Most Injured Cranial Nerve During Carotid Endarterectomy
The hypoglossal nerve (CN XII) is the most commonly injured cranial nerve during carotid endarterectomy. 1, 2
Frequency of Cranial Nerve Injuries
Based on the available evidence, the pattern of cranial nerve injuries during carotid endarterectomy (CEA) shows:
- Hypoglossal nerve (XII): 3.3% of cases 2
- Vagus nerve (X): 2.6% of cases 2
- Glossopharyngeal nerve (IX): 0.7% of cases 2
- Facial nerve (VII): 0.4% of cases 2
The American Heart Association and American College of Radiology guidelines specifically highlight the hypoglossal nerve as being at particular risk during CEA procedures 1.
Risk Factors for Hypoglossal Nerve Injury
Several anatomical and surgical factors increase the risk of hypoglossal nerve injury:
- High carotid bifurcation requiring more extensive dissection 1
- Atheromatous lesions extending into the internal carotid artery beyond the exposed surgical field 1
- Reoperative CEA with accumulated scar tissue 1
- Lesions at or above the level of the second cervical vertebra 1
- Prior neck surgery or radiation therapy 1
Clinical Presentation of Hypoglossal Nerve Injury
When the hypoglossal nerve is injured, patients typically present with:
- Tongue deviation toward the affected side when protruded
- Dysarthria
- Difficulty with mastication
- Dysphagia 1
Prevention of Cranial Nerve Injuries
To minimize the risk of hypoglossal nerve injury during CEA:
- Apply careful surgical technique with gentle tissue handling
- Identify and protect cranial nerves during dissection
- Avoid excessive retraction
- Maintain thorough knowledge of regional anatomy 1
Prognosis
Most cranial nerve injuries following CEA are transient and show improvement within weeks 1, 2. In one study, all patients with cranial nerve injuries showed improvement within a few weeks and none had residual disability at the last follow-up (two weeks to 14 months) 2.
Clinical Implications
Understanding that the hypoglossal nerve is the most commonly injured cranial nerve during CEA should guide surgical planning and technique. Surgeons should be particularly vigilant about identifying and protecting this nerve, especially in patients with high-risk anatomical features.