What is the cranial nerve most commonly injured during carotid (carotid endarterectomy) surgery?

Cranial Nerve Injury During Carotid Endarterectomy

The hypoglossal nerve (XII) is the cranial nerve most commonly injured during carotid endarterectomy. 1, 2, 3

Incidence and Distribution of Cranial Nerve Injuries

• Cranial nerve injuries occur in approximately 5.6-13.5% of carotid endarterectomy procedures 2, 3
• Hypoglossal nerve (XII) injuries are among the most frequent, occurring in 2.6-4.8% of cases 2, 3
• Other cranial nerves that may be injured include:
  • Recurrent laryngeal branch of vagus nerve (X): 1.4-6% of cases 2, 4
  • Facial nerve (VII), particularly the marginal mandibular branch: 0.4-2.4% of cases 2, 3
  • Glossopharyngeal nerve (IX): 0.7% of cases 2, 5
  • Spinal accessory nerve (XI): 0.3% of cases 3

Anatomical Vulnerability of the Hypoglossal Nerve

• The hypoglossal nerve travels caudally within the carotid space and then courses anteriorly inferior to the hyoid, making it particularly vulnerable during carotid endarterectomy 1
• Its anatomical proximity to the surgical field places it at higher risk compared to other cranial nerves 1, 2

Risk Factors for Cranial Nerve Injury

• High carotid bifurcation requiring extended exposure 6, 1
• Atheromatous lesions extending high into the internal carotid artery 6, 1
• Lesions at or above the level of the second cervical vertebra 6, 1
• Reoperation for recurrent stenosis due to accumulated scar tissue 6, 1
• Prior radical neck surgery or radiation 6
• Dissection cephalad to the level of the hypoglossal nerve 5

Clinical Presentation of Hypoglossal Nerve Injury

• Deviation of the tongue to the side of the lesion upon protrusion 1
• Dysarthria and difficulty with deglutition in more severe cases 1
• Most injuries are transient, with improvement within weeks to months 2, 4
• Complete recovery typically occurs within 2-14 months in most cases 2, 4

Prevention and Management

• Limiting high cervical exposure when possible can help prevent cranial nerve injury 1
• Knowledge of cranial nerve anatomy is essential for surgeons to avoid such injuries 2
• Thorough otolaryngological evaluation should be performed in patients manifesting symptoms of cranial nerve dysfunction 2
• Preoperative clinical evaluation is important to document possible preexisting cranial nerve deficits 3
• Long-term follow-up is necessary to monitor recovery of function 2, 3

Surgical Technique Considerations

• The incidence of cranial nerve injuries appears similar between standard and eversion carotid endarterectomy techniques 4, 7
• Regional anesthesia does not appear to significantly alter the risk of cranial nerve injury compared to general anesthesia 7