Wyburn-Mason Syndrome

Article Author:
Jason So
Article Editor:
Ronald Holman
Updated:
2/18/2019 11:09:34 PM
PubMed Link:
Wyburn-Mason Syndrome

Introduction

Wyburn-Mason syndrome, also known as racemose angioma, is a rare nonhereditary disorder that presents with multiple arteriovenous malformations that predominantly affect the face and brain. The disorder is also referred to as the Bonnet-Dechaume-Blanc syndrome and is classified as one of the nonhereditary congenital phakomatoses. Bonnet (1937) and Wyburn-Mason (1943) reported the vascular abnormalities associated this condition, and the syndrome is frequently referred to as Wyburn-Mason syndrome in recognition of these authors. The arteriovenous malformations range in size but often tend to be large and may affect the eye, brain, and other facial structures. When involving the brain, these arteriovenous malformations tend to localize to the midbrain region, thus necessitating neurologic imaging to rule out life-threatening or potentially debilitating lesions in this area. Presenting vision may range from normal to no light perception. Vascular malformations may be present elsewhere in the body. Unlike other phakomatoses that involve the eyes, Wyburn-Mason does not commonly cause cutaneous manifestations.[1][2][3][4]

Etiology

Wyburn-Mason syndrome is thought to be a congenital, nonhereditary, sporadic disorder. There is no known gender or racial predilection. The precise etiology and risk factors associated with this condition are presently unknown. Recent studies show that some vascular dysgenesis occurs in the early embryonic period and leads to an alteration in the arteriolar and capillary network. Small, arteriovenous malformations can be subtle, causing only mild changes in the capillary system. In contrast, the large, racemose, “bag of worms” arteriovenous malformation lesions have direct artery-to-vein communication without interposing capillary networks.[4][5][6][7]

Epidemiology

Wyburn-Mason is extremely uncommon. In the United States, less than 100 cases have been reported in the literature. Wyburn-Mason is a congenital disorder. Large retinal arteriovenous malformations, which cause visual or neurologic impairment usually are diagnosed in early life. Smaller arteriovenous malformations may remain asymptomatic or be diagnosed only in later life.

Pathophysiology

Vision loss from Wyburn-Mason syndrome occurs secondary to the location of the arteriovenous malformations in the retina or the orbit. The effect on vision may be directly from the arteriovenous malformations causing obscuration of the visual centers, choroidal infarctions, retina ischemia or by causing compression of the optic nerve or retinal vascular occlusions. These high-flow arteriovenous malformations usually do not bleed or cause exudation in the retina.

History and Physical

Wyburn-Mason syndrome presents with a range of neurological symptoms that primarily depend on the location and size of the arteriovenous malformations. Neurological symptoms may include seizures, headaches, hemiparesis, visual deficits, cranial neuropathies, and hydrocephalus. Arteriovenous malformations located outside the central nervous system (CNS) may present with hematuria, hemoptysis, epistaxis, or frank bleeding. Small arteriovenous malformations within the eye may cause no visual symptoms. Large arteriovenous malformations can produce severe vision loss. Eye problems can include retinal hemorrhages, vitreous hemorrhages, retinal detachments, vein occlusions (which can be complicated by associated rubeosis iridis and secondary glaucoma), optic disc edema, and optic atrophy.

The majority of individuals have involvement of the eye at a young age and are severely visually impaired. If the arteriovenous malformations are diagnosed at an early age, the risk of systemic involvement is high.

An individual with retinal and intracranial arteriovenous malformations often has vascular malformations of the orbit, lungs, face, and bone. Some orbital lesions can be pulsatile and present with proptosis. Orbital lesions can have an accompanying bruit.

Evaluation

The diagnosis of Wyburn-Mason syndrome is made on clinical exam. Retinal arteriovenous malformations are usually diagnosed by ophthalmoscopy although fluorescein angiography may be required to demonstrate smaller lesions. Most arteriovenous malformations do not leak on angiography. Ultrasound and optical coherence tomography can also confirm the diagnosis and be used to follow changes in the nerve fiber layer, macula, and retina over time. Lesions will be unilateral. Intracranial arteriovenous malformations can be diagnosed with computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), or cerebral arteriography. Catheter angiography can demonstrate the size, location, and characteristics of the feeding arteries and draining veins and is felt to be the best method to analyze the exact angioarchitecture of the lesion. Lesions have been reported in the skin but are very uncommon. CNS vascular lesions are typically on the same side as the involved eye. Central nervous system vascular lesions often involve the midbrain.

Treatment / Management

Once there is a diagnosis of Wyburn-Mason syndrome, the treatment is based on the location of the arteriovenous malformations and the corresponding symptoms. Unruptured arteriovenous malformations without symptoms can be observed; other options include radiation therapy, embolization, surgical resection, or a combination of these approaches. Most retinal arteriovenous malformations do not bleed externally but can produce minute hemorrhages that affect vision. Vision loss can occur by different mechanisms (retinal vascular occlusions, retinal ischemia, retinal detachment, and neovascular glaucoma). Because of the stability of retinal lesions, ophthalmologists often serve to mainly diagnose Wyburn-Mason, obtain neuroimaging, organize systemic referrals, and perform periodic ophthalmologic assessments. Patients who develop neovascular glaucoma require treatment. Retinal photocoagulation may be necessary to treat retinal ischemia. Pars plana vitrectomy may be done for non-clearing vitreous hemorrhage, and cyclodestructive procedures may be required to treat neovascular glaucoma.[8][9]

Differential Diagnosis

Sturge-Weber syndrome should be considered if there are port-wine stains (facial angioma) or ipsilateral juvenile or congenital open-angle glaucoma. Hemangiomas of the meninges are found in Sturge-Weber syndrome.

Von Hippel-Lindau disease is associated with a cerebral aneurysm, renal cell carcinoma, pheochromocytoma, and thus, should be considered as a differential diagnosis to decrease the risk of complications including the risk of death.

Staging

Archer et al. classified retinal arteriovenous malformations into 3 groups:

  • Group 1 (small arteriole-venule anastomoses) which can be subtle and difficult to detect clinically
  • Group 2 (direct artery-vein communication without an in-between capillary network). Edema and hemorrhage can occur.
  • Group 3 (markedly convoluted, dilated, tortuous retinal vessels) which extend throughout the fundus. It can be nearly impossible to separate arteries from veins. These eyes usually have severe vision loss. These patients are usually diagnosed in childhood, and they have a higher risk of systemic vascular involvement.

Prognosis

Patients may remain asymptomatic both visually or systemically. However, it is common for patients to have significantly decreased vision. Cases of retinal ischemia have been noted. Involvement of maxillofacial or mandibular vessels has led to excessive hemorrhages during dental procedures.

Enhancing Healthcare Team Outcomes

Once there is a diagnosis of Wyburn-Mason syndrome, the treatment is based on the location of the arteriovenous malformations and the corresponding symptoms. Because the condition is associated with high morbidity and mortality linked to hemorrhage, the disorder is best managed by a multidisciplinary team that includes an internist, geneticist, hematologist, radiologist, ophthalmologist and intensivist. Follow up is usually done by the primary care provider and nurse practitioner.  Patients with unruptured arteriovenous malformations without symptoms can be observed; other options include radiation therapy, embolization, surgical resection, or a combination of these approaches. Before the patient undergoes any invasive procedure, the healthcare professional should be familiar with the syndrome and how to manage the hemorrhage. Even during a simple tooth extraction, significant hemorrhage can occur. The outcomes for patients with eye involvement are guarded; most patients do end up with some degree of vision loss.[10] (Level V)