A 64 year old female developed an insidious onset of progressive difficulties with her memory. Early complaints that her vision was "not working right" were prominent. Her memory continued to decline requiring family supervision 5 months later. She was then noted to manifest personality changed where she became less outgoing. Mobility problems were evident with complaints of "balance" and she deteriorated with resultant falls requiring frequent assistance from others. On evaluation, she seated in a wheelchair and noted to be withdrawn with limited spontaneous interaction. Impairment in memory, visual fixation and pursuit, rapid alternating movements, and gait was evident. A CT of the brain had been normal. MRI was pending and a routine EEG revealed the following;
Figure: EEG obtained utilizing a longitudinal bipolar montage with a sensitivity 10 uv and filter settings of 1-70 Hz.
Creutzfeldt-Jakob disease is a transmissible spongiform encephalopathy caused by an accumulation of an abnormal isoform of host-encoded cellular prion protein. The progressive neurodegeneration and early visual symptoms supported by EEG are characteristic of the Heidenhain variant of CJD. The EEG is an essential part of the diagnosis1. Non-specific findings such as diffuse slowing of the background or FIRDA may be apparent initially. By the mid-stage of CJD the classic generalized periodic sharp wave complexes are noted in 2/3rds of cases. Periodic complexes appear with a sensitivity of 64%, specificity of 91% (also rarely reported in other dementias), a positive predictive value of 95%, and negative predictive value of 49% according to one study2. In the Heidenhain variant of CJD (above), the periodic sharp waves are localized to the occipital region but occurred without seizures despite their epileptiform morphology.
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