Introduction
Wyburn-Mason syndrome (WMS) is an arterio-venous malformation. It involves arteries, veins, and capillaries. Capillaries are tiny vessels that connect more prominent veins and arteries. The arteriovenous malformation in WMS is more frequently seen in the blood vessels of the brain and eyes. Wyburn-Mason syndrome is a rare condition. Less than a hundred cases are reported worldwide. There is no sexual or racial predilection, and it affects both sexes equally.
WMS have been grouped under neurocutaneous or phakomatosis disorders. Phakomatosis disorders present with tumors in the brain and other regions. However, unlike other neurocutaneous disorders, WMS does not show cutaneous manifestations.
What Causes Wyburn-Mason Syndrome?
The exact cause for the development of Wyburn-Mason syndrome is not known. However, the primary reason behind the arterial and venous malformation remains the abnormal development of the precursor cells of the blood vessels during fetal growth.
What Are the Clinical Signs and Symptoms of Wyburn-Mason Syndrome?
The clinical presentations of the condition vary among individuals. The most common site involved in an infant is the eyes and the central nervous system. The various findings in patients suffering from Wyburn-Mason syndrome include:
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Absence of the small blood vessels or capillaries.
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Arteriovenous malformations (AVM) are in the brain, skin, and eye regions.
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Presence of tangled and wider blood vessels, also known as racemose hemangioma.
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Abnormal flow of downstream blood results in ischemia.
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Nausea.
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Vomiting.
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The rigidity of the neck.
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Paralysis of the cranial nerves.
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Spontaneous bleeding.
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Severe headaches.
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Fluid build-up inside the brain cities (hydrocephalus).
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In prolonged bleeding, the chances of paralysis of the half side of the body (hemiplegia) also occur.
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Dermal presentations, although rare, associated with WMS include small bumps of blood vessels all over the face.
What Are the Ocular Manifestations of Wyburn-Mason Syndrome?
The patients suffering from Wyburn-Mason syndrome present with the following clinical presentations of the eye:
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WMS involves the retina (nerve bundle present at the back of the eye) and the orbit. Retinal involvement is more common. The involvement of the retina can be diffuse or focal.
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Racemose hemangioma of the eye is a vision-threatening condition that may result in blindness.
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Bulging of the eyeball (proptosis). It is more common in orbital AVM.
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Drooping of the upper eyelids (blepharoptosis).
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Inability to move the eyes.
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Reduced visual acuity.
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Dilation of the blood vessels supplying the conjunctiva (loose connective tissue covering the eyeball).
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Paralysis of the ocular nerve.
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Transient vision loss can occur if AVM is present in the brain's cortex region.
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Nystagmus.
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Optic atrophy.
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Optic disc edema.
Risk Factors for the Ocular Presentations.
The factors that accelerate the growth of AVM of the retina in WMS are:
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Menarche.
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Pregnancy.
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Ocular pathologies like retinal neovascularization (formation of new blood vessels inside the retina) and neovascular glaucoma.
What Are the Different Groups of Wyburn-Mason Syndrome?
The WMS is grouped into three categories based on their severity and characteristics;
Group 1: Major retinal artery and vein with capillary involvement. These patients are asymptomatic.
Group 2: Major retinal artery and vein with no capillary involvement present. These patients may acquire retinal complications.
Group 3: There are extensive AVM malformations with no capillary involvement. These patients may present with intracranial manifestations also.
Conditions Similar to Wyburn-Mason Syndrome.
Conditions that share similarities with the condition and are to be ruled out before forming a confirmatory diagnosis of WMS are:
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Sturge-Weber syndrome.
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Von-Hippel Lindau syndrome.
How Is Wyburn-Mason Syndrome Diagnosed?
The diagnosis of WMS is reached by obtaining a complete history of the patient, and a physical evaluation of the patient. Imagings such as computed tomography (CT), magnetic resonance imaging (MRI), and contrast imaging by injecting dye into the blood vessels are performed to detect the lesions inside the brain.
Examination of the Ocular Lesions
The ocular lesions are evaluated by a complete eye examination, including ocular movements. Other means of ophthalmic examination include:
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Fundoscopic examination of the retina reveals the AVM of the retina.
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Fluorescein angiography delineates the rapid filling of vascular defects.
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Optical coherence tomography (OCT) helps view retinal edema and the thickening of the retinal blood vessels.
How Is Wyburn-Mason Syndrome Managed?
Wyburn-Mason syndrome does not have any specific treatment modality. All the treatments of WMS are aimed at managing the symptoms associated with the syndrome. Most of the intracranial lesions are removed with surgery and embolization (blocking of blood vessels). In case the surgery is not possible, radiation is applied precisely at the point of the lesion with the help of Linac, gamma knife, cyberknife, etc.
Management of Ocular Lesions
Retinal lesions are mostly stable. They do not require any treatment. In case of excessive bleeding from the retinal or vitreous membrane (jelly-like material present in the middle layer of the eye), lasers and cryosurgery are performed to destroy the tissue with the abnormality and hence control the bleeding. However, surgical management of ocular lesions remains controversial.
What Are the Ocular Complications Related to Wyburn-Mason Syndrome?
The ocular complications of WMS mainly occur due to the ischemia in the retinal region preceded by occlusion of the retinal vein and thrombi formation. The major complications of the syndrome are:
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Retinal detachment.
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Retinal vein occlusion.
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Hemorrhage.
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Intraretinal edema.
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Macular edema.
What Is the Prevention and Prognosis of Wyburn-Mason Syndrome?
It is not possible to prevent WMS as there is no clear-cut causative factor associated with the disease. Retinal AVM usually remains stable, and some show spontaneous regression. Patients with cerebral hemorrhage suffer from high mortality. However, the recurrence rate of extracranial AVM is very high; hence it is essential to monitor the condition for any worsening.
Conclusion
Wyburn-Mason syndrome is a rare arteriovenous malformation involving both cranial and extracranial sites. The extracranial lesions that are more common in the eyes remain stable in most cases. However, in long-standing or recurrent cases, the chances of blindness increase. Regular follow-up of patients for any deterioration of the condition helps prevent ocular complications.
