Safe” Antipsychotic Becomes a Toxic Exposure: Postoperative Catatonia Mistaken for Delirium in an Elderly Patient

Background: Antipsychotics such as haloperidol are widely prescribed for postoperative delirium in older adults, yet they can act as toxic exposures in vulnerable patients and precipitate malignant catatonia—a life-threatening neuropsychiatric syndrome with autonomic instability resembling sepsis. From a medical toxicology and public health standpoint, this represents an underrecognized adverse drug reaction (ADR) with significant morbidity and mortality.
Case Presentation: A 67-year-old woman developed hypo-arousal and disorientation on the second postoperative day after hip fracture surgery and was initially treated as having delirium with low-dose haloperidol (0.5 mg twice daily). Instead of improving, she paradoxically deteriorated, developing negativism, resistance to passive eye opening, and progressive rigidity—findings consistent with antipsychotic-triggered catatonia. A lorazepam challenge (2 mg intramuscular) produced partial and fluctuating improvement, consistent with its role as a diagnostic and therapeutic antidote in catatonia. Escalation of scheduled lorazepam failed to consolidate recovery, and because of autonomic lability, the treatment plan shifted to ICU-monitored electroconvulsive therapy (ECT). The first session was ineffective, likely due to peri-ECT benzodiazepine exposure, but subsequent optimized treatments generated adequate seizures and clear clinical improvement.
Conclusion: This case illustrates how a common clinical exposure—antipsychotic administration—can produce a toxicological syndrome mislabeled as delirium. It highlights the need for public health awareness, pharmacovigilance, and toxicity-informed prescribing in elderly surgical patients. Recognizing antipsychotic non-response, performing a lorazepam challenge, and considering early ECT in high-risk elderly patients may be lifesaving and prevent prolonged morbidity.