Postoperative delirium is a common complication of anesthesia and surgery that can affect patients, especially older adults. It is typically characterized by confusion, disorientation, fluctuating levels of consciousness, and impaired attention. While these hallmark symptoms of postoperative delirium are well-documented and usually recognizable, some rare or atypical manifestations may be overlooked or misattributed, possibly resulting in a delayed diagnosis and suboptimal care. Understanding these uncommon presentations is vital to improving patient outcomes and ensuring timely interventions.
Though confusion and disorientation are common, some patients may develop elaborate religious delusions or intense spiritual experiences during delirium. This hyper-religiosity can include hearing divine voices, believing they are chosen for a spiritual mission, or experiencing extreme guilt over perceived moral failings. These symptoms are sometimes misdiagnosed as primary psychiatric disorders 1–3.
Emotional fluctuations in postoperative delirium are also rather common. However, only rare cases involve extreme mood swings that mimic acute mania or severe depression. In such cases, a patient might exhibit excessive euphoria followed by intense despair or tearfulness within short intervals. Such symptoms can be particularly challenging to differentiate from mood disorders—this is especially true when delirium is hypoactive and lacks dramatic behavioral disturbances 4,5.
While visual hallucinations are relatively common as symptoms of postoperative delirium, other types of hallucinations are rarer and more disorienting. These might include but are not limited to a range of tactile (feeling things crawling on the skin), olfactory (smelling nonexistent odors), or gustatory (tasting strange flavors) hallucinations. These symptoms might suggest substance use or neurological disorders. However, they can occur in delirium due to altered neurochemical signaling and medication interactions 6,7.
Patients may very rarely develop Capgras syndrome linked to postoperative delirium. Capgras syndrome is a delusional misidentification whereby the patient believes that a loved one has been replaced by an imposter, incurring distress and resistance to care. This tends to be especially relevant in hospital contexts in which unfamiliar faces and environments might tend to exacerbate a patient’s paranoia 8,9.
Some delirious patients might also display repetitive behaviors or speech patterns such as perseveration (continuously repeating an idea or phrase) or echolalia (the involuntary repetition of another person’s spoken words). These signs, though rare, are indicators of cognitive dysfunction and neurological involvement 10,11.
In addition, a patient’s hypoactive delirium can result in akinetic mutism, whereby a patient is alert but fails to move or speak. It might be clinically mistaken though for a stroke or severe depression12,13.
Recognizing these rare symptoms of postoperative delirium requires heightened clinical vigilance, especially when managing vulnerable populations like the elderly, those with pre-existing cognitive decline, or patients undergoing high-risk procedures. Early identification and intervention can significantly improve prognosis 2,14,15.
While the classic signs of postoperative delirium are well-recognized, atypical symptoms such as religious delusions, rare hallucinations, and bizarre behavioral changes can complicate diagnosis and the clinical management of postoperative delirium.
References
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8. Capgras Delusion – an overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/medicine-and-dentistry/capgras-delusion.
9. Joshi, D. et al. Capgras Syndrome in Postictal Delirium. Psychiatry (Edgmont) 7, 37–39 (2010).
10. Patra, K. P. & De Jesus, O. Echolalia. in StatPearls (StatPearls Publishing, Treasure Island (FL), 2025).
11. https://depts.washington.edu/mbwc/content/page-files/Post-operative_delirium_and_dementia5_-_Read-Only83.pdf. https://depts.washington.edu/mbwc/content/page-files/Post-operative_delirium_and_dementia5_-_Read-Only83.pdf.
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