Bonnet-Dechaume-Blanc syndrome or Wyburn mason’s syndrome or Retinoencephalofacial angiomatosis is a rare arteriovenous malformation (AVMs) condition. The special name for wyburn mason’s syndrome is called congenital retinocephalofacial vascular malformation syndrome” (“CRC syndrome”). 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.

• Bonnet-Dechaume-Blanc syndrome was first discovered by Magnus, in 1874.^[1]
• In 1932, Yates and Payne was the first to discover retinal and cerebral arteriovenous malformation (AVMs) in patients with Bonnet-Dechaume-Blanc syndrome.^[2]
• In 1937, Bonnet, Dechaume and Blanc was the first to discover arteriovenous malformations in face, retina, and brain.^[3][4]

• Arteriovenous malformations(AVM) may be classified according to Archer et al. into 3 groups:^[6]

• 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.

• On microscopic histopathological analysis, fibromuscular media and fibrohyaline adventitial coats are characteristic findings of retinal AVMs.

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

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

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

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

• Common complications of Bonnet-Dechaume-Blanc syndrome include:^{[7][8][9][10][11][12][13][14][15][16]}
  • Retinal detachment(serous type)
  • Cutaneous reactive angiomatosis
  • Central retinal vein occlusion
    • Central retinal vein occlusion when in association with rubeosis iridis and secondary glaucoma gets complicated
  • Acute or subacute, recurrent, or catastrophic hemorrhagic
  • Seizures
  • Hemiparesis
  • Hydrocephalus
  • Significantly decreased vision

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

• Bonnet-Dechaume-Blanc syndrome must be differentiated from sturge-weber syndrome, congenital open-angle glaucoma, and von hippel-lindau disease.^[17]

• Fewer than 100 cases of Bonnet-Dechaume-Blanc syndrome have been reported worldwide.^[20]

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

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

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

• There is no racial predilection to Bonnet-Dechaume-Blanc syndrome.^[21]

• Bonnet-Dechaume-Blanc syndrome affects men and women equally.^[22]

• Common symptoms of Bonnet-Dechaume-Blanc syndrome include:^{[23][24][25][26][27]}
  • Mental status changes
  • Headaches
  • Seizures
  • Stroke
  • Hemiparesis
  • Visual-field abnormalities
  • Papilledema
  • Hydrocephalus

• Less common symptoms of Bonnet-Dechaume-Blanc syndrome include:^[28][29][30]
  • Hematuria
  • Epistaxis
  • Oral hemorrhages

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

• Ophthalmoscopic exam may be abnormal with findings of retinal and vitreous hemorrhages, retinal detachment, venous occlusive disease, optic disc edema, or optic atrophy.^{[32][33][34][35][36][37][38]}
• Racemose haemangioma.^{[39][40][41][42][43][44][45][46]}
• Macular ischemia.^[47]
• Proptosis which can be accompanied by bruit^[48]
• Blepharoptosis: Drooping of the upper eyelid
• Neck stiffness (nuchal rigidity)

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

• Hematuria
• Hemoptysis
• Epistaxis

• Seizures
• Hemiparesis

• Ophthalmoscopy is the gold standard test for the diagnosis of Bonnet-Dechaume-Blanc syndrome.^[51]

• Other diagnostic studies for Bonnet-Dechaume-Blanc syndrome include:^[52][53][54]
• Fluorescein angiography: Helps in identifying the small lesions^[55]
• 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)
• Digital subtraction angiography (DSA): Helps in identifying nidus of the arteriovenous malformations(AVM) located around the optic chiasm and behind the globe.^[56]

• 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

• 

  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:^[58][59][60]
  • Intracranial arteriovenous malformations
  • Midbrain involvement
  • Optic nerve, chiasm and thalamus involvement
  • Arachnoidal cyst
  • Enlarged retrobulbar vessels
  • Retinal arteriovenous malformations(AVM)

• The optimal therapy for Bonnet-Dechaume-Blanc syndrome depends on the location of arteriovenous malformation at the time of diagnosis.^[61]
• The majority of patients with Bonnet-Dechaume-Blanc syndrome shows no symptoms with unruptured arteriovenous malformations and these patients are under observation.^[62]
• 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.^[63][64][65]
• Intravitreal ranibizumab helps in treating the patients who are with retinal artery macroaneurysm and exudation.^{[66][67][68][69]}

• Intervention options in Bonnet-Dechaume-Blanc syndrome include^[70][71]
  • Radiation therapy
  • Laser photocoagulation for patients who are having peripheral ischemia

• Surgery is not the first-line treatment option for patients with Bonnet-Dechaume-Blanc syndrome.
• In patients with Bonnet-Dechaume-Blanc syndrome the options are as follows
• Endovascular embolization
• Surgical resection, or a combination are the choices for the patients to manage AVMs.