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 Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, and eye abnormalities such as glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). 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 Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations 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 Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures and hemiparesis.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Overview

Epidemiology

The incidence is 1 in 50,000 live births.

Etiology

  • Congenital but not inherited
  • Sporadic mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations 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 Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the 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 Nevus Nevi (singular nevus), also known as "moles," are benign neoplasms of the skin. Nevus is a non-specific medical term because it encompasses both congenital and acquired lesions, hyper- and hypopigmented lesions, and raised or flat lesions. Nevus/Nevi flammeus 
  • Present from birth
  • Distribution: 
    • Facial: ophthalmic and maxillary branches of the trigeminal nerve
    • Trunk
    • Arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). 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 Cerebral cortex The cerebral cortex is the largest and most developed part of the human brain and CNS. Occupying the upper part of the cranial cavity, the cerebral cortex has 4 lobes and is divided into 2 hemispheres that are joined centrally by the corpus callosum. Cerebral Cortex below the tumor, causing:
    • Seizures:
      • Early onset (by 6 months)
      • Usually the presenting complaint
      • Focal seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures
    • Hemiparesis/hemianopia: 
      • Stroke-like symptoms
      • Transient 
    • Intellectual disability, learning difficulties
    • Mood disorders

Ophthalmological

  • Episcleral angioma → glaucoma Glaucoma Glaucoma is an optic neuropathy characterized by typical visual field defects and optic nerve atrophy seen as optic disc cupping on examination. The acute form of glaucoma is a medical emergency. Glaucoma is often, but not always, caused by increased intraocular pressure (IOP). Glaucoma (early onset)
  • Homonymous hemianopia
  • Strabismus Strabismus Strabismus is the misalignment of the eyes while fixating the gaze on an object. Strabismus can be idiopathic, but it may also be caused by cerebral palsy, uncorrected refractive errors, and extraocular muscle or cranial nerve dysfunction. Strabismus
  • Increased tearing
  • Choroidal hemangioma

Endocrine

  • Reduced growth hormone (GH) → short stature
  • Central hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto's disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. 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 Epilepsy Epilepsy is a chronic brain disorder marked by recurrent and unprovoked seizures. These seizures can be classified as focal or generalized and idiopathic or secondary to another condition. Clinical presentation correlates to the classification of the epileptic disorder. 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 Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures)
    • Regular ophthalmological examination to monitor IOP

Prognosis

  • Determined by extent of lesion and age of onset for seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. 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 Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones 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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