Description
Sturge-Weber Syndrome (SWS), also known as encephalotrigeminal angiomatosis, is a neurocutaneous disorder with vascular skin lesions (port-wine stains), leptomeningeal angiomatosis, and ocular abnormalities, typically in the form of glaucoma.
Pathogenesis
The pathogenesis of SWS is believed to stem from a somatic mutation in the GNAQ gene that occurs during early embryonic development. The mutation affects the development of blood vessels leading to vascular malformations in the skin, eye, and leptomeninges.
Subtype
There are three types of SWS:
- Type 1 (most common, 85-90%): Facial and leptomeningeal angiomas with glaucoma.
- Type 2: Facial angiomas with glaucoma but without leptomeningeal involvement
- Type 3: Isolated leptomeningeal angioma without facial involvement or glaucoma
Epidemiology, Risk Factors & Associations
- Occurs sporadically, with an estimated prevalence of 1 in 20,000-50,000.
- No known familial or hereditary associations.
- No known risk factors due to the sporadic nature of the condition.
Clinical Features
- Facial port-wine stain (PWS), typically unilateral and along the distribution of the trigeminal nerve (98%)
- Neurological symptoms secondary to leptomeningeal angioma, including seizures, spastic hemiparesis contralateral to the side of the angioma, visual field deficits (homonymous hemianopsia) and mental retardation.
- Characteristic macular haemangiomas, especially of the face
- Glaucoma, which can lead to buphthalmos (enlargement of the eyeball).
Complications
- Neurological complications such as developmental delay, intellectual disability, and epilepsy
- Vision loss due to glaucoma or choroidal angioma
- Hormonal abnormalities
Pathological Features
Histopathology
- Macroscopic: The involved leptomeninges may appear thickened and hyperpigmented.
- Microscopic: Leptomeningeal angiomatosis characterised by blood vessels with thickened walls and a reduced number of neurons in the underlying cortex.
Serology
- No specific serological markers for SWS.
Biochemistry
- No specific biochemical markers for SWS.
Immunohistochemistry
- Positive staining for vascular endothelial markers such as CD31 and CD34 in the leptomeningeal angiomas.
Molecular
- Mutation in the GNAQ gene.
Genetics
- Somatic mosaic mutation in GNAQ, typically not inherited.
Radiological Features
General Features
- Imaging features result from progressive venous occlusion, recruitment of alternate drainage pathways and chronic venous ischaemia
- Leptomeningeal angiomatosis is typically unilateral (80-90%) but can be bilateral (10-20%) and typically affects the occipital and parietal lobes
- Characteristically demonstrates gyriform tram-track calcifications of the cerebral cortex and cerebral lobar atrophy on the same side as the facial PWS.
- Gyral calcifications are progressive, may not be present early
- There may be compensatory ipsilateral ventricular dilatation, calvarial hyperostosis and hyperneumatisation of sinuses
- Enlarged and hypervascular ipsilateral choroid plexus
CT
- Non-contrast: Tram-track calcifications along the cortex, typically in the parieto-occipital region. Ipsilateral choroid plexus enlargement.
- Contrast-enhanced: Leptomeningeal enhancement may be seen.
MRI
- T1WI: Isointense or hypointense signal in the affected cortex
- T2WI: Hyperintense signal in the affected cortex due to gliosis. Hypointense cortical calcification calcifications
- FLAIR: Gliosis. Bright sulcal signal of leptomeningeal angiomatosis
- MRV: Absent cortical veins in affected region. Deep draining and medullary veins may be enlarged.
- T1 C+: Leptomeningeal enhancement
PET FDG
- May show decreased uptake in affected areas.
Grading and Staging
- No specific grading or staging system is currently available for SWS.
Diagnosis
- The diagnosis of SWS is typically made based on clinical features of facial PWS, neurological symptoms, and ocular abnormalities, confirmed by imaging findings.
Differential Diagnosis
- Klippel-Trenaunay syndrome: also presents with port-wine stain but involves a different cutaneous distribution and lacks neurological involvement.
- Neurocutaneous melanosis: can have leptomeningeal enhancement and increased skin pigmentation but lacks the port-wine stain and glaucoma of SWS.
Management
- The management of SWS typically involves a multidisciplinary approach with dermatologists for the management of the PWS, ophthalmologists for glaucoma management, and neurologists/neurosurgeons for seizure control. The use of anti-epileptic drugs is common, and in severe cases, surgical intervention such as hemispherectomy may be required.