Chapter 10 Sympathetic Nerve Block and Neurolysis

Chul-Joong Lee, MD, PhD, Sang-Chul Lee, MD, PhD

Sympathetic nerve block may relieve pain by several mechanisms. One possible mechanism is interruption of afferent nociceptive fibers that accompany the autonomic nerves. Another possible mode of action of sympathetic block involves disruption of reflex control systems, which causes alteration of peripheral or central sensory processing. Finally, the peripheral vasodilation caused by sympathetic block may relieve ischemic pain and facilitate the healing of painful skin ulcers.

Preoperative preparation

The following conditions must be met before sympathetic nerve block, radiofrequency lesioning, or neurolysis is performed:

The patient’s written informed consent is obtained.

The operator must have a full understanding of the relevant anatomy and the pathophysiology of the underlying condition, because the complications of sympathetic blocks can be very serious.

The patient must understand all the risks of the procedure and must give consent.

Resuscitation equipments must be immediately available.

Secure venous access is essential for all patients, and facilities for the treatment of hypotension must be available. An intravenous fluid preload with crystalloid solution is usually given for all blocks (e.g., splanchnic, celiac, lumbar sympathetic, or superior hypogastric plexus block).

The patient’s blood pressure and pulse oximetry must be monitored constantly.

Contraindications

Sympathetic nerve block, radiofrequency lesioning, and neurolysis should not be performed if any of the following conditions is present:

Patient refusal.

Coagulopathy (International Normalized Ratio (INR) value > 1.5 or platelet count < 50,000/mm ³) or prescribed anticoagulant therapy. There is significant risk of vessel injury in a patient with either condition, because the sympathetic trunks are deeply placed and close to major blood vessels. A large hematoma may be produced if the patient has a coagulation disorder. Aspirin or antiplatelet agents should be stopped 7 days, and warfarin 5 days, before injection is performed.

Allergy to local anesthetics, corticosteroids, or the contrast agent.

Local infection or neoplasm at the needle trajectory: There is a risk of spreading the infection to deeper structures.

Anatomical or vascular anomalies: Anatomical distortion, such as pressure from a neoplasm or spinal scoliosis, may make the block more difficult and reduce the chance of success. Anomalous vessels increase the risk of accidental needle puncture.

Uncorrected severe hypovolemia: Splanchnic, celiac, and lumbar sympathetic blocks can precipitate marked hypotension, especially when performed bilaterally.

Congestive heart failure.

Corticosteroid injection should not be performed in the patient with uncontrolled diabetes mellitus or Cushing syndrome.

Procedures

Stellate Ganglion

Unlike other types of neurolytic techniques, radiofrequency thermocoagulation (RFTC) does not tend to produce Horner’s syndrome (unilateral miosis ptosis, anhidrosis, and enophthalmos), and it can be performed simply with very little morbidity.

Anatomy

The stellate ganglion, which is formed by the fusion of the inferior cervical and T1 sympathetic ganglia, lies anterior to the transverse processes of C7 and T1 and to the neck of the first rib (Fig. 10-1).

Figure 10–1 Position of the stellate ganglion. C6, sixth cervical vertebra; T1, first thoracic vertebra.

(Modified from Justins DM: Pain and autonomic nerve block. In Wildsmith JAW, Armitage EN, McClure JH [eds]: Principles and Practice of Regional Anaesthesia, 3rd ed. Edinburgh, Churchill Livingstone, 2002, pp 291-309.)

Physical examinations that imply successful sympathetic nerve block consist of the following findings:

In face: Horner syndrome

In upper extremity: temperature elevation at the ipsilateral upper extremity.

Temperature measurements in both hands (Fig. 10-2) are required to evaluate successful upper extremity block [1]. Digital infrared thermal imaging is helpful (refer to Fig. 15-29) [2]. Horner syndrome does not guarantee success of ipsilateral upper extremity sympathetic block.

