A 70-year-old man presents to the emergency department due to right-sided arm and leg weakness that occurred several hours ago. The episode lasted 15 minutes and resolved spontaneously. He had a similar episode of right arm weakness two days ago. He was diagnosed with hypercholesterolemia on routine check-up three months ago, and has been treated with pravastatin. He does not smoke or consume alcohol. His blood pressure is 140/90 mmHg and his heart rate is 70/min. Doppler studies shows 89% stenosis in his left carotid artery and 40% stenosis in his right carotid artery. He undergoes left carotid endarterectomy. The surgery goes well and he recovers from the anesthesia without any complications. In the recovery room, upon protrusion of the tongue, the tongue deviates to the left. Which of the following structures is most likely damaged?

Question

A 70-year-old man presents to the emergency department due to right-sided arm and leg weakness that occurred several hours ago.  The episode lasted 15 minutes and resolved spontaneously.  He had a similar episode of right arm weakness two days ago.  He was diagnosed with hypercholesterolemia on routine check-up three months ago, and has been treated with pravastatin.  He does not smoke or consume alcohol.  His blood pressure is 140/90 mmHg and his heart rate is 70/min.  Doppler studies shows 89% stenosis in his left carotid artery and 40% stenosis in his right carotid artery.  He undergoes left carotid endarterectomy.  The surgery goes well and he recovers from the anesthesia without any complications.  In the recovery room, upon protrusion of the tongue, the tongue deviates to the left.  Which of the following structures is most likely damaged?

Quizplus · Accepted Answer

Explanation: A number of nerve injuries can occur during carotid endarterectomy. Inadvertent retraction or transection of the hypoglossal nerve causes tongue deviation to the site of injury, as observed in this patient. (Choice C)Recurrent laryngeal nerve injury leads to unilateral vocal cord paralysis, with a resultant change in voice quality. This nerve lies distal to the area of carotid dissection. (Choice D)The facial nerve can be damaged after it exits from the stylomastoid foramen and courses along the inferior portion of the ear. Its marginal mandibular branch (which supplies the orbicularis oris muscle) is most commonly injured, with a resultant asymmetric smile. The vagus nerve lies posterolaterally in the carotid sheath and is also at risk for injury during the procedure (Choice A). The ansa hypoglossus nerve innervates the strap muscles of the neck; unlike the other nerves, this nerve may be sacrificed with impunity (Choice E). Educational objective: A number of nerve injuries can occur during carotid endarterectomy. Inadvertent retraction or transection of the hypoglossal nerve causes tongue deviation to the side of injury. *Extremely important question for USMLE step-3

A 70-Year-Old Man Presents to the Emergency Department Due to Right-Sided Arm