Bonnet-Dechaume-Blanc syndrome is the name given to a very rare condition that is already congenital. The condition is noticeable by arteriovenous malformations in the retinal blood vessels and facial changes.
What is Bonnet-Dechaume-Blanc syndrome?
In the medical community, Bonnet-Dechaume-Blanc syndrome is also known as congenital retinocephalofacial vascular malformation syndrome (CRC syndrome) or Wyburn-Mason syndrome. Among others, the French ophthalmologist Paul Bonnet (1884-1959) served as the eponym. Bonnet-Dechaume-Blanc syndrome is congenital and extremely rare. It is caused by a developmental disorder that occurs during embryogenesis. Typical features of the syndrome include unilateral arterviovenous malformations (malformations) of the retinal blood vessels of the eye, malformations of the cerebral and cephalic blood vessels, and changes in the face. Many physicians have found it difficult to classify Bonnet-Dechaume-Blanc syndrome precisely. It is not uncommon for the disease to be classified as a neurocutaneous syndrome. The rare Bonnet-Dechaume-Blanc syndrome has been known since the 19th century. Partial aspects were described by the German neuropathologist Hugo Spatz (1888-1969). The first detailed case reports occurred in the 1930s. The name Bonnet-Dechaume-Blanc syndrome came about in 1937 through a case report by the French physicians Paul Bonnet, Jean Dechaume as well as Emile Blanc. A case report by Roger Wyburn-Mason originated in 1943, so that he was also used as the eponym for the syndrome. It has not been possible to determine exactly how many people have Bonnet-Dechaume-Blanc syndrome. As of 2009, there were 132 known cases of the disease. The syndrome presents equally in both sexes.
Causes
The reason for the development of Bonnet-Dechaume-Blanc syndrome is a developmental disorder during the 7th week of pregnancy. However, what causes this disorder is still unknown. Arteriovenous malformations (AVM) represent shunts that occur between the venous and arterial vascular systems. The vessels are often in the form of a tangle and form a connection between the high and low pressure systems. Pressure results in increased blood flow to the vessels as well as their dilation. This results in a continuous remodeling of the vascular bed. As this affects the vessel wall, it results in complications such as narrowing and rupture of the vessels.
Symptoms, complaints, and signs
Bonnet-Dechaume-Blanc syndrome is noticeable by various changes in the face, eyes, and intracranial blood vessels, depending on the form of the syndrome. In the case of a complete syndrome, unilateral changes of the face appear in addition to the arteriovenous malformations of the retina as well as the cerebral vessels. These are mostly frontal, cheek or conjunctival vessels, which are partly protruding. In addition, the eyelid vessels change. Sometimes the nose, ears or lips are also affected. Changes in the eyes occur in incomplete Bonnet-Dechaume-Blanc syndrome and in isolated malformations of the retina. Almost 50 percent of all patients go blind on the affected side of the body. Furthermore, there is a risk of optic atrophy (loss of optic nerve cells) and secondary glaucoma. Hemorrhages in the vitreous or retina also sometimes occur. Cerebral arteriovenous malformation may result in outward strabismus (extropia), nystagmus, or ocular motility disorders. Arteriovenous malformations exist within the orbit in approximately two-thirds of patients. In addition to cerebral malformations of the vessels, unilateral protrusion of an eyeball from the orbit is possible. Not infrequently, the optic nerve is also affected. In case of a complete or incomplete Bonnet-Dechaume-Blanc syndrome, malformations of the cerebral vessels appear, which are primarily located in the supply region of the middle cerebral artery (Arteria cerebri media). One third of patients suffer from altered vessels in the cerebral optic tract. In some cases, the vascular changes do not cause any symptoms. In other patients, however, there is a risk of various forms of cerebral hemorrhage, increased intracranial pressure, or symptomatic epilepsy. Furthermore, paralysis of the facial nerve (facial paresis) is within the realm of possibility.
Diagnosis
If Bonnet-Dechaume-Blanc syndrome is suspected, the treating physician performs a neurologic examination. Also of importance are ophthalmologic examination procedures such as perimetry (visual field measurement) or ophthalmoscopy (ophthalmoscopy). To visualize an arteriovenous malformation, digital subtraction angiography, computed tomography (CT) or magnetic resonance imaging (MRI) can be performed. Magnetic resonance imaging is considered the best method of examination because it provides the most data on the extent of the disease. The course of Bonnet-Dechaume-Blanc syndrome depends on the extent of the damage and the site of the damage.
