What are the presentations of vagus nerve (cranial nerve X) injury in an older adult patient with pre-existing vascular disease after undergoing carotid endarterectomy (CEA)?

Vagus Nerve Injury After Carotid Endarterectomy: Clinical Presentation

Vagus nerve injury after CEA most commonly presents with hoarseness from recurrent laryngeal nerve dysfunction, though the injury is rare (0.7% incidence) and typically transient, with only 0.7% of patients experiencing persistent deficits beyond 10 months. 1

Primary Clinical Manifestations

Voice Changes (Most Common)

• Hoarseness is the hallmark symptom resulting from adductor vocal cord paralysis when the recurrent laryngeal nerve (a branch of the vagus) is injured 2
• The ipsilateral vocal cord becomes paralyzed and cannot adduct properly during phonation 2, 3
• Voice changes occur in approximately 0.7% of CEA patients at discharge 1
• Acoustic voice parameters show measurable functional changes of the larynx postoperatively 4

Swallowing Dysfunction

• Dysphagia develops from cricopharyngeal dysfunction when vagus nerve injury affects pharyngeal motor control 2
• Aspiration risk increases significantly, particularly when combined with vocal cord paralysis 2
• Laryngopharyngeal sensory thresholds initially worsen postoperatively (increasing from 6.73 ± 1.73 mm Hg preoperatively to 7.62 ± 1.98 mm Hg at 2 days), though they paradoxically improve by 6 weeks (6.08 ± 2.02 mm Hg) 4
• Globus sensation (feeling of lump in throat) may occur from altered laryngopharyngeal sensation 4

"Double Trouble" Syndrome

• The combination of vocal cord paralysis AND cricopharyngeal dysfunction creates severe disability with both hoarseness and aspiration 2
• This represents the most debilitating presentation of vagus nerve injury after CEA 2
• Patients experience difficulty swallowing both solids and liquids with >20% aspiration rate in severe cases 2

Risk Factors and Clinical Context

High-Risk Scenarios

• High cervical exposure (lesions at or above C2 vertebra) significantly increases cranial nerve injury risk 5
• Urgent procedures carry 1.6-fold increased risk (OR 1.6,95% CI 1.2-2.1) 1
• Immediate re-exploration under same anesthetic doubles the risk (OR 2.0,95% CI 1.3-3.0) 1
• Return to operating room for neurologic event or bleeding increases risk 2.3-fold (OR 2.3,95% CI 1.4-3.8) 1
• Contralateral laryngeal nerve palsy is a relative contraindication because bilateral palsies could compromise the airway 5

Anatomic Considerations

• Prior radical neck surgery or radiation increases technical difficulty but does NOT statistically increase CNI rates (OR 0.9,95% CI 0.3-2.5) 1
• Redo CEA does NOT increase CNI risk (OR 1.0,95% CI 0.5-1.9) 1
• Rare anatomic variants exist where the vagus passes anterior to the internal carotid artery rather than posterior, increasing injury risk if not recognized 6

Severity Classification

Mild Dysfunction

• Difficulty swallowing solids only
• No aspiration detected 2

Moderate Dysfunction

• Difficulty swallowing solid foods
• Aspiration <20% 2

Severe Dysfunction

• Difficulty swallowing both solids and liquids
• Aspiration >20% 2
• May require Teflon injection to medialize paralyzed vocal cord and cricopharyngeal myotomy 2

Temporal Course and Prognosis

Immediate Postoperative Period

• Laryngopharyngeal mucosal hematoma develops in 30.8% of patients on the operated side 4
• When hematoma present, sensory threshold markedly elevated to 9.50 ± 0.93 mm Hg 4
• Symptoms typically manifest within first 2 days postoperatively 4

Resolution Timeline

• The vast majority of vagus nerve injuries are transient 1
• Most symptoms fade within weeks without specific intervention 4
• Only 0.7% of patients have persistent CNI at median 10-month follow-up 1
• Permanent unilateral vocal fold immobility occurs rarely 4

Associated Complications

Perioperative Stroke Connection

• Patients with perioperative stroke have dramatically higher CNI risk (23.4% vs 5.6% overall) 1
• This suggests shared mechanisms of injury or more extensive surgical manipulation 1

Bilateral Injury Considerations

• Bilateral vagus nerve injury could compromise the airway, making this a critical concern 5
• This is why contralateral laryngeal nerve palsy represents a relative contraindication to CEA 5

Diagnostic Evaluation

Immediate Assessment

• Comprehensive speech evaluation by speech therapist 2
• Video stroboscopy to visualize vocal cord movement 2
• Video fluoroscopy to assess swallowing mechanics 2
• Methylene blue testing for aspiration 2
• Fiberoptic Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST) can quantify laryngopharyngeal sensory thresholds 4

Intraoperative Monitoring

• Vocal cord electromyography (EMG) should be added to routine EEG monitoring in anatomically complex cases (prior radiation, distorted anatomy, contralateral vocal cord paralysis) to detect vagus nerve injury during surgery 3