What is commonly the second symptom experienced in lidocaine toxicity?

Lidocaine toxicity typically progresses through a series of symptoms as the plasma concentration increases. Following the initial symptom of peri-oral paresthesias, which is often the first sign of systemic toxicity, the second symptom that is commonly observed is CNS excitatory effects, which include visual and auditory hallucinations.

These CNS effects can manifest as a change in mental status, ranging from anxiety and agitation to more severe disturbances such as hallucinations. The reason for this sequence is related to the effects of lidocaine on sodium channels, which can cause hyperexcitability in the central nervous system before leading to more severe outcomes, including seizures and potential CNS depression at higher levels.

While tremors and cardiac arrhythmias can also occur during lidocaine toxicity, they typically arise after the initial excitatory symptoms, making visual and auditory hallucinations a key marker in this progression. Understanding this sequence is vital for timely recognition and management of lidocaine toxicity in clinical practice.