The Neuropsychiatric Phenotype of Klüver-Bucy Syndrome: A Systematic Review of Reported Cases.

Klüver-Bucy syndrome (KBS) is a neuropsychiatric condition characterized by hypersexuality, hyperorality, hyperphagia, visual agnosia, hypermetamorphosis, and emotional changes such as placidity and loss of fear. Distinct diagnostic criteria are used to define both complete and partial KBS, but clinicians often face challenges due to symptom variability and unvalidated criteria. In this systematic review, the authors searched the PubMed, Embase, PsycNet, Latin America and the Caribbean Literature on Health Sciences, and OpenGrey literature databases from their inception to January 24, 2025, focusing on KBS case reports and series. Inclusion criteria required patients to meet at least three of the six classic KBS features (partial KBS) or all six features (complete KBS). Studies involving orbitofrontal syndrome were excluded. Data were independently extracted and summarized. In total, 141 articles describing 157 cases that met the inclusion criteria were included. Hypersexuality (84%), hyperorality (84%), and hyperphagia (73%) were most common in KBS, whereas hypermetamorphosis (52%) and visual agnosia (47%) were less frequent. Cognitive changes, such as attentional and memory disturbances, were also common. Neuroimaging showed bilateral temporal lobe lesions in 73% of KBS cases. Major KBS causes included central nervous system infections (27%), traumatic brain injuries (14%), and autoimmune conditions (12%). Most reports lacked standardized symptom assessment, risking underreporting of features such as visual agnosia and hypermetamorphosis. This review highlights variability in KBS and its neuropsychiatric features. A new diagnostic framework with defined certainty levels is proposed. Future research should validate these criteria and explore targeted therapies to improve the understanding and management of this syndrome.