Brain tumor, clinical presentation

a. Supratentorial cerebral tumors

In the clinical symptoms of patients with supratentorial space-occupying lesions three main syndromes can be distinguished: epilepsy, focal deficits and increased intracranial pressure. These syndromes are not specific for the tumor type, but depend more on the region in which the tumor develops and on the rate of growth.

Seizures associated with brain tumors can be focal (e.g. Jacksonian type of unilateral clonic movements of the limbs seen with tumors in the region of the prerolandic motor area, uncinate seizures seen with temporal lobe tumors) or generalized (e.g. Grand Mal seizures). Epileptic activity is frequently associated with both extra-axial tumor types (meningioma) and with intra-axial tumors (gliomas and metastases). In gliomas, epilepsy is more often found in benign types (astrocytoma, oligodendroglioma) than in malignant tumors (glioblastoma).

The occurrence of focal deficits due to compression, peritumoral edema and ischemia depends primarily on the rate of tumor growth and the location. Hemiparesis, aphasia, hemisensory disturbances and hemianopsia occur when the tumor is situated in the respective eloquent cortical areas. The deficits are contralateral to the tumor. Slowly growing tumors can become very large before neurological deficits develop.

The syndrome of increased intracranial pressure is characterized by headaches (esp. lying down), vomiting, papilledema and associated visual problems, and alteration of the level of consciousness. It usually develops insidiously, esp. in tumors of non-eloquent brain regions, but sudden decompensation can lead to the dramatic syndrome of "brain herniation", with coma, decerebrate rigidity and pupillary abnormalities.

b. Tumors of the region of the sella turcica and the optic chiasm

Tumors found in this region are pituitary adenoma, craniopharyngioma, glioma of the optic nerve and chiasm, meningioma, metastasis, and some rare cases of dermoid cyst, hamartoma, hypothalamic glioma, etc.

Approximately half of the pituitary adenomas are diagnosed because of endocrine disturbances: Cushing disease, acromegaly, hyperprolactinemia, etc. These tumors are often small at diagnosis. Other tumors are only found when the optic nerves or the chiasm is compressed, leading to unilateral or bitemporal visual loss.

c. Tumors of the cerebellopontine angle

The most typical tumor in this region is the vestibular schwannoma, originating in the eighth cranial nerve. Other tumor types are meningioma, dermoid cyst and metastasis. Early symptoms are usually due to compression of the eighth cranial nerve, resulting in hearing loss, tinnitus and vertigo. Later hemifacial spasm and brainstem signs may occur.

d. Infratentorial and cerebellar tumors

Tumors originating in the posterior fossa outside the brainstem and the cerebellopontine angle usually develop insidiously until increased intracranial pressure (intracranial hypertension) occurs as the tumor obstructs the CSF outflow tract (Sylvian aqueduct, fourth ventricle, fourth ventricle outlets). This leads to supratentorial hydrocephalus, and the symptoms already described. Patients with tumors in the median part of the posterior fossa (vermis) often complain of dysequilibrium (ataxia), while lateral tumors (cerebellar hemisphere) are associated with dysmetria and coordination difficulties in the ipsilateral limbs.

The tumor types most often found are glioma (astrocytoma, pilocytic astrocytoma, ependymoma, malignant glioma), medulloblastoma (or Primitive Neuro-Ectodermal Tumor), hemangioblastoma and metastasis.

e. Brainstem tumors

Tumors developing in the brainstem (gliomas; metastases) are usually situated in the pons. The symptoms are a combination of intrinsic brainstem signs (diplopia, facial palsy, swallowing dysfunction) and symptoms due to compression of the ascending and descending tracts (uni- or bilateral paresis, hypoesthesia, etc.).

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