
Nerve Block (27)
Intramuscular Nerve (Motor Point) Block
Written by Nicolas E. Walsh and Maxim EckmannIndications
Intramuscular nerve blockade is used for diagnostic, prognostic, and therapeutic treatment of non–velocity-dependent muscle tone, flexor spasm, and dystonia.
Techniques
After informed consent is obtained, the patient is positioned comfortably to allow optimal access to the muscles involved. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A skin wheal is raised over the main muscle bulk of the muscles to be injected. A 1½- to 4-in. (4- to 10-cm) insulated needle is advanced through the wheal, with a nerve stimulator used to localize the motor nerve branches or motor points. The current is reduced until the minimum current is required to elicit muscle contraction. When the needle tip is within 1 mm of the motor nerve, and after negative aspiration, 1 to 2 mL of 4% to 6% phenol is injected for neurolysis (see Figure).
Comments
Intramuscular nerve or motor point blockade is reported to have duration of effect from 1 to 36 months (median, 11.5 months). No dose-response or dose-duration of effects relationship has been demonstrated for motor point blocks (51,52). The needle is positioned to produce the maximal twitch at the lowest stimulus. The needle is usually adjacent to the nerve when 0.5 to 0.1 mA produces motor stimulation with an insulated needle, and 1 mA with an uninsulated needle. The motor points of each muscle cluster at the midpoint of the muscle fibers.
Complications
Significant complications are rare with intramuscular nerve injections, and transitory side effects include pain of mild intensity, tenderness and swelling at injection sites, and dysesthesia. Inadvertent neurolysis of a mixed nerve results in painful paresthesia in about 11% of patients.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Saphenous Nerve Block At The Ankle
Written by Nicolas E. Walsh and Maxim EckmannIndications
Saphenous nerve blockade is used to diagnose and treat pain disorders of the saphenous nerve distribution in the foot.
Techniques
After informed consent is obtained, the patient is placed in a prone position with the foot elevated on a pillow. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1-in. (2.5-cm), 25-gauge needle is inserted immediately above and anteriorly to the medial malleolus and advanced to the anterior border of the tibia. After negative aspiration, 3 to 5 mL of local anesthetic is injected over the course of the needle to block the saphenous nerve (see Fig. 67-19).
FIGURE 67-19. Nerve blocks at the ankle. Approach for nerve injection and neural blockade at the ankle.
Comments
The saphenous nerve is the terminal branch of the femoral nerve. It becomes cutaneous at the lateral aspect of the knee joint and follows the great saphenous vein to the medial malleolus. It supplies cutaneous innervation to the medial aspect of the lower leg anterior to the medial malleolus and the medial aspect of the foot, and may extend as far forward as the metatarsophalangeal joint.
Complications
Hematoma and intravascular injection are possible due to the close proximity of the great saphenous vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Deep Peroneal Nerve Block At The Ankle
Written by Nicolas E. Walsh and Maxim EckmannIndications
Deep peroneal nerve blockade is used to diagnose and treat pain disorders in the deep peroneal nerve distribution of the foot.
Techniques
After informed consent is obtained, the patient is placed in a supine position with the foot elevated on a pillow. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1-in. (2.5-cm), 25-gauge needle is inserted between the extensor hallucis longus tendon and the anterior tibial tendon, just superior to the level of the malleoli. The extensor hallucis longus tendon can easily be identified by having the patient extend the great toe. If the artery can be palpated, the needle is placed just laterally to the artery. The needle is advanced toward the tibia, and after negative aspiration, 3 to 5 mL of local anesthetic is injected deep to the fascia to block the deep peroneal nerve (see Fig. 67-19).
FIGURE 67-19. Nerve blocks at the ankle. Approach for nerve injection and neural blockade at the ankle.
Comments
The deep peroneal nerve travels down the anterior portion of the interosseus membrane of the leg and extends midway between the malleoli onto the dorsum of the foot. At this point, the nerve lies laterally to the extensor hallucis longus tendon and the anterior tibial artery. It supplies motor innervation to the short extensors of the toes and cutaneous innervation to adjacent areas of the first and second toes.
