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.
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.

The ophthalmic features of Bonnet–Dechaume–Blanc syndrome occur as retinal arteriovenous malformation (AVMs).
There are three categories of AVMs based on their severity.
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 between an artery and a vein; without it, edema, hemorrhage, and visual impairment can result.
Category three refers to malformations so severe that their dilated vessels no longer distinguish between artery and vein, and the patient has a significantly increased risk of vision loss.
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 can cause a wide range of symptoms, including decrease in visual sharpness, proptosis, pupillary defects, optic nerve degeneration, and visual field defects.
The most common type of visual field impairment due to AVMs is homonymous hemianopia, which is usually unilateral.

Central nervous system (CNS) symptoms of Bonnet–Dechaume–Blanc syndrome are highly dependent on the locations and sizes of cerebral AVMs.
The most common CNS feature is an intracranial hemangioma in the midbrain.
Cerebral malformations can result in severe headaches, cerebral hemorrhages, vomiting, meningism, seizures, acute strokes, and progressive neurological deficits due to acute or chronic ischaemia caused by arteriovenous shunting.

The facial features of Bonnet–Dechaume–Blanc syndrome vary from case to case.
A person showing signs of the syndrome may display faint skin discoloration, nevi, or angiomas of the skin.
Some patients with this disorder also present with high-flow AVMs in the maxillofacial or mandibular (jaw) regions.
Another facial indicator of this disease is malformations affecting the frontal or maxillary sinuses.
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. 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.
The ophthalmic features of Bonnet–Dechaume–Blanc syndrome occur as retinal arteriovenous malformation (AVMs). There are three categories of AVMs based on their severity. 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 between an artery and a vein; without it, edema, hemorrhage, and visual impairment can result. Category three refers to malformations so severe that their dilated vessels no longer distinguish between artery and vein, and the patient has a significantly increased risk of vision loss. 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 can cause a wide range of symptoms, including decrease in visual sharpness, proptosis, pupillary defects, optic nerve degeneration, and visual field defects. The most common type of visual field impairment due to AVMs is homonymous hemianopia, which is usually unilateral.
Central nervous system (CNS) symptoms of Bonnet–Dechaume–Blanc syndrome are highly dependent on the locations and sizes of cerebral AVMs. The most common CNS feature is an intracranial hemangioma in the midbrain. Cerebral malformations can result in severe headaches, cerebral hemorrhages, vomiting, meningism, seizures, acute strokes, and progressive neurological deficits due to acute or chronic ischaemia caused by arteriovenous shunting.
The facial features of Bonnet–Dechaume–Blanc syndrome vary from case to case. A person showing signs of the syndrome may display faint skin discoloration, nevi, or angiomas of the skin. Some patients with this disorder also present with high-flow AVMs in the maxillofacial or mandibular (jaw) regions. Another facial indicator of this disease is malformations affecting the frontal or maxillary sinuses.
Bonnet–Dechaume–Blanc syndrome