Which nerve may be anesthetized during deep cervical plexus block and cause diaphragmatic paralysis if bilateral blocks are performed?

Which nerve may be anesthetized during deep cervical plexus block and cause diaphragmatic paralysis if bilateral blocks are performed?

• A. Phrenic nerve
• B. Spinal accessory nerve
• C. Hypoglossal nerve
• D. Vagus nerve

Answer: (A)

Blocking the deep cervical plexus can inadvertently affect the phrenic nerve, which originates from C3 to C5 and travels on the anterior surface of the scalene muscles toward the diaphragm. If local anesthetic diffuses to or near the phrenic nerve, it can abolish diaphragmatic movement on that side. When both phrenic nerves are blocked with bilateral blocks, diaphragmatic paralysis can occur, leading to significant respiratory compromise, especially in patients with limited pulmonary reserve. The other nerves listed do not control the diaphragm; the spinal accessory nerve innervates neck muscles, the hypoglossal nerve controls the tongue, and the vagus nerve has widespread thoracic/abdominal functions but does not cause diaphragmatic paralysis when blocked in this context.

Blocking the deep cervical plexus can inadvertently affect the phrenic nerve, which originates from C3 to C5 and travels on the anterior surface of the scalene muscles toward the diaphragm. If local anesthetic diffuses to or near the phrenic nerve, it can abolish diaphragmatic movement on that side. When both phrenic nerves are blocked with bilateral blocks, diaphragmatic paralysis can occur, leading to significant respiratory compromise, especially in patients with limited pulmonary reserve. The other nerves listed do not control the diaphragm; the spinal accessory nerve innervates neck muscles, the hypoglossal nerve controls the tongue, and the vagus nerve has widespread thoracic/abdominal functions but does not cause diaphragmatic paralysis when blocked in this context.