Appendix A: Nerve Blocking Techniques

The following is a guide to the performance of some common techniques used in a pain management practice. For other blocks, the reader is referred to any standard textbook of regional anesthesia. Although not specifically mentioned, the anesthesiologist should use their own discretion regarding such details as whether intravenous placement before the block is necessary, whether the patient should be maintained with an empty stomach for several hours before the injection, and whether resuscitative equipment is needed at the bedside.

The complications and side effects mentioned are those specific to the particular nerve block discussed. Other potential complications inherent in any injection technique include intravascular injection, hematoma formation, and infection, the seriousness of which will be determined by the particular site of injection. The anesthesiologist is advised to keep these potential complications in mind when attempting to perform any block.

Technique

See Figure A-1.

The patient lies supine with the neck hyperextended and a thin pillow under the shoulders. The carotid artery is palpated, the trachea identified, and using two fingers, the transverse body of C6 (Chassaignac tubercle) is palpated (block at C7 is associated with a higher incidence of pheumothorax). This is the most prominent of the cervical transverse processes and lies at the level of the cricoid cartilage. A skin wheal is raised and a 22-gauge 1½-inch needle is advanced between the carotid and cricoid perpendicular to the skin until it contacts the transverse process. The needle then is pulled approximately 2 mm back, the syringe is aspirated, and a 1-ml test dose is given. Assuming there is no untoward reaction, the remaining solution is injected. This volume will spread along the fascial plane, typically from the middle cervical ganglion to T4 or T5 ganglion, thus affecting the sympathetic supply to structures of the head and neck, upper extremity, and chest.

Drugs

Use 8 to 20 ml of lidocaine 0.5% to 1%, or bupivacaine 0.25% to 0.5%, or procaine 1%.

Tips

• 1. Patient should be informed to expect a Horner syndrome, hoarseness, and warmth.
• 2. Success of block is confirmed by a Horner syndrome (miosis, ptosis, and anhidrosis) and more importantly, a skin temperature of the arm of at least 2°F greater than the contralateral arm.
• 3. The patient should be cautioned not to swallow or talk during the procedure but should be instructed to communicate paresthesias by raising a hand.
• 4. Avoid bilateral blocks.
• 5. Meticulous aspiration for blood or cerebrospinal fluid should be done before and during the procedure.
• 6. After the block is completed, the patient should be instructed to sit up to avoid undue edema of the airway and promote caudad spread of the drug to the nerve of Kuntz.

Complications and Side Effects

• 1. Vertebral or carotid artery injection with central nervous system toxicity.
• 2. High spinal or epidural injection.
• 3. Pneumothorax.
• 4. Vocal cord paralysis.
• 5. Vasovagal syncope.
• 6. Orthostatic hypotension.

Technique

See Figure A-2.

The patient is positioned prone with a pillow under the hips. At the lateral edge of the paravertebral muscle opposite to the L2 spinous process, a skin wheal is made and the deeper tissues are infiltrated with a local anesthetic. A 20-gauge 6-inch needle is directed medially at a 45° angle under x-ray control. The vertebral body generally is encountered at a depth of approximately 4 in. The anteroposterior and lateral view of the L2 vertebra is important in verifying the depth and location of the needle tip. The position of the needle tip will be satisfactory if it is close to the anterior aspect of the L2 vertebral body. To determine if the needle is still in the psoas sheath, a small 2 to 3-ml injection of normal saline or local anesthetic is attempted. As long as the needle is in muscle, there will be some resistance to injection. The needle then is advanced slowly until it pierces the fascia when a sudden loss of resistance will be felt. (If a needle smaller than 20 gauge is used, this loss of resistance may be missed.) The correct placement of the tip of the needle is verified repeatedly by aspirating with a dry syringe for the presence of blood or spinal fluid. If a permanent chemical sympathectomy is planned, 1 to 2 ml of contrast media is injected, and radiographic evidence of the spread is verified by taking an x-ray to localize the position of the tip of the needle.

