Which of the following is TRUE about the effect of local anesthetics on the central nervous system?

Local anesthetics have the potential to affect the central nervous system (CNS), and in cases of systemic toxicity, they can produce a clinical sequence of symptoms. When an overdose occurs, the initial response often includes CNS excitation, which can manifest as symptoms such as anxiety, restlessness, and eventually more severe outcomes like tonic-clonic convulsions. This phase is followed by CNS depression, resulting in lethargy, respiratory depression, and potentially unconsciousness. This biphasic response is critical for understanding the potential dangers associated with local anesthetic overdose, as it highlights the progression from excitation to depression.

The other options do not accurately reflect the relationship between local anesthetics and the central nervous system. It is important to note that while local anesthetics can cross the blood-brain barrier, not all local anesthetics exhibit the same degree of permeability. Additionally, although tonic-clonic convulsions can occur with overdose, they do not always occur; the clinical presentation can vary widely based on the extent of overdose and individual patient factors. Lastly, it is possible for signs of toxicity to manifest within the first 10 minutes post-injection, particularly if a substantial amount has been administered or if the agent has a rapid onset. Understanding these nuances helps practitioners