Complications
Characteristic of Bonnet-Dechaume-Blanc syndrome are pronounced malformations of the face, blood vessels in the brain, and eyes. If the patient suffers from the complete syndrome, malformations of the ocular retina and cerebral vessels as well as unilateral facial changes are classic symptoms. In many cases, conjunctival, buccal and frontal vessels become prominent. Other complications include changes in the eyelid vessels. The nose, ears and lips can also be affected by this developmental disorder. In incomplete Bonnet-Dechaume-Blanc syndrome, as well as in isolated retinal malformations, the characteristic ocular changes occur. Every second patient goes blind on the affected side of the body. Other complications include loss of optic nerve cells and secondary glaucoma. Hemorrhages in the retina or vitreous body are potential concomitants. Malformed blood vessels in the brain can lead to various forms of strabismus and unilateral protrusion of the eyeball from the orbit. The malformed cerebral vessels are predominantly located in the supply area of the middle cerebral artery. Two-thirds of patients suffer from changes in the blood vessels within the orbits, often affecting the optic nerve. The cerebral optic tract may be equally involved. Some patients do not notice any symptoms, while others develop complications such as increased intracranial pressure, cerebral hemorrhage, paralysis of the facial nerve, or symptomatic epilepsy. Treatment success and prognosis depend on the extent of the disease and the body sites involved.
When should you see a doctor?
In most cases, Bonnet-Dechaume-Blanc syndrome is detected immediately after birth or in the first few months after birth, so a visit to the doctor for diagnosis is not necessary. The affected person suffers from various changes and malformations, which occur mainly in the face of the affected person. However, it is not possible to predict how severely the affected person will be affected by this syndrome. In many cases, patients are dependent on various treatments that can make everyday life easier. Especially in the case of epileptic seizures caused by Bonnet-Dechaume-Blanc syndrome, a doctor must be consulted. However, paralysis of the face or cerebral hemorrhage may also occur as the disease progresses. In this case, a visit to a doctor is also necessary in any case, otherwise, in the worst case, the affected person may die. Usually, Bonnet-Dechaume-Blanc syndrome is diagnosed directly by a general practitioner or by a pediatrician. Further treatment of the syndrome is then carried out by the respective specialists. As a rule, not all symptoms can be completely limited. It is also possible that the patient’s life expectancy is reduced by Bonnet-Dechaume-Blanc syndrome.
Treatment and therapy
Treatment of Bonnet-Dechaume-Blanc syndrome should be performed by a specialist in vascular anomalies if an arteriovenous malformation is present. However, therapy is rarely considered appropriate in infancy or childhood. While treatment is not advised for silent arterial lesions, intracranial impairment can be treated with embolization or proton beams. If the malformations appear in other parts of the body, embolization is possible, followed by surgery. However, there is also the option of embolization alone or a single surgical procedure. Embolization involves occlusion of the afferent vessels. In some patients, surgery cannot be performed. In such cases, only embolization is performed.In this procedure, the neuroradiological surgeon glues the arteriovenous shunts. For this purpose, he uses a catheter in the course of an arteriography. However, there is a risk of skin necrosis with this procedure. In the case of diffuse AVM, treatment with drugs is an alternative.
Outlook and prognosis
The prospect of a cure is almost hopeless in Bonnet-Dechaume-Blanc syndrome. The disease, with all its accompanying symptoms, places a considerable burden on the patient throughout his or her life. Therapy and medical care are complicated by the uncertainty of the cause. The causes of the developmental disorder have not been adequately demonstrated by researchers and scientists to date. Therefore, Bonnet-Dechaume-Blanc syndrome is treated according to the individually occurring symptoms and complaints. Refusal of medical care is associated with numerous complications and should be avoided. The deformities in the face and also the visual disturbance reduce the general well-being and the quality of life to a considerable extent. If brain hemorrhages set in, the patient may furthermore die. Conventional medicine offers the patient options for improving health in a comprehensive treatment plan. The serious sequelae of Bonnet-Dechaume-Blanc syndrome are treated gradually and according to urgency. The additional complications from surgical procedures further worsen the prognosis. Nevertheless, with initiated corrections of the vascular changes, the patient may experience relief from his or her symptoms. Included in the treatment plan, in addition to the current treatment, are further preventive examinations. These are intended to allow early detection of possible critical conditions in the patient so that possible hemorrhage or increased intracranial pressure can be treated in a timely manner.
Prevention
There are no preventive measures against Bonnet-Dechaume-Blanc syndrome. Thus, the precipitating causes of the congenital malformations have remained unclear.
What you can do yourself
Bonnet-Dechaume-Blanc syndrome cannot be treated causally. Therapy focuses on surgical intervention and physical therapy, as well as cognitive training, which can be supported at home. Parents of affected children should start cognitive training early and consult with the appropriate professional for this purpose. The physiotherapeutic measures can be supported by moderate sports. Depending on the age of the child, swimming, walking or targeted muscle training may be suitable. Since Bonnet-Dechaume-Blanc syndrome can occur in a wide variety of types and forms, the measures must first be planned by a physician so that a targeted improvement in the child’s state of health can take place. Furthermore, a change in diet is an option. By avoiding certain foods, for example, the risk of epileptic seizures can be reduced. Lastly, parents should carefully monitor their child, as there is an increased risk of accidents. If a fall occurs, emergency services must be called. Otherwise, serious complications such as vitreous hemorrhage or intraocular bleeding may develop. Accompanying the above measures, comprehensive therapeutic support is always needed.
