Sturge-Weber syndrome (SWS) is a rare condition present from birth that affects blood vessels in the skin, brain, and eyes. It’s classified as a neurocutaneous disorder, meaning it involves both the nervous system and the skin. The hallmark sign is a facial birthmark called a port-wine stain, but the condition can also cause seizures, vision problems, and developmental challenges depending on which structures are involved.
What Causes It
Sturge-Weber syndrome results from a genetic mutation that happens spontaneously during early fetal development. It is not inherited in the traditional sense. The mutation occurs in a gene called GNAQ, which produces a protein involved in signaling between cells. Specifically, a single amino acid change at one position in this gene disrupts the protein’s ability to regulate a key energy molecule (GTP) inside cells. This throws off the signaling pathways that guide normal blood vessel formation.
Because the mutation happens after conception rather than being passed down from a parent, it only affects some of the body’s cells. This is called a somatic mutation. The timing of when the mutation occurs during development determines which tissues are affected and how severe the condition becomes. If it happens very early, more of the face, brain, and eye may be involved. If it happens later, only the skin might be affected.
The Three Types
Doctors classify Sturge-Weber syndrome into three types based on which parts of the body are involved:
- Type I (classic): Both a facial port-wine stain and abnormal blood vessels on the surface of the brain (leptomeningeal angioma). Glaucoma may also be present.
- Type II: A facial port-wine stain without any brain involvement. Glaucoma may still occur.
- Type III: Abnormal blood vessels on the brain only, with no skin birthmark and typically no glaucoma. This type is the hardest to recognize early because there’s no visible sign on the face.
The Port-Wine Stain
Port-wine stains are flat, pink-to-red birthmarks caused by abnormally widened blood vessels just beneath the skin. They occur in about 3 out of every 1,000 births, but most port-wine stains are isolated and not connected to Sturge-Weber syndrome. Only about 6% of babies born with a facial port-wine stain also develop brain involvement.
The location of the birthmark matters. Port-wine stains in Sturge-Weber syndrome follow the distribution of a major facial nerve called the trigeminal nerve, which has three branches. A birthmark on the forehead, temple, or upper eyelid (the territory of the first branch) carries a 20% to 50% risk of brain involvement. When the stain covers both the upper and lower eyelid, the risk of eye involvement and glaucoma jumps to around 50%. In studies of patients with port-wine stains, the most common pattern is involvement of both the first and second branches of the trigeminal nerve (about 41% of cases), while roughly 10% of patients have staining across all three branches.
Over time, untreated port-wine stains tend to darken from pink to deep purple and can thicken or develop a cobblestone texture. This progression is one reason early treatment is recommended.
Seizures and Brain Effects
The abnormal blood vessels on the brain’s surface (leptomeningeal angiomas) are the source of the most serious complications. These tangled, slow-flowing vessels don’t drain blood efficiently, which leads to reduced oxygen delivery to the brain tissue underneath. Over time, this causes progressive damage.
Seizures are one of the earliest and most common neurological symptoms. The median age of seizure onset is just 4.5 months. Seizures in SWS often begin on one side of the body, reflecting the side of the brain affected by the abnormal vessels. They can be difficult to control with medication alone.
On brain MRI, the leptomeningeal angioma appears as abnormal enhancement along the brain’s surface after contrast dye is given. Associated findings include shrinkage of the underlying brain tissue, calcium deposits, and enlarged veins in the white matter. The parietal region (toward the top and back of the head) is a common location.
Cognitive effects vary widely. In one study of 55 patients, 36% had IQ scores below 70, placing them in the range of intellectual disability. Others have normal or near-normal intelligence. The severity of cognitive impact is closely linked to how well seizures are controlled and how much brain tissue is affected. Weakness on one side of the body (hemiparesis) is also common when brain involvement is significant.
Glaucoma and Eye Involvement
Glaucoma, a condition where increased pressure inside the eye damages the optic nerve, affects a substantial number of people with SWS. It develops through two main age peaks: about 60% of cases appear as congenital (present at or shortly after birth), while the remaining 40% emerge later during childhood or adolescence.
The increased eye pressure stems from a few different mechanisms. Abnormal blood vessels can raise the pressure in the veins that drain fluid from the eye, making it harder for fluid to exit. In some cases, the drainage structures inside the eye itself are malformed from birth. Left untreated, glaucoma can lead to permanent vision loss, so regular eye pressure checks starting in infancy are essential for anyone with SWS.
Treating the Port-Wine Stain
Pulsed dye laser therapy is the standard treatment for port-wine stains. This laser targets the abnormal blood vessels in the skin, gradually lightening the birthmark. Most patients achieve 50% to 90% clearance, though results depend heavily on age. In one large study, children treated during their first year of life had a 93.9% response rate, compared to just 25% in adults over 50.
The process requires patience. Most people need eight to ten treatment sessions or more for optimal lightening, and touch-up treatments are often necessary even after a successful initial round. The interval between sessions varies, typically ranging from two weeks to three months depending on individual factors. Starting treatment early not only improves results but may help prevent the darkening and thickening that naturally occurs over the years.
Managing Seizures
Seizure control is a central focus of SWS management. Many patients respond to anti-seizure medications, but a significant number develop drug-resistant epilepsy. For those patients, surgery becomes an option.
The most definitive surgical procedure is hemispherotomy, which disconnects the affected half of the brain from the other. This has been established as a successful approach for patients with one-sided disease. In a case series of children with bilateral (both sides) SWS who underwent the procedure on their more affected side, outcomes were encouraging: one patient remained seizure-free for 10 years after surgery. Hemispherotomy tends to provide more effective long-term seizure control than alternatives like nerve stimulation or smaller disconnection procedures, particularly in extensive cases.
The decision to pursue surgery involves weighing the potential for seizure freedom against the expected neurological effects. Because the affected hemisphere is already significantly damaged in most surgical candidates, the additional deficits from disconnection are often less severe than one might expect. These decisions are made on a case-by-case basis by specialized teams.
Long-Term Outlook
The course of Sturge-Weber syndrome varies enormously from person to person. Someone with Type II (skin only) may face primarily cosmetic concerns and glaucoma risk, while someone with extensive Type I disease may deal with seizures, cognitive challenges, and vision problems throughout life. Early seizure control, consistent eye monitoring, and timely laser treatment all improve outcomes. Many people with SWS lead independent lives, particularly when brain involvement is limited or well-managed, though those with more severe disease may need ongoing support with learning, mobility, or daily activities.