Complications
Hematoma and intravascular injection are possible due to the close proximity of the anterior tibial vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Superficial Peroneal Nerve Block At The Ankle
Written by Nicolas E. Walsh and Maxim EckmannIndications
Superficial peroneal nerve blockade is used to diagnose and treat pain disorders of the superficial peroneal nerve distribution in the foot.
Techniques
After informed consent is obtained, the patient is placed in a supine position with the foot elevated on a pillow. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1-in. (2.5- cm), 25-gauge needle is inserted just laterally to the anterior border of the tibia at the proximal level of the lateral malleolus. The needle is carefully advanced to the superior aspect of the lateral malleolus. After negative aspiration, 5 mL of local anesthetic is injected over the course of the needle to block all the branches of the superficial peroneal nerve (see Fig. 67-19).
FIGURE 67-19. Nerve blocks at the ankle. Approach for nerve injection and neural blockade at the ankle.
Comments
The superficial peroneal nerve exits the deep fascia of the leg at the anterior aspect of the distal two thirds of the leg. From that point, the superficial peroneal nerve runs subcutaneously to supply the dorsum of the foot and toes, with the exception of the contiguous surfaces of the great and second toes.
Complications
Complications are rare with the superficial peroneal nerve block.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Sural Nerve Block At The Ankle
Written by Nicolas E. Walsh and Maxim EckmannIndications
Sural nerve blockade is used to diagnose and treat pain disorders in the sural nerve distribution.
Techniques
After informed consent is obtained, the patient is placed in a prone position with the foot supported by a pillow. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A skin wheal is raised lateral to the Achilles tendon at the level of the lateral malleolus. A 1-in. (2.5-cm), 25-gauge needle is inserted to a depth of 1 cm, directed toward the lateral border of the fibula. If a paresthesia is elicited, 2 to 3 mL of a local anesthetic is injected after negative aspiration. If a paresthesia cannot be elicited, after negative aspiration, 3 to 5 mL of local anesthetic is injected subcutaneously in a fan distribution from the lateral border of the Achilles tendon to the lateral border of the fibula to block the sural nerve (see Fig. 67-19).
FIGURE 67-19. Nerve blocks at the ankle. Approach for nerve injection and neural blockade at the ankle.
Comments
The sural nerve is a cutaneous nerve that contains fibers from both the tibial and common peroneal nerves. It lies subcutaneous somewhat distally to the middle of the leg and travels with the short saphenous vein behind and below the lateral malleolus. It supplies the posterolateral surface of the leg, the lateral side of the foot, and the lateral aspect of the fifth toe.
Complications
Intraneural injection may result in nerve damage. Severe pain on injection suggests the possibility of an intraneural injection, and the needle should be immediately repositioned. Hematoma and intravascular injection are possible, owing to the close proximity of the sural vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Tibial Nerve Block At The Ankle
Written by Nicolas E. Walsh and Maxim EckmannIndications
Tibial nerve blockade is used to treat pain disorders in the tibial nerve distribution of the foot.
Techniques
After informed consent is obtained, the patient is placed in the prone position with the foot supported by a pillow. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A skin wheal is raised along the medial aspect of the Achilles tendon at the level of the superior border of the medial malleolus. A 1-in. (2.5-cm), 25-gauge needle is advanced through the wheal toward the posterior aspect of the tibia, behind the posterior tibial artery. If a paresthesia is elicited after negative aspiration, 3 to 5 mL of local anesthetic is injected after negative aspiration. If a paresthesia is not elicited, the needle is advanced until the tibial periosteum is contacted. The needle is withdrawn 0.5 cm, and after negative aspiration, 5 to 7 mL of local anesthetic is injected to block the posterior tibial nerve. A nerve stimulator may be used to identify the posterior tibial nerve by eliciting contraction of muscles in the sole of the foot (Fig. 67-19).
FIGURE 67-19. Nerve blocks at the ankle. Approach for nerve injection and neural blockade at the ankle.
