Bonnet–Dechaume–Blanc syndrome

CT scan showing intracranial hemorrhage

Bonnet–Dechaume–Blanc syndrom, also known as Wyburn-Mason syndrome, is a rare congential arteriovenous malformation of the brain, retina or facial nevi.[1] The syndrome has a number of possible symptoms and can affect the skin, bones, kidneys, muscles, and gastrointestinal tract.[2] When the syndrome affects the brain, people can experience severe headaches, seizures, acute stroke, meningism and progressive neurological deficits due to acute or chronic ischaemia caused by arteriovenous shunting.[2][3]

As for the retina, the syndrome causes retinocephalic vascular malformations that tend to be present with intracranial hemorrhage and lead to decreased visual acuity, proptosis, pupillary defects, optic atrophy, congestion of bulbar conjunctiva, and visual field defects.[3][4] Retinal lesions can be unilateral and tortuous, and symptoms begin to appear in the second and third decades of life.[3]

The syndrome can present cutaneous lesions, or skin with different texture, thickness, and color, usually on the face.[4] The facial features caused by the syndrome vary from slight discoloration to extensive nevi and angiomas of the skin.[3] In some cases, the frontal and maxillary sinus can present problems in the subject due to the syndrome.[4]

There have only been 52 reported cases of patients with Bonnet–Dechaume–Blanc syndrome as of 2012.[2] Symptoms are rarely noticed in children and the syndrome is often diagnosed in late childhood or early adulthood when visual impairment is noticed.[3] Fluorescein angiography is commonly used to diagnose the syndrome.[5]

There have been several methods in treating patients who display Bonnet–Dechaume–Blanc syndrome. However, which method seems to work the most is within argument. Patients with intracranial lesions have been treated with surgical intervention and in some cases, this procedure has been successful. Other treatments include embolization, radiation therapy, and continued observation.[4]

With limited research on Bonnet–Dechaume–Blanc syndrome, researchers have focused on the clinical and radiological findings rather than how to manage this rare and non-heritable syndrome.[3]

Signs and symptoms

Left eye showing proptosis.

Typically not diagnosed until late childhood or later, Bonnet–Dechaume–Blanc syndrome usually presents itself with a combination of central nervous system features (midbrain), ophthalmic features (retina), and facial features.[6] The degree of expression of the syndrome's components varies both clinically and structurally. Common symptoms that lead to diagnosis are headaches, retro-orbital pain and hemianopia.[4]

Visual field of homonymous hemianopia

The ophthalmic features of the Bonnet–Dechaume–Blanc syndrome occur as retinal arteriovenous malformation (AVMs). There are three categories of AVMs that are categorized depending on the severity of the malformation. The first category consists of the patient having small lesions that usually are asymptomatic. The second category, more severe than the first, is when the patient’s malformation is missing a connecting capillary. The missing capillary is meant to serve as a link between an artery and a vein; without it, edemas, hemorrhages, and visual impairments can result. Category three, the most severe, occurs when the patient’s malformations are so severe that the dilated vessels cause no distinction between artery and vein. When the symptoms are this severe, the patient has a significantly increased risk of developing vision loss.[3] Since the retinal lesions categorized vary from large vascular malformations that affect a majority of the retina to malformations that are barely visible, the lesions cause a wide range of symptoms including decrease in visual sharpness, proptosis, pupillary defects, optic degeneration and visual field defects.[4] The most common type of visual field impairment due to AVMs is homonymous hemianopia.[2] Homonymous hemianopia typically presents unilaterally, but bilateral cases have been reported as well.[6]

The extent of the central nervous system (CNS) features/symptoms of Bonnet–Dechaume–Blanc syndrome is highly dependent of the location of the cerebral AVMs and the extent of the malformation.[2][4][6] The most common symptom affecting the CNS is an intracranial hemangioma in the midbrain.[3] Along with hemangiomas, the malformations result in severe headaches, cerebral hemorrhages, vomiting, meningism, seizures, acute strokes or progressive neurological deficits due to acute or chronic ischaemia caused by arteriovenous shunting.[3]

The distinguishable facial features that result from Bonnet–Dechaume–Blanc syndrome vary from case to case. A person showing signs of the syndrome may display faint skin discoloration, nevi and angiomas of the skin.[3] Some patients with this disorder also present with high flow arteriovenous malformations of the maxillofacial or mandibular (jaw) regions.[7] Another facial indicator of this disease is malformations affecting the frontal and/or maxillary sinuses.[4]

Causes

The syndrome is a congenital disorder that begins to develop around the seventh week of gestation when the maturation of retinal mesenchymal cells do not properly grow.[3][6][8] The abnormal development of vascular tissue leads to arteriovenous malformations. These malformations affect both the visual and cerebral structures and lead to the development of the syndrome.[8]

Mechanism

Using fluorescein angiographies to reveal malformations in arteriovenous connections.

Bonnet–Dechaume–Blanc syndrome results mainly from arteriovenous malformations. These malformations are addressed previously in the article, under “Signs and Symptoms.” Due to lack of research, it is difficult to provide a specific mechanism for this disorder. However, a number of examinations, mentioned under “Diagnosis,” can be performed on subjects to investigate the disorder and severity of the AVMs.

