Sturge-Weber Syndrome (SWS)

Sturge-Weber syndrome (SWS) is a congenital neurocutaneous disorder presenting with a facial birthmark called a port-wine stain (PWS), neurological abnormalities such as seizures, and eye abnormalities such as glaucoma. Not all of these symptoms have to be present in an affected individual, and some may develop later in life. While the condition is congenital, it is not inherited, as the causative mutation in the gene GNAQ is somatic and sporadic. Diagnosis is suspected based on symptoms and neuroimaging and confirmed with genetic testing. Management is targeted at symptom management and prevention of seizures and hemiparesis.

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Overview

Epidemiology

The incidence is 1 in 50,000 live births.

Etiology

  • Congenital but not inherited
  • Sporadic mutation with no known cause
  • Somatic mosaicism of the GNAQ gene → not passed onto offspring

Pathophysiology

  • GNAQ gene: encodes G-alpha-q, a guanine nucleotide-binding protein → regulates intracellular signaling pathways
  • Mutation results in irregular growth of the endothelial cells.
  • Presents as capillary-venous malformation, especially in the dermal and leptomeningeal regions

Clinical Presentation

Symptoms are usually due to the effect of capillary-venous malformation within the brain, skin, and eye. Not all symptoms have to be present in an individual for them to be diagnosed with SWS, and some symptoms may develop later in life.

Dermatological

Port-wine stain (PWS):

  • A nevus flammeus 
  • Present from birth
  • Distribution: 
    • Facial: ophthalmic and maxillary branches of the trigeminal nerve
    • Trunk
    • Arm
  • Light pink to deep red

Neurological

  • Leptomeningeal vascular malformation, also called leptomeningeal angioma
  • Benign tumor of the arachnoid and pia mater
  • Ipsilateral to PWS
  • Mainly in parietal and occipital lobes
  • Leads to atrophy and calcifications in the cerebral cortex below the tumor, causing:
    • Seizures:
      • Early onset (by 6 months)
      • Usually the presenting complaint
      • Focal seizures
    • Hemiparesis/hemianopia: 
      • Stroke-like symptoms
      • Transient 
    • Intellectual disability, learning difficulties
    • Mood disorders

Ophthalmological

  • Episcleral angioma → glaucoma (early onset)
  • Homonymous hemianopia
  • Strabismus
  • Increased tearing
  • Choroidal hemangioma

Endocrine

  • Reduced growth hormone (GH) → short stature
  • Central hypothyroidism

Mnemonic

An easy way to remember is by using the mnemonic STURGE:

  • Seizures
  • Tram-track-like calcification
  • Unilateral PWS
  • Retardation
  • Glaucoma
  • Epilepsy

Diagnosis and Management

Diagnosis

  • Neuroimaging:
    • MRI with contrast: enhances leptomeningeal angiomas
    • CT: tram-track-like calcification
    • Done immediately if patient presents with neurological symptoms
    • Done after 1 year of age in patients with PWS
  • Eye exam, measurement of intraocular pressure (IOP)
  • EEG → to assess seizure activity
  • Confirmation: genetic testing for mutations in GNAQ
Epilepsy associated with SWS

Epilepsy associated with Sturge-Weber syndrome (SWS): Sturge-Weber syndrome in a 14-year-old boy with multiple epileptic foci in the right cerebral hemisphere and chronic partial epilepsy
A: axial T2-weighted image showing right cerebral hemiatrophy (white arrows)
B: axial T1-weighted sequence after gadolinium injection, demonstrating leptomeningeal enhancement of the frontoparietal region (white arrows)
C: White arrows point to cortical calcification in the frontal lobe, appearing as signal voids from subjected weighted images.

Image: “Sturge-Weber syndrome in a 14-year-old boy with multiple epileptic foci in the right cerebral hemisphere” by Abud LG, Thivard L, Abud TG, Nakiri GS, Dos Santos AC, Dormont D. License: CC BY 4.0

Management

  • Symptom treatment:
    • PWS: pulsed dye laser therapy
    • Seizures: 
      • Anticonvulsants (carbamazepine)
      • Hemispherectomy in refractory cases
    • Glaucoma: topical or surgical management 
  • Prevention:
    • Low-dose aspirin (likely reduces the risk of cerebral ischemic events and seizures)
    • Regular ophthalmological examination to monitor IOP

Prognosis

  • Determined by extent of lesion and age of onset for seizures
  • Neurological function likely deteriorates with age, impairing daily function.

Differential Diagnosis

Klippel-Trenaunay syndrome (KTS): a rare congenital and sporadic disease that results in vascular malformation similar to SWS. In contrast to SWS, neurological and ophthalmological symptoms are rare and PWSs are more commonly noted on the limbs. Bone and muscle involvement results in hypertrophy of limbs. Treatment consists of surgical debulking or sclerotherapy of the malformed vessels.

References

  1. NORD (National Organization for Rare Disorders). (2017). Sturge Weber syndrome. Retrieved August 17, 2021, from https://rarediseases.org/rare-diseases/sturge-weber-syndrome/ 
  2. Shirley, MD, Tang, H, Gallione, CJ, et al. (2013). Sturge-Weber syndrome and port-wine stains caused by somatic mutation in GNAQ. N Engl J Med. 368(21), 1971–9. https://doi.org/10.1056/NEJMoa1213507
  3. Comi, AM. (2011). Presentation, diagnosis, pathophysiology, and treatment of the neurological features of Sturge-Weber syndrome. Neurologist. 17(4), 179–184. https://doi.org/10.1097/NRL.0b013e318220c5b6
  4. Sujansky, E, & Conradi, S. (1995). Sturge-Weber syndrome: Age of onset of seizures and glaucoma and the prognosis for affected children. J Child Neurol. 10(1), 49–58. https://doi.org/10.1177/088307389501000113
  5. Patterson, MC. (2021). Sturge-Weber syndrome. UpToDate. Retrieved August 18, 2021, from https://www.uptodate.com/contents/sturge-weber-syndrome

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