Diagnostic challenges of atypical neuroleptic malignant syndrome after laparoscopic surgery for perforated peritonitis in a patient with class II obesity: a case report

AI Summary

Atypical neuroleptic malignant syndrome can mimic persistent postoperative infection, making diagnosis difficult in the postoperative setting.
Persistent fever and leukocytosis despite improving sepsis, with autonomic and extrapyramidal symptoms, are key clues to atypical NMS after psychotropic withdrawal.
Laparoscopic exploration is supported for peritonitis of unknown origin; resumption of antipsychotic therapy resulted in gradual clinical improvement.

Int J Surg Case Rep. 2026 Sep 22;138(11):4846-4850. doi: 10.1097/RC9.0000000000001024. eCollection 2026 Nov.

ABSTRACT

INTRODUCTION: Atypical neuroleptic malignant syndrome (NMS) can be difficult to recognize in the postoperative setting because its clinical features may overlap with those of persistent infection.

PRESENTATION OF CASE: A 53-year-old man with class II obesity (body-mass index of 35 kg/m²) and bipolar disorder treated with multiple psychotropic medications was hospitalized for sepsis and renal failure. He developed abdominal distension, and computed tomography revealed pneumoperitoneum without an identifiable perforation site. Laparoscopic exploration identified a transverse colon perforation, which was followed by a diverting colostomy with lavage and drainage. Although septic shock improved postoperatively, persistent fever and leukocytosis (>30 000/µL) persisted. He developed diaphoresis, sialorrhea, dysphagia, dysarthria, and altered consciousness. Repeated investigations identified no infectious source. A hematologic disorder was suspected but subsequently excluded. Based on the clinical course, atypical neuroleptic malignant syndrome associated with perioperative discontinuation of antipsychotic medications was considered the most likely diagnosis. Resumption of psychotropic medications was followed by gradual clinical improvement.

DISCUSSION: Persistent postoperative fever initially suggested uncontrolled infection, whereas subsequent clinical and laboratory findings raised suspicion of a hematological disorder. In retrospect, persistent autonomic and extrapyramidal symptoms, together with persistent fever despite improving sepsis, were important clues to atypical NMS.

CONCLUSIONS: This case highlights the diagnostic challenges of atypical postoperative NMS and supports laparoscopic exploration for peritonitis of unknown origin. Postoperative NMS should be considered in patients recently withdrawn from psychotropic medications when persistent fever and leukocytosis are accompanied by autonomic and extrapyramidal symptoms that are not fully explained by infection.

PMID:43006068 | PMC:PMC13747494 | DOI:10.1097/RC9.0000000000001024

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