Table 2. Recognizing sporadic Creutzfeldt-Jakob disease in its early stages: important caveats to current criteria.

Criteria
1	Rapid cognitive decline and myoclonus occur in a variety of brain disorders and are not specific for sporadic sCJD. In the early stages of sCJD, myoclonus may be absent and cognitive decline may be subtle. Cognitive decline may also be present without myoclonus and myoclonus may be present without evidence of cognitive impairment.
2	Focal/lateralized neurological manifestations are not uncommon in sCJD. In the early stages of sCJD, focal signs/symptoms may confuse the diagnosis, especially if cognitive impairment and myoclonus are not yet evident. The focal signs/symptoms may also be abrupt in onset and mimic a stroke.
3	Epilepsia partialis continua (EPC), which is synonymous with focal myoclonic status epilepticus, should be counted as myoclonus. Failing to will delay the diagnosis of sCJD. The evolution of EPC to bilateral or multifocal myoclonus can increase one's confidence in diagnosing sCJD
4	Scalp electroencephalography (EEG) may show periodic lateralized epileptiform discharges (PLEDs) days/weeks before the appearance of characteristic periodic sharp wave complexes (PSWCs). The PLEDs may or may not be associated with myoclonus/EPC. Serial EEG (e.g. every 5-7 days) may demonstrate the evolution of PLEDs towards PSWCs and increase one's confidence in diagnosing sCJD.
5	Cerebrospinal fluid (CSF) 14-3-3 protein assay has a relatively low specificity and a modest sensitivity for diagnosing sCJD. However, it can still be useful if a patient is suspected of having sCJD whilst the diagnosis of sCJD remains uncertain.
6	Magnetic resonance imaging (MRI), particularly diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping, is proving to be very useful in the early diagnosis of sCJD. The sCJD lesions appear as areas of restricted diffusion (DWI hyperintensities/ADC hypointensities) in the cerebral cortex, basal ganglia, and/or thalamus. Serial MRI (e.g. after 7-14 days) may show the spread of the gray matter lesions and increase one's confidence in diagnosing sCJD.

sCJD, sporadic Creutzfeldt-Jakob disease.