Comments
The posterior tibial nerve is located along the medial aspect of the Achilles tendon, lying just behind the posterior tibial artery. The nerve gives off a medial calcaneal branch to the medial aspect of the heel, then divides behind the medial malleolus into the medial and lateral plantar nerves. The medial plantar nerve supplies the medial two thirds of the sole of the foot as well as the plantar portion of the medial three and onehalf toes. The lateral plantar nerve supplies the lateral one third of the sole and the plantar portion of the lateral one and onehalf toes.
Complications
Intraneural injection may result in nerve damage. Severe pain on injection suggests the possibility of an intraneural injection, and the needle should be repositioned immediately. Hematoma and intravascular injection are possible due to the close proximity of the posterior tibial vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Saphenous Nerve Block At The Knee
Written by Nicolas E. Walsh and Maxim EckmannIndications
Saphenous nerve blockade is useful as a diagnostic, prognostic, or therapeutic procedure in painful disorders involving the knee, ankle, and foot.
Techniques
After informed consent is obtained, the patient is placed in the supine or lateral position. The saphenous nerve is located at the medial surface of the medial condyle of the femur at about the same level as the apex of the patella. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1½-in. (4-cm), 25-gauge needle is inserted perpendicular to the skin just below the medial surface of the tibial condyle. After negative aspiration, 5 to 10 mL of local anesthetic is injected subcutaneously to block the saphenous nerve (Fig. 67-18).
FIGURE 67-18. Saphenous nerve block at the knee. Approach for saphenous injection and neural blockade at the knee.
Comments
The saphenous nerve is the terminal branch of the femoral nerve. It provides cutaneous innervation to the skin overlying the medial, anteromedial, and posteromedial aspects of the leg from just above the knee to the level of the medial malleolus and, in some patients, to the medial aspect at the base of the great toe. There is no motor component.
Complications
The saphenous vein may accompany the saphenous nerve, and the patient should be made aware of the possibility of a hematoma from venous puncture. Other complications from the saphenous nerve block are rare, especially when care is taken to avoid an intraneural injection. Severe pain on injection suggests the possibility of an intraneural injection, and the needle should be repositioned immediately.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Common Peroneal Nerve Block At The Knee
Written by Nicolas E. Walsh and Maxim EckmannIndications
Common peroneal nerve blockade is useful as a diagnostic, prognostic, or therapeutic procedure in painful disorders involving the ankle and foot.
Techniques
After informed consent is obtained, the patient is placed in the supine or lateral position. The common peroneal nerve can be easily palpated as it crosses the neck of the fibula. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1-in. (2.5-cm), 25-gauge needle is inserted next to the nerve and advanced to contact the periosteum, with care being taken to avoid an intraneural injection. A sudden, intense pain on injection suggests intraneural injection. If this occurs, the needle should be repositioned before proceeding. A nerve stimulator may be used to identify the nerve by eliciting contraction of the anterior compartment muscles. The needle is withdrawn slightly, and after negative aspiration, 5 mL of local anesthetic is injected to block the peroneal nerve (see Fig. 67-17).
FIGURE 67-17. Tibial and common peroneal nerve block at the knee. Approach for tibial and common peroneal nerve injection and neural blockade at the knee. Tibial and common peroneal (lateral popliteal) nerve.
Comments
The common peroneal nerve is about half the size of the tibial nerve and contains articular branches to the knee joint. It provides motor innervation to the extensor muscles of the foot and cutaneous nerves to the lateral aspect of the leg, heel, and ankle. It separates from the tibial nerve at the superior aspect of the popliteal fossa and courses laterally around the fibular head where it divides into the deep and superficial peroneal nerves.
Complications
Complications from the common peroneal nerve block are rare, especially when care is taken to avoid an intraneural injection. Severe pain on injection suggests the possibility of an intraneural injection, and the needle should be immediately repositioned.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Tibial Nerve Block At The Knee
Written by Nicolas E. Walsh and Maxim EckmannIndications
Tibial nerve blockade is useful as a diagnostic, prognostic, or therapeutic procedure in painful disorders involving the ankle and foot.
