Presentation of Cerebellar Astrocytomas in Children

Symptoms

Elevation in ICP due to obstructive hydrocephalus common

• Macrocrania in infants: Infants may present with macrocrania or regression of previously achieved motor milestones (15).
• Headaches and lethargy in children and adolescents: The most common presentation of cerebellar astrocytoma in children is signs and symptoms of elevated ICP from gradual obstruction of the fourth ventricle and resulting hydrocephalus (11).

Less common signs and symptoms

• Cerebellar signs: These can include truncal or appendicular ataxia (2).
• Nystagmus (2)

Patterns of evolution

• Nonspecific signs of elevated ICP: Signs of elevated ICP are the most common presenting signs, as described above. Specific signs of cerebellar dysfunction may be noted less frequently.

Time for evolution

• Subtle development slowly over time: Because these tumors are relatively indolent, symptom progression tends to be gradual (over a period of months to years) until patients develop obstructive hydrocephalus, at which point symptoms of elevated ICP may develop acutely (2, 6).

Evaluation at Presentation

• See EVALUATION

Intervention

Stabilization

• ICU admission: The child should be admitted to an intensive care unit if any signs or symptoms of obstructive hydrocephalus are present or there is rapid worsening on neurological examination.
• Dexamethasone: Steroids 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:  In general, an antacid should be started for gastrointestinal protection when dexamethasone is started.
• Preparation for surgery: A type and crossmatch for blood should be done in preparation for surgery.  Cerebellar astrocytomas are typically not very vascular, but young children may have extensive venous sinuses in the posterior fossa dura.

Preparation for definitive intervention, nonemergent

• Hydrocephalus: In general, hydrocephalus is managed with steroids when the patient is stable. An ETV can be considered, but this is an area of current controversy.  While there is some indication that ETVs may reduce the incidence of postoperative hydrocephalus (22), only a small proportion of children require CSF diversion after tumor resection (6). A pretumor resection ventricular shunt is not currently recommended, as only a minority of patients require permanent CSF diversion, and it exposes patients to a lifetime of shunt dependency and shunt-related complications.
• Imaging: MRI of the brain with and without gadolinium contrast should be obtained preoperatively.  MRI of the spine is considered.

Preparation for definitive intervention, emergent

• Hydrocephalus: Ventriculostomy placement is indicated when a patient is lethargic, bradycardic, or has experienced neurological deterioration and the ventricles are enlarged. Rapid decompression of the ventricles must be avoided and the drain level set no lower than 15 cm H2O above the external auditory meatus to minimize the risk of upward herniation.
• Imaging: If a patient’s neurological condition is deteriorating, a CT scan without contrast should be performed emergently after stabilization. Hydrocephalus may potentially be treated with ventriculostomy as described above. In the nonemergent setting, MRI scan is the imaging study of choice.

Admission Orders

• Admission to ICU: Generally a child is kept in an ICU environment with close monitoring for neurological changes until surgery is performed, particularly when hydrocephalus is present.
• Standard preoperative laboratory tests
• Packed red blood cells: A type and crossmatch of packed red blood cells is done in preparation for possible bleeding at surgery.
• Steroids: Dexamethasone or a similar steroid is started on admission after imaging demonstrates a tumor, is continued until surgery, and is tapered slowly after surgery.
• MRI of brain: MRI is the preoperative imaging study of choice.  For a tumor with imaging findings consistent with a pilocytic astrocytoma, MRI of the total spine preoperatively may be considered.