Final answer:
Early signs of local anesthetic toxicity typically involve CNS excitation which includes tremors and restlessness, preceding any CNS depression or cardiac and respiratory arrest if toxicity advances.
Step-by-step explanation:
Early signs of local anesthetic toxicity are most often related to CNS excitation.
Local anesthetics are designed to block nerve conduction when applied to nerve tissue, hence diminishing the sensory and motor functions in the intended area. The signs of toxicity initially manifest as excitatory symptoms due to the initial overactivation of the central nervous system, which can include symptoms such as tremors, restlessness, anxiety, tinnitus (ringing ears), blurred vision, and muscular twitching.
As systemic toxicity increases, excitatory symptoms may progress to CNS depression, leading to more severe conditions like seizures or unconsciousness before potentially resulting in respiratory or cardiac arrest. It is crucial, therefore, to monitor patients for early signs of toxicity to manage and prevent progression to life-threatening conditions effectively.