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CJD
A guide for patients and carers
How is CJD diagnosed?
Currently, the only specific diagnostic test for any form of CJD involves looking at brain tissue.Therefore, an absolutely definite diagnosis is only possible if brain tissue is obtained during life (brain biopsy) or following a post-mortem examination after the patient dies. However, using a combination of clinical information and investigations, a reasonably confident diagnosis can be reached in life, in the majority of cases, without the need for invasive tests such as brain biopsy.
Before the diagnosis is made, other illnesses with similar symptoms must be ruled out, and the typical pattern of CJD seen.This requires the expertise of a clinical neurologist, who may use any of the following investigations:
MRI Scan
An MRI (magnetic resonance imaging) brain scan is often performed. This may be very useful in excluding other possible diagnoses, as well as revealing abnormalities that support the diagnosis of sporadic or variant CJD.
EEG
An EEG (electroencephalogram, which measures patterns of activity within the brain) may be helpful as it can show an abnormality characteristic of sporadic CJD.This pattern has never been seen in variant CJD.
Lumbar puncture
A lumbar puncture involves using a hollow needle inserted into the base of the spine to remove a small amount of the fluid which bathes the brain and spinal cord (cerebro-spinal fluid, CSF). Analysis of this fluid is important as it can exclude other possible illnesses.A test for a protein called 14-3-3 may also be undertaken.This is found in nearly all cases of sporadic CJD and about 50% of cases of variant CJD.The 14-3-3 test may therefore be helpful in supporting the diagnosis of CJD, especially sporadic CJD. However, a negative test result cannot absolutely exclude the diagnosis, nor can a positive result absolutely confirm it.
Tonsil biopsy
A small piece of tissue may be taken from the tonsils (tonsil biopsy) in certain cases. In variant CJD, abnormal prion protein is present in the tonsil and a biopsy may show this. It is not present in other forms of CJD and hence such biopsy is only useful to confirm suspect variant cases. However, its presence in tonsil tissue does not absolutely confirm the diagnosis – it may be possible to have abnormal prion protein in the tonsils but not have variant CJD. Brain biopsy (see below) is necessary to confirm this. In the majority of cases a very confident diagnosis of variant CJD can be made, and other possible diagnoses excluded, using the symptoms and a variety of clinical tests including MRI (see above) without the need for a tonsil biopsy.
Brain biopsy
A brain biopsy may be undertaken, but only in exceptional cases as it is a test with potential complications.The main reason for testing is concern that the patient may in fact have not have CJD but have another, potentially treatable, illness. However, such possibilities can be investigated in the vast majority of cases without using brain biopsy.
Genetic testing
Genetic testing can help doctors to make or refine a diagnosis of CJD.
MRI Scan
An MRI (magnetic resonance imaging) brain scan is often performed. This may be very useful in excluding other possible diagnoses, as well as revealing abnormalities that support the diagnosis of sporadic or variant CJD.
EEG
An EEG (electroencephalogram, which measures patterns of activity within the brain) may be helpful as it can show an abnormality characteristic of sporadic CJD.This pattern has never been seen in variant CJD.
Lumbar puncture
A lumbar puncture involves using a hollow needle inserted into the base of the spine to remove a small amount of the fluid which bathes the brain and spinal cord (cerebro-spinal fluid, CSF). Analysis of this fluid is important as it can exclude other possible illnesses.A test for a protein called 14-3-3 may also be undertaken.This is found in nearly all cases of sporadic CJD and about 50% of cases of variant CJD.The 14-3-3 test may therefore be helpful in supporting the diagnosis of CJD, especially sporadic CJD. However, a negative test result cannot absolutely exclude the diagnosis, nor can a positive result absolutely confirm it.
Tonsil biopsy
A small piece of tissue may be taken from the tonsils (tonsil biopsy) in certain cases. In variant CJD, abnormal prion protein is present in the tonsil and a biopsy may show this. It is not present in other forms of CJD and hence such biopsy is only useful to confirm suspect variant cases. However, its presence in tonsil tissue does not absolutely confirm the diagnosis – it may be possible to have abnormal prion protein in the tonsils but not have variant CJD. Brain biopsy (see below) is necessary to confirm this. In the majority of cases a very confident diagnosis of variant CJD can be made, and other possible diagnoses excluded, using the symptoms and a variety of clinical tests including MRI (see above) without the need for a tonsil biopsy.
Brain biopsy
A brain biopsy may be undertaken, but only in exceptional cases as it is a test with potential complications.The main reason for testing is concern that the patient may in fact have not have CJD but have another, potentially treatable, illness. However, such possibilities can be investigated in the vast majority of cases without using brain biopsy.
Genetic testing
Genetic testing can help doctors to make or refine a diagnosis of CJD.
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Contents
- Introduction
- What is CJD?
- What are the different types of CJD?
- What precautions do I need to take to stop CJD spreading?
- Can I get CJD from eating meat?
- How does the brain of someone with CJD differ from normal?
- What causes CJD?
- What does "genetic susceptibility" to CJD mean?
- Is there a genetic test for CJD?
- Can CJD be avoided, and is it catching?
- What are the symptoms of CJD, and how does the disease progress?
- How is CJD diagnosed?
- Are other conditions easily mistaken for CJD?
- How is CJD treated?
- What impact can CJD have on families of poepl with the condition?
- What support is available for carers of people with CJD?
- Conclusion
- Organisations that may be able to help
