In the event of reaching toxic CNS levels from local anesthesia, what is the initial neurological response?

The initial neurological response to reaching toxic central nervous system (CNS) levels from local anesthesia is excitement. When local anesthetic agents enter the systemic circulation in excessive amounts, they can lead to a dose-dependent response that initially activates the CNS. This can result in symptoms such as tinnitus, dizziness, agitation, and seizures, which are all manifestations of excitation of the nervous system.

Following this initial phase of excitation, a progression to depression of the CNS may occur, leading to more serious complications such as coma or respiratory failure if the toxic levels are not managed. Understanding this sequence of events is crucial for healthcare providers in recognizing and promptly treating local anesthetic systemic toxicity (LAST).