(758) Atypical Etiology of Lidocaine Toxicity Presenting as Bradycardia and Status Epilepticus

Introduction: Lidocaine toxicity is rare, but can arise when local anesthetics are used in high concentrations. Systemic toxicity can present as cardiac or neurotoxicity. Only rare cases of toxicity from topically administered lidocaine have been reported.

Description: A 41-year-old male with schizophrenia, chronic skin wounds self-treated with topical lidocaine and no history of epilepsy presented with seizures. He was witnessed to have a generalized tonic-clonic seizure, self-resolving in 2 minutes. On EMS arrival, the patient was bradycardic to 30bpm, post-ictal, and had an additional tonic-clonic seizure. He was administered lorazepam and transcutaneous pacing was initiated. The patient arrived at the Emergency Department unresponsive, tachycardic to 122bpm, tachypneic to 22, with BP 89/48mm/hg. He had continuous rhythmic twitching and gaze deviation. His physical exam was pertinent for superficial ulcerative lesions covering his cheeks and neck. He was given 4mg IV lorazepam and 4.5g IV levetiracetam which did not stop the twitching, prompting intubation for status epilepticus and airway protection. CT angiography of the head and neck did not show any acute structural pathology. The patient was admitted to the neurological ICU. Given history of excessive topical lidocaine use, lidocaine toxicity was suspected. He was treated with lipid emulsion therapy and standard ICU care with no further seizures or dysrhythmias. His workup was significant for a plasma lidocaine level of 5ug/mL (1.5-5ug/mL), noninfectious/inflammatory cerebrospinal fluid studies, and an MRI brain with no structural lesions. The patient was extubated the next day and discharged one week later in good health.

Discussion: Lidocaine toxicity causes central nervous system effects, such as slurred speech, tremors, and seizures, cardiac conduction disturbances, arrhythmias, and respiratory arrest. This case demonstrates excessive topical application of lidocaine through open skin wounds can lead to toxicity. Additionally, acidosis increases free drug levels of lidocaine, and this patient’s undetectably low pH after seizing likely exacerbated the drug’s toxicity. Awareness of this atypical etiology for lidocaine toxicity is critical to ensure early detection and prompt treatment.