What adverse effect can occur due to excessive doses of local anesthetic?

Excessive doses of local anesthetic can lead to central nervous system toxicity, which is often manifested as seizures. Local anesthetics work by blocking sodium channels, which are essential for nerve impulse transmission. In high concentrations, they can also affect the brain, leading to excitability and potentially resulting in seizures. This reaction can occur very quickly after administration, especially if the local anesthetic is inadvertently injected into a blood vessel, leading to high systemic levels.

The other options listed do not typically connect as directly to the excessive use of local anesthetics. For instance, hyperkalemia refers to elevated potassium levels in the blood, which is not a common result of local anesthetic overdose. Hypoxia, or low oxygen levels, is also not a direct effect of local anesthetics, although it can occur in clinical settings for other reasons. Hepatotoxicity, which relates to liver damage, is more associated with certain medications and not primarily with local anesthetic use, especially not acutely. Therefore, seizures are the most relevant and immediate risk when excessive doses of local anesthetics are administered.