When the Signs Deceive: Lidocaine Toxicity Imitating Brain Death in a Teenager

Introduction: There have been several reports in the literature regarding intoxications that mimic an exam concerning for brain death/death by neurologic criteria (BD/DNC) in patients who later have full neurologic recovery. Substances such as baclofen and methanol as well as envenomation from specific snake species have been documented to produce exams that are temporarily concerning for BD/DNC. Below we describe a case of oral lidocaine intoxication that mimicked brain death in a pediatric patient.


Description: A 16-year-old female with history of multiple past suicide attempts presented to our PICU after cardiac arrest. She was found unconscious at home with an empty bottle of an over-the-counter mouth wash containing 4% lidocaine; an estimated total exposure dose of 7 grams. She received 20 minutes of CPR prior to ROSC. On exam, she was noted to have fixed and dilated pupils. Her initial blood gas showed a pH < 6.5 and a lactate of >16. She required high doses of multiple vasoactives as well as sodium bicarbonate and methylene blue. Her initial lidocaine level was >24 mg/L. She received no sedatives. Her neurologic exam was concerning for BD/DNC, confirmed by multiple PICU physicians, for the first 32 hours of admission. By hospital day 2, her pupils were reactive with a return of cough and gag reflexes. She was arousing to stimulation and following simple commands. She was extubated on hospital day 2; a full neurologic exam showed no deficits, and she had an entirely normal mental status. MRI brain obtained 4 days after presentation was normal with no evidence of hypoxic injury. She was able to transfer out of the PICU on hospital day 8.


Discussion: Lidocaine toxicity due to oral ingestion is a rare but potential toxicologic confounder of BD/BNC. The most recent Pediatric Death by Neurologic Criteria Consensus guidelines published in 2023 recommend waiting 24 hours prior to performing a brain death exam in patients in this age group and waiting for 5 half-lives of conscious altering medications to allow serum levels to fall below accepted thresholds. However, lidocaine is not listed as an agent that requires these additional steps. In cases of lidocaine toxicity, it may be beneficial to wait for longer than the recommended amount of time prior to formal evaluation for BD/DNC.