Techniques
After informed consent is obtained, the patient is placed in the prone position. The knee is flexed to allow palpation of the superior popliteal fossa borders and identification of the skin crease behind the knee joint. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1½-in. (3- to 4-cm), 21- to 23-gauge needle is inserted just above the crease line in the middle of the popliteal fossa. A nerve stimulator is used to identify the tibial nerve by eliciting plantar flexion of the foot. The average depth from skin to nerve in adults is 1.5 to 2 cm. After negative aspiration, 5 mL of local anesthetic is injected to block the tibial nerve (Fig. 67-17).
FIGURE 67-17. Tibial and common peroneal nerve block at the knee. Approach for tibial and common peroneal nerve injection and neural blockade at the knee. Tibial and common peroneal (lateral popliteal) nerve.
Comments
The tibial nerve is the larger of the two branches of the sciatic nerve and supplies motor innervation to the flexor muscles at the back of the knee joint and calf. The cutaneous innervation supplies the skin overlying the popliteal fossa and down the back of the leg to the ankle. It travels through the center of the popliteal fossa as it proceeds distally down the leg.
Complications
Hematoma and intravascular injection are possible, owing to the close proximity of the popliteal vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Indications
Sciatic nerve blockade is typically used to treat painful conditions of the lower leg such as complex regional pain syndrome and to facilitate physical therapy by decreasing pain in the lower extremity.
Techniques
A regional block of the sciatic nerve can be achieved anywhere along the course of the nerve. Most of the approaches have been developed mainly to avoid positioning problems that may be present in trauma patients or elderly people. The nerve can be blocked at the sciatic notch, at the level of the ischial tuberosity, greater trochanter, or superior aspect of the popliteal fossa.
Classic Approach
The classic technique described by Labat (37) blocks the nerve at the level of the greater sciatic notch, using the piriformis muscle as a landmark. After informed consent is obtained, the patient is placed in the lateral Sims’ position with the side to be blocked uppermost. The upper knee is flexed, and the patient’s back is rotated slightly forward. Some patients may find this position uncomfortable, particularly those with orthopedic problems.
The landmarks are the cephalad portion of the greater trochanter and the posterosuperior iliac spine. A line is drawn connecting these two points, corresponding to the superior border of the piriformis muscle and the upper border of the sciatic notch. A perpendicular line is drawn distally from the midpoint of the first line. The point of injection is 3 to 5 cm distal on the perpendicular line. Verification of the insertion point can be made by drawing a third line connecting the cephalad portion of the greater trochanter and the sacrococcygeal joint. This third line is used to compensate for the height of the patient. The intersection of lines 2 and 3 is the point of needle insertion (Fig. 67-15).
FIGURE 67-15. Sciatic nerve block: classic approach. Classic approach for sciatic nerve injection and neural blockade.
The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 4- to 5-in. (10- to 12-cm), 22-gauge spinal needle is introduced at right angles to the skin and advanced to a depth of 6 to 10 cm until a paresthesia is reported in the distribution of the sciatic nerve, preferably involving the foot. If periosteum is contacted, the needle is then redirected medially or superiorly. Touching the periosteum may produce a local paresthesia, which could be mistaken for a true sciatic nerve paresthesia. A nerve stimulator is extremely helpful in locating the nerve (39).
Doppler ultrasound also can be used to locate the dominant arterial structure within the sciatic notch (40). The needle is then advanced in the same orientation as the probe until a paresthesia is obtained. Successful blockade has been reported after one or two attempts in 70% of patients. After negative aspiration for blood, 20 to 30 mL of local anesthetic is injected to block the sciatic nerve.
A continuous sciatic nerve block can be performed by using a standard 16-gauge intravenous infusion cannula attached to a nerve stimulator. After obtaining muscle contraction in the lower leg, preferably dorsal or plantar flexion of the foot, an epidural catheter is advanced about 6 cm into the neurovascular space. Continuous infusion of a local anesthetic using an infusion pump can then be used to provide continuous analgesia (41). With the classic approach, both the posterior femoral cutaneous and pudendal nerves are usually blocked with the sciatic nerve.
