To completely numb the great toe, must a ring block be performed or can numbing the median dorsal nerve suffice?

Digital Anesthesia for the Great Toe

A ring block is necessary to completely numb the great toe, as numbing only the median dorsal nerve would provide inadequate anesthesia for procedures involving the entire toe. 1, 2

Anatomy and Innervation of the Great Toe

The great toe receives sensory innervation from multiple nerves:

• Dorsal aspect: Superficial peroneal nerve and deep peroneal nerve branches
• Plantar aspect: Medial plantar nerve (branch of posterior tibial nerve)
• Medial aspect: Saphenous nerve
• Web space: Digital nerves

This complex innervation pattern means that targeting only the median dorsal nerve would leave significant portions of the toe with intact sensation, particularly the plantar and medial aspects.

Recommended Technique: Ring Block

For complete anesthesia of the great toe, a circumferential ring block is the most effective approach:

1. Injection sites: Four-sided approach at the base of the toe

   • Dorsal aspect (2 injections)
   • Plantar aspect (2 injections)
   • Ensure complete circumferential coverage

2. Anesthetic choice:

   • Mixture of short and long-acting agents (e.g., 1:1 mixture of 1% lidocaine and 0.5% bupivacaine) 3
   • Amide local anesthetics are preferred over ester types 4

3. Volume: 3-5 mL total, divided among injection sites

   • Adjust based on patient size

Evidence Supporting Ring Block

Research demonstrates that ring blocks have success rates of 60-100% for digital anesthesia 2. In a study of onychocryptosis surgery (ingrown toenail) of the great toe, complete anesthesia was achieved in over 90% of cases using circumferential blocking techniques 5.

The transthecal digital nerve block technique has shown a 94% success rate in pediatric patients, including 83% success in thumbs, which have similar innervation patterns to the great toe 3.

Limitations of Single Nerve Block Approach

Blocking only the median dorsal nerve would:

• Leave the plantar aspect with intact sensation
• Miss innervation from other nerve branches
• Result in incomplete anesthesia for procedures involving the entire toe

Special Considerations

• Ultrasound guidance: Can improve accuracy and reduce the risk of vascular puncture 4
• Tourniquet use: May require additional nerve blocks depending on tourniquet placement 6
• Sedation: Should be used cautiously, especially in elderly patients 4

Potential Complications

• Local anesthetic systemic toxicity: Calculate safe dose based on patient weight
• Vascular injury: Avoid direct arterial injection
• Nerve injury: Use appropriate technique and needle size

For complete anesthesia of the great toe for any procedure, the ring block technique is superior to isolated nerve blocks, as it ensures coverage of all sensory territories.