular check-ups, generally with an MRI once a year, are recommended after the discovery of a CCM, as additional asymptomatic lesions may appear with time. Treatment of seizures and headaches is symptomatic. Lesions causing severe disabling seizures and/or focal neurologic deficits call for surgical removal of lesions whenever possible. Aspirin, heparin and warfarin may increase the risk of hemorrhage.
FCCM is an evolutive condition with a strong correlation between the patient's age and the number of CCM lesions. The hemorrhagic event rate is estimated at 2-5 % per lesion per year. Functional outcome is mostly conditioned by the location of CCM lesions, brainstem and basal ganglia lesions having a worse prognosis. Available data suggest that in most patients the long-term prognosis is quite favorable with a preserved autonomy in 80% of cases.
Last update: March 2014
- Pr Elisabeth TOURNIER-LASSERVE