Posterior Approach
An alternate approach may be used, with the patient positioned as above or prone. The ischial tuberosity and the greater trochanter are identified and a line drawn connecting these two points. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 3- to 4-in. (8- to 10-cm), 22-gauge spinal needle is inserted at the midpoint of the line until a paresthesia is elicited in the lower leg. After negative aspiration, 20 to 30 mL of local anesthetic is injected to block the sural nerve. The posterior femoral cutaneous nerve is often blocked at this level, but the pudendal nerve is frequently spared.
Anterior Approach
The anterior approach allows the sciatic nerve to be blocked without moving the patient, enabling the patient to remain in the supine position (37,42). This approach is especially helpful in trauma patients with a painful leg, but it is quite painful, and sedation is often necessary. The nerve is very deep at this point and can be difficult to locate. In adults, the sciatic neurovascular compartment is usually 4.5 to 6 cm below the surface of the femur. In children, however, the distance varies according to age and size of the child (43). The use of a nerve stimulator is advised in identifying the nerve. The posterior cutaneous nerve of the thigh may not be blocked with this approach, as tourniquet pain could result if a thigh tourniquet is applied (Fig. 67-16).
FIGURE 67-16. Sciatic nerve block: anterior approach. Anterior approach for sciatic nerve injection and neural blockade. Cross section of the leg at the level of the lesser trochanter to show the relationship between the sciatic nerve and femur and the fascia separating it from the adductor magnus.
The patient is placed in the supine position with the leg in a neutral position. The anterosuperior iliac spine and the pubic tubercle are identified and marked. A line is then drawn connecting these two points, overlying the inguinal ligament, and trisected into equal parts. A perpendicular line is drawn distally from the junction of the medial and middle thirds. A third line is drawn parallel to the first, starting from the cephalad aspect of the greater trochanter. The point of intersection of this third line and the perpendicular line is the insertion point of the needle.
The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 6-in. (15- cm), 22-gauge spinal needle is inserted and directed slightly laterally from a plane perpendicular to the skin. The needle is advanced until periosteum is contacted (usually the lesser trochanter). The needle is partially withdrawn and redirected medially and posteriorly to pass about 5 cm beyond the femur until a paresthesia is elicited. After negative aspiration, 20 to 25 mL of local anesthetic agent is injected to block the sural nerve.
Lateral Approach
The lateral approach, initially described by Ichiyanaghi (44), was found to be very difficult and never became popular. A new lateral approach described by Guardini et al. (45) is easier. It blocks the sciatic nerve just posterior to the quadratus femoris muscle in the subgluteal space.
The greater trochanter is identified, and the patient is prepared in a standard sterile fashion. A 5- to 6-in. (12- to 15-cm), 22-gauge spinal needle is advanced 3 cm distal to the maximum lateral prominence of the trochanter, close to its posterior margin. The needle is inserted until the periosteum is contacted. The needle is then partially withdrawn and redirected posteriorly and medially to slide beneath the femoral shaft until a paresthesia, or contraction of the calf or the anterior compartment muscles, occurs with the use of a nerve stimulator. After negative aspiration, 20 to 30 mL of local anesthetic is injected to block the sural nerve.
The main advantage of this technique is that the patient can remain in the supine position and the leg need not be manipulated. When using a nerve stimulator, it is important to make sure that the muscle contractions occur in the calf muscles or in the muscles of the anterior compartment. It is possible with this technique to stimulate inadvertently the nerve branch supplying the two heads of the biceps femoris muscle, producing thigh muscle contraction and misplacement of the local anesthetic.
