퇴행성 뇌질환 - 2. CJD(Creutzfeldt-Jakob Disease)’s Diagnosis

▣ CJD(Creutzfeldt-Jakob Disease)’s Diagnosis

Laboratory tests cannot detect CJD but may be used to check for other, treatable conditions. Cerebral spinal fluid may be tested for the presence of a protein associated with CJD, but this protein is not the prion that causes disease, and it also is present in people with other types of dementia. This makes it an imperfect test.

Brain imaging tests, including computed tomography (CT) and magnetic resonance imaging (MRI) scans may be done to look for atrophied (shrunken) brain tissue. An electroencephalogram (EEG) records the brain's electrical pattern and may support the diagnosis because CJD causes a particular pattern of electrical activity in 75% to 95% of people with this disease. These EEG changes are not usually present at very early or very late stages of the disease.

A small sample of brain tissue may be taken to be analyzed in a laboratory. In CJD, brain tissue contains small round holes called spongiform changes, meaning the tissue resembles a sponge. However, a brain biopsy could hurt the patient, and it would only be done if there were a possibility the patient may have another disorder that could be treated.

The diagnosis of CJD is suspected when there are typical clinical symptoms and signs such as rapidly progressing dementia with myoclonus. Further investigation can then be performed to support the diagnosis including

♣ Electroencephalography; often has characteristic triphasic spikes
♣ Cerebrospinal fluid analysis for 14-3-3 protein
♣ MRI or CT of the brain; often shows high signal intensity in the caudate nucleus and putamen bilaterally on T2-weighted images

Diffusion Weighted Imaging (DWI) images are the most sensitive. In about 24% of cases DWI shows only cortical hyperintensity; in 68%, cortical and subcortical abnormalities; and in 5%, only subcortical anomalies. The involvement of the thalamus can be found in sCJD, is even stronger and constant in vCJD.

Clinical testing for CJD has always been an issue. Diagnosis has mostly been based on clinical and physical examination of symptoms. In recent years, studies have shown that the tumour marker Neuron-specific enolase (NSE) is often elevated in CJD casess.

In one third of patients with sporadic CJD, deposits of 'prion protein (scrapie)', PrPSc, can be found in the skeletal muscle and/or the spleen. Diagnosis of vCJD can be supported by biopsy of the tonsils, which harbour significant amounts of PrPSc; however, biopsy of brain tissue is the definitive diagnostic test.