Neurological Disorders: Brain Tumors

Introduction

Brain Tumors result from an abnormal & excessive proliferation of the brain cells. A host of tumor conditions are associated with the brain and the prognosis depends generally on whether tumor is cancerous or not, and also on its size and the location inside the skull.

They are relatively common Neurological disorders, and a Neurologist and tumor-specialist are frequently involved in the care of these patients.

What are the types tumors in the brain?

Brain tumors are generally classified as;

• Primary or
• Secondary

Primary tumor in this context means the tumor originates from the brain tissue itself, or from the coverings of the brain and an example for this type of tumor is - meningioma. Secondary means the tumor originates somewhere else in the body and then reaches brain by a process called as metastasis e.g. breast cancer spreading to the brain.

The primary brain tumors can be further classified as;

• Benign tumors (non cancerous)
• Malignant tumors (cancers)
• Tumor with either benign or malignant potential

Lipoma and vestibular schwannoma (acoustic neuroma) are some examples for a benign tumors; by and large they remain to be benign always.

Common malignant brain tumors (cancers) are;

• GBM (Glioblastoma multiforme) - grade 4 astrocytoma
• Anaplastic astrocytoma (grade 3 astrocytoma)
• Primary CNS Lymphoma
• Medulloblastoma (mostly in children) etc.

However many tumors of the brain can have both benign & malignant potentials and few examples include;

• Meingioma
• Astrocytoma (early stages)
• Ependymoma
• Oligodendroglioma
• Chordoma
• Choroid plexus papilloma etc.

At an early stage some of these tumors may be found as benign but at a later stage as malignant e.g. astrocytoma. Some of them may not be cancers from a strict definition however they are locally destructive and causing lot of damage and even death e.g. chordoma.

Another way of classifying brain tumors is as below;

• Intra-axial tumors or
• Extra-axial tumors

Intra-axial tumor indicates it originated within the brain tissue e.g. oligodendroglioma, while extra-axial tumor implies it originated out side the brain but in the contiguous areas to the brain tissue like meninges, skull bone, sinus etc and may spread in to the brain tissue, or lie near to the brain e.g. meningioma.

Unlike tumors in organs like lung the brain tumors can occur anytime in life and children are not spared either. Certain tumors like medulloblastoma typically occur in children. Astrocytomas also can occur at any age, but when they occur in kids the favored location is brain stem, and in adults, cerebral hemispheres. Pilocytic astrocytoma is more common in children. Certain tumors like meningimoas and pituitary tumors are extremely rare in children.

Some Common types of Brain Tumors

Examples include;

• Meningioma
• Glioblastoma multiforme (GBM)
• Malignant astrocytoma grade 3
• Malignant lymphoma
• Carcinomatous meningitis
• Medulloblastoma (children)

Meningioma: These are usually benign tumors and arise from the brain coverings (meninges). They grow slowly and eventually compress the neighbor brain tissue. GBM & malignant astrocytoma grade 3 are very malignant tumors. GBM is the commonest brain cancer in the adults & medulloblastoma is the commonest brain cancer in children. Malignant lymphoma is another aggressive tumor in adults and arises generally in the setting of immuno suppression like AIDS. Carcinomatous meningitis occurs when tumors like breast or lung cancer spread to the meninges instead of to the brain tissue.

What stimulates a tumor growth?

Tumors are the result of abnormally excessive proliferation of cells in a tissue. Normally there are inhibitory factors to keep a curb on any such abnormal proliferation however due to some reason, when those checking factors get dysfunctional, unrestrained cell growth takes place and results in a tumor.

How does patient manifests?

The clinical presentations depend upon the location of tumor and they can be;

• Local symptoms and/or
• Symptoms due to increased pressure in the skull cavity

The local manifestations occur due to the direct pressure effect of the growth on to the surrounding brain tissue. For example, a tumor growing in and around the motor centers of the limbs can present as weakness. The local effect can also produce an obstruction to CSF (cerebrospinal fluid) flow resulting in a serious condition called as hydrocephalus (enlarged fluid filled cavities inside the brain called ventricles). Seizure is another manifestation of the local effects of a tumor.

And as a tumor increases in its size, the volume of the contents inside the skull cavity increases too, however the volume of the skull cavity being fixed it starts exerting pressure effect on the brain diffusely and this will manifest as decreased level of consciousness, obtundation, coma etc. The unabated build up of pressure inside the skull cavity will cause a catastrophic condition called as brain herniation.

Some of the frequent manifestations of brain tumors include;

• Headache (especially early morning)
• Vomiting (usually without warning)
• Decreased level of consciousness
• Change in mental status
• Fits (seizures)
• Loss of consciousness
• Paralysis of extremities
• Sensory abnormalities like numbness
• Drooping of eyelids
• Double vision etc.

Diagnosis

A tumor in the brain is suspected clinically and confirmed by obtaining a picture of the brain and later usually by a biopsy procedure. Brain picture is obtained by a CT and/or MRI with and without contrast agent. A SPECT or PET scan also may be necessary in some cases. CSF analysis is required if carcinomatous meningitis.

Treatment

Treatment depends on the type of tumor, benign or cancer, stage of cancer etc. Chemotherapy, radiotherapy and surgical resections are some of the available options for the management of the brain tumors. Steroids are usually used to reduce brain swelling. If seizures manifest anti seizure medications like phenytoin is necessary.

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