Comments
The sciatic nerve is the largest in the body. It arises from both the lumbar and sacral plexuses. Anatomically, the sciatic nerve consists of two major nerve trunks: the tibial and common peroneal components. The tibial nerve is derived from the anterior rami of L4 to S3 nerve roots. The common peroneal nerve is derived from the dorsal branches of the anterior rami of the same roots. It leaves the pelvis along with the posterior cutaneous nerve of the thigh through the sciatic foramen beneath the inferior margin of the piriformis muscle. It passes halfway between the greater trochanter and the ischial tuberosity. It becomes superficial at the inferior border of the gluteus maximus muscle and travels down the posterior aspect of the thigh. At the superior aspect of the popliteal fossa, the sciatic nerve physically separates into the tibial and common peroneal nerves.
In the past, the sciatic nerve block was considered unreliable, technically difficult, and uncomfortable for the patient. Sedation was often required, and this interfered with the patient’s ability to provide accurate verbal feedback. This was especially the case if a paresthesia was used to identify the nerve. Reported rates of success ranged between 33% and 95% using various techniques. Today’s insulated needles and nerve stimulators have made it easier to perform this block safely in sedated or even anesthetized patients with a higher rate of success.
Complications
Although the sciatic nerve is composed of mostly somatic nerves, it has a sympathetic component. The resulting sympathetic block may allow some mild venous pooling, but this is usually insufficient to cause clinically significant hypotension. Residual dysesthesias have been reported but usually improve in 1 to 3 days. This may be the result of nerve injury from the use of long beveled needles. Using short beveled needles for regional blocks may decrease the incidence of nerve injury.
Source: Physical Medicine and Rehabilitation - Principles and Practice
More...
Indications
Obturator nerve blockade is extremely useful as a diagnostic, prognostic, or therapeutic procedure in patients with adductor spasm that interferes with rehabilitation or personal hygiene.
Techniques
After informed consent is obtained, the patient is placed in the supine position with the leg to be blocked placed in slight abduction. It is not necessary to shave the pubic area. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 3-in. (8-cm), 22-gauge needle is inserted perpendicular to the skin at a point 1.5 cm lateral and inferior to the pubic tubercle. The needle is advanced until the inferior ramus of the pubis is contacted. The needle depth at which the bone is contacted should be noted. The needle is withdrawn to skin level and redirected in a lateral and slightly superior direction, parallel to the superior ramus of the pubis. The needle is advanced 2 to 3 cm beyond the previously noted depth until a paresthesia is elicited. A nerve stimulator makes it relatively easy to identify the obturator nerve by adductor muscle contraction. After negative aspiration for blood, 10 mL of local anesthetic is injected to block the obturator nerve. This traditional approach was first described by Labat (37) (Fig. 67-14).
FIGURE 67-14. Obturator nerve block. Approach for obturator nerve injection and neural blockade. Using the above techniques, Wassef has described an alternative approach using the femoral artery and adductor longus tendon as landmarks (38). A mark is made on the skin 1 to 2 cm medial to the femoral artery just below the inguinal ligament. This mark is used to indicate the direction of the needle toward the obturator canal. The adductor longus tendon is then identified near its insertion site at the pubis. A 3-in. (8-cm), 22-gauge insulated needle is introduced behind the adductor longus tendon and directed laterally, with a slight posterior and superior inclination toward the skin mark. The needle is advanced until adductor muscle contraction is elicited with a nerve stimulator (39).
Comments
The obturator nerve is formed by the union of the ventral branches of the anterior primary rami of L2, L3, and L4 within the substance of the psoas muscle. It emerges from the medial border of the psoas muscle at the brim of the pelvis. The nerve runs caudad and anteriorly along the lateral wall of the pelvis, along the obturator vessels to the obturator foramen. There it enters the thigh, supplying the adductor muscles and providing innervation to the hip and knee joints.
As the nerve passes through the obturator canal, it divides into anterior and posterior branches. The anterior branch supplies the hip joint, the anterior adductor muscles, and cutaneous branches to the medial aspect of the thigh. The cutaneous innervation of the obturator nerve can be extremely variable and can be nonexistent in some people. The posterior branch supplies the deep adductor muscles and frequently sends a branch to the knee joint.
