What is the most commonly injured cranial nerve during carotid (carotid artery) endarterectomy (surgical procedure to remove plaque from the carotid artery)?

Cranial Nerve Injury During Carotid Endarterectomy

The hypoglossal nerve (XII) is the most commonly injured cranial nerve during carotid endarterectomy.

Incidence and Patterns of Cranial Nerve Injury

• Cranial nerve injuries occur in approximately 5-10% of carotid endarterectomy procedures, with most being transient 1
• The hypoglossal nerve (XII) has the highest incidence of injury at approximately 3.3-13.5% of cases 1, 2
• Vagus nerve (X) injuries causing vocal cord paralysis occur in about 2.6-5.8% of procedures 1, 2
• Glossopharyngeal nerve (IX) injuries are less common, occurring in approximately 0.7% of cases 1
• Facial nerve (VII) injuries, particularly to the marginal mandibular branch, occur in about 0.4-5.8% of procedures 1, 3

Mechanism of Hypoglossal Nerve Injury

• The hypoglossal nerve is particularly vulnerable due to its anatomical course across the surgical field during carotid endarterectomy 4
• The nerve travels caudally within the carotid space and then courses anteriorly inferior to the hyoid 5
• Injury typically occurs during:
  • Excessive retraction of tissues during exposure of the carotid bifurcation 3
  • Manipulation of the carotid artery near where the hypoglossal nerve crosses 4
  • Dissection extending high into the neck above the level of the hypoglossal nerve 6

Clinical Presentation of Hypoglossal Nerve Injury

• Hypoglossal nerve palsy presents with:
  • Deviation of the tongue to the side of the lesion upon protrusion 5
  • Dysarthria (difficulty with speech articulation) 5
  • Difficulty with deglutition (swallowing) in more severe cases 2
• Most injuries are temporary with full recovery occurring within 3 months 2

Risk Factors for Cranial Nerve Injury

• High carotid bifurcation requiring extended exposure 5
• Atheromatous lesions extending high into the internal carotid artery 5
• Reoperation for recurrent stenosis due to scar tissue 5
• Prior neck radiation or radical neck surgery 5
• Lesions at or above the level of the second cervical vertebra 5

Prevention Strategies

• Thorough knowledge of regional anatomy is essential 4, 1
• Careful identification and gentle handling of nerves during dissection 3
• Minimizing excessive retraction of tissues 3
• Limiting high cervical exposure when possible 5
• Avoiding trauma during vessel clamping 3

Evaluation and Management of Suspected Nerve Injury

• Thorough otolaryngological evaluation for patients with symptoms of cranial nerve dysfunction 1
• For hypoglossal nerve injury:
  • MRI is useful for evaluating the entire course of the nerve 5
  • CT provides complementary information on osseous structures 5
• Most injuries are transient and resolve within 3-6 months without specific intervention 1, 2

Long-term Outcomes

• The majority of cranial nerve injuries following carotid endarterectomy are temporary 1
• Complete recovery of hypoglossal nerve function typically occurs within 3 months 2
• Even patients with severe symptoms typically show improvement within a few weeks 1
• Permanent disability from isolated hypoglossal nerve injury is rare 1