Presentation of Medulloblastomas in Children

Symptoms and Signs

Obstructive hydrocephalus

• Elevated ICP: Patients with a medulloblastoma most commonly present with signs and symptoms of elevated ICP from obstructive hydrocephalus, especially headaches and vomiting.
• Nonspecific signs in infants and young children: Younger patients may present with irritability alone, sometimes associated with macrocephaly and/or full fontanelle, or loss of developmental milestones.  Infants may also present with torticollis (15).

Less common signs and symptoms

• Cerebellar signs: Signs of cerebellar dysfunction such as truncal or appendicular ataxia and gait abnormalities may be present.
• Cranial neuropathies: Cranial neuropathies, especially sixth nerve palsy, may also be present.

Time for evolution

• Rapid evolution typical: Symptoms typically evolve rapidly in patients with malignant neoplasms such as medulloblastoma (18).

Evaluation at Presentation

• See EVALUATION

Intervention

Stabilization

• Admission to intensive care unit: If any signs or symptoms of obstructive hydrocephalus or of rapidly worsening condition on neurological examination are present, the patient should be admitted immediately to an ICU.
• Dexamethasone: Dexamethasone should be started on admission (0.5–1 mg/kg IV loading dose, up to 10 mg, then 0.25–0.5 mg/kg/day IV or PO divided every 6 hours).
• Antacid: An antacid should be started for gastrointestinal protection when dexamethasone is started.

Preparation for definitive intervention, nonemergent

• Type and cross-match packed red blood cells in preparation for surgery:  Malignant tumors may be quite vascular, and young children may have extensive venous sinuses in the posterior fossa dura.
• MRI of the brain and total spine: Preoperative MRI with and without gadolinium contrast should be obtained.

Hydrocephalus management

• Dexamethasone Dexamethasone is administered (0.5–1 mg/kg IV loading dose, up to 10 mg, then 0.25–0.5 mg/kg/day IV or PO divided every 6 hours) accompanied by an antacid for gastrointestinal protection, admission to an intensive care unit, and timely tumor resection.
• Ventriculostomy placement: A ventriculostomy may be placed when the patient exhibits lethargy, bradycardia, or neurological deterioration.  Avoid rapid decompression of the ventricles, and set no lower than 15 cm H2O above the external auditory meatus to minimize the risk of upward herniation.
• ETV before tumor resection: This is an area of current controversy.  It may reduce the incidence of postoperative hydrocephalus (22).  However, only a minority of children require CSF diversion after tumor resection (6).
• Shunt placement: Shunt placement is not currently recommended, as only a few patients require permanent CSF diversion, and it exposes patients to a lifetime of shunt dependency and shunt-related complications.

Admission Orders

• HOB, positioning and activity: Bed rest with head of bed at 30 degrees is indicated for patients presenting with symptomatic hydrocephalus.
• VS: Hourly VS with neurological checks are indicated for any patient with mental status changes, vomiting, or signs of elevated ICP.
• BP parameters: BP is monitored hourly, but no specific parameters are typically ordered pre-operatively
• IVF and rate: Isotonic fluid such as normal saline is administered with the rate determined on the basis of the patient’s weight.
• CSF drainage parameters: Most patients do not require ventriculostomy placement pre-operatively. If a ventriculostomy is required, care must be taken to avoid overdrainage. Initially, the drain is placed at a height of 20 cm H2O above the external auditory meatus, a maximum of 10 ml per hour is drained, and ICP is monitored.