Vascular malformation of the brain (VMB) is an inflammation of blood vessels (Vasculitis) in the brain, caused when the immune system attacks blood vessels. Reasons for this happening can be due to a reaction to certain medicine, an infection, or other disease; the root cause is still unknown.
Vasculitis can affect arteries, veins, and capillaries. Arteries are vessels that carry blood from the heart to the body’s organs. Veins are the vessels that carry blood back to the heart. Capillaries are tiny blood vessels that connect the small arteries and veins.
This inflammation can harm veins, capillaries, and arteries. Veins carry blood to the heart; capillaries are small blood vessels connecting small arteries and veins; and arteries transfer blood from the heart to the rest of the body.
VMB is also a collective term for ranging conditions involving blood vessels in the brain. These conditions include vein of Galen malformations, telangiectasias, venous angiomas (VAs), Cavernous malformations, and arteriovenous malformation.
When a blood vessel becomes inflamed, it can:
- Taper, making it harder for blood to move through
- Entirely close movement, so blood cannot travel
- Bulge from over stretching, weakening it. This is referred to as an aneurysm. If it ruptures, it can cause dangerous internal bleeding.
- Symptoms of vasculitis can vary, but usually include nausea, fever, swelling and a general sense of sickness. The purpose of treatment is to stop any inflammation. Medicines like certain steroids can occasionally stop inflammation.
Commonly Associated With
- Occult Intracranial Vascular Malformations
- Intracranial Vascular Malformations
- Cerebral Malformations, Vascular
There is a strong genetic cause in two forms of VMB. These are cavernous hemangiomas and telangiectasias cases. A Genetic factor exists but is much weaker in arteriovenous malformation of the brain (AVM). In each of these cases, the condition is passed as an autosomal dominant trait. This gives a strong case connected to the chromosomes not tied to the sex chromosomes.
Humans typically have 46 chromosomes. These are pairs and each pairs from 1 to 22. Sex chromosomes labeled “X” and “Y”. People born male at birth have an X and Y chromosome, and people born female have 2 X chromosomes. Genetic diseases come from a total combination of gene traits on a chromosome passed down from both parents.
Dominant And Recessive Genetic Disorders
A dominant genetic disorder happens when one abnormal gene is only needed for the condition to be present. An abnormal gene can be the outcome of a new gene mutation, or can be passed down from either parent. The risk of passing an abnormal gene down to a child is 50%, regardless of sex, per pregnancy
A recessive genetic disorder happens when an abnormal gene for the same trait is passed down to a child. Examples of this include sickle cell anemia and cystic fibrosis. Being passed down one normal gene and one abnormal gene makes you a carrier but does not necessarily mean you have the disorder. Having two carrier parents makes a child’s chance of being a carrier of that specific disorder by 25%. As well, this makes that child have a 25% of having two normal genes and not a carrier. This is constant between females and males.
A child’s likelihood of obtaining a recessive genetic condition increases more if one or both parents are either carriers or are affected by a specific disorder. However, it is important to know that all people carry some abnormal genes.
X-linked Genetic Disorders
X-linked recessive genetic disorders are vascular malformations of the brain that come from an abnormal gene on an X chromosome. People born female have two X chromosomes. However, one of those X chromosomes is in-activated and all of the genes on that chromosome are not functioning. People born female with a disease gene on one of their X chromosomes are a carrier for that condition. Carriers typically do not have symptoms because it is generally affected by the X chromosome with the abnormal gene that is inactive.
A person born male has one X chromosome. If this person inherits an X chromosome with a disease gene, they will most likely have the disease. People born male with X-linked disorders pass the disease gene to all of their female bron children. These children will then be carriers. A male born person cannot pass an X-linked gene to male born child because people with X and Y chromosomes will always pass down their Y chromosome instead of their X chromosome to male born children. Female carriers of an X-linked disorder have a 25% chance with each pregnancy to have a female born carrier, like themselves, a 25% chance to have a non-carrier female born child, a 25% chance to have a male born child affected with the disease, and a 25% chance to have an unaffected male born child.
X-linked dominant disorders originate from an abnormal gene on the X chromosome. However, these are rare conditions. People with two X chromosomes who have an abnormal gene are generally affected by the disease. People with an X and Y chromosome and have an abnormal gene are more severely affected, and many of these people do not survive with x-linked dominant disorders.
Vascular malformations of the brain may cause headaches, seizures, strokes, or bleeding in the brain (cerebral hemorrhage). Some researchers believe that the type of malformation determines the symptoms and progression of the disease. Other researchers believe that only the severity rather than the type of malformation is important.
Specific Symptoms For Each Condition
Arteriovenous malformations (AVM):
AVMs affect veins, arteries, and middle-sized vessels. Here, arteries and veins connect directly, instead of connected through fine capillaries. These abnormal “feeding” arteries continually enlarge, and as a result, the “draining” veins expand as well. The brain tissue between these vessels grows atrophied, or rigid. This becomes a full network of fine fibers named fibrils. Flattened cells fill these and calcify the fibrils. These draw blood away from the brain and cause brain cell atrophy. Hemorrhages or seizures are common side effects of AVMs.
Cavernous malformations (CM):
CMs show unusually large areas of blood-filled spaces. A cavernous hemangioma acts like a “blood sponge” that douses up blood between capillaries and larger cavern-like spaces. These are slow to fill spaces. There is not typically any brain tissue in these spaces. Hemorrhages or seizures are also common with CMs.
Venous angiomas (VA):
VAs involve enlarged, tangled, and twisted veins that vary in size but do not involve the arteries. These growths cites then often follow after the capillary stage of the vessel, post-capillary malformation. The defect appears as a connection of small veins that meet to form part of a larger vein (trunk).
These are malformations that come from dilated capillaries. These enlarged capillaries are small pink-to-red spots that apear throughout the body, like in the eyes, face, and membranes that cover the spinal chord, brain, and mucous membranes.
Vein of Galen malformations (VGM):
VGMs begin while the embryo is developing. The vein of Galen is located under the cerebral hemispheres and drains the forward and central regions of the brain into the sinuses. This happens when the head does not develop surrounding tissue around the vein of Galen and lacks a normal fibrous wall. And so, the vein of Galen looks free-floating in the sinus fluids. If pressure increase in the vein of Galen, it changes from a cylinder to sphere shape. These changes follow with abnormal fetal blood circulation. And then in extreme conditions, there may be cardiac failure or brain swelling occur (hydrocephalus).
Current treatment options vary according to the location and severity and of a malformation. Though, surgical removal and irradiation currently the most common ways to treat VMBs.
In some cases, treatment may not be necessary. However, recently introduced techniques involve particle beam and stereotaxic radio-surgery. Genetic counseling may be of benefit for patients and their families if they have a hereditary form of this disorder. Other treatment is symptomatic and supportive.
Vascular malformations of the brain affect males and females in equally. A hereditary form of cavernous malformations tends to occur more in people of Latin-American descent. Arteriovenous malformations happen generally more frequently in people with XY chromosomes.
Symptoms of the following disorders can be similar to those of vascular malformations of the brain. Comparisons may be useful for a differential diagnosis:
- Moyamoya disease
- Cerebral aneurysm
- Cerebrovascular accident (stroke)