Figure 10–2 Monitoring of surface temperature during thoracic sympathetic block. For lumbar sympathetic block, the surface temperature monitoring probes are attached at the plantar surfaces of both feet.

Technique

Stellate ganglion block

The simplest and most satisfactory approach is the anterior paratracheal approach, which is performed as follows:

1. The patient’s written informed consent is obtained.

2. The patient is placed in supine position on a radiology table, with the head extended by placement of a roll under the neck.

3. The operator applies pressure with two fingers in the groove between the trachea and the carotid sheath to feel the transverse process of C6, which lies at the level of the cricoid cartilage (Fig. 10-3).

4. After sterile skin preparation, a 23-gauge, 3-cm needle is inserted directly backwards to strike the transverse process of C6. The needle should then be withdrawn 2 to 3 mm.

5. The operator fixes the needle in this position with one hand and performs an aspiration test for checking blood regurgitation.

6. 6 to 8 mL of local anesthetic (0.2%-0.375% ropivacaine or 0.125%-0.25% bupivacaine) is injected slowly with repeated aspiration tests. For complete sympathetic block of the upper limb to be obtained, the solution must extend to the T2 or T3 ganglion, and volumes greater than 10 mL may be necessary.

Figure 10–3 Landmarks for stellate ganglion block. The blue box indicates the cricoid cartilage and the blue dotted line represents the medial margin of the sternocleidomastoid muscle. The blue solid line represents the sternal notch. The transverse process of C6 is firmly held between the index and middle finger of the operator’s left hand. The needle should be inserted between the surgeon’s finger tips.

We prefer thoracic sympathetic block to stellate ganglion block for block of the upper extremity sympathetic nerve.

Pulsed radiofrequency lesioning or radiofrequency thermocoagulation of the stellate ganglion

Some authors had introduced the technique of radiofrequency lesioning of the stellate ganglion under the guidance of fluoroscope. We do not agree with their techniques and do not perform the procedure under the guidance of fluoroscope. One author introduced the technique previously in his book. According to his technique the radiofrequency needle tip should rest at the junction of the transverse process and the vertebral body. Where is the stellate ganglion?

The stellate ganglion formed by the fusion of the inferior cervical and the first thoracic ganglion as they meet anterior to the vertebral levels of the C7 and T1 vertebra. The ganglion lies on the longus colli at the vertebral level covered by prevertebral fascia and is surrounded by important structures, such as common carotid artery, internal jugular vein, thyroid, vagus nerve, phrenic nerve, and brachial plexus. The distance from the junction of the transverse process and the vertebral body to the stellate ganglion may show individual differences according to the individual shape and volume of longus colli. We, therefore, cannot estimate where the ganglion is on the lateral image of C-arm. In addition, the location of the ganglion is also highly variable. We, also cannot estimate where the ganglion is on the AP image of C-arm. When we use the radiofrequency lesioning techniques (Fig. 8-16) we should remember how and where the lesion is made. If radiofrequency needle tip rests at the junction of the transverse process and the vertebral body, where the radiofrequency lesion is made? These are the reason why we do not perform the procedure under the guidance of fluoroscope.

Ultrasound-guided and CT-guided radiofrequency lesioning of the stellate ganglion can be alternative procedures. However, the identification of the ganglion or its chain at the vertebral levels on the ultrasound or CT images is also very difficult.

Thoracic Sympathetic Ganglion

Anatomy

The upper thoracic sympathetic ganglia are located around the heads of the ribs and are covered by the pleura. The lower two or three ganglia are on the sides of the vertebral bodies. The thoracic sympathetic trunk runs between the ganglia and just in front of the somatic nerves (Fig. 10-4) [1].

Figure 10–4 The anatomical dissection of the thoracic sympathetic ganglia. Arrowheads indicate the rami communicantes. BP, brachial plexus; N1, the first intercostal nerve; N2, the second intercostal nerve; N3, the third intercostal nerve; N4, the fourth intercostal nerve; SG, stellate ganglion; T2, the second thoracic sympathetic ganglion; T3, the third thoracic sympathetic ganglion; T4, the fourth thoracic sympathetic ganglion.

