History
The majority of medulloblastoma tumors arise in the 4th ventricle and cause obstructive hydrocephalus. About 70-90% of patients with medulloblastomas present with a history of headaches, emesis, and lethargy; these symptoms are generally intermittent and subtle at first. Duration of symptoms for 3 months or more before diagnosis is common.
Increased intracranial pressure (ICP)
Early symptoms are secondary to increased ICP. The classic triad consists of morning headaches, vomiting, and lethargy. Headache consists of head pain present upon arising that is relieved by vomiting and gradually lessens during the day. Cushing triad (ie, hypertension, bradycardia, and hypoventilation), an uncommon finding in children with increased intracranial pressure, usually indicates impending herniation.
Initial signs of increased ICP are usually subacute, nonspecific, and nonlocalizing.
School-aged children may complain of vague intermittent headaches and fatigue. They may demonstrate declining academic performance and personality changes.
Infants may present with irritability, anorexia, and developmental delay.
Cerebellar dysfunction
With increasing tumor size and invasion into the surrounding brain tissue, more characteristic symptoms appear. One symptom is progressively worsening ataxia involving the lower extremities, often with relative sparing of the trunk and upper extremities.
Brain stem deficits
Tumor infiltration of the brain stem or increased ICP may result in diplopia and multiple other cranial nerve findings, such as facial weakness, tinnitus, hearing loss, head tilt, and stiff neck.
Metastatic disease
Uncommonly, patients may present with back pain or leg weakness secondary to spinal metastasis.
Physical Examination
The earliest signs are nonlocalized and caused by increased ICP. Later signs are generally due to tumor invasion of the surrounding tissue.
Increased ICP
Funduscopic evaluation reveals papilledema or optic pallor in infants.
Palsy of cranial nerve VI resulting in the inability to abduct one or both eyes is common.
Infants may have the "setting sun" sign. This is demonstrated by impaired upgaze and seemingly forced downward deviation of the eyes.
Measurement of head circumference in infants with open cranial sutures also may reveal macrocephaly.
Cerebellar findings
Localized deficits in truncal steadiness, upper extremity coordination, and gait are common.
Brain stem findings
Invasion into the brain stem may cause loss of conjugate gaze (gaze palsy) or the inability to adduct one eye on attempted lateral gaze. This is observed most commonly in combination with deficits of cranial nerves V, VII, and IX.
Invasion into the cerebellopontine angle results in facial weakness and hearing loss, often with associated unilateral cerebellar deficits.
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MRI showing a medulloblastoma of the cerebellum.
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Section displaying Homer-Wright rosettes and pseudorosettes of a medulloblastoma.
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This section displays a typical medulloblastoma, composed of undifferentiated cells with deeply basophilic nuclei of variable size and shape and little discernible cytoplasm.
Tables
Tumor Stage |
|
T1 |
tumor < 3 cm in diameter |
T2 |
tumor ≥3 cm in diameter |
T3a |
tumor >3 cm and with extension into Aqueduct of Sylvius or foramen of Luschka |
T3b |
tumor >3 cm and with unequivocal extension into brainstem |
T4 |
tumor >3 cm with extension past Aqueduct of Sylvius or down past foramen magnum |
Metastases Stage |
|
M0 |
no evidence of gross subarachnoid or hematogenous metastasis |
M1 |
microscopic tumors cells found in CSF |
M2 |
gross nodular seeding intracranially beyond the primary site (in cerebellar/cerebral subarachnoid space or in third or lateral ventricle) |
M3 |
gross nodular seeding in spinal subarachnoid space |
M4 |
metastasis outside cerebrospinal axis |
