Is a parasternal block the same as a pectoral fascia block?

Parasternal Block vs. Pectoral Fascia Block: Anatomical and Clinical Differences

No, a parasternal block is not the same as a pectoral fascia block (PECS block). These are distinct regional anesthetic techniques that target different anatomical areas and nerve distributions.

Anatomical Differences

Parasternal Block

• Targets the anterior cutaneous branches of T2-T6 intercostal nerves 1
• Provides anesthesia and analgesia to the anterior chest wall/internal mammary region 2
• Two main approaches:
  • Superficial parasternal block: injection between pectoralis major and external intercostal muscles 3
  • Deep parasternal block: injection between internal intercostal muscle and transversus thoracis muscle 4

Pectoral Fascia Block (PECS)

• PECS I: targets lateral and medial pectoral nerves between pectoralis major and minor muscles
• PECS II: extends PECS I to include the anterior branches of intercostal nerves, long thoracic nerve, and thoracodorsal nerve 5
• Primarily targets the anterior chest wall and axilla 6

Clinical Applications

Parasternal Block

• Indicated for:
  • Median sternotomy pain
  • Internal mammary region analgesia
  • Anterior chest wall procedures
  • Post-thoracotomy pain syndrome in the internal mammary region 2

PECS Block

• Indicated for:
  • Breast surgery (particularly lateral and anterior aspects)
  • Recommended for major breast surgery when paravertebral block is contraindicated 5
  • Not indicated for shoulder surgery as it doesn't target the posterior and superior aspects of the shoulder 6

Important Considerations

Parasternal Block Safety Concerns

• Risk of internal mammary artery injury (critical consideration in cardiac surgery patients)
• Proximity to pleura with risk of pneumothorax
• The deep parasternal approach places the needle approximately 3-5mm from the internal mammary artery 4
• Superficial approach may be safer for protecting the internal mammary artery and pleura 1

Complementary Use

• PECS and Serratus Plane Block cannot block the internal mammary region effectively
• Parasternal blocks can complement these techniques when internal mammary region analgesia is needed 2

Recent Developments

• Standardized nomenclature for parasternal blocks is still evolving 7
• Modified approaches to parasternal blocks are being developed to improve local anesthetic spread and reduce required volumes 3
• Deep parasternal blocks provide greater parasternal spread but carry higher risk due to proximity to the internal mammary artery 4

Clinical Decision Making

When choosing between these blocks, consider:

1. The anatomical area requiring analgesia
2. Risk factors (especially for parasternal blocks near the internal mammary artery)
3. The surgical procedure being performed
4. Whether complementary blocks are needed for complete analgesia

For breast surgery specifically, the PROSPECT guidelines recommend paravertebral block as first-line, with PECS blocks as an alternative when axillary node dissection is not performed or paravertebral block is contraindicated 5.