What are earliest signs of LAST?

• A. Circumoral numbness, tinnitus, metallic taste, perioral tingling
• B. Chest pain and tachycardia
• C. Seizures only
• D. Hypotension with bradycardia

Answer: (A)

Early signs of LAST are neurotoxic and typically appear first. Classic manifestations around the mouth—circumoral numbness, perioral tingling, and a metallic taste or tinnitus—signal rising CNS levels of local anesthetic before the heart and vessels are affected. These symptoms reflect CNS excitation from the surge in blood concentration, a warning that progression to more severe toxicity is possible if the drug isn’t stopped and the patient is treated promptly.

As toxicity worsens, seizures and other CNS symptoms can occur, and then cardiovascular effects emerge, such as chest pain, tachycardia, hypotension, or bradycardia. That progression is why the earliest signs are neuro‑sensory rather than cardiovascular.

In practice, recognizing these early neuro signs is crucial because prompt actions—stopping the local anesthetic, ensuring airway and oxygenation, and, if needed, treating seizures and initiating lipid emulsion therapy—can prevent progression to life-threatening cardiovascular collapse.