Can vocal cord paralysis occur after a Blalock-Taussig (BT) shunt procedure?

Vocal Cord Paralysis After BT Shunt Procedure

Yes, vocal cord paralysis can occur after a Blalock-Taussig (BT) shunt procedure, with a significant risk particularly for left-sided vocal cord paralysis due to potential injury to the recurrent laryngeal nerve during the operation.

Mechanism of Injury

The risk of vocal cord paralysis after BT shunt procedures stems from several anatomical and procedural factors:

1. Recurrent Laryngeal Nerve Anatomy:

   • The left recurrent laryngeal nerve has a longer intrathoracic course as it loops around the aortic arch, making it vulnerable during thoracic procedures 1
   • The right recurrent laryngeal nerve lies in a more superficial plane along the lateral esophageal edge 2

2. Surgical Risk Factors:

   • Direct manipulation near the aortic arch during BT shunt placement
   • Traction on surrounding structures
   • Hypothermic injury from cooling techniques used during surgery 1
   • Retraction of the heart and surrounding structures 1

Incidence and Risk

The incidence of vocal cord paralysis varies by procedure type:

• 1-5% for ascending aortic procedures
• 20-25% for total arch or descending aortic procedures 3
• Higher risk with procedures involving the aortic arch with brachiocephalic artery reconstruction (OR 8.708) 4

For context, the BT shunt procedure involves anastomosis between the subclavian artery and pulmonary artery, which places surgical manipulation in proximity to the recurrent laryngeal nerve path.

Clinical Presentation

Symptoms of vocal cord paralysis after BT shunt may include:

• Hoarseness (most common symptom)
• Weak cry in infants
• Stridor (particularly with bilateral paralysis)
• Difficulty swallowing
• Ineffective cough
• Aspiration risk 1, 5

Symptoms typically appear within 24 hours after extubation for unilateral paralysis, while bilateral paralysis may present with respiratory distress ranging from mild stridor to acute airway obstruction 5.

Diagnosis

If vocal cord paralysis is suspected:

1. Direct visualization via laryngoscopy is essential for diagnosis 6
2. Findings include immobility of affected vocal cord(s)
3. Assessment should be performed by an otolaryngologist 4

Management

Management depends on severity and whether the paralysis is unilateral or bilateral:

For Unilateral Paralysis:

• Conservative management with voice therapy for mild cases
• Monitoring for spontaneous recovery (may occur within 6 months)
• Vocal cord injection or medialization procedures for persistent cases 6, 3

For Bilateral Paralysis:

• Airway management is critical - may require reintubation or tracheostomy
• Corticosteroids to reduce edema
• Close monitoring for respiratory compromise 6, 5

Prevention and Risk Reduction

To minimize risk during BT shunt procedures:

1. Meticulous surgical technique with careful dissection
2. Awareness of anatomical variants
3. Consideration of preoperative vocal cord assessment in high-risk cases
4. Gentle retraction of surrounding structures
5. Avoiding excessive cooling near nerve pathways 2, 1

Prognosis

• Many cases of vocal cord paralysis are transient, resolving within 6 months
• Permanent paralysis occurs in a subset of patients
• Early identification and management can reduce associated morbidity 3
• Patients with vocal cord paralysis have higher rates of pneumonia (58% vs 17%), respiratory failure requiring ICU readmission, and longer hospital stays 3

Special Considerations for Pediatric Patients

In pediatric patients undergoing BT shunt procedures:

• Smaller anatomy increases technical challenges
• Vocal cord assessment may be more difficult
• Symptoms may present differently (weak cry rather than hoarseness)
• Increased risk of respiratory complications due to smaller airway diameter 7

Vocal cord paralysis should be considered in any patient with voice changes, breathing difficulties, or swallowing problems following a BT shunt procedure, with prompt otolaryngology consultation for definitive diagnosis and management.