Continuing Education Activity

Lumbar sympatholysis can be an effective treatment for individuals suffering from chronic pain in the lower extremity as a result of various causes. Sympathectomy can be performed by chemical neurolysis, radiofrequency ablation, or surgically with variations in technique. The most common indications for this procedure include lower extremity complex regional pain syndrome (formally known as RSD and Causalgia), vascular insufficiency in the leg, phantom limb pain, erythromelalgia (a rare condition causing episodic burning pain and redness usually in the feet, less commonly in the upper extremities and face or ears likely due to postganglionic sympathetic dysfunction as well as hypersensitivity of C-fibers resulting in abnormal skin perfusion and arteriovenous shunting), post-herpetic neuralgia, and hyperhidrosis. This activity reviews the lumbar sympatholysis technique, anatomy, and associated clinical considerations. It also highlights the role of the healthcare team in improving outcomes for patients who undergo lumbar sympatholysis.

Objectives:

• Review the indications for lumbar sympatholysis.
• Describe the common techniques in regards to lumbar sympatholysis.
• Describe the appropriate evaluation of the potential complications of lumbar sympatholysis.
• Review interprofessional team strategies for improving care coordination and communication to ensure the appropriate selection of candidates for lumbar sympatholysis and to improve outcomes in patients undergoing lumbar sympatholysis.

Introduction

Lumbar sympathetic blocks to result in a sympathectomy have been described as an effective pain management treatment strategy for several causes of chronic pain since the early 1900s.  The first reports of a lumbar sympathetic block technique, as well as sympatholysis, were initially documented in the 1920s.  The conditions for which this treatment has been effectively implemented include lower extremity complex regional pain syndrome (CRPS, formally known as RSD or causalgia) as well as various painful conditions resulting in circulatory insufficiency in the lower extremity such as Buerger's disease, embolic occlusions, frostbite, vasospastic disease, and peripheral arterial disease.  Other possible indications may include phantom limb pain, hyperhidrosis,  and postherpetic neuralgia. Procedural techniques have evolved with the involvement of fluoroscopy, chemical neurolysis approaches, and radiofrequency thermocoagulation approaches.[1] 

Surgical procedures (although not performed as often) have also been documented. An overview of interventional procedural anatomy, physiology, indications, contraindications, complications, and interventional technique is provided for practitioners in order to help improve understanding and outcomes as well as to help minimize mortality and other adverse effects.

It is important to distinguish lumbar sympatholysis from a lumbar sympathetic block in that this procedure specifically seeks to accomplish a more long-term or permanent disruption of the sympathetic chain output to the lower extremity in comparison to the lumbar sympathetic block which typically utilizes only local anesthetics. However, the lumbar sympathetic block is often useful for diagnostic purposes on a potential candidate before performing more long-term treatment with lumbar sympatholysis.

Anatomy and Physiology

The sympathetic chain (also referred to as the sympathetic trunk) consists of a bilaterally paired set of paravertebral nerves extending from the neck to the coccyx. These nerves play an essential role in the autonomic nervous system and subdivide into cervical, thoracic, lumbar, and sacral sections.

The majority of the sympathetic output to the lower extremity is in the upper lumbar region. The presynaptic efferent nerve roots emerge from the anteromedial spinal cord, via white rami of the ventral roots of the spinal nerves, which then synapse at the appropriate lumbar sympathetic ganglion. These ganglia provide the sympathetic output to the lower extremity. The postganglionic neurons continue to innervate their target sites. 

