What is the procedure for performing a nerve block on the great toe?

Digital Nerve Block for the Great Toe

To perform a digital nerve block on the great toe, use 1% lidocaine without epinephrine as the first-line anesthetic agent, and employ a two-sided web space block technique targeting the digital nerves at the base of the toe. 1

Equipment Needed

• 1% lidocaine without epinephrine (3-5 mL)
• 25-27 gauge needle
• Sterile preparation supplies (antiseptic solution, gloves)
• Optional: sodium bicarbonate to reduce pain of infiltration

Anatomical Considerations

The great toe is innervated by four digital nerves:

• Two dorsal digital nerves (medial and lateral aspects)
• Two plantar digital nerves (medial and lateral aspects)

Step-by-Step Procedure

1. Patient Positioning

   • Position the patient supine with the foot slightly elevated
   • Cleanse the area with antiseptic solution

2. Web Space Block Technique

   • Identify the web space between the great toe and second toe
   • Insert the 25-27G needle at the dorsal web space
   • Advance the needle toward the plantar aspect without penetrating too deeply
   • Aspirate to ensure no intravascular placement
   • Inject 1-2 mL of anesthetic on each side of the toe

3. Medial Digital Nerve Block

   • Insert the needle at the medial aspect of the great toe base
   • Advance to a depth of approximately 0.5-1 cm
   • Aspirate and inject 1-2 mL of anesthetic

4. Testing Block Effectiveness

   • Wait 5-10 minutes for onset of anesthesia
   • Test sensation using pinprick on both dorsal and plantar aspects
   • Ensure complete anesthesia before proceeding with any procedure

Anesthetic Considerations

• Use 1% lidocaine without epinephrine (first choice) 1
  • Onset: 1-3 minutes
  • Duration: 1.5-2.5 hours
  • Maximum dose: 4-5 mg/kg (not to exceed 300 mg total)
• For longer procedures (>1.5 hours), consider 0.75% ropivacaine 1
  • Onset: 3.5-5.5 minutes
  • Duration: 19-23 hours of postoperative analgesia

Important Safety Considerations

• Avoid epinephrine-containing solutions in digits due to risk of ischemia and necrosis 1
• Use low concentrations of local anesthetic (bupivacaine or ropivacaine 0.1-0.25% for single shot) 2
• Monitor distal circulation after the block, especially with circumferential injuries 1
• Do not exceed maximum recommended doses of local anesthetics 1
• Adding sodium bicarbonate to local anesthetics can reduce pain of infiltration 1

Advantages of Digital Nerve Block

• Complete anesthesia of the entire digit
• Avoidance of tissue distortion
• Reduced total anesthetic volume needed
• Prolonged anesthesia duration
• Decreased postoperative discomfort 1

Potential Complications

• Hematoma formation at the injection site
• Nerve damage (rare)
• Local anesthetic systemic toxicity (rare with proper dosing)
• Inadequate anesthesia requiring supplemental block 1

Special Considerations for Pediatric Patients

• Adjust volume based on patient age and weight
• A transthecal digital nerve block can be considered as an alternative technique with a 94% success rate in pediatric patients 3

Digital nerve blocks provide excellent anesthesia and pain relief, and patients may safely be discharged home with residual sensory blockade, provided they receive written instructions about the expected duration of the block and proper care until normal sensation returns 2.