Clinical Presentation

At time of presentation, brain tumors in children are often large and, as a consequence, cause significant brain distortion. It appears that two factors account for this feature. First, children often cannot articulate their symptoms, and some are too young to understand the problem that is affecting them. Second, the developing nervous system appears to have a tremendous capacity to compensate for an enlarging mass lesion, and symptoms develop late in the course of the disease.

In general, presenting symptoms fall into 3 categories: raised intracranial pressure, focal neurological deficits, or seizures. As in adults, raised intracranial pressure

Table 2. Distribution of common

brain tumors in

children

Location and

% of All Pediatric

Type of Tumor

Brain Tumors

Infratentorial

PNET (medulloblastoma)

20-25

Low-grade astrocytoma (cerebellar)

12-18

Ependymoma

4-8

Malignant glioma, brainstem

3-9

Low-grade glioma, brainstem

3-6

Other

2-5

Total

45-60

Supratentorial hemispheric

8-20

Low-grade astrocytoma

6-12

Malignant glioma

2-5

Ependymoma

1-5

Ganglioglioma

1-5

Oligodendroglioma

1-2

Choroidplexus tumor

1-2

PNET

1-2

Meningioma

0.5-2

Other

1-3

Total

25-40

Supratentorial midline

Suprasellar

Craniopharyngioma

6-9

Low-grade glioma, chiasmatic, hypothalamic

4-8

Germ cell tumor

1-2

Pituitary adenoma

0.5-2.5

Pineal region

Low-grade glioma

1-2

Germ cell tumor

0.5-2

Pineal parenchymal tumor

0.5-2

Total

15-20

From: Pollack IF. Current Concepts: Brain Tumors in Children. N Engl J Med 331:1500-1507, ©1994 Massachusetts Medical Society, with permission.

will manifest as headaches, vomiting and somnolence. While this may be due to the mass effect of the tumor itself, in children it is usually due to the development of hydrocephalus. The presence ofvomiting alone that persists over weeks is a concerning feature. A focal neurological deficit is due to involvement of eloquent brain tissue or due to a mass adjacent to or within the brainstem. These symptoms are often related to direct brain impression or invasion by the growing tumor. In very young children, focal motor deficits may be missed due to compensation. Finally, some tumors, particularly benign tumors that involve the cortex, will cause seizures that bring the child to medical attention. It should be noted that in infants the only presenting finding may be failure to thrive, irritability, or developmental delay.

The classic triad of headache, vomiting and ataxia is observed in many patients with tumors that are located in the posterior fossa. Headache may occur from direct mass effect and dural stretch in the posterior fossa but also from obstruction of the cerebrospinal fluid (CSF) pathways leading to hydrocephalus. The severity of hydrocephalus will cause either mild headaches or changes in the child's level of consciousness, resulting in drowsiness and confusion. Once this stage is reached, however, rapid deterioration leading to coma and death from brain her-niation can occur. While vomiting and irritability are common problems in young children, the presence of persistant symptoms without obvious gastrointestinal complaints and the persistance of symptoms should alert the clinician to the possibility of an intracranial mass. Additional signs seen with posterior fossa tumors include papilledema, diplopia, dysarthria, head tilt and long-tract signs (hyperre-flexia and sensory changes).

Focal neurological deficits are more commonly seen with hemispheric lesions although, if slow growing, the tumors may reach enormous size before symptoms develop. Younger children will 'mask' a deficit by compensating with another extremity or unconsciously changing their behavior. Lesions in the region of the sella will produce visual disturbances and visual loss. Hypopituitarism is rare as a presenting symptom, but does occur following surgical intervention for sellar lesions.

Finally, seizures occur from lesions that arise in the cerebral hemispheres. These are usually intrinsic tumors such as astrocytomas, gangliogliomas and various hama-rtomas. Some tumors such as gangliogliomas (neoplastic neuronal and glial cells) are usually benign but often cause seizures. Various other pathological entities bridge the gap between benign tumors and developmental anomalies (e.g., dysplastic neuroepithelial tumors) and also frequently present with seizures.

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