Sturge-Weber Syndrome 

Sturge-Weber syndrome belongs to a group of disorders collectively known as the phakomatoses ("mother-spot" diseases). It consists of congenital hamartomatous malformations that may affect the eye, skin, and central nervous system (CNS) at different times. (See Clinical.)

The 3 types of Sturge-Weber syndrome are as follows:

• Complete trisymptomatic Sturge-Weber syndrome - All 3 organ systems are involved
• Incomplete bisymptomatic Sturge-Weber syndrome - The involvement is either oculocutaneous or neurocutaneous
• Incomplete monosymptomatic Sturge-Weber syndrome - Only neural or cutaneous involvement is noted

Patients with no cutaneous involvement appear to be spared from the ocular manifestations of the syndrome. Examples of ocular manifestations are shown in the images below.

Clinically related features include focal or generalized motor seizures in as many as 85% of patients, some degree of mental retardation in approximately 60% of patients, and such neurologic deficits as hemiplegia and homonymous hemianopsia. Focal or generalized motor seizures usually begin in the first year of life, and profound seizure activity sometimes may be observed, with resultant further neurologic and developmental deterioration.^[1] Therefore, diagnosing and treating the disease early, before permanent damage to the brain occurs, is preferable. (See Clinical and Workup.)

Progressive characteristic calcifications in the external layers of the cerebral cortex underlying the angiomatosis associated with ipsilateral cortical atrophy frequently develop and progress with age, occasionally extending anteriorly to the frontal and temporal lobes. (See Etiology.)

The hallmark of Sturge-Weber syndrome is a facial cutaneous venous dilation, also referred to as nevus flammeus or port-wine stain, which is present in as many as 96% of patients and is visible at birth. The facial venous dilation appears as one or several dull red patches of irregular outline, along, but not limited to, the distribution of 1 or more divisions of the trigeminal nerve. (See Etiology and Treatment.)

A leptomeningeal congenital venous angiomatosis, usually ipsilateral to the facial lesion and located most commonly in the meninges overlying the occipital and posterior parietal lobes, results in involvement of the CNS.

Patient education

Counseling may assist with treatment.^[2] Support groups for persons with Sturge-Weber syndrome include The Sturge-Weber Foundation, PO Box 418, Mount Freedom, NJ, 07970-0418.

The clinical manifestations of Sturge-Weber syndrome have a common embryologic basis. The primary defect is a developmental insult affecting precursors of tissues that originate in the promesencephalic and mesencephalic neural crest. These affected precursors then give rise to vascular and other tissue malformations in the meninges, eye, and dermis.^[3]

Although the exact nature of the insult is unknown, a somatic mutation in these precursors may lead to overproduction of an angiogenic factor. Others have suggested that Sturge-Weber syndrome may be due to a lethal gene surviving by mosaicism.

Incomplete Sturge-Weber syndrome results from the same developmental defect, affecting only those cells whose clonal progeny are destined for the affected tissues. In contrast with the other phakomatoses, in which clear-cut hereditary patterns are often evident, the influence of heredity in Sturge-Weber syndrome has not been documented. To date, no gene defect has been associated with the syndrome. Several types of chromosomal abnormalities have been reported, but most patients with Sturge-Weber syndrome have normal karyotypes and most have a sporadic, nonfamilial disease.

Numerous mechanisms have been postulated to explain the pathogenesis of glaucoma in Sturge-Weber syndrome. At present, the most accepted explanation for the elevated intraocular pressure is a combination of developmental angle anomalies, which have a dominant role in infantile onset glaucoma and elevated episcleral venous pressure, which is more important in later onset glaucoma.

Sturge-Weber syndrome is found worldwide. Generally, the condition is easily diagnosed at birth or in early infancy based on the external clinical signs alone. However, the development of morbidity from secondary changes and complications occurs throughout life.

