What vessels and nerves are at risk in the axilla during a sentinel lymph node (SLN) biopsy for a breast lumpectomy?

Vessels and Nerves at Risk During Sentinel Lymph Node Biopsy in Axilla

The primary vessels and nerves at risk during sentinel lymph node biopsy (SLNB) in the axilla include the long thoracic nerve, thoracodorsal nerve, medial pectoral nerve, intercostal brachiocutaneous nerve, and the axillary vein, each associated with specific functional complications if damaged. 1

Key Anatomical Structures at Risk

Nerves at Risk

1. Long Thoracic Nerve

   • Function: Innervates the serratus anterior muscle
   • Complication if injured: Scapular winging (inability to stabilize the scapula against the chest wall) 1
   • Clinical significance: Affects shoulder function and arm movement

2. Thoracodorsal Nerve

   • Function: Supplies the latissimus dorsi muscle
   • Complication if injured: Impaired shoulder function, particularly during adduction and internal rotation 1
   • Clinical significance: May affect certain arm movements and strength

3. Medial Pectoral Nerve

   • Function: Innervates the pectoralis muscles
   • Complication if injured: Chest wall weakness 1
   • Clinical significance: May affect strength and appearance of the anterior chest wall

4. Intercostal Brachiocutaneous Nerve

   • Function: Provides sensory innervation to the posterior upper arm
   • Complication if injured: Numbness in the posterior upper arm 1
   • Clinical significance: Sensory deficit but no motor impairment

Vascular Structures at Risk

1. Axillary Vein
   • Complication if injured: Increased risk of lymphedema 1
   • Clinical significance: Careful handling is necessary as stripping increases lymphedema risk

Surgical Approach to Minimize Risk

• A transverse incision in the low axilla from just posterior to the pectoralis major border to the anterior border of the latissimus dorsi provides excellent exposure while minimizing risk 1
• Alternative approach: Vertical incision posterior and parallel to the pectoralis major border 1
• Important: The breast incision and axillary incision should be separate to avoid unnecessary deformity 1

Technical Considerations

• The accuracy of SLNB exceeds 95% when performed by an experienced multidisciplinary team with proper patient selection 2
• Sentinel node identification rate reaches 96.7% when using a combined method of scintigraphy and blue dye 3
• Preservation of identified nerves is essential to minimize post-operative morbidity 1
• Surgeons should have a low threshold to convert to axillary lymph node dissection (ALND) when:
  • The SLNB procedure is technically unsatisfactory
  • Clinically suspicious nodes remain after removal of all sentinel nodes
  • Mapping fails (occurs in approximately 5.6% of cases) 1

Common Pitfalls and Caveats

1. Nerve Identification Challenges

   • The nerves in the axilla can be difficult to identify, particularly in patients with significant adipose tissue
   • Solution: Careful dissection and thorough anatomical knowledge are essential

2. Vascular Injury Risk

   • Axillary vein injury can lead to significant bleeding and increased lymphedema risk
   • Solution: Careful handling of tissues and adequate exposure of the surgical field

3. Technical Failure

   • Mapping failure occurs in approximately 5.6% of cases 1
   • Solution: Be prepared to convert to ALND when necessary

4. Post-Operative Morbidity Awareness

   • Despite being less invasive than ALND, SLNB still carries significant short-term upper-limb morbidity 4
   • Patients should be counseled about potential pain, reduced range of motion, and strength changes

By understanding these anatomical risks and employing meticulous surgical technique, surgeons can minimize complications while achieving accurate axillary staging in breast cancer patients.