THE fascia iliaca compartment block 1has been used to provide postoperative analgesia after knee and hip surgery. 2–4This nerve block may be performed before induction, during the course of anesthesia, or after emergence. The safety of performing regional anesthesia in an anesthetized adult patient has been questioned. It is essential that every effort be made to minimize the potential for nerve damage because the warning signs of paresthesia or pain are lost during injection. Use of a fascia iliaca compartment block rather than a traditional (three-in-one) femoral nerve block should provide an additional margin of safety because the needle is inserted in an area distant from the femoral nerve and vessels. We report a case in which a patient underwent a fascia iliaca compartment block at completion of surgery during spinal anesthesia and in which hypoesthesia subsequently developed, and resolved after 8 days, in the distribution of the femoral nerve.
A 78-yr-old woman with a history of degenerative joint disease was scheduled to undergo left total hip replacement. Medical history was positive for hypertension, mild mitral regurgitation, paroxysmal atrial fibrillation, chronic active hepatitis, and hypothyroidism. The patient had no history of diabetes and no preexisting neuropathy.
She received an L3–L4 spinal anesthetic, which consisted of 15 mg isobaric bupivacaine, 0.5%, and 25 μg fentanyl. The surgical procedure was uneventful. The patient received 3 mg midazolam and 150 μg fentanyl intravenously during the 3-h procedure. At completion of the surgical procedure, a left fascia iliaca compartment block was performed, as described by Dalens et al. , 1to block the femoral and the lateral femoral cutaneous nerves. The injection is administered approximately 1 cm below the inguinal ligament, at the junction of the lateral third and the medial two thirds of a line that joins the pubic spine to the anterior superior iliac spine (fig. 1A). After the short bevel needle traverses the skin, two “pops” are felt. The first corresponds to the fascia lata, the second to the fascia iliaca (fig. 1B). A loss of resistance then is experienced. Forty milliliters of bupivacaine, 0.5%, was injected without untoward effects. The patient was admitted to the postanesthesia care unit.
After resolution of the spinal anesthetic, the anterior, medial, and lateral aspects of the left thigh remained anesthetized, indicating a successful fascia iliaca compartment block. The patient reported mild left hip pain (visual analog scale score, 2 or 3) that was controlled readily using oral analgesics.
Twenty-four hours later, the patient continued to exhibit complete anesthesia over the anterior thigh. No hypoesthesia was found in the areas innervated by the lateral femoral cutaneous nerve (i.e., lateral aspect of the thigh) or by the obturator nerve (i.e., medial aspect of the knee.) Motor strength of the quadriceps muscle seemed to be decreased; however, accurate evaluation was hindered by postoperative pain. No decrease was noted in muscular strength of the adductor muscle group. There was no tight dressing or hematoma. Hypoesthesia resolved over the ensuing week, with complete resolution occurring on the eighth postoperative day. Because of the rapid resolution of the neuropathy, a neurologist was not consulted.
Numerous advantages have been attributed to regional versus general anesthesia for lower limb surgery, including prolonged postoperative pain control. However, there is controversy whether performing regional anesthesia is safe in an anesthetized adult patient (in the current case, we performed a fascia iliaca compartment block in a patient during spinal anesthesia) and whether the benefits outweigh the risks, as they do in pediatric anesthesia. 5
Results of numerous studies have supported the belief that pain or paresthesia during needle placement or injection is a warning sign of potential nerve damage. 6,7Use of a peripheral nerve stimulator permits the induction of regional anesthesia in an anesthetized patient. It does not eliminate the risk of anesthesia-related nerve damage. 8,9Moreover, it is unnecessary to perform a fascia iliaca compartment block. 3
There are reports of neurologic complications after femoral nerve blockade, but none to our knowledge after fascia iliaca compartment block. Dalens et al . 1described the use of this block in children, followed by subsequent reports of its use in adults. 10In addition, a continuous catheter technique has been used to provide prolonged postoperative analgesia. 3When using a nerve block for postoperative analgesia after total hip replacement, a fascia iliaca compartment block provides more reliable blockade of the lateral femoral cutaneous nerve than does a three-in-one block. This results in more effective analgesia in the area of the skin incision. 10
The point of needle insertion should be distant from the course of the femoral nerve; therefore, we performed a fascia iliaca compartment block rather than a femoral nerve block in an anesthetized patient. The needle insertion point is approximately midway between the femoral artery and the anterior superior iliac spine, i.e., approximately 4 cm lateral to the artery in an average-sized person. It is our practice to identify these two landmarks (and hence the position of the femoral nerve immediately lateral to the femoral artery) as a safeguard to avoid inadvertent insertion of the needle in the direction of the nerve. The width of the femoral nerve at this level is 9–4 mm, 11which makes it unlikely but not impossible 3that the needle is inserted into the lateral aspect of the nerve.
The femoral nerve is derived from the dorsal branches of the second, third, and fourth lumbar ventral rami. It descends initially within the substance of the psoas muscle, emerges from its lower lateral border, and descends to enter the thigh deep into the inguinal ligament, in the groove between the psoas and the iliacus muscles, immediately lateral to the femoral artery. The fascia iliaca separates the nerve from the femoral vessels. Slightly before or at the entrance to to the femoral triangle, the femoral nerve separates into numerous branches that supply the muscles and skin of the anterior thigh, knee, and hip joints. 12Some of the branches of the femoral nerve to the sartorius muscle and neighboring skin depart from the main trunk of the nerve as it emerges under the inguinal ligament. 11
We believe that there are three explanations for the transient neuropathy experienced by the patient: (1) incorrect identification of the point of needle insertion, (2) a normal anatomic variation, leading to unanticipated needle contact with the nerve, or (3) related to the surgery rather than the anesthesia. Incorrect identification is unlikely because the landmarks were identified easily (inguinal ligament, femoral artery, and anterior superior iliac spine) and clearly marked before block performance. Postoperative neuropathies associated with hip surgery have been reported; however, usually these involve the sciatic rather than the femoral nerve. 13,14This case is a reminder that, although we chose a fascia iliaca compartment block to limit the risk of nerve damage, injury still may occur.