Sturge-Weber Syndrome

What causes Sturge-Weber syndrome

SWS is caused by a somatic mosaic mutation in the GNAQ gene that happens during early development. Only some cells carry the change, so it is not inherited and not passed on. The mutation leads to malformed small blood vessels (capillary-venous malformations) in the skin, the brain's surface layers (leptomeninges) and the eye.

The abnormal brain vessels cause poor blood flow and drainage in the underlying brain, leading to low oxygen, calcification and gradual brain tissue loss on the affected side.

Features

Port-wine birthmark

A flat, pink to dark red port-wine stain is present at birth, usually on one side of the face. A birthmark involving the forehead and upper eyelid carries the highest risk of SWS. Most babies with a facial port-wine stain do not have SWS, and a small number of people with SWS have no birthmark.

Brain involvement

• seizures in about 75 to 90%, often leading to epilepsy, usually starting in the first year of life
• weakness on one side of the body (hemiparesis), often after seizures
• stroke-like episodes that can resemble a stroke
• headaches and migraine
• developmental delay, intellectual disability and learning or behavioral problems in many
• visual field loss

Eye involvement

• glaucoma in about 30 to 70%, either at birth or later in childhood or adulthood
• choroidal hemangioma (vascular malformation at the back of the eye)

Types (Roach scale)

Diagnosis

• Brain MRI with contrast: shows the leptomeningeal angioma, brain atrophy and enlarged deep veins. Very early MRI can miss changes, so imaging timing is discussed with specialists.
• Eye exam with eye pressure measurement soon after birth and regularly thereafter.
• EEG to evaluate seizures.
• Genetic testing of the birthmark tissue can confirm the GNAQ mutation.

Treatment

There is no cure. Care is coordinated by neurology, ophthalmology, dermatology and developmental specialists.

• Seizure control: anti-seizure medicines. Rapid treatment of seizures may reduce brain injury. Rescue medication plans are provided for families.
• Low-dose aspirin: used by many specialists to reduce stroke-like episodes and seizures, under medical supervision. Aspirin is otherwise avoided in children because of Reye's syndrome risk, so this must only be given as directed.
• Epilepsy surgery: for seizures that do not respond to medicine, including focal resection or hemispherectomy.
• Glaucoma treatment: eye drops, laser or surgery; lifelong monitoring.
• Port-wine stain: pulsed dye laser treatment, ideally started in infancy, lightens the birthmark and may prevent thickening.
• Developmental support: physical, occupational and speech therapy, and educational support.
• Headache management.

Outlook

Outcomes vary widely. Some people have mild involvement and normal intelligence, while others have frequent seizures and significant disability. Early-onset seizures, extensive brain involvement and poorly controlled epilepsy are associated with more severe outcomes. Regular eye and neurological follow-up is lifelong.

Frequently asked questions

What is Sturge-Weber syndrome?

Sturge-Weber syndrome is a rare condition present from birth in which a facial port-wine birthmark occurs with abnormal blood vessels on the brain's surface and in the eye. It can cause seizures, weakness on one side, developmental delays and glaucoma.

Is Sturge-Weber syndrome inherited?

No. It is caused by a GNAQ gene mutation that occurs by chance in some cells during early development. It is not inherited from parents and is not passed on to children.

Does every port-wine stain mean Sturge-Weber syndrome?

No. Most babies with a port-wine stain do not have SWS. The risk is highest when the birthmark involves the forehead and upper eyelid. These babies need an eye exam and neurological follow-up, sometimes with an MRI.

What are the first signs of Sturge-Weber syndrome?

The first sign is usually a port-wine birthmark on the face at birth. Seizures commonly begin in the first year of life. An enlarged, cloudy or watery eye may signal glaucoma.

How is Sturge-Weber syndrome treated?

Treatment includes anti-seizure medicines, specialist-directed low-dose aspirin, glaucoma treatment, laser therapy for the birthmark, epilepsy surgery for resistant seizures, and therapy and educational support for developmental needs.