Charles Bonnet syndrome with auditory hallucinations: a diagnostic dilemma.

Charles Bonnet syndrome (CBS) appears to be commoner in elderly people than was previously thought. Nonetheless, as yet, no firm diagnostic criteria have been established for CBS, leaving the need for well-defined diagnostic criteria describing this syndrome unfulfilled. Two recently proposed diagnostic criteria for CBS insist on an absence of hallucinations in modalities other than visual. However, we experienced 2 cases suffering from probable CBS who experienced auditory hallucinations. In this report, we recommend that even if CBS coexists with other hallucinations, we should not exclude CBS as a probable diagnosis when the patients recognize their hallucinations as unreal. We believe that this modification of CBS diagnostic criteria will contribute to psychiatric epidemiology by correcting the current underestimation of CBS prevalence.