In a deep cervical plexus block for thyroidectomy, which complication would be LEAST likely?

In a deep cervical plexus block for thyroidectomy, which complication would be LEAST likely?

• A. Horner’s syndrome
• B. Subarachnoid injection
• C. Blockade of the recurrent laryngeal nerve
• D. Blockade of the spinal accessory nerve

Answer: (D)

Understanding deep cervical plexus block anatomy helps explain why certain complications are more or less likely. This block targets the upper cervical nerve roots around the C2–C4 transverse processes, with local anesthetic spreading to the nerves of the cervical plexus and, occasionally, nearby structures such as the sympathetic chain. That explains why Horner’s syndrome can occur: the sympathetic fibers to the eye can be affected if the anesthetic track extends cephalad to the superior cervical chain. Subarachnoid injection is a known danger if the needle goes too deep or is placed in the wrong plane, leading to high spinal anesthesia with significant consequences. The recurrent laryngeal nerve lies close to the lower trachea and esophagus; spread of anesthetic in this region can reach it and cause hoarseness or even airway compromise. Blockade of the spinal accessory nerve, however, is least likely with this approach. The spinal accessory nerve travels in the posterior neck, superficial to the deep processes and in the posterior triangle, not in the deep prevertebral plane where the cervical plexus block is deposited. With correct technique, the injection remains near the transverse processes and the cervical plexus roots, making unintended spread to the spinal accessory nerve unlikely.

Understanding deep cervical plexus block anatomy helps explain why certain complications are more or less likely. This block targets the upper cervical nerve roots around the C2–C4 transverse processes, with local anesthetic spreading to the nerves of the cervical plexus and, occasionally, nearby structures such as the sympathetic chain. That explains why Horner’s syndrome can occur: the sympathetic fibers to the eye can be affected if the anesthetic track extends cephalad to the superior cervical chain. Subarachnoid injection is a known danger if the needle goes too deep or is placed in the wrong plane, leading to high spinal anesthesia with significant consequences. The recurrent laryngeal nerve lies close to the lower trachea and esophagus; spread of anesthetic in this region can reach it and cause hoarseness or even airway compromise.

Blockade of the spinal accessory nerve, however, is least likely with this approach. The spinal accessory nerve travels in the posterior neck, superficial to the deep processes and in the posterior triangle, not in the deep prevertebral plane where the cervical plexus block is deposited. With correct technique, the injection remains near the transverse processes and the cervical plexus roots, making unintended spread to the spinal accessory nerve unlikely.