Cerebrospinal fluid (CSF) exam

In all cases of CJD or other rapidly progressive dementia, an examination of your cerebrospinal fluid (CSF - the clear and colorless, watery liquid that surrounds your brain and spinal cord) should be performed. Many different tests may be ordered from the CSF to rule out or investigate the possibility of various conditions. For instance, an elevated white blood cell count in the CSF may suggest a possible infection or inflammatory condition. A doctor collects the CSF by doing a lumbar puncture (spinal tap) in which a very thin needle is gently inserted in your lower back between two vertebrae, the bony structures that make up your spine. The procedure usually is done in a doctor’s office and takes about 30-45 minutes, during which time it is important to remain still. Afterwards, drink plenty of fluids to help prevent "lumbar puncture headache." If you have a headache or develop a fever after a lumbar puncture, let your doctor know immediately, as there are things that can be done to make the headache go away.

In people with CJD, the results of the CSF examination are usually normal, with the exception of a slightly increased total protein count. If there is an increased white blood cell count, your doctor should consider other neurological diseases, particularly infections, such as encephalitis.

Although we cannot yet detect prions in the CSF of patients with CJD, detection of elevated levels of the 14-3-3 protein in the CSF has been reported to support a CJD diagnosis in the scientific literature. The UCSF doctors do not feel this test is a very good diagnostic test for CJD because many people with confirmed CJD have a negative or normal result, and many others who do not have CJD, but have other neurological disease, have a positive result. Only half of the patients diagnosed with CJD at UCSF have an elevated 14-3-3 protein. Furthermore, in about 1/3 of patients referred to UCSF with an elevated 14-3-3 protein, UCSF doctors identify another diagnosis, not CJD! In many cases, these other diagnoses are very treatable.

Other CSF proteins, including neuron-specific enolase (NSE) and total tau protein (T-tau), have also been reported to be helpful in diagnosing CJD. UCSF doctors currently are studying the usefulness of these tests for CJD diagnosis, but at present, the medical and scientific community is still debating the use of any of these as a diagnostic test for CJD. So far, the data accumulated through the CJD research group suggests that MRI is a much better test than these CSF markers, but we still recommend ordering these tests as they may indicate that there is rapid injury to nerve cells in the brain.

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