NYSORA Textbook of Regional Anesthesia and Acute Pain Management

Chapter 40. Cutaneous Nerve Blocks of the Lower Extremity

Anna Barczewska-Hillel, MD; Jerry D. Vloka, MD

Blocks of the lateral femoral cutaneous, posterior femoral cutaneous, saphenous, sural, and superficial peroneal nerves are useful anesthetic techniques for a variety of superficial surgical procedures. These blocks are simple to learn and perform. They are essentially devoid of complications and can nicely complement major conduction blocks of the lower extremity.1,2 The combination of their applicability and {simplicity} mandate that these blocks should be in the armamentarium of every anesthesiologist.

Indications & Contraindications

Cutaneous nerve blocks of the lower extremity can be used to anesthetize patients for a variety of surgical procedures. The lateral femoral cutaneous nerve block has been used to provide anesthesia for pediatric patients undergoing muscle biopsy3 and to provide analgesia after femoral neck surgery in older patients.4,5 The posterior femoral cutaneous nerve block is used for any surgical procedure performed on the posterior aspect of the thigh.6 The saphenous, sural, and superficial peroneal nerve blocks can be used as part of an ankle block to provide complete anesthesia to the foot and ankle, or they can be used separately to provide anesthesia to specific portions of the foot and ankle. These blocks can be used for a variety of foot and ankle procedures.

The contraindications to performing cutaneous nerve blocks of the lower extremity are few, but include local infection at the sites of needle insertion, preexisting central or peripheral nervous systems disorders, and allergy to local anesthetic.

Functional Anatomy

The cutaneous nerves of the extremities are blocked by injection of local anesthetic in the subcutaneous layers above the muscle fascia. The subcutaneous tissue contains a variable amount of fat, superficial nerves, and vessels. Deep into this area lies a tough membranous layer, deep fascia of the lower extremity enclosing muscles of the leg. Deep fascia is penetrated by numerous superficial nerves and vessels.

The cutaneous innervation of the lower extremity is accomplished by nerves that are part of the lumbar and sciatic plexuses (Figures 40–1 and 40–2). The largest cutaneous nerves are the lateral femoral cutaneous nerve, the posterior femoral cutaneous nerve, the saphenous nerve, the sural nerve, and the superficial peroneal nerve. A more detailed review of the relevant anatomy is provided with a description of the individual block procedures and in Chapter 3.