Another Etiology of persistent pupillary fluctuations: A case of pesticide poisoning.

ObjectiveThis report details a rare and severe case of intentional pyridaben poisoning, highlighting the diagnostic challenges posed by its presentation with coma and anisocoria, and the successful treatment strategy employing extracorporeal blood purification.Case summaryA patient in early 50 s was found unconscious and admitted to the emergency department. Neurological examination revealed coma and bilateral, fixed, dilated pupils, initially raising strong suspicion for a catastrophic cerebrovascular accident. However, normal neuroimaging and subsequent arterial blood gas analysis revealed profound metabolic acidosis (pH 7.21, lactate >17 mmol/L) with compensatory hyperventilation. Further history from relatives suggested a suicidal attempt following familial discord, later confirmed by the discovery of a pyridaben container at her home. Toxicological monitoring is essential for confirming the diagnosis; however, this test could not be performed at our institution. We have therefore acknowledged this limitation in the Discussion section. The patient's condition deteriorated with refractory hypotension and generalized seizures. Management included endotracheal intubation, mechanical ventilation, vasopressor support, and seizure control. A combination of hemoperfusion (HP) and continuous renal replacement therapy (CRRT) was initiated for enhanced toxin elimination and metabolic correction. The patient showed remarkable improvement; lactate levels normalized within 13 h, and she regained full consciousness with intact neurological function 23 h post-admission. She was successfully weaned from the ventilator on day 4 and was discharged after a full recovery.ConclusionThis case underscores that pyridaben poisoning can mimic brainstem herniation, but the finding of unexplained severe lactic acidosis is a pivotal diagnostic clue. A multifaceted management approach, including early extracorporeal blood purification with HP and CRRT, can be life-saving and lead to complete neurological recovery even in the most severe presentations.