brain, spinal cord, and nerve disorders
Abscess of the Brain
Diagnosis of a Brain Abscess
Magnetic resonance imaging or computed tomography Withdrawal and testing of a sample of pus from the abscess If doctors suspect a brain abscess, magnetic resonance imaging (MRI) is done before and after gadolinium is injected intravenously. Gadolinium (an MRI contrast agent) makes abscesses easier to see on MRI scans. If MRI is unavailable, computed tomography (CT) can be done after a radiopaque contrast agent (which makes abscesses easier to see on CT scans) is injected intravenously. MRI has higher resolution and can show early abnormalities better than CT. However, additional tests may be needed to establish the diagnosis because a brain tumor or damage due to a stroke or multiple sclerosis can resemble a brain abscess. To identify the causative organism and thus determine which drugs would be most effective, doctors withdraw a sample of pus from the abscess with a needle. It is examined under a microscope and sent to a laboratory to grow (culture) bacteria in the fluid so that they can be identified. MRI or CT is used to guide the needle into the abscess. For this procedure (called stereotactic needle aspiration), a frame is attached to the skull. The frame provides reference points that can be identified on the MRI or CT scan. Thus, after drilling a small hole through the skull, doctors can guide the needle precisely into the abscess. However, doctors do not wait to get the result of culture to start treatment. 