Is Charles Bonnet Syndrome a Harbinger of Neurocognitive Disorder With Lewy Bodies? A Clinical Conundrum.

Charles Bonnet syndrome (CBS) is a clinical condition in which patients with visual impairment experience visual hallucinations (VH) in the presence of clear consciousness. It typically occurs in elderly people and confuses clinicians with multiple differential diagnoses due to VH, which can be present in a variety of clinical conditions ranging from psychosis to neurocognitive disorders (eg, neurocognitive disorder with Lewy bodies). In the latter, the concomitant presence of cognitive decline and parkinsonism aids the diagnosis. Here we report the case of an elderly man with retinitis pigmentosa (and thus significant visual loss), who presented with VH, thus warranting a diagnosis of CBS, but who later also manifested a rapid onset cognitive decline and parkinsonism, which necessitated a new diagnosis of major neurocognitive disorder with Lewy bodies. This case prompted us to consider whether CBS is a harbinger of neurocognitive disorder with Lewy bodies or whether there is a clinical overlap between these 2 clinical constructs. This case report attempts to unravel this clinical conundrum.