For routine diagnostic or therapeutic lumbar sympathetic blocks, radiologic facilities are helpful but not required. The block can be done safely only with the anatomic landmarks described. If the transverse process is encountered (usually at a depth of approximately 2 in, the needle should be redirected caudad to about twice this depth. After correct placement of the needle and after aspiration with a syringe, a 2-ml test dose of local anesthetic solution is injected. After waiting a few minutes to observe for untoward effects, 15 to 20 ml of local anesthetic is injected.

Drugs

• 1. Local anesthetic of 12 to 20 ml of lidocaine 1% or bupivacaine 0.25%.
• 2. Neurolytic of 10 to 15 ml of phenol in saline 6%.

Tips

• 1. Block at L2 alone is usually sufficient to provide sympathectomy to the entire leg; may alternatively be performed at L3. Some prefer individual blocks at L2, L3, and L4, especially for neurolysis since a smaller volume can be used.
• 2. If a neurolytic procedure is done, a permanent copy of the x-ray confirming correct needle position should be retained.

Complications and Side Effects

• 1. Orthostatic hypotension.
• 2. Spinal or epidural injection.
• 3. Injury to kidney, ureter, or renal pelvis.
• 4. Genitofemoral block.

Technique

See Figure A-3.

With the patient in the prone position and a pillow under the abdomen, the T12 and L1 spinous processes and the 12th rib are palpated and marked. The position is confirmed by fluoroscopy if possible. A triangle is drawn using the inferior portion of each spinous process and the third point 7 to 8 cm lateral at the inferior edge of the 12th rib. A skin wheal of local anesthetic is raised at the lateral apex of the triangle, and deeper infiltration along the path is done.

Using a 6-in 20- or 22-gauge needle, the needle is advanced at approximately a 45° angle from the apex, under the inferior edge of the 12th rib toward the body of L1. In an average-sized person, this will approach a depth of approximately 10 to 12 cm. After bony contact is made, the position can be confirmed by fluoroscopy. After this is done and a note is made of the angle and depth of the needle, the needle is redirected so that it ultimately lies 1 to 2 cm beyond the anterolateral edge of the body of L1. Fluoroscopic examination can confirm the position, and aspiration should be done to exclude the possibility of blood, cerebrospinal fluid, or urine aspirate. At this point, a small test dose is given before injection of the usual 20 ml of solution. The same procedure then may be done on the contralateral side.

Drugs

• 1. Local anesthetic of 15 to 20 ml of lidocaine 1% or bupivacaine 0.5%. (A unilateral block with a large volume (50 ml) should provide bilateral anesthesia.)
• 2. Neurolytic of 15 to 20 ml of alcohol 50% to 95% or phenol 6% (phenol 10% in Renografin 76 is useful for observing dispersion of the injection).

Tips

• 1. Patient should be well hydrated before the block.
• 2. Because the left ganglion is usually lower than the right, needle placement on the left should be two-thirds of the way down L1 and, on the right, 1 cm above L1.
• 3. Fluoroscopy with a permanent spot film to confirm needle placement may be desirable for a neurolytic procedure.

Complications and Side Effects

• 1. Orthostatic hypotension.
• 2. Aortic or venacaval puncture with retroperitoneal hematoma.
• 3. Pneumothorax.
• 4. Puncture of liver, spleen, kidney, pancreas, or ureter.
• 5. Neurolytic blocks may result in neuritis, sensory and motor loss, skin sloughing, and alcohol intoxication.

Technique

See Figure A-4.

The patient is positioned in the lateral decubitus position with the painful side down. Standard sterile precautions are observed, and local anesthesia of the injection site is obtained by infiltration. A 17- to 20-gauge Tuohy needle is used, and the epidural space is identified with loss of resistance to air or saline. After the solution is injected slowly, the needle is cleared with 1 ml of a local anesthetic or saline. The patient should remain in the lateral decubitus position for 15 min.

Drugs

• 1. 50 to 100 mg of triamcinolone diacetate in 5 to 10 ml of lidocaine 1% or bupivacaine 0.5%.
• 2. 80 to 120 mg of methylprednisolone acetate also has been used.

