Hereditary Hemorrhagic Telangiectasia
Hereditary Hemorrhagic Telangiectasia, also known as Osler–Weber–Rendu disease and Osler–Weber–Rendu syndrome, is a genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain. This is an equal opportunity disorder; all ethnicities and all genders are similarly affected. It affects about 1 in every 5,000 people.
HHT is a disorder you inherit from one of your parents. It’s an autosomal dominant disorder, meaning that if one of your parents has HHT, you have a 50/50 chance of inheriting the dominant gene responsible for HHT. If you inherit this gene, you will have Hereditary Hemorrhagic Telangiectasia.
Arteriovenous malformations (AVM)
People with HHT are missing capillaries in some of their blood vessels. These abnormal blood vessels are known as arteriovenous malformations (AVM). Because there’s nothing to lower the pressure of the blood before it flows into the veins, people with HHT often experience strained veins that may eventually rupture.
When large AVMs occur, hemorrhages can occur. Hemorrhages in these areas can become life-threatening:brain, lungs, liver, and the gastrointestinal tract. AVMs can be particularly dangerous when they occur in the brain. When one bleeds, it can cause seizures and minor strokes.
High blood pressure in the AVM can lead to rupture, so people known to have the condition should be even more careful about avoiding hypertension. In women with an AVM, the changes in blood pressure and hormones may aggravate the condition causing symptoms to appear. While doctors cannot predict accurately if and when an AVM may hemorrhage, careful and consistent monitoring are important to prevention of arteriovenous malformation rupture in people with the condition.
An aneurysm is often discovered after it has ruptured or by chance during diagnostic examinations such as computed tomography (CT scan), magnetic resonance imaging (MRI), or angiography that are being done for other conditions. Most brain aneurysms don’t cause symptoms until they burst. When an aneurysm ruptures, it often causes bleeding in the brain, which is a medical emergency. Bleeding in the brain usually leads to a very severe headache (often described as “the worst headache of my life”). Brief loss of consciousness, nausea and vomiting, changes in vision, or neck stiffness may accompany the headache.
The two surgical treatments for aneurysms are called microvascular clipping and occlusion. For both procedures, the patient is put under general anesthesia and a neurosurgeon temporarily removes part of the skull bone to get access to the aneurysm.