This procedure is often performed on rehabilitation patients with spasticity or contractures that result in positioning difficulty. Confirmation of a successful obturator nerve block is demonstrated by paresis of the adductor muscles because the cutaneous contribution of the obturator nerve is inconsistent. An alternative to this procedure is selective root blockade at levels L2, L3, and L4 using a nerve stimulator to establish muscle innervation.
Complications
Hematoma and intravascular injection are possible due to the close proximity of the obturator vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Indications
Femoral nerve blockade is useful in conjunction with other lower extremity blocks in treating complex regional pain syndrome and as an aid to decrease knee and ankle pain during physical therapy.
Techniques
After informed consent is obtained, the patient is placed in the supine position, and the femoral artery is located. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. The femoral artery is palpated below the inguinal ligament. A 1½-in. (4-cm), 22-gauge needle is inserted 1 to 2 cm below the inguinal ligament and lateral to the femoral artery. The needle is advanced in a lateral and posterior direction just distal to the inguinal ligament. A characteristic pop, when using a short, beveled needle, can be used to identify penetration of the fascia lata and the fascia iliaca, remembering that the femoral nerve lies deeper than both. When a nerve stimulator is used, contraction of the quadriceps muscle confirms correct placement of the needle. After negative aspiration, 10 mL of local anesthetic is injected to block the femoral nerve (Fig. 67-13).
FIGURE 67-13. Femoral nerve block. Approach for femoral nerve injection and neural blockade.
Comments
At the level of the inguinal ligament, the femoral nerve lies anterior to the iliopsoas muscle and slightly lateral to the femoral artery. It does not lie within the femoral sheath. The nerve lies underneath the fascia lata and fascia iliaca within its own sheath. At the level of the inguinal ligament, the femoral nerve divides into anterior (superficial) and posterior (deep) bundles. The anterior bundle provides cutaneous innervation of the skin overlying the anterior surface of the thigh as well as providing motor innervation to the sartorius muscle. The posterior bundle provides innervation to the quadriceps muscles and the knee joint. It also gives off the saphenous nerve, which supplies cutaneous innervation to the medial aspect of the calf to the level of the medial malleolus. A catheter also can be placed within the femoral nerve sheath for continuous infusion of local anesthetics.
It is important to remember that the upper portion of the anterior thigh is innervated by the ilioinguinal and genitofemoral nerves and is not blocked when performing a femoral nerve block.
Complications
Significant complications associated with femoral nerve blockade are uncommon. Dysesthesia may result if the nerve is injured during the injection. Hematoma at the site is a possibility but is usually not clinically significant. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma. The presence of a femoral artery vascular graft is a relative contraindication to femoral nerve blockade.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Lateral Femoral Cutaneous Nerve Block
Written by Nicolas E. Walsh and Maxim EckmannIndications
Lateral femoral cutaneous nerve blockade is useful for diagnosing and treating pain in the lateral thigh, thought to be from irritation of this nerve.
Techniques
After informed consent is obtained, the patient is placed in a supine position, and the anterosuperior iliac spine is palpated. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 1½-in. (4-cm), 21- to 23-gauge needle is inserted 1 cm medially and below the anterosuperior iliac spine. The needle is advanced deeply into the fascia lata toward the shelving of the iliac crest. After negative aspiration, 5 mL of local anesthetic is injected in a fanwise manner (Fig. 67-12).
This nerve can be blocked through an alternative approach by directing the needle superiorly beneath the inguinal ligament into the fascial compartment containing the nerve above the level of the inguinal ligament. This fascial compartment can be identified by directing a short, beveled needle medially to the anterosuperior iliac spine and advancing through the external oblique aponeurosis, the internal oblique muscle, and the fascia iliaca. The short, beveled needle allows the physician to feel a distinct loss of resistance or characteristic pop as the two fascial layers are penetrated. After negative aspiration, 5 mL of local anesthetic is injected to block the lateral femoral cutaneous nerve.
FIGURE 67-12. Lateral femoral cutaneous nerve block. Approach for lateral femoral cutaneous nerve injection and neural blockade.
