When you suspect a possible rapidly progressive dementia (RPD), there are certain tests you should order to help rule out or confirm a diagnosis. Many tests are needed for a complete work up, but a brain MRI including FLAIR (fluid attenuated inversion recovery) and DWI (diffusion weighted imaging) is the single most helpful tool in diagnosing CJD.
Physical Exam & Patient History
Because the first symptoms of CJD are sometimes constitutional, identifying the actual date of onset may require some probing. An assessment of the patient’s ability to complete activities of daily living helps quantify disease progression. Ask about any family history of neurological or psychiatric disease (relatives may have been misdiagnosed; many patients with genetic prion disease are mistaken for other neurological or psychiatric disorders, including Alzheimer’s, Parkinson’s disease or atypical parkinsonian dementias). Medical and travel history may help assess the risk of acquired CJD.
Blood Work
The following labs will cover a broad groundwork for an initial workup: CBC, chemistry panel (including Ca, Mg and P), LFTs, RPR, rheumatology screen (ESR, ANA, RF, CRP, C-ANCA and P-ANCA), thyroid function, B12, homocysteine, anti-thyroglobulin and anti-thyroperoxidase antibodies, HIV, Lyme and paraneoplastic antibodies. We recommend testing blood for genetic forms of prion disease in all patients with suspected CJD, particularly those with a family history of dementia or a cerebellar or parkinsonian disorder. In more than 60% of patients identified as having genetic prion disease, there is no known family history of prion disease. See CJD Differential Diagnosis for additional suggested testing.
Urinalysis
UA and cultures should be sent to rule out infection. Collect 24-hour urine for heavy metal screen including arsenic, lead, mercury, copper, aluminum and bismuth, with a history of exposure.
MRI
This is the single most helpful test& you can do to diagnose CJD. Order axial and coronal T1, T2, DWI (and ADC map) and FLAIR sequences. To rule out other conditions at least one MRI should be done with and without contrast.
EEG
In most people with CJD, the EEG will show a nonspecific slowing of activity which occurs in many forms of dementia. About 65% of patients with sCJD will show characteristic Periodic Sharp Wave Complexes (PSWCs) about once every second, but often not until late in the disease course. These changes are also not specific to CJD; they can occur in hepatic encephalopathy, Hashimoto’s encephalopathy and late stages of other neurodegenerative diseases such as Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB).
CT
A CT of the chest, abdomen and pelvis with and without IV contrast can help rule out malignancy and paraneoplastic disorders.
Brain Biopsy
With the utility of DWI MRI, we rarely do brain biopsies. However, a brain biopsy sometimes may help confirm CJD or another diagnosis. Brain biopsies, even in CJD, may not be diagnostic, as they do not always obtain tissue from the affected part of the brain.