Sturge-Weber Syndrome

Synonyms: Fourth phacomatosis ("mother-spot") or encephalotrigeminal angiomatosis

This is a neurocutaneous disorder with angiomas involving the leptomeninges and skin of the face.

The cutaneous angioma is called a port-wine stain (PWS). These are usually seen in the ophthalmic and maxillary distributions of the trigeminal nerve.

Sturge-Weber syndrome (SWS) is referred to as complete when both central nervous system and facial angiomas are present and incomplete when only one area is affected.
The Roach Scale is used for classification:¹

• Type I:
  • Both facial and leptomeningeal angiomas (LA)
  • May have glaucoma
• Type II:
  • Facial angioma alone
  • May have glaucoma
• Type III:
  • Isolated LA
  • Usually no glaucoma

• Incidence is 1/50,000 live births¹
• Males and females equally affected
• No racial predilection

SWS is a phacomatosis i.e. one of a group of congenital and hereditary diseases characterised by the development of hamartomas in various tissues e.g. tuberous sclerosis and neurofibromatosis. SWS cases appear randomly without clear evidence of familial inheritance.²

• Normally a vascular plexus develops around the cephalic portion of the neural tube.
  • This is under ectoderm destined to become facial skin.
  • It develops in the sixth week and regresses around the ninth week of gestation.
  • The residual vascular tissue forms the angiomata of the leptomeninges, face, and ipsilateral eye.
  • Persistence of these embryonic blood vessels also has secondary effects on surrounding brain tissue.
• The secondary effects include:
  • Hypoxia
  • Ischaemia (caused by "vascular steal phenomenon")
  • Venous occlusion, thrombosis and infarction
• Recurrent seizures, status epilepticus, intractable seizures, and recurrent vascular events may aggravate cortical ischaemia.
• This leads to more calcification, gliosis, and atrophy, which in turn increase the chance of seizures and neurological deterioration.

It is important to understand that not all infants with facial nevi have Sturge-Weber disease. Incidence of SWS has been reported to be 8-33% in those with a PWS.³

• Facial naevus is present at birth:⁴
  • It always involves upper face and eyelid and tends to be unilateral.
  • It may also appear on lower face, trunk and oropharyngeal mucosa.
• Macular lesions can be progressive:
  • They may be a light pink color initially and then progress to a dark red or purple nodular lesion.
• Ipsilateral eye commonly shows buphthalamos and glaucoma.
• There may be macrocephaly and choroidal haemangiomata.
• Focal tonic-clonic seizures typically appear in first year on the opposite side to the naevus.
  • The incidence of epilepsy in patients with SWS is 75-90%.⁵
  • The seizures may become generalised and evolve into other types such as drop attacks, myoclonic or infantile spasms.
  • The seizures are often very frequent and prolonged seizures may occur.
  • In many cases seizures are associated with slowly progressive hemiparesis.
  • The incidence is approximately 33%.
  • The severity of weakness is closely related to the severity of the seizures.
  • As the child grows the weakness may become more severe and permanent.
  • The seizures may be resistant to drug treatment.
• Developmental delay and mental retardation are related to the degree of neurological involvement. They occur in 50-60% of patients and are more likely in patients with bilateral involvement.⁵
• Headaches occur secondary to vascular disease.
  • The symptoms are similar to a migraine headache.

The maximum extent of disease may require a combination of structural and functional imaging, as each investigation may demonstrate abnormalities not detected by the other.⁶

• EEG:
  • This is used for evaluation of seizures and for localisation of seizure activity in refractory seizures when epilepsy surgery is considered.
  • Typical findings include reduced background activity, polymorphic delta activity and epileptiform features.
• Skull X-ray:
  • This shows intracranial calcification in the occipito-parietal region.
  • Typically it has a serpentine appearance.
  • This is often a late finding and may not be present initially.
• CT scan:
  • This may show calcifications in infants and even neonates.
  • Other findings include brain atrophy, ipsilateral choroid plexus enlargement, abnormal draining veins, and a breakdown of the blood-brain barrier with seizures.
• Doppler ultrasound:
  • High resistance patterns that are typical of venous stasis and may contribute to chronic hypoperfusion of brain tissue have been picked up by this method.⁷

Cosmetic camouflage creams can be used to the PWS. It is more effective than OTC foundation/make-up because it is both lightweight and available in a wide range of colours.⁸

Pharmacological treatments

Carbamazepine is an anticonvulsant effective for treatment of complex partial seizures:

• Major mechanism of action is reduction of sustained high-frequency repetitive neural firing.
• The chance of achieving seizure control with medical therapy in SWS varies. There is a wide range of reported seizure control in studies, with no overall consensus.
• The age of seizure onset may be a prognostic sign for ultimate seizure control. Early onset is associated with refractory seizures and developmental delay.

Surgical treatments

• Pulsed dye laser treatment is used for port wine stain:⁹
  • They are particularly effective in improving facial PWS in infants ≤ 6 months of age.¹⁰
  • This is often recommended for lesions near the eyes or orifices, or if the lesions bleed, ulcerate or become infected.
  • They have low complication rates.¹¹
  • Significant redarkening of port-wine stains has been noted at 10 year follow-up.¹²
  • External laser treatment of vascular abnormalities may not be effective if they are deep, because the laser beam does not penetrate far beneath the skin.¹³
  • Intralesional photocoagulation is a laser treatment that involves inserting a laser fibre into the lesion to deliver the light deep within it.
  • Topical local anaesthetics are effective in post-op pain control.¹⁴
• Surgical options are available for focal seizures refractory to medical treatment:¹⁵
  • Surgical procedures include focal cortical resection, hemispherectomy, corpus callosotomy and recently, vagal nerve stimulation (VNS).
  • Criteria for medical intractability should be fulfilled before considering surgery.

Although, apparently neurologically normal in first year of life, over half of cases are found to have severe learning disability in later childhood. This is probably due to prolonged generalised seizures and use of anticonvulsants.