Secondary glaucoma may present at any age, although early onset is the rule, with approximately 60% of glaucomas presenting at birth or early infancy and another 30% presenting during childhood. The median ages reported for onset of visual symptoms related to secondary retinal changes range from age 8-20 years.

The glaucoma associated with Sturge-Weber syndrome is a significant cause of morbidity because of its early onset and resistance to conventional forms of treatment. Glaucoma has been estimated to occur in 30-70% of patients with Sturge-Weber syndrome.

Surgical complications

Surgical management of secondary open-angle glaucoma in patients with Sturge-Weber syndrome, with filtering surgery and Seton procedures, bears an increased risk for a number of surgical complications; the most vision threatening and feared of these are expulsive choroidal hemorrhage and intraoperative massive choroidal effusion.

Sudden change in the intraocular pressure gradient when the eye is opened may result in expulsive choroidal hemorrhage from the choroidal hemangioma. Treatment involves rapid closure of all scleral incisions, with restoration of intraocular pressure. Transscleral drainage of suprachoroidal blood may also be indicated.

The intraoperative formation of a massive choroidal effusion without hemorrhage occurs frequently during filtering surgery in patients with Sturge-Weber syndrome. Increased episcleral venous pressure in these patients is assumed to cause a similar increase in the venous pressure within the ciliary body and choroid.

During surgery, when the eye is opened and the intraocular pressure falls, rapid transudation of fluid from the intravascular to the extravascular space results. The extravasation of fluid can be massive enough to instantly cause choroidal detachment and, later, serous retinal detachment. Although the mechanism is probably similar to that for the more commonly seen benign postoperative choroidal detachment, the degree and the speed of fluid extravasation during surgery make this entity more serious.

This intraoperative event can mimic an expulsive suprachoroidal hemorrhage because of rapid fluid accumulation after the commencement of surgery. It differs, however, because, if the suprachoroidal space is evacuated, clear, copious amounts of yellow fluid are found and the eye can be decompressed transiently.

It seems that once the intraoperative effusion is treated with immediate drainage, the postoperative prognosis becomes excellent despite the persistence of some degree of choroidal and serous retinal detachment. Postoperative smaller serous choroidal detachment is another possible complication in Sturge-Weber syndrome.

Serous retinal detachment often occurs in association with choroidal effusion and hypotony. A choroidal effusion may temporarily interfere with the metabolic transport systems of the retinal pigment epithelium. These serous retinal detachments usually resolve spontaneously as the intraocular pressure normalizes.

Various preoperative and perioperative prophylactic measures to counteract or prevent these complications have been suggested, including use of hyperosmotics; maximum preoperative antiglaucoma therapy; prophylactic posterior sclerotomy; prophylactic radiotherapy or laser photocoagulation of the choroidal hemangioma; and electrocautery of the anterior episcleral vascular anomaly.

Eibschitz-Tsimhoni and colleagues demonstrated minimal risk of subchoroidal hemorrhage or effusion in a large case series of patients with Sturge-Weber syndrome undergoing filtration surgery using modern surgical techniques.^[4] The authors questioned the need for prophylactic posterior sclerotomy in patients with Sturge-Weber syndrome.

Suggested steps to minimize the intraoperative and postoperative hypotony are preplacement of scleral flap sutures, injection of a viscoelastic prior to excision of the trabecular meshwork, and tight suturing of the scleral flap with releasable sutures that can be lysed after surgery with argon laser, removed at the slit lamp or at the time of examination under anesthesia.

Any recent intraocular surgery predisposes the eye to the risk of bacterial endophthalmitis. Patients with filtering blebs, especially the thin, avascular blebs seen with the use of mitomycin-C, are at increased risk for developing bacterial endophthalmitis months, and even years, after surgery. Because this risk is increased further by contact lens wear, the use of any type of contact lens in these patients is discouraged. Other potential sources of infection include normal conjunctival flora, episodes of bacterial conjunctivitis, and contaminated medicine dropper bottle tips.