Most Commonly Injured Cranial Nerve During Carotid Endarterectomy
The hypoglossal nerve (CN XII) is the most commonly injured cranial nerve during carotid endarterectomy. 1
Incidence of Cranial Nerve Injuries
Based on the available evidence, cranial nerve injuries occur in approximately 5.6% of carotid endarterectomy procedures 1. The specific distribution of these injuries shows:
- Hypoglossal nerve (CN XII): 3.3% 1
- Vagus nerve (CN X): 2.6% 1
- Glossopharyngeal nerve (CN IX): 0.7% 1
- Facial nerve (CN VII): 0.4% 1
Anatomical Considerations
The hypoglossal nerve is particularly vulnerable during carotid endarterectomy because:
- It arises from the dorsal medulla and traverses the premedullary cistern
- It enters the hypoglossal canal before traveling within the carotid space
- It innervates the tongue musculature 2
- High carotid bifurcations significantly increase the risk of hypoglossal nerve injury 2
Risk Factors and Prevention
Several factors contribute to the risk of cranial nerve injury during carotid endarterectomy:
- High carotid bifurcation is a significant risk factor 2
- Dissection cephalad to the level of the hypoglossal nerve increases risk of injury to other nerves, particularly the glossopharyngeal nerve 3
- Anatomical variations in nerve position present additional challenges 4
To minimize the risk of cranial nerve injury:
- Thorough knowledge of regional anatomy is essential
- Careful surgical technique with gentle tissue handling
- Identification and protection of cranial nerves during dissection 2
- Avoiding excessive retraction and clamping of vessels 5
Clinical Presentation and Prognosis
Most cranial nerve injuries during carotid endarterectomy are transient:
- Hypoglossal nerve injury presents with tongue deviation toward the affected side
- Patients typically show improvement within a few weeks
- Most patients have no residual disability at follow-up (two weeks to 14 months) 1
It's worth noting that while individual nerve injuries are generally well tolerated, bilateral or combined nerve injuries can pose serious threats to patient safety 6.