(Adapted from Cho HM, Lee DY, Sung SW: Anatomical variations of rami communicantes in the upper thoracic sympathetic trunk. Eur J Cardiothorac Surg. 2005;27:320-324.)

Techniques

Thoracic sympathetic block

The following procedure is used for thoracic sympathetic block:

1. The patient’s written informed consent is obtained.

2. The patient is placed in the prone position on a radiology table.

3. The temperature probes for surface temperature monitoring are attached to the palms of both hands to monitor the temperature changes (Fig. 10-2).

4. The overlying skin is prepared and draped in a sterile fashion.

5. The C-arm is rotated in the caudocephalad direction to align the end plates of the T2 and T3 vertebrae parallel in the AP projection.

6. Then the C-arm is rotated to a 10- to 15-degree oblique angle, toward the side being injected (Fig. 10-5A).

7. The skin entry points are identified and infiltrated midway between the transverse processes of T3 and T4, which meet at the lateral margin of the vertebral column in the oblique projection.

8. A 21-gauge, 15-cm Chiba needle is advanced by means of the tunnel vision technique and with C-arm guidance to the lateral margin of vertebral column in the oblique projection.

Figure 10–5 Typical pattern of contrast agent spread thoracic sympathetic block in oblique (A) and anteroposterior (B) fluoroscopic images. No intravascular, intrathecal, epidural, or intrapleural spread of contrast agent is noted in either image.

To reduce the risk of pleural puncture, advancing the needle beyond the lateral margin of the vertebral column in the oblique view should be avoided. Frequent checks of lateral images should be made to measure the depth of the needle tip, especially when the needle enters the thoracic cavity.

9. If the needle touches the lateral margin of the vertebral column in oblique projection, the C-arm is rotated to lateral projection. Then the needle is carefully manipulated to arrive at the target point, the posterior third of the vertebral body. The needle tip should be kept close to the vertebral body during this step.

10. 0.5 to1 mL of contrast agent is injected to confirm compartmental flow of the injectate and to rule out any intravascular, intrathecal, epidural, or intrapleural spread (Fig. 10-5). Epidural spread can easily be detected in the oblique projection (Fig. 10-5A).

11. 2 to 3 mL of local anesthetic (0.2%-0.375% ropivacaine or 0.125%-0.25% bupivacaine) can be injected.

12. For neurolysis of thoracic sympathetic ganglions, diagnostic thoracic sympathetic block is performed at both the T2 and T3 levels, with injection of 1 to 1.5 mL of the local anesthetic at each level. A neurolytic agent, such as 99% alcohol, should be injected 20 to 30 minutes after the diagnostic block.

In cases in which intrathecal, epidural, intercostal nerve, or intrapleural spread of contrast agents has occurred, neurolytics should not be injected, and the procedure should be postponed for about 1 week. If at any time during the neurolytic injection the patient complains of pain, further injection should be stopped immediately.

13. After neurolytic injection, absolute bed rest for 3 to 4 hours without position change is necessary to avoid unwanted spread of neurolytics to important adjacent structures.

Pulsed radiofrequency lesioning or radiofrequency thermocoagulation

We do not perform radiofrequency lesioning of the thoracic sympathetic ganglion under the guidance of fluoroscope because of high individual variation of the location of the ganglion. CT-guided lesioning can be an alternative.

Splanchnic Nerve

Anatomy

As shown in Figure 10-6, the greater (T5 through T10), lesser (T10 and T11), and least (T11 and T12) splanchnic nerves cross the lateral side of the body of T12 as they sweep forward to penetrate the diaphragm and form the celiac plexus. The pleura are attached posteriorly to the vertebral bodies and create a well-defined compartment.