Medulloblastoma
Description
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Medulloblastoma is a primitive neuroectodermal tumour of the cerebellum.
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It is the most common posterior fossa malignant tumour in children, accounting for approximately 20% of all paediatric brain tumours.
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Children suspected of having a brain tumour should be referred promptly to a facility with MRI or CT imaging and neurosurgical services.
Signs and Symptoms
| System / Area | Clinical Features |
|---|---|
| CNS / General | Headache, vomiting, convulsions, ataxia, cranial nerve palsies, coma, unconsciousness |
| Cardiovascular | Changes in BP and pulse due to raised intracranial pressure |
Investigations
Baseline and staging investigations:
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Detailed history and physical examination
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CSF cytology (for metastatic evaluation)
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MRI or CT scan of brain and whole spine
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Full Blood Count (FBC) and Urea/Electrolytes
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Audiometry (baseline before chemotherapy)
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Histological confirmation after craniotomy and maximal tumour resection
Risk Stratification
| Risk Category | Definition |
|---|---|
| Average Risk | Children >3 years, no metastasis, near-total resection, residual disease <1.5 cm² on early postoperative imaging (24–48 hours) |
| High Risk | Children <3 years, overt metastatic disease on imaging or CSF cytology, residual disease >1.5 cm² |
Treatment
Surgery
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Maximal, safe surgical resection is the cornerstone of therapy.
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Postoperative complications can include posterior fossa syndrome (15% incidence) characterized by:
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Difficulty swallowing (dysphagia)
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Truncal ataxia
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Mutism
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Rarely respiratory failure
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Radiation Therapy
| Risk Category | Radiation Protocol |
|---|---|
| Average Risk | Cranial-Spinal Irradiation (CSI) to 23.4 Gy plus platinum-based chemotherapy, OR CSI to 35 Gy without chemotherapy. Posterior fossa boost to total 54 Gy in both scenarios. |
| High Risk | Postoperative irradiation first, followed by chemotherapy (preferred). Some centers may give pre-irradiation chemotherapy, though with risk of disease progression. |
Chemotherapy
Regimen repeated every 4–6 weeks:
| Drug | Dose / Route | Schedule |
|---|---|---|
| Vincristine | 1.5 mg/m² IV | Day 1, weekly for 3 consecutive weeks |
| Lomustine (CCNU) | 75 mg/m² orally | Day 1 |
| Cisplatin | 75 mg/m² IV | Day 1 |
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Chemotherapy complements surgery and radiotherapy and is essential for high-risk and metastatic disease.