Wyburn-Mason Syndrome

 Wyburn-Mason Syndrome

Summary

Wyburn-Mason syndrome is a rare nonhereditary disorder that is present at birth (congenital). Affected infants have arteriovenous malformations (AVMs), which are developmental abnormalities affecting the blood vessels, specifically the arteries, veins and capillaries. Arteries typically carry oxygen-rich blood from the heart to body cells, while veins transport oxygen-deficient blood to the heart and lungs for the exchange of oxygen and carbon dioxide. The network of very tiny blood vessels (capillaries) that normally connects arteries and veins may be absent and the arteries and veins may be directly linked together forming a malformation. Without the capillaries, there can be damage to the walls of the arteries and veins, causing abnormal and high blood flow and leakage, and lack of blood flow further downstream. Larger AVMs may consist of a tangled mass of abnormal or malformed blood vessels (the nidus). AVMs associated with Wyburn-Mason syndrome are usually found in the eyes (retina) and brain. The exact cause of Wyburn-Mason syndrome is unknown, although it is hypothesized that during early development, the precursor cells to blood vessels have abnormal movement (migration) causing abnormal development later.

Introduction

The disorder is named for the investigator (Dr. R. Wyburn-Mason) who extensively described the disease entity in 1943. It is also referred to as Bonnet-Dechaume-Blanc syndrome after 3 investigators who identified AVMs in the face, retina and brain in 1937.

Wyburn-Mason syndrome is sometimes grouped with the phakomatoses or neurocutaneous syndromes. This broad group of disorders is characterized by masses or tumors that may grow in the brain, spinal cord and other organs. In children, skin lesions are also prominent. Unlike other so-called phakomatoses, Wyburn-Mason syndrome rarely has skin abnormalities.

Signs & Symptoms

The symptoms associated with Wyburn-Mason syndrome vary greatly among affected individuals based upon the specific number and location(s) of associated arteriovenous malformations. Affected infants may have abnormalities affecting the eyes, central nervous system and, in rare cases, the skin.

In Wyburn-Mason syndrome, AVMs may range from absence of the capillaries to the presence of large masses of widened, twisted, tangled blood vessels known as a racemose hemangioma. Absence of capillaries results in the abnormal, direct connection of the arteries to the veins. This abnormal connection can result in excessive blood flow and subsequently inadequate blood flow (ischemia) further downstream.

AVMs in Wyburn-Mason syndrome often affect the thin layer of nerve cells that lines the back of the eyes (retina). In some cases, an AVM may extend into the eye socket (orbit) or brain. The specific symptoms associated with an ocular AVM vary depending upon the exact location and extent the abnormality. Small AVMs affecting tiny blood vessels may not cause any symptoms (asymptomatic) and may be difficult to detect. Large AVMs such as a racemose hemangioma may cause significant loss of vision, usually from lack of blood flow to the retina (retinal ischemia).

Additional eye abnormalities may occur in some individuals with Wyburn-Mason syndrome including pressure on the eyeball so that the eyes bulge forward (proptosis), drooping of the upper eyelid (blepharoptosis), difficulty moving the eyes (ocular motility disorders), abnormally widened (dilated) blood vessels of the thin membrane that covers the outer surface of the eye (conjunctiva), and nerve paralysis (palsies).

AVMs of the central nervous system may not cause any symptoms (asymptomatic) or can cause severe symptoms. Although AVMs are present at birth, in many cases they may not cause symptoms until the second or third decade of life or even later. Neurological symptoms associated with Wyburn-Mason syndrome include severe headaches, vomiting, seizures, paralysis (palsy) of various cranial nerves and neck stiffness (nuchal rigidity). Spontaneous bleeding (hemorrhaging) of these lesions can lead to the sudden onset of symptoms. If the bleeding is severe, it can cause partial or full paralysis of one side of the body (hemiparesis or hemiplegia) or even death.

In rare cases, the skin may be involved in Wyburn-Mason syndrome including the formation of small bumps or clusters of blood vessels (angiomas) on the face. If the jaw bones are involved, dental procedures can lead to excessive bleeding. Other areas of the body may also develop AVMs including the lungs or the kidneys or other bones and muscles.

Causes

The exact cause of Wyburn-Mason syndrome is unknown. It is considered a developmental abnormality characterized by AVMs. No specific genetic abnormality or hereditary tendencies have been identified. The specific, underlying mechanism(s) that cause AVMs in Wyburn-Mason syndrome are not known. However, they are thought to result from abnormalities of blood vessel development during embryonic or fetal growth.

Disorders with Similar Symptoms

Comparisons with the following conditions may be useful for a differential diagnosis.

Sturge-Weber syndrome is a rare inherited disorder characterized by the presence of a port wine colored birthmark (angioma) on the facial area and intracranial abnormalities that are present at birth (congenital). Affected infants may also have an enlarged head (macrocephaly). Generalized seizures and additional neurological symptoms usually occur between one and two years of age. Vascular lesions (telangiectasias and angiomas) in the brain usually involve the occipital or parieto-occipital regions. Glaucoma may be present in the eye located on the same side of the face where the port wine stain occurs. This eye may also be enlarged (buphthalmos). The iris color may be different between the two eyes (heterochromia). (For more information on this disorder, choose “Sturge Weber” as your search term in the Rare Disease Database.)

Von Hippel-Lindau disease is an autosomal dominant condition characterized by multiple localized tissue malformations called hemangioblastomas and angiomas. These growths may be found in the retina, brain, kidneys, adrenal glands, and other organs. Symptoms may include headaches, dizziness and difficulty coordinating muscle movement (ataxia). Chronic high blood pressure (hypertension) can also occur. The disorder may begin during young adulthood or may develop during early childhood. Tumors (pheochromocytomas) of the adrenal glands may be present as well, causing chronic high blood pressure, pounding heartbeat, headache, cold hands and feet, and excessive sweating. This condition is found equally in males and females and can affect any ethnic group. (For more information on this disorder, choose “von Hippel Lindau” as your search term in the Rare Disease Database.)

Diagnosis

A diagnosis of Wyburn-Mason syndrome may be made based upon a thorough clinical evaluation, a detailed patient history, and identification of characteristic findings, especially ocular findings. Imaging studies such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be performed to detect potentially dangerous central nervous system (CNS) malformations. During CT scanning, a computer and x-rays are used to create a film showing cross-sectional images of certain tissue structures. An MRI uses a magnetic field to produce cross-sectional images of particular organs such as the brain. Dye (contrast) can be injected into blood vessels and X-ray images taken (cerebral angiogram) to see AVMs in the brain, or photos can be taken of the back of the eye (fluorescein angiogram) to detect the AVM in the eye. The combination of AVM in the brain and eye make the diagnosis of Wyburn Mason syndrome.

Treatment

No specific treatment for Wyburn-Mason syndrome exists. Treatment is directed toward the specific symptoms that are apparent in each individual. Some AVMs may not require treatment, especially retinal lesions which usually remain stable. If lesions in the eyes cause bleeding (hemorrhaging) in the retina or the clear, jelly-like substance that fills the middle of the eye (vitreous), laser treatment or the use of extreme cold to destroy abnormal tissue (cryosurgery) may be performed in an attempt to control the bleeding. Surgical removal of the vitreous (vitrectomy) has been performed in some cases if bleeding is persistent, although surgery is controversial.

TYPE OF DOCTOR AND DEPARTMENT: Neurosurgeon SPECIALIST CAN DIAGNOSE THIS DISEASE.