Polymyxin B neurotoxicity as manifestation of a serious life-threatening adverse reaction: clinical case

The aim of this work is to describe a clinical case of a serious life-threatening adverse reaction in the form of neurotoxicity (convulsions, apnea requiring mechanical ventilation) to the polymyxin B drug, and also to remind that manifestations of neurotoxicity can be extremely varied and nonspecific, and do not occur after every administration, can be delayed, require vigilance and careful monitoring both from the attending physicians and from anesthesiologistsresuscitators, neurologists, ophthalmologists, etc.

A 62-year-old female patient diagnosed with stage IIIB T4G3N0M0 pleomorphic soft tissue sarcoma of the right thigh, condition after combination treatment, developed infection and necrosis of the postoperative wound (recto-abdominal flap). According to the results of a microbiological study and an antibiogram, the patient received polymyxin B as part of combination antibacterial therapy. On days 4, 5, 6, 7 of polymyxin administration, the patient experienced the following symptoms in various combinations: weakness, numbness of the face, paresthesia, paresis of the limbs, partial convulsions, respiratory depression, and apnea.

After establishing a connection between neurologicalsymptoms and intravenous administration of polymyxin B (the total score on the Naranjo scale was 6 points, the degree of reliability of the “adverse reaction–drug” relationship was probable) and drug withdrawal, manifestations of neurotoxicity completely disappeared and did not reoccur. The patient was discharged in satisfactory condition.

In a patient with symptoms of damage to the nervous system, it is necessary to conduct multiple differential diagnostic search to exclude stroke, epilepsy, encephalitis, hereditary and acquired neurodegenerative diseases, as well as side effects of medications. At the slightest suspicion of the likelihood of an adverse reaction to polymyxin B/colistimethate sodium, the Naranjo algorithm must be used to establish a cause-and-effect relationship between the adverse reaction and the drug.

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