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Hereditary Hemorrhagic Telangiectasia (HHT)
Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an inherited disorder involving the development of abnormal artery and vein connections, arteriovenous malformation (AVM), that can affect any part of the body. It is seen in 1:5000 to 1:8000 people and remains underdiagnosed. Symptoms may not manifest until adolescence or later in some patients.
The most typical AVM is known as telangiectasia and can involve the face, mouth, and hands. Larger AVMs can form in any organ of the body and lead to the bleeding as well as other symptoms described below.
The most common early symptom is nose bleeding (epistaxis), caused by telangiectasias of the nasal mucosa. Large AVMs can develop anywhere in the body and are typically seen in the lungs, brain, spinal cord, and liver. AVMs involving the lungs can lead to poor oxygen uptake by the body as well as stroke and severe, life threatening brain infections (cerebral abscess). Gastrointestinal bleeding (blood in stool) may also develop, but is usually a later manifestation of the disease.
HHT is a clinical diagnosis based on four features:
- Spontaneous, recurrent nosebleeds
- Telangiectasias of the lips, oral mucosa (inside the mouth), tongue, fingertips
- Visceral involvement with AVMs (lung, brain, liver, etc.)
- Family history of first degree relative (i.e. parent, sibling) with HHT
Manifestations of HHT can be diagnosed by imaging using Computed Tomography (CAT scan) and Magnetic Resonance Imaging (MRI). AVMs involving the lung, brain, and spinal cord can be identified to allow early treatment. Many gene mutations have been identified for HHT and can be tested for in the appropriate clinical setting.
Mostly the treatment is aimed at improving symptoms or avoiding potential complications. This requires proper screening for the more common AVMs. Several drugs are available or are in clinical trials that help alleviate symptoms and potentially decrease AVM formation.
Nose bleeds. Although not typically life threatening, recurrent nose bleeds can affect quality of life and cause anemia. Conservative management with nasal lubricants is used to treat chronic bleeding. Special surgical techniques have been developed to help reduce bleeding. There are also minimally invasive options including sclerotherapy and transarterial embolization. There is no cure and all treatments are aimed at reducing the frequency and quantity of nose bleeds.
Pulmonary AVM. Due to the potential for stroke and life threatening cerebral abscess, when a pulmonary AVM is identified treatment is recommended. Minimally invasive procedure, AVM embolization, can be performed to close off the abnormal artery to vein connection.
Brain and spine AVM. Surgical and minimally invasive options are available depending on the location of the AVM.
Gastrointestinal manifestations. Most gastrointestinal telangiectasias will not become symptomatic, but liver AVMs may be present in ~50% of the patients especially during adulthood and may require follow-up by a liver specialist.