Accuracy and reliability of periodic sharp wave complexes in Creutzfeldt-Jakob disease

Objective: To assess the sensitivity, specificity, and interobserver reliability of periodic sharp wave complexes in the electroencephalograms of patients with Creutzfeldt-Jakob disease. Design: Sixty-eight electroencephalograms in 29 patients who had been suspected of having Creutzfeldt-Jakob disease were reanalyzed by an investigator who was unaware of the clinical data. The incidence of periodic sharp wave complexes in neuropathologically confirmed Creutzfeldt-Jakob disease vs progressive dementia other than Creutzfeldt-Jakob disease was assessed. Blinded electroencephalogram analysis was performed by a second investigator. The interobserver reliability was assessed by the kappa value. Setting: University hospital, base of the German National Creutzfeldt-Jakob Disease Surveillance Study. Patients: Fifteen patients with neuropathologically confirmed Creutzfeldt-Jakob disease and 14 patients who had been suspected of having Creutzfeldt-Jakob disease because of rapidly progressive dementia but in whom other dementias were diagnosed by unblinded investigators based on clinical and electroencephalographic criteria. Main Outcome Measure: Sensitivity and specifity of periodic sharp wave complexes assessed by their incidence in Creutzfeldt-Jakob disease vs other dementias. Interobserver reliability of periodic sharp wave complexes was expressed by the kappa value. Results: For periodic sharp wave complexes, blinded electroencephalographic analysis resulted in a sensitivity and a specificity of 67% and 86%, respectively. Interobserver reliability was excellent (kappa=0.95). Conclusion: This blinded electroencephalographic study in Creutzfeldt-Jakob disease confirms the high diagnostic value of electroencephalography, as previously reported by open studies.