Testing for encephalitis:
To confirm a diagnosis of encephalitis there are two main tests that must be carried out:
CT Scan: A CT (computerised tomography) brain scan is a special type of x-ray which gives clear images of the brain.
CT scans can be very useful for detecting changes in the structure of your brain, such as inflammation, while ruling out other possible causes of your symptoms, such as a stroke, brain tumour, or aneurysms (a swollen blood vessel in the brain).
|Image14. CT scan of a brain with encephalitis
MRI scan: An MRI scan is a scanning procedure that pictures of the brain that are clearer a CT scan.
|Image15. MRI of brain with encephalitis
A lumbar puncture, also known as a spinal tap, is a procedure that is used to test a sample of CSF from your spinal cord.
A lumbar puncture is performed by inserting a hollow needle into the lower part of your spinal canal in order to draw out a sample of CSF. (See diagram)
The CSF is subjected to a series of tests that can help to confirm a diagnosis of encephalitis. The tests can range from a simple white blood cell count (a high number of white blood cells would suggest the presence of infection) to more complex tests, such as polymerase chain reaction (PCR).
PCR is a recent innovation that has been very useful in helping to confirm a diagnosis of encephalitis. It involves taking small samples of genetic material and reproducing, or ‘cloning’ it in order to build up a more detailed genetic picture that can allow hospital staff to quickly identify the virus responsible for encephalitis.
An electroencephalogram involves having wires attached to the scalp, and then
over a period of 20-30 minutes, a recording of the electrical activity of the brain
is taken. The test is painless and safe. It is a useful procedure since it can
show if the activity over the temporal lobes is abnormal - suggesting herpes
simplex encephalitis - or show whether epilepsy is arising from a specific part of