Nerve Block

Nerve Block (27)

Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
Thứ năm, 06 Tháng 3 2014 22:03

Saphenous Nerve Block At The Ankle

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
Thứ tư, 05 Tháng 3 2014 22:58

Sural Nerve Block At The Ankle

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
Thứ tư, 05 Tháng 3 2014 09:52

Tibial Nerve Block At The Ankle

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
Thứ tư, 05 Tháng 3 2014 04:50

Saphenous Nerve Block At The Knee

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
Thứ ba, 04 Tháng 3 2014 11:21

Tibial Nerve Block At The Knee

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Indications

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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
Thứ ba, 04 Tháng 3 2014 04:19

Sciatic Nerve Block

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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.

Refferences

Source: Physical Medicine and Rehabilitation - Principles and Practice
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