| Summary: | A systematic study of all patients with pathologically or electrophysiologically confirmed Creutzfeld-Jakob disease (CJD) referred to the U.K. national surveillance unit between May, 1990 and April, 1994 has been undertaken. The numbers of sporadic, familial and iatrogenic cases were 144, 14 and 12 respectively. Sporadic CJD cases had a median age at presentation of 65 years, and a median disease duration of 4 months. Familial cases (associated with mutations of the open reading frame of the prion protein gene, PRNP ORF) presented 10 years earlier and had disease durations which were twice as long. Clinical characteristics at different stages of illness were identified. At presentation, around 40% of sporadic cases had some aspect of cognitive impairment in isolation, 30% had cerebellar dysfunction in isolation, 10% had a combination of cognitive and cerebellar dysfunction, and 10% had occipital blindness. Alternative modes of presentation were unusual (<10%), and the forms of CJD characterised by pure progressive cerebellar ataxia was rare (<4%). The clinical characteristics of the sporadic and the grouped familial cases did not differ. Characteristic electroencephalographic findings were present in 35% of pathologically confirmed cases. Familial cases were more likely to have a family history of (non-specific) neurodegeneration. Iatrogenic cases in whom the agent was inoculated outside the central nervous system were shown to have a different clinical profile early in the illness from sporadic cases. The clinical characteristics of the sporadic and familial cases were compared at different stages of illness with those of a group of patients with suspected CJD whose neuropathological examinations had revealed an alternative neurodegenerative process (non-CJD). The relative sensitivities and specificities of the standardised criteria used in the clinical evaluation of suspect CJD cases were high, with the exception of "neurogenic muscle wasting". The non-CJD group had a disease duration that was four times as long as the sporadic CJD cases.
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