Voltage-gated potassium channel limbic encephalitis presenting as functional cognitive impairment.

Limbic encephalitis is often reported to present as seizures and impaired cognition with little focus on psychiatric presentations. In this case report, we present a 49-year-old man who initially presented to the Psychiatric Liaison Service with a several month history of confusion with the additional emergence of visual hallucinations and delusions. Due to the inconsistent nature of the symptoms in the context of a major financial stressor, a provisional functional cognitive impairment diagnosis was made. Investigations later revealed a positive titre of voltage-gated potassium channel (VGKC) antibodies, subtype leucine-rich glioma inactivated 1 accounting for his symptoms which dramatically resolved with steroids and immunoglobulins. This case highlighted the need for maintaining broad differential diagnoses in a patient presenting with unusual psychiatric symptoms.