Atypical neuroleptic malignant syndrome and non-alcoholic Wernicke's encephalopathy

We report the case of a middle-aged woman with a history of bipolar disorder, in the absence of alcohol or substance misuse. The patient had been maintained on fluphenazine decanoate depot and now presented acutely with cognitive dysfunction and rigidity. Laboratory tests revealed elevated creatine kinase, acute kidney injury with metabolic acidosis and transaminitis, leading to a provisional diagnosis of neuroleptic malignant syndrome (NMS). Neuroleptics were withheld; dialysis was commenced; and blood biochemistry parameters improved in tandem. However, mental status changes persisted, and re-evaluation revealed multidirectional nystagmus with bilateral past-pointing. MRI confirmed the diagnosis of Wernicke's encephalopathy (WE). Prompt recovery followed treatment with high-dose intravenous thiamine. We discuss the co-occurrence of NMS and non-alcoholic WE-highlighting the need for a high index of suspicion for these relatively rare neuropsychiatric diagnoses which are often missed in those with atypical presentations.