Epidemiology

The syndrome was first described in 1943 and believed to be associated with racemose hemangiomatosis of the retina and arteriovenous malformations of the brain. It is non-hereditary and belongs to phakomatoses that do not have a cutaneous (pertaining to the skin) involvement. This syndrome can affect the retina, brain, skin, bones, kidney, muscles, and the gastrointestinal tract.[5]

Diagnosis

Diagnosis commonly occurs later in childhood and often occurs incidentally in asymptomatic patients or as a cause of visual impairment.[3] The first symptoms are commonly found during routine vision screenings.

A number of examinations can be used to determine the extent of the syndrome and its severity. Fluorescein angiography is quite useful in diagnosing the disease, and the use of ultrasonography and optical coherence tomography (OCT) are helpful in confirming the disease.[5] Neuro-ophthalmic examinations reveal pupillary defects (see Marcus Gunn Pupil). Funduscopic examinations, examinations of the fundus of the eye, allow detection of arteriovenous malformations.[2] Neurological examinations can determine hemiparesis and paresthesias.[2] Malformations in arteriovenous connections and irregular functions in the veins may be distinguished by fluorescein angiographies. Cerebral angiography examinations may expose AVMs in the cerebrum. MRIs are also used in imaging the brain and can allow visualization of the optic nerve and any possible atrophy. MRI, CT, and cerebral angiography are all useful for investigating the extent and location of any vascular lesions that are affecting the brain.[2][4] This is helpful in determining the extent of the syndrome.

Treatment

The treatment for Bonnet–Dechaume–Blanc syndrome is controversial due to a lack of consensus on the different therapeutic procedures for treating arteriovenous malformations.[8] The first successful treatment was performed by Morgan et al.[7] They combined intracranial resection, ligation of ophthalmic artery, and selective arterial ligature of the external carotid artery, but the patient did not have retinal vascular malformations.[6]

If lesions are present, they are watched closely for changes in size. Prognosis is best when lesions are less than 3 cm in length. Most complications occur when the lesions are greater than 6 cm in size.[2] Surgical intervention for intracranial lesions has been done successfully. Nonsurgical treatments include embolization, radiation therapy, and continued observation.[4] Arterial vascular malformations may be treated with the cyberknife treatment. Possible treatment for cerebral arterial vascular malformations include stereotactic radiosurgery, endovascular embolization, and microsurgical resection.[2]

When pursuing treatment, it is important to consider the size of the malformations, their locations, and the neurological involvement.[6] Because it is a congenital disorder, there are not preventative steps to take aside from regular follow ups with a doctor to keep an eye on the symptoms so that future complications are avoided.

References

  1. ↑ Liu, Anthony; Chen, Yi-Wen; Chang, Steven; Liao, Yaping Joyce (March 2012). "Junctional Visual Field Loss in a Case of Wyburn-Mason Syndrome". Journal of Neuro-Ophthalmology. 32 (1): 42–44. doi:10.1097/WNO.0b013e31821aeefb. PMID 21613961.
  2. 1 2 3 4 5 6 7 8 9 10 SINGH, A; RUNDLE, P; RENNIE, I (March 2005). "Retinal Vascular Tumors". Ophthalmology Clinics of North America. 18 (1): 167–176. doi:10.1016/j.ohc.2004.07.005.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 Kim, Jeonghee; Kim, Ok Hwa; Suh, Jung Ho; Lew, Ho Min (20 March 1998). "Wyburn-Mason syndrome: an unusual presentation of bilateral orbital and unilateral brain arteriovenous malformations". Pediatric Radiology. 28 (3): 161–161. doi:10.1007/s002470050319.
  4. 1 2 3 4 5 6 7 8 9 10 Dayani, P. N.; Sadun, A. A. (18 January 2007). "A case report of Wyburn-Mason syndrome and review of the literature". Neuroradiology. 49 (5): 445–456. doi:10.1007/s00234-006-0205-x.
  5. 1 2 3 Singh, ArunD; Turell, MaryE (2010). "Vascular tumors of the retina and choroid: Diagnosis and treatment". Middle East African Journal of Ophthalmology. 17 (3): 191. doi:10.4103/0974-9233.65486.
  6. 1 2 3 4 5 6 Lester, Jacobo; Ruano-Calderon, Luis Angel; Gonzalez-Olhovich, Irene (July 2005). "Wyburn-Mason Syndrome". Journal of Neuroimaging. 15 (3): 284–285. doi:10.1111/j.1552-6569.2005.tb00324.x.
  7. 1 2 Bhattacharya, JJ; Luo, CB; Suh, DC; Alvarez, H; Rodesch, G; Lasjaunias, P (30 March 2001). "Wyburn-Mason or Bonnet-Dechaume-Blanc as Cerebrofacial Arteriovenous Metameric Syndromes (CAMS). A New Concept and a New Classification.". Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences. 7 (1): 5–17. PMID 20663326.
  8. 1 2 3 Schmidt, D; Pache, M; Schumacher, M (2008). "The congenital unilateral retinocephalic vascular malformation syndrome (bonnet-dechaume-blanc syndrome or wyburn-mason syndrome): review of the literature.". Survey of ophthalmology. 53 (3): 227–49. doi:10.1016/j.survophthal.2007.10.001. PMID 18501269.
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