✅ Model Answer:
• Tram-track (gyriform) calcifications – parallel curvilinear densities following the gyral pattern of the brain.
• Unilateral predominance – typically ipsilateral to facial port-wine stain.
• Thickened skull – may be seen overlying the affected hemisphere.
• Choroid plexus enlargement – may be visible.
• Diagnosis: Sturge-Weber syndrome.

✅ Model Answer:
• Tram-track sign: Parallel curvilinear densities seen on skull X-ray or CT in Sturge-Weber syndrome.
• They represent cortical calcifications in the brain parenchyma, underlying a leptomeningeal angioma.
• Mechanism: The leptomeningeal angioma causes chronic venous stasis and hypoxia → local tissue damage → calcium deposition in the cortical and subcortical layers.
• The calcifications follow the gyral pattern of the brain, creating a "tram-track" or "railroad track" appearance.
• Location: Usually occipital or parietal lobes; may be unilateral or bilateral.

✅ Model Answer:
• The classic clinical triad of Sturge-Weber syndrome includes:
1. Facial port-wine stain (nevus flammeus) – involving the ophthalmic (V1) dermatome of the trigeminal nerve. Usually unilateral, may extend to V2/V3.
2. Leptomeningeal angioma – ipsilateral to the facial stain. Most commonly affects the occipital and parietal lobes.
3. Glaucoma – ipsilateral to the facial stain. Due to increased episcleral venous pressure (affects the eye on the same side as the stain).
• Not all patients have all three features; the full triad is present in ~30-50% of cases.

✅ Model Answer:
• Sturge-Weber syndrome is caused by a somatic mosaic mutation in the GNAQ gene (Guanine nucleotide-binding protein G(q) subunit alpha).
• The most common mutation is GNAQ p.R183Q.
• Mechanism: The mutation leads to constitutive activation of the GNAQ protein, activating the MAPK and PI3K pathways → abnormal vascular development → leptomeningeal angioma and facial port-wine stain.
• Inheritance: Not inherited (somatic mosaic) – occurs sporadically. There is no risk of transmission to offspring.
• The mutation occurs post-zygotically, affecting cells in the ectoderm (skin, brain, eye).

✅ Model Answer:
• Cutaneous: Facial port-wine stain (V1 dermatome), often present at birth.
• Neurological:
- Seizures – focal or generalized, often starting in the first year of life (most common presentation).
- Contralateral hemiparesis (stroke-like episodes).
- Developmental delay / intellectual disability (variable severity).
- Headaches – migrainous, often with visual aura.
- Behavioral problems, attention deficit.
• Ocular:
- Glaucoma (ipsilateral) – due to increased episcleral venous pressure.
- Choroidal hemangioma.
- Buphthalmos (enlarged eye) if glaucoma is severe.
• Other: Hyperkeratosis, soft tissue hypertrophy, vascular malformations in other organs (rare).

✅ Model Answer:
• Seizure management:
- Antiepileptic drugs (AEDs) – first-line: levetiracetam, oxcarbazepine, valproate.
- If refractory, consider hemispherectomy or focal resection (if the seizure focus is localized).
• Glaucoma management:
- Intraocular pressure monitoring (ophthalmology).
- Topical beta-blockers (timolol), carbonic anhydrase inhibitors (dorzolamide).
- Surgical options: Trabeculotomy, goniotomy, or tube shunt surgery.
• Port-wine stain: Pulsed dye laser therapy (for cosmetic purposes).
• Stroke-like episodes: Low-dose aspirin (2-5 mg/kg/day) may be used to reduce thromboembolic events.
• Multidisciplinary team: Neurology, ophthalmology, dermatology, neurosurgery.
• Monitor: Developmental progress, seizure frequency, visual acuity.

✅ Model Answer:
• This is refractory epilepsy – consider surgical intervention.
• Next steps:
1. MRI brain with contrast – to assess the extent of leptomeningeal angioma and cortical involvement.
2. EEG/video EEG – to localize the seizure focus.
3. PET scan – to assess metabolic activity (hypometabolism in affected areas).
4. Surgical options:
- Hemispherectomy – if the seizures are unilateral and refractory.
- Focal resection – if the seizure focus is localized.
- VNS (vagus nerve stimulator) – if surgery is not feasible.
5. Continue AEDs post-surgery.
6. Rehabilitation: Physical, occupational, and speech therapy.

✅ Model Answer:
• Role of skull X-ray: Detects tram-track (gyriform) calcifications, which are characteristic of Sturge-Weber syndrome.
• Historical role: It was a key diagnostic tool before CT and MRI were widely available.
• Current role: Now largely replaced by CT and MRI, which provide better resolution and more detailed assessment.
- CT: Better for detecting calcifications (higher sensitivity than X-ray).
- MRI: Shows leptomeningeal angioma (pial enhancement), cerebral atrophy, and associated brain abnormalities.
- CT/MRI: Also assess the extent of the angioma and plan surgical interventions.
• However, skull X-ray may still be used in resource-limited settings or as an initial screening tool.

✅ Model Answer:
• This is a stroke-like episode – a common complication of Sturge-Weber syndrome.
• Mechanism: Venous stasis due to the leptomeningeal angioma → impaired venous drainage → cerebral ischemia or infarction.
• Management:
1. MRI brain with diffusion-weighted imaging (DWI) – to confirm ischemia and assess for infarction.
2. Low-dose aspirin: To prevent thromboembolism (2-5 mg/kg/day).
3. Seizure control: AEDs to prevent seizure-related worsening of ischemia.
4. Rehabilitation: Physical, occupational, and speech therapy.
5. Monitor: For recurrent episodes and long-term neurological deficits.

✅ Model Answer:
• A newborn with a facial port-wine stain in the V1 (ophthalmic) dermatome should be evaluated for Sturge-Weber syndrome.
• Evaluation:
1. Neurological: MRI brain (with contrast) to assess for leptomeningeal angioma.
2. Ophthalmological: Ophthalmology exam to rule out glaucoma and choroidal hemangioma.
3. Neurological monitoring: Baseline and follow-up neurologic exams, developmental surveillance.
4. EEG: Baseline EEG to detect subclinical seizures.
5. Management: If Sturge-Weber is confirmed, start low-dose aspirin (in some cases) and monitor for seizures.
• Note: Not all children with V1 port-wine stains develop Sturge-Weber syndrome (only ~10-15%).

✅ Model Answer:

Feature	Sturge-Weber	NF1	Tuberous Sclerosis
Skin	Port-wine stain	Café-au-lait, neurofibromas	Ash-leaf spots, adenoma sebaceum
Brain	Leptomeningeal angioma	Gliomas, optic pathway tumors	Cortical tubers, subependymal nodules
Calcifications	Tram-track (gyriform)	None	Subependymal calcifications
Eye	Glaucoma, choroidal hemangioma	Lisch nodules	Retinal hamartomas
Genetics	GNAQ (somatic)	NF1 (AD)	TSC1/TSC2 (AD)