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Astrocytoma is a primary malignant tumour of the brain that arises from the glial tissue (the supportive tissue) of the brain.
Astrocytomas are classified into non-infiltrating, mildly anaplastic,
moderately anaplastic and anaplastic types depending on the grade of
malignancy. The non-infiltrating astrocytoma is a slow-growing tumour that does
not invade the surrounding tissues. The mildly anaplastic astrocytoma and the
moderately anaplastic astrocytoma grow at a comparatively faster rate and
invade the adjoining tissues. The anaplastic astrocytoma grows at a very fast
rate and usually presents with non-specific complaints along with symptoms of
raised intracranial pressure such as dizziness, nystagmus, headache, vomiting,
truncal ataxia and focal neurological signs.
Cerebellar haemangioblastoma is a slow-growing
primary tumour of the brain. It accounts for about 2 per cent of the primary
brain tumours. Cerebellar haemangioblastoma has a familial tendency and appears
to be associated with retinal vascular lesions, polycythaemia and
hypernephroma. Cerebellar haemangioblastoma usually leads to ataxia of the
trunk and the limbs. There may be signs and symptoms due to increased
intracranial pressure, which include dizziness, nystagmus, headache, vomiting,
truncal ataxia and focal neurological signs.
Ependymoma arises from the ependyma (the membrane
lining ventricles of the brain) usually in the fourth ventricle. It is a slow-growing tumour that affects young adults. Ependymoma usually leads to
raised intracranial pressure causing dizziness, nystagmus, headache, vomiting,
truncal ataxia and focal neurological signs. Ependymoma may arise from the central
canal of the spinal cord. Ependymoma of the spinal cord accounts for about 60
per cent of the primary tumours of the spinal cord.
Glioblastoma multiforme is also known as grade IV
astrocytoma. It comprises about 15 per cent of the primary malignant tumours of
the brain. Glioblastoma multiforme is the most malignant and the fastest
growing tumour of the brain. It usually presents with non-specific complaints
and signs of electrical disturbances in the brain. There may be symptoms of
raised intracranial pressure such as dizziness, nystagmus, headache, vomiting,
truncal ataxia and focal neurological signs. As the tumour grows in size, there
may be a focal deficit. The total surgical removal of the tumour is usually not
possible.
Medulloblastoma comprises about 25 per cent of the
intracranial tumours in children. It usually arises from the roof of the fourth
ventricle. Medulloblastoma often leads to increased intracranial pressure that
causes dizziness, nystagmus, headache, vomiting, truncal ataxia and focal
neurological signs.
Meningioma is a slow-growing tumour of the meninges
(the fibrous tissue that covers the brain and the spinal cord). It usually
arises from the duramater and arachnoid membrane. Meningioma comprises about 20
per cent of the primary intracranial tumours. Meningioma is more common in
women as compared to men. The tumour is usually encapsulated and benign in
character. The incidence of meningioma increases with age. Symptoms of
meningioma vary depending on the size and site of the tumour, for example, the
tumour located in the sphenoidal ridge may lead to unilateral exophthalmos and
that located in the olfactory groove may lead to anosmia. Meningioma usually
presents with seizures, headache and focal neurological signs.
Oligodendroglioma is a slow-growing tumour that
mostly occurs in adults. It arises from oligodendrocytes in the cerebral
hemispheres. Oligodendroglioma usually remains confined to a supratentorial
region of the brain and may remain undetected for many years. Oligodendroglioma
usually presents with seizures along with signs and symptoms of raised
intracranial pressure such as dizziness, nystagmus, headache, vomiting, truncal
ataxia and focal neurological signs. Calcification may be seen in about 40 per
cent lesions of the oligodendroglioma.
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Primary Tumours of the Brain