What EEG findings are characteristic of Creutzfeldt-Jakob disease (CJD)?

Updated: Oct 09, 2019
  • Author: Eli S Neiman, DO, FACN; Chief Editor: Selim R Benbadis, MD  more...
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Answer

In Creutzfeldt-Jakob disease (CJD), electroencephalography (EEG) shows a fairly typical repetitive pattern of bilateral synchronous periodic epileptiform discharges (BiPEDs; see the first image below) such as triphasic waves (TWs; see the second image below) approximately 1-1.5 seconds apart. These usually are present during wakefulness and disappear during sleep.

Bilateral periodic epileptiform discharges (BiPEDs Bilateral periodic epileptiform discharges (BiPEDs).
Triphasic waves, maximum amplitude bilateral front Triphasic waves, maximum amplitude bilateral frontal.

Periodic synchronous discharges (PSDs) seem to be the EEG hallmark of CJD; however, a number of atypical EEG presentations have been reported without these waveforms.

Aoki et al reported giant spikes with photic stimulation. [43] These photic-stimulated giant spikes simultaneously suppressed PSDs. Necropsy exhibited extensive gray and white matter lesions. Both lateral geniculate bodies and pregeniculate bodies were involved preferentially. The superior colliculus, optic nerve, and optic tracts were not affected. The cortices of the occipital lobes were damaged severely. The Gennari line was spared. The lesion of the lateral geniculate body appeared to be associated with the unusual EEG feature.

These findings indicate that the visual pathway may be involved in the generation of PSD in CJD (see the image below).

MRI axial diffusion weighted image: Cortical ribbo MRI axial diffusion weighted image: Cortical ribbon sign in CJD.

The EEG findings and the evolution of clinical signs were investigated by Hansen et al in 7 patients with CJD who underwent serial EEG recordings. [44] At the onset (mean 8.7 weeks) of periodic slow-wave complexes (PSWC), 5 patients already had progressed to akinetic mutism characterized by loss of verbal contact and movement disorders (ie, myoclonus, exaggerated startle reaction, or focal dyskinesia started in 5 patients).

When akinetic mutism commenced (average 7.5 weeks), runs of frontal intermittent rhythmic delta activity (FIRDA), like that shown below, were found in all cases. These were later replaced by PSWC in 6 patients. Occurrence of PSWC often related negatively to external stimuli and sedative medication. [44]

These data help in the selection of EEG recording dates to detect PSWC in patients in whom CJD is suspected. The survival time is short after the onset of PSWC (average 8 weeks). In earlier disease stages, FIRDA-like EEG activities should be regarded as compatible with the diagnosis of CJD and should encourage further EEG studies for the demonstration of PSWC in a more advanced stage of CJD.

EEG characteristics of CJD and its differential diagnosis were studied by Steinhoff et al, who found some nonspecific EEG findings and also typical PSWC in the course of the disease, [45] obtaining a sensitivity of 67% and a specificity of 86%. With the exception of one familial variant of CJD, PSWC are usually absent in all other human prion diseases.

The authors presented a pathophysiologic hypothesis on the development of PSWC based on the assumption that the specific periodicity of PSWC results from a still functionally active but greatly impaired subcortical-cortical circuit of neuronal excitability. [45] They stressed the use of clinical signs, laboratory data, and EEG correlation and suggested that the clinical diagnosis of CJD should be reconsidered if repeated EEG recordings fail to reveal PSWC under technically adequate conditions. Some patients with CJD presented with visual blurring, diplopia, and visual loss—ie, the Heidenhain 5 variant.

Focal EEG abnormalities as described in the Heidenhain variant of CJD are uncommon. Lee et al reported a 73-year-old man presenting with visual symptoms, right hemianopia, and rapidly progressive dementia. Myoclonus was synchronous with generalized periodic epileptiform discharges on EEG (see the image below).

Generalized periodic epileptiform discharges (GPED Generalized periodic epileptiform discharges (GPED).

In addition, periodic focal sharp waves were present at the left occipital region. Diffusion-weighted magnetic resonance imaging (MRI) of the brain showed slightly increased signal intensity in the occipital parasagittal area, left more than right. The 14-3-3 protein was detected in the cerebrospinal fluid (CSF). The patient died within 5 months of presentation. [46]


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