- Risks and Complications
What is a deep peroneal nerve block?
A deep peroneal nerve block is a procedure to anesthetize the web space between the big toe and the toe adjacent to it. An anesthetic injection is administered at the midpoint in the lower front of the leg. The anesthetic solution blocks transmission of pain signals by the nerve from the foot to the brain.
The deep peroneal nerve is one of the five nerves that provide muscle function and sensation to the lower leg and foot. The deep peroneal nerve is a terminal division of the common peroneal nerve (also known as common fibular nerve), which is one of the branches of the sciatic nerve.
The deep peroneal nerve provides function to the muscles in the front of the lower leg and the top of the foot, and sensation to the web space between the big toe and its adjacent toe, extending to a small area under the foot adjoining this web space.
Why is a deep peroneal block performed?
A deep peroneal nerve block is administered
- During surgeries involving the foot’s first web space for conditions such as Morton’s neuroma (thickening of tissue around the nerve from toes)
- Along with a superficial peroneal nerve block for
- As a treatment for acute pain on the top of the foot from entrapment of the deep peroneal nerve (anterior tarsal tunnel syndrome)
- For pain management in conditions such as gouty arthritis
- Prior to certain treatment procedures that destroy nerve fibers, such as neurolysis or rhizotomy, to treat chronic nerve pain
A nerve block is superior to local tissue infiltration anesthesia to numb the deep peroneal nerve because:
- It achieves anesthesia in a larger area with just one injection of minimal volume of anesthetic agent
- Reduces complications of wound healing
- Provides better post-operative pain relief
A deep peroneal nerve block is avoided if the patient has
How is a deep peroneal nerve block performed?
Depending on the duration anesthesia is required, the anesthetic agent used may be:
- The patient lies flat on their back.
- The doctor performs a physical examination to assess the patient’s neurovascular function in the foot.
- The patient flexes the big toe to help the doctor visualize the tendon connecting the big toe to the lower leg muscle.
- May use ultrasound guidance and nerve stimulator for the procedure.
- Marks the injection site between the big and second toe tendons in the front of the leg just below the level of the two bony ankle projections.
- Sterilizes the injection area with antiseptic solution.
- Inserts the needle and injects a small amount of the anesthetic solution to raise a bump (wheal) in the skin.
- Advances the needle perpendicularly close to the bone.
- Aspirates the syringe to be certain that the needle is not inside a blood vessel.
- Slowly injects the anesthetic.
- Withdraws the needle and applies pressure to arrest bleeding.
- Gently massages the injection area to help the solution spread in the tissues.
How long does a deep peroneal nerve block last?
The approximate duration that anesthetic effects last are:
- Lidocaine: up to three hours
- Ropivacaine: up to six hours
When the nerve block is combined with a steroid, the long-term pain relief from chronic pain may last for months, though some patients may find no benefit.
What are the risks and complications of a deep peroneal nerve block?
A deep peroneal nerve block is generally a safe procedure. Complications that may occur include:
- Infection at the injection site
- Allergic reaction to the local anesthetic
- Local anesthetic systemic toxicity
- Injection into a blood vessel
- Injury to a blood vessel causing bruising (ecchymosis) and hematoma
- Injury to the deep peroneal nerve causing tingling and numbness (paresthesia)
- Unsuccessful nerve block