DIAGNOSIS

Neurological examination involves testing the ability of the nervous system in various aspects. Any abnormality in the test outputs might be linked to brain tumour which can only be confirmed after further tests and scans. In this test basically the General physician or the neurologists check the patient’s awareness and understanding, the body’s balance and motor skills, reflexes and response to surrounding and sense of touch. Also the functioning of the 12 cranial nerves might be examined for their functioning like smell, vision, eye movement, taste and swallowing.

Magnetic resonance imaging uses strong magnets which are large and tube shaped to generate images of brains internal parts. It uses a combination of magnetic field and radio waves to create detailed cross sectional view of the brain. Before MRI is performed generally a dye is injected into the vein in the arm to generate clear pictures even of small tumours and also helps the Physician to differentiate between tumour tissue from normal tissue. There are various types of MRI like Functional MRI, Magnetic resonance spectroscopy, magnetic resonance perfusion etc. The method is selected based on the function or region of the brain which is to be analyzed for the abnormality.

Computed tomography of the brain involves the use of special X rays that generates horizontal or axial images of the brain. They provide more information compared to normal X rays. The process involves moving the X ray beam in a circle around the body part allowing multiple views of the brain this is then sent to the computer generating a 2 dimensional image on the screen. Contrasting images can also be generated by injecting a substance intravenously prior to the procedure by the health care specialist.

Biopsy is an invasive procedure that helps the physician to identify the type of the brain tumour and also helps in detecting how fast the tumour is growing. It can also help to check certain genes or proteins that are specifically expressed in the tumour cells which can act as target for the treatment. It is performed by drilling a small hole into the skull followed by taking a small piece of the tissue sample with the help of a needle and analyzing it in the pathology lab. The two major type of biopsy for brain tumour include stereotactic biopsy and open biopsy of which the open biopsy is the more invasive one.

Lumbar puncture also known as spinal tap is used to determine the spread of the tumour by detecting cancer cells in the cerebrospinal fluid.  To perform this the patient lies on their one side on the bed or examination desk and fold the knees up to the chest. Then the back is numbed in the lumbar region of the spine. Now a hollow needle is placed in between the bones of the spine to extract some CSF. This sample is then sent to the laboratory for examination for the presence of tumour cells. It’s generally used to diagnose tumours that spread through cerebrospinal fluid like the ependymoma.

Positron emission tomography is a nuclear imaging technique. Unlike X ray and CT scan which only shows the structural aspects PET scan give insights about the functional aspects. The procedure involves injecting tiny amount of radioactive substance known as the radiotracer into the bloodstream of the patient. These radiotracer tags molecules like glucose, ammonia or water which are preferentially absorbed by specific organ or tissue depending on the tracer. After the accumulation they release positrons that collides with body’s electron emitting gamma rays which is detected by the PET scanner. These images shows the regions with an increased metabolic activity helping in identifying abnormalities.