Tips

• 1. Injection should be made at the involved level.
• 2. A paramedian approach may be useful for patients who cannot flex and is mandatory for patients with previous posterior spinal fusion.

Complications and Side Effects

• 1. Immediate: high spinal injection.
• 2. Late: spinal headache, exacerbation of symptoms for 24 to 48 h, epidural hematoma, arachnoiditis, adrenal suppression, Cushing syndrome, and neurologic deficit.

Technique

See Figure A-5.

The patient is positioned prone on a radiolucent table with a pillow under the hips. Under fluoroscopic control, the appropriate vertebral level is located in the anteroposterior direction. The image intensifier (or patient) then is rotated until the facet joint space is seen clearly. A skin wheal is raised where an imaginary line from the center of the image intensifier intersects the skin. A 22-gauge 3½-in needle is advanced at right angles to the image intensified under fluoroscopic guidance until it enters the joint.

Drugs

Use 1 to 2 ml of lidocaine 1% or bupivacaine 0.5% followed by 20 to 25 mg of triamcinolone diacetate.

Tips

To confirm needle placement, rotate the patient or image intensifier after the needle is in the joint. The needle should continue to appear to be in the joint regardless of the angle of view.

Complications and Side Effects

• 1. Spinal anesthesia.
• 2. Neurologic deficit.

Technique

See Figure A-6.

With the patient in the prone position, a skin wheal is raised, and a 22-gauge 3½-in needle is inserted 3 cm lateral to the cephalad end of the dorsal spinous process of the vertebral level to be blocked. It is directed perpendicular to the skin to meet the corresponding transverse process. The needle then is redirected so that it lies approximately 3 cm medial and caudad to the transverse process. The aim is to have the tip of the needle close to the intervertebral foramen, where the corresponding nerve emerges. Paresthesias may or may not be elicited.

Drugs

Use 10 ml of lidocaine 1%, bupivacaine 0.5%, or procaine 1%.

Tips

When a paresthesia is elicited, less local anesthetic (6 to 8 ml) will be needed.

Complications and Side Effects

• 1. Subdural, epidural, and subarachnoid block.
• 2. Pneumothorax.
• 3. Hypotension from sympathetic block.

Technique

See Figure A-7.

The following implantation technique for permanent intraspinal narcotic catheters has been used successfully at the Beth Israel Hospital in Boston:

“After informed consent is obtained, the patient is given a dose of an anti-staph antibiotic, is positioned in the lateral decubitus position and the back, flank and lower lateral abdominal wall are prepped and draped. After infiltration with local anesthetic a three centimeter paraspinous incision is made at the appropriate lumbar level. A Tuohy needle is introduced through the incision and the epidural space identified via a paraspinous approach with a loss of resistance technique. The epidural catheter is then threaded six to eight centimeters past the tip of the needle. The needle is removed, the catheter is aspirated and a test dose of local anesthetic is injected to rule out entry into the subarachnoid space or vessel. Local anesthetic is then injected through the catheter in a dose and volume adequate to not only confirm positioning within the epidural space but also to provide anesthesia for the tunneling procedure (20cc 3% chlorprocaine, for example). The catheter is secured with a purse string suture. The catheter is then tunneled subcutaneously around the flank to the lower abdominal wall and is connected either to an externalized catheter, a subcutaneous injection port, or a subcutaneous continuous infusion device. The wounds are then closed.”

Technique

See Figure A-8.

The injection may be made at the angle of the ribs; at the lateral border of the sacrospinalis muscle; or at the posterior, mid, or anterior axillary line as indicated. With the patient in the lateral or prone position with the arms abducted overhead, the rib is palpated and the skin retracted slightly upward. A 25-gauge 1½-in needle is introduced through a skin wheal until it contacts the rib. It then is “walked off” the inferior edge of the rib and advanced approximately 2 mm. After a negative aspiration, 3 to 5 ml of local anesthetic are injected, and the needle is removed. This procedure is repeated at each of the levels to be blocked. Control of the needle at all times is of the utmost importance in this procedure, and the hand must at all times stabilize its position.

