Bonnet-Dechaume-Blanc syndrome

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Vamsikrishna Gunnam M.B.B.S [2]

Synonyms and keywords: Wyburn mason's syndrome; Retinoencephalofacial angiomatosis

CT scan showing intracranial hemorrhage

Overview

Bonnet-Dechaume-Blanc syndrome or Wyburn mason's syndrome or Retinoencephalofacial angiomatosis is a rare arteriovenous malformation (AVMs) condition. In The United States of America in order to categorise a condition as a rare disease it should affect fewer than 200,000 people. Rare diseases also called as orphan diseases. Orphan Drug Act was passed on 1983 by congress for the rare diseases. Today an average of 25-30 million americans have been reported with rare diseases. The number of people with individual rare disease may be less but overall the number of people with rare diseases are large in number.

Historical Perspective

• Bonnet-Dechaume-Blanc syndrome was first discovered by Magnus, in 1874.
• In 1932, Yates and Payne was the first to discover retinal and cerebral arteriovenous malformation (AVMs) in patients with Bonnet-Dechaume-Blanc syndrome.
• In 1937, Bonnet, Dechaume and Blanc was the first to discover arteriovenous malformations in face, retina, and brain.

Pathophysiology

• The exact pathogenesis of Bonnet-Dechaume-Blanc syndrome is not completely understood.
• It is understood that Bonnet-Dechaume-Blanc syndrome may be caused by genetic factors but which are involved are difficult to say.
• It is understood that Bonnet-Dechaume-Blanc syndrome is also may be caused by anomaly in organogenesis.
• Origin of cells of the vessel walls in the cephalic region in the brain, and their migration may explain the connection between lesions looks alike but at different locations in the body.
• Vision loss in patients with Bonnet-Dechaume-Blanc syndrome can be due to retinal arteriovenous malformations(AVM) which are tend to be large and lead to obscuration of the visual centers in the eye.
• Vision loss in patients with Bonnet-Dechaume-Blanc syndrome can also be due to compression of retinal arteries by arteriovenous malformations(AVM)
• In gestational period of the fetus vascular dysgenesis of anterior plexus may occur and leads to AVMs.
• Large network of arteriovenous malformations(AVM) in an area look like "bag-of-worms" and are characterized by direct artery-to-vein communication devoid of capillaries that results in high pressure blood flow.

Causes

• The cause of Bonnet-Dechaume-Blanc syndrome has not been identified yet.

Genetic Causes

• Bonnet-Dechaume-Blanc syndrome may be is caused by a mutation in the genes.

Risk Factors

• There are no established risk factors for Bonnet-Dechaume-Blanc syndrome.

Natural History, Complications, and Prognosis

Natural History

• The symptoms of Bonnet-Dechaume-Blanc syndrome usually develop in the first decade of life, and start with symptoms such as visual-field abnormalities.

Complications

• Common complications of Bonnet-Dechaume-Blanc syndrome include:
  • Retinal detachment(serous type)
  • Cutaneous reactive angiomatosis
  • Central retinal vein occlusion
  • Seizures
  • Hemiparesis
  • Hydrocephalus
  • Significantly decreased vision

Prognosis

• Maxillofacial or mandibular vessels involvement in Bonnet-Dechaume-Blanc syndrome patients may lead to excessive hemorrhages and associated with poor prognosis.

Differentiating Bonnet-Dechaume-Blanc syndrome from other Diseases

• Bonnet-Dechaume-Blanc syndrome must be differentiated from sturge-weber syndrome, congenital open-angle glaucoma, and von hippel-lindau disease.

Epidemiology and Demographics

Incidence

• Fewer than 100 cases of Bonnet-Dechaume-Blanc syndrome have been reported worldwide.

• The incidence of Bonnet-Dechaume-Blanc syndrome is unknown yet.

Prevalence

• The prevalence of Bonnet-Dechaume-Blanc syndrome is unknown yet.

Age

• Bonnet-Dechaume-Blanc syndrome is a congenital disorder.

Race

• There is no racial predilection to Bonnet-Dechaume-Blanc syndrome.

Gender

• Bonnet-Dechaume-Blanc syndrome affects men and women equally.

History and Symptoms

Common Symptoms

• Common symptoms of Bonnet-Dechaume-Blanc syndrome include:
  • Mental status changes
  • Headaches
  • Seizures
  • Stroke
  • Hemiparesis
  • Visual-field abnormalities
  • Papilledema
  • Hydrocephalus

Less Common Symptoms

• Less common symptoms of Bonnet-Dechaume-Blanc syndrome include:
  • Epistaxis
  • Oral hemorrhages

Physical Examination

Appearance of the Patient

• Patients with Bonnet-Dechaume-Blanc syndrome usually appear normal.

Macular ischemia and extensive arteriovenous communications and dilated intertwined vessels. Case courtesy by Dimitrios A Karagiannis

Retinal racemose angioma. Case courtesy by Dimitrios A Karagiannis

HEENT

• Ophthalmoscopic exam may be abnormal with findings of retinal and vitreous hemorrhages, retinal detachment, venous occlusive disease, optic disc edema, or optic atrophy.
• Racemose haemangioma.
• Macular ischemia.
• Proptosis
• Blepharoptosis: Drooping of the upper eyelid
• Neck stiffness (nuchal rigidity)

Lungs

Based on the locations of arteriovenous malformations(AVM), Bonnet-Dechaume-Blanc syndrome patients may present with:

• Hematuria
• Hemoptysis
• Epistaxis

Neuromuscular

• Seizures
• Hemiparesis

Diagnosis

Diagnostic Study of Choice

• Ophthalmoscopy is the gold standard test for the diagnosis of Bonnet-Dechaume-Blanc syndrome.

Stagining

• According to Archer et al. retinal arteriovenous malformations can be divided into 3 groups:

Type 1	Small arteriole-venule anastomoses	Hard to detect clinically
Type 2	Direct artery-vein communication devoid capillary network	Edema and hemorrhage may occur
Type 3	Dilated, tortuous retinal vessels	Severe visual impairment

Other Diagnostic Studies

• Other diagnostic studies for Bonnet-Dechaume-Blanc syndrome include:
  • Fluorescein angiography: Helps in identifying the small lesions
  • Optical coherence tomography: Helps in identifying the changes in nerve fiber layer, macula, and retina
  • Catheter angiography: Catheter angiography helps in identifying size, location, feeding arteries and draining veins in arteriovenous malformations(AVM)

CT scan

• Head CT scan may be helpful in the diagnosis of Bonnet-Dechaume-Blanc syndrome. Findings on CT scan suggestive of Bonnet-Dechaume-Blanc syndrome include:
  • Intracranial arteriovenous malformations

MRI

• Head MRI scan may be helpful in the diagnosis of Bonnet-Dechaume-Blanc syndrome. Findings on MRI scan suggestive of Bonnet-Dechaume-Blanc syndrome include:
  • Intracranial arteriovenous malformations
  • Midbrain involvement
  • Optic nerve, chiasm and thalamus involvement

Treatment

Medical Therapy

• The optimal therapy for Bonnet-Dechaume-Blanc syndrome depends on the location of arteriovenous malformation at the time of diagnosis.
• The majority of patients with Bonnet-Dechaume-Blanc syndrome shows no symptoms with unruptured arteriovenous malformations and these patients are under observation.
• Bevacizumab( intravitreal injection) helps in decreasing the pressure and fluid build up in the eye in case of retinal racemose hemangioma and helps in improving the vision.