The lumbar sympathetic chain of ganglia innervating the lower extremity is located anterolaterally along the lumbar spine, usually at the levels of L2 through L4, lying at the medial margin of the psoas muscle. The aorta is anterior and medial to the left lumbar sympathetic chain, while the inferior vena cava is located closely anteriorly to the right lumbar sympathetic chain.[1] Significant variation has been reported in the specifics of the location, size, and quantity of ganglia. The number of ganglia varies between 2 and 5, with an average of 3. The ganglia may appear as up to six individual ganglia or fused into a single mass of tissue. Frequently there are no ganglia corresponding to the L1 level.[2] 

Neurolysis can be performed to disrupt the sympathetic ganglia at the levels of L2-L4, leading to decreased vasomotor tone and decreased afferent pain signals. This phenomenon explains the symptomatic relief patients experience as well as findings of hyperemia of the foot that often occur following successful lumbar sympathetic neurolysis, due to increased vasodilation and arteriovenous shunting of cutaneous capillary beds.[1] 

Indications

Numerous disorders affecting the lower extremities are treatable with lumbar sympathetic neurolysis, such as complex regional pain syndrome (CRPS), postherpetic neuralgia, and phantom limb pain. From a vascular standpoint, lumbar sympathetic neurolysis has also been useful for patients with severe ischemic rest pain and peripheral arterial disease that is considered non-reconstructable. Patients considered for this procedure often demonstrate significant interruption in quality of life as a result of their symptoms and likely have failed medical management as well as other modalities of treatment.[1] 

Cases of chronic visceral pain (e.g., inoperable malignancy) associated with the descending colon and upper portion of the sigmoid colon, kidney, and parts of bladder and ovaries may also benefit from this procedure; more specifically, the hypogastric plexus and ganglion impar are usually the targets.[3][4] Lumbar sympathetic neurolysis has also seen use in the treatment of plantar hyperhidrosis.[5]

In today's practice, spinal cord stimulation has largely replaced lumbar sympatholysis for many chronic pain indications. 

Contraindications

Strong contraindications include a lack of informed consent as well as an infection at the procedure site. Relative contraindications include coagulation abnormalities, bleeding dyscrasias such as various platelet dysfunctions, malignancy near the treatment site, systemic infection, bacteremia, and severe cardiac and/or pulmonary disease.[6]

Equipment

Typically fluoroscopic guidance is required requiring icluding a C-arm and a fluoroscopy-compatible table as well as the required needles and medications.

Technique or Treatment

Lumbar sympatholysis is performable using modalities such as radiofrequency ablation (RF), chemical neurolytic agents, and rarely surgery. A plethora of techniques and recommendations have been described for each option. In this article, we will provide an overview of common basic techniques, focusing on RF and chemical methods.

Fluoroscopy frequently aids sympathectomy procedures, allowing the provider to navigate the bony landmarks and allow visualization of injected contrast material.

For this procedure in its various modalities, the patient is placed prone on the fluoroscopy bed. Monitors are attached. Anxiolytic agents are an option. Prophylactic antibiotics are not indicated in usual circumstances. Routine surgical time-out is necessary to verify patient identity, procedure, and site. The lumbar region of the patient is prepped in a sterile fashion. Fluoroscopy is used in a posterolateral oblique projection to identify the targeted region(s) in L2-L4. Local anesthesia is administered into the skin and subcutaneous tissue at the needle entry site at the discretion of the provider. Cutaneous temperature is usually monitored before and after at bilateral lower extremities to determine the efficacy of successful sympathetic blockade.[1][7][8]

Chemical Neurolysis

To target the anterolateral aspect of the vertebral body, a 15 cm, 20 to 22 gauge needle is entered immediately below the transverse process. The needle is advanced until it reaches the targeted anterior margin of the vertebral body using intermittent biplane fluoroscopy. The needle entry site is estimated at 7 cm lateral from midline. The proceduralist will often “walk” the needle anteriorly and medially into the perivertebral space when they make contact with the vertebral body as the needle advances. Contrast material is injected after aspiration, looking for a craniocaudal longitudinal spread of the contrast agent in the perivertebral space. Once the correct injection site is confirmed, 3 to 5 mL bupivacaine 0.5% is injected to anesthetize the nerve root, before injection of the neurolytic agent (approximately 5 mL of absolute alcohol).[1] Other injectates depending on the patient, situation, and availability, as well as depending on practitioner preference, include lidocaine for the local anesthetic and phenol for the neurolytic.