Drugs

Use 3 to 5 ml of lidocaine 1%, bupivacaine 0.5%, or procaine 1%.

Tips

• 1. A 25-gauge needle is associated with a low incidence of pneumothorax, but breath sounds should be checked and documented after the block.
• 2. A large dose of local anesthetic may provide a block of several interspaces.

Complications and Side Effects

• 1. Local anesthetic toxicity from rapid intravascular absorption.
• 2. Pneumothorax.
• 3. Epidural or spinal block.

Technique

See Figure A-9.

With the patient lying supine, a skin wheal is raised 2 to 3 cm medial to and 2 to 3 cm caudad to the anterior superior iliac spine. A 22-gauge 3½-in needle is inserted at right angles to the skin until a “pop” is felt when it passes through the fascia. Then 10 to 15 ml of a local anesthetic is injected as the needle is moved in and out of the fascia in a lateral and medial fan-like direction.

Drugs

Use 10 to 15 ml of lidocaine 1%. (When this block is used to treat meralgia paresthetica, 40 mg of methylprednisolone acetate or triamcinolone often are added to the local anesthetic.)

Tips

Because this is actually a field block, the fanning motion during injection is critical.

Complications and Side Effects

Femoral nerve block with resultant temporary motor loss may occur.

Technique

See Figure A-10.

With the patient seated and their head flexed, a skin wheal is raised just caudad to the superior nuchal line at the lateral edge of the insertion of the trapezius muscle. This point is midway between the mastoid and the midline. A 22- to 25-gauge 1½-in needle then is inserted in a cephalad direction until bone is contacted. After negative aspiration, 3 to 5 ml of a local anesthetic is injected.

Drugs

Use 3 to 5 ml of lidocaine 1% or bupivacaine 0.5%. (Methylprednisolone or triamcinolone 20 to 40 mg sometimes are added to the local anesthetic in the treatment of occipital neuralgia.)

Tips

In a patient with occipital neuralgia, the greater occipital nerve often is tender, and therefore, the most tender spot along the superior nuchal ridge will provide the location for injection.

Complications and Side Effects

• 1. Accidental occipital artery injection may produce seizures.
• 2. Injection into the foramen magnum may produce a cisternal block or damage to the brainstem.

Technique

See Figure A-11.

The patient is positioned at a 45° angle with the painful side uppermost for alcohol and downward for phenol. Under fluoroscopic control, a 22-gauge spinal needle for alcohol, or 20-gauge for phenol, then is inserted into the subarachnoid space at the level of the most painful segment. The needle is withdrawn until cerebrospinal fluid just flows. Then 0.2 ml of solution is injected, and pain relief is assessed. The table is tilted as necessary to confine the flow, and additional 0.1-ml increments of solution are injected at 3-min intervals as needed. The patient’s position is maintained for 45 min.

Drugs

• 1. 0.2 to 0.5 ml of phenol 5% in glycerin or
• 2. 0.2 to 0.5 ml of alcohol 95% ± 0.1 to 0.2 ml of absorbable contrast medium.

Tips

• 1. Bilateral block should not be done at the same time because it is associated with a higher incidence of paresis.
• 2. A permanent spot film should be obtained for later confirmation of needle position.
• 3. The injection is made at the level corresponding with the spinal cord segment involved; this may be above the level corresponding with root exit.
• 4. Alcohol is more painful on injection than phenol, and the patient must be warned of this. Some practitioners use local anesthetic to ablate the pain and confirm positioning before neurolysis. Others believe this interferes with the patient’s feedback regarding pain relief.
• 5. Saddle block for rectal pain may be performed with the patient sitting and a 20-gauge spinal needle placed at L5S1. Phenol 5% in .5 ml increments is injected. Bowel and bladder dysfunction are possible.

Complications and Side Effects

• 1. Motor weakness.
• 2. Neuritis.
• 3. Tissue necrosis.
• 4. Bowel and bladder dysfunction.