Comments
The lateral femoral cutaneous nerve emerges along the lateral border of the psoas muscle below the ilioinguinal nerve. It runs obliquely under the iliac fascia across the iliacus muscle and enters the thigh by passing posteriorly to the inguinal ligament, just medial to the anterosuperior iliac spine. It provides cutaneous innervation to the lateral aspect of the thigh to the knee. A large area over the lateral aspect of the thigh can be easily blocked with this technique.
Complications
The lateral femoral cutaneous nerve block has no significant complications, with the rare exception of a dysesthesia if the nerve is injured during the injection. Severe pain on injection suggests the possibility of an intraneural injection, and the needle should be immediately repositioned. It is possible to block the femoral nerve inadvertently when large amounts of local anesthetic is injected, resulting in a temporary weakness of knee extension and impaired ambulation. This occurs secondary to the medial spread of local anesthetic beneath the fascia iliaca.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Indications
The caudal approach to the epidural space is used to treat pain in the lower back and pelvis.
Techniques
After informed consent is obtained, the patient may be placed in a variety of positions, with patient comfort probably as the prime concern. The preferred position is the lateral Sims’ position with the left side down for right-handed clinicians. With the upper leg flexed, the buttocks are separated, allowing easy access to the sacral-coccygeal junction. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. The midline is identified by palpating the tip of the coccyx with a finger and moving cephalad about 4 to 5 cm in an adult, until the fingertip lies over the sacral hiatus with the sacral cornua palpable on each side. The palpating hand is kept in position, and a 2-in. (5-cm), 18-gauge short, beveled needle is inserted. The initial angle of insertion is about 120 degrees to the coccyx. A “pop” is felt as the sacrococcygeal ligament is penetrated. The needle is then depressed to align with the long axis of the canal and inserted 1 cm. Once the caudal space has been entered, epidural positioning is confirmed by negative aspiration blood or CSF, then 40 to 80 mg of methylprednisolone acetate or 6 mg mixture of betamethasone sodium phosphate and acetate is injected. The steroids can be injected as is or diluted in 5 to 10 mL of preservative-free normal saline (Fig. 67-11).
FIGURE 67-11. Caudal injection. A: Landmarks and approach for needle insertion. B: Needle insertion through sacral- coccygeal membrane for injection.
Comments
Epiduroscopy, a technique used to visualize the lumbar epidural space, depends on this approach because the fiberoptic catheter cannot tolerate bending. Advantages of this approach include minimal risk for inadvertent dural puncture. Continuous catheter techniques can be used, but maintenance of site cleanliness is more difficult when compared with the lumbar approach to the epidural space. A Tuohy needle is not used for catheter placement because it will direct the catheter against the wall of the caudal canal and make catheter advancement difficult. Caudal epidurals and epidural lysis of adhesions can be performed via radiopaque catheter through a nonshearing needle under fluoroscopic guidance. Betamethasone sodium phosphate and acetate mixture is best used for localized nerve root irritation. Triamcinolone diacetate is water soluble and results in optimal outcome in generalized nerve root irritation such as arachnoiditis.
Complications
Improper needle placement can result in inadequate or absent block. This is due to variability in anatomy and inexperience. Rapid injection of large volumes of fluid is not recommended because this may result in large increases in CSF pressures, with the risk for cerebral hemorrhage, visual disturbances, headache, or compromised spinal cord blood flow. Pain at the injection site is a common complaint. Urinary retention can result from local anesthetic injection and should last only as long as the block.
Source: Physical Medicine and Rehabilitation - Principles and Practice
Latest Items
Chính sách bảo mật
Hits:255 Chính sách & Hướng dẫn BS Mai Trung Dũng
Cám ơn quý khách đã truy cập vào website Điều Trị Đau Shop được vận hành bởi CÔNG TY CỔ PHẦN PHÁT TRIỂN KHOA HỌC KỸ THUẬT Y SINH - BIOMEDICAL TECH. Chúng tôi tôn trọng và cam kết sẽ...
Read more