Diagnosis of Creutzfeldt-Jakob disease (CJD) is normally based on medical history, symptoms and a series of tests.
A neurologist (a doctor who specialises in conditions of the nervous system) will carry out the tests to rule out other conditions with similar symptoms, such as Alzheimer's disease, Parkinson's disease or a brain tumour.
The only way to confirm a diagnosis of CJD is to examine the brain tissue with a brain biopsy or, when the patient is dead, during a post-mortem.
Specialist services to advise local teams in diagnosis are available at the National CJD Surveillance Unit in Edinburgh and the National Prion Clinic in London.
Tests for CJD
A clinical neurologist will rule out other diseases with similar symptoms and check for some common signs of CJD by carrying out the tests below:
- A magnetic resonance imaging (MRI) brain scan. This uses strong magnetic fields and radio waves to produce a detailed image of the brain and can show up abnormalities that are particular to CJD.
- An electroencephalogram (EEG). This records brain activity and may pick up abnormal electrical patterns seen in sporadic CJD.
- A lumbar puncture. During a lumbar puncture a needle is inserted into the lower part of the spine to draw out a sample of cerebrospinal fluid (which surrounds your brain and spinal cord) to be tested. If a protein called 14-3-3 is found in the fluid, it indicates that you may have CJD (this protein is found in almost all cases of sporadic CJD and half of variant CJD cases).
- A prototype blood test for variant CJD has been developed by the prion unit at the Medical Research Council (MRC). This is available through the National Prion Clinic.
- Tonsil biopsy. A small piece of tissue can be taken from the tonsils and checked for the abnormal prions found in variant CJD (they are not present in other types of CJD).
- Genetic test. This is a simple blood test to see if you have a mutation (fault) in the gene that produces normal protein. A positive result may indicate inherited prion disease.
Brain biopsy
During a brain biopsy, a surgeon drills a tiny hole into your skull and removes a small piece of brain tissue using a very thin needle. This is done under general anaesthetic (you are put to sleep).
As a brain biopsy carries the risk of causing brain damage or seizures (fits), it is only performed in a few cases, where there is a concern that the patient does not have CJD but some other treatable condition.
Read more about biopsies.
