How it's diagnosed (continued)

Doctors commonly use these tests to help detect CJD:

Electroencephalogram (EEG): Using electrodes placed on your scalp, this test measures your brain's electrical activity. People with CJD and vCJD show a characteristically abnormal pattern.

Magnetic resonance imaging (MRI). This technique uses radio waves and a magnetic field to create cross-sectional images of your head and body. It's especially useful in diagnosing brain disorders because of its high-resolution images of the brain's white matter and gray matter.

Spinal fluid tests: Cerebral spinal fluid surrounds and cushions your brain and spinal cord. In a test called a lumbar puncture — popularly known as a spinal tap — doctors use a needle to withdraw a small amount of this fluid for testing. The presence of a particular protein in spinal fluid is often an indication of CJD or vCJD.