Numerous techniques on specifications of chemical neurolysis exist, and it has been shown that a 3-needle approach has superior efficacy while using less volume of the neurolytic agent.[9] If using a multi-needle method, it is critical to confirm all levels and perform aspiration before injection of the neurolytic agent.

Radiofrequency Thermocoagulation

Denervation is also possible with a percutaneous approach using radiofrequency(RF) thermocoagulation, also referred to as RF ablation. The initial setup is comparable to that of chemical neurolysis, as described above. The anatomical targets are largely similar as well; however, specialized needles and radiofrequency probes are used to perform thermocoagulation at the targets.[8] A radiofrequency lesion generator in the closed circuit produces a high-frequency current that produces neurolysis on application to the neural tissue. Important variables that affect the RF ablation technique include electrode size, duration of the lesion, and tissue temperature.[6]

Surgical Sympathectomy

There are various surgical approaches that usually involve cutting or clipping the sympathetic chain. This procedure is typically at or below L2 to minimize sexual dysfunction side effects and complications that more often occur when performed at higher levels, such as the thoracic region.

It is essential to point out that lumbar sympatholysis is not a permanent effect. The interventional radiofrequency or neurolytic approaches typically last up to six months before the nerves can regenerate. Surgical lumbar sympatholysis can have effects lasting up to a few years.

Complications

Complications of performing lumbar sympatholysis can include bleeding, infection, neuraxial injection, intravascular injection, genitofemoral neuralgia, injury to nerve roots, and rarely injury to pelviureteric structures. [1]

Genitofemoral neuralgia is the most common complication, with an incidence of 5 to 7% following chemical lumbar sympathectomy. Some data suggest a higher incidence when using alcohol instead of phenol. The groin dysesthesia symptoms of genitofemoral neuralgia are usually transient and often resolve within 4 to 6 weeks.[10][11] The risk of genitofemoral neuralgia is reducible by avoiding injection of medications into the psoas muscle, especially at levels L3 and L4, where the intramuscular injection is more common.[9] There are also reports of post-sympathectomy neuralgia, which presents more as a dull ache, and its mechanism remains unclear.

An inadvertent neuraxial injection can have devastating consequences such as total spinal and even death.[12][13] Intrathecal injection of chemical neurolytic medications reportedly causes transient weakness and paralysis, with reports of permanent cases as well.[14][15] 

Unintentional intravascular injection of neurolytic agents can occur given the proximity of the lumbar sympathetic chain to major vessels such as the aorta and inferior vena cava, as described in the anatomy section. Variations in lumbar vessel anatomy, such as the artery of Adamkiewicz, may also be a factor in inadvertent intravascular injection, resulting in direct toxic or ischemic injury to the spinal cord.[16] These risks highlight the importance of aspiration before injection to avoid accidental intravascular injection of medication.

Clinical Significance

Lumbar sympatholysis can be an effective treatment option for patients suffering from chronic, intractable pain in the lower extremity as a result of various causes such as complex regional pain syndrome, post-herpetic neuralgia, inoperable peripheral arterial disease, phantom limb pain, erythromelalgia, or hyperhidrosis.  The relief and symptom improvement resulting from the destruction of the lumbar sympathetic chain can last up to several years at a time and can be performed by chemical neurolysis, radiofrequency thermocoagulation, and surgical sympathectomy approaches.  In order to help provide effective and safe care for patients suffering with these often debilitating conditions, it is important for healthcare providers to have an understanding of these techniques as well as having an understanding of the indications for, contraindications for, potential side effects of, and potential complications of lumbar sympatholysis.

Enhancing Healthcare Team Outcomes

Lumbar sympatholysis is an invasive procedure and can be associated with serious complications such as paralysis or even death.[12][13] Thus it is critical to determine if a patient would be an ideal candidate. Interdisciplinary communication between different medical specialties is often needed to evaluate the patient properly pre-procedure. It is also imperative for the performing provider to understand the anatomy, physiology, and various approaches of the technique to produce improved outcomes and minimize complications, and that these ideas are clearly explained to the patient as well.