Lumbar Sympathetic Block

The lumbar section of the spine is located in the lower back. A network of nerves run along the spine and into various tissues in the lower body. The sympathetic nervous system is responsible for a variety of unconscious reactions in the body, most notably the “fight or flight” response. Many people experience chronic lower back or leg pain. One of the ways to manage this pain is through nerve blocks or neurolysis of the sympathetic nerves in the lower back.

A lumbar sympathetic nerve block is an injection of anesthesia and/or steroid medication between specific vertebrae of the lower spine. The nerves are “blocked” from sending pain signals back to the brain. A block can be used to help diagnose a sympathetic nerve issue, and with additional medication, can help alleviate pain. Lumbar sympathetic neurolysis involves intentional damage to the sympathetic nerves in the lower back. When the nerves are damaged, by chemical or radiofrequency, the nerve is no longer able to transmit signals back to the brain, thus providing pain relief. The specific method used should be considered on a patient by patient basis. Due to the nature of the procedures and their unlikely but possible complications, lumbar sympathetic nerve blocks or neurolysis are used after other pain management techniques have failed to provide relief.

Anatomy of the Spine

The spine is a curved line of 33 bones (called vertebrae) stacked on top of one another that run from the base of the skull through the pelvic area. A number of essential nerves run the length of the spine (spinal cord) and branch out into the limbs, organs, and tissues that make up the body. All of the information going from the brain to different parts of the body goes through the spinal cord. Additionally, information from the various tissues of the body travels through the spinal cord to send information back to the brain. The spine is essential to allowing humans to stand, twist and move in addition to providing protection of the spinal cord.

The spinal vertebrae are divided into 5 distinct sections. From top to bottom they include the cervical (7 vertebrae), thoracic (12 vertebrae), lumber (5 vertebrae), sacral (5 vertebrae), and the coccyx regions. The lumbar section of the spine consists of five vertebrae, numbered L1-L5, with the top (L1) located between the rib cage and the bottom (L5) located above the pelvis. Sympathetic nerves run along both sides of the spine. They connect with tissues specific to that side of the body in the lower back and legs. The largest concentration of sympathetic nerve material is located between L2 and L3.

Sympathetic Nervous System

The sympathetic nervous system (SNS) is responsible for maintaining various aspects of the body that are not consciously controlled. These include such things as heart rate, dilation and contraction of blood vessels, and sweat secretion, among other functions. The SNS is most known for the “fight or flight” response which is a response to stress.

Lumbar Sympathetic Nerve Block Procedure

A special type of x-ray called a fluoroscope is commonly used so that the doctor is able to see the internal structures of the spine in real time while performing the block. This helps to ensure accurate placement of the needle and medication. In most cases, a patient will lay on their stomach for the procedure, on the bed of the fluoroscope.

Some practitioners may give the patient a mild IV sedative. The skin on the back is cleaned thoroughly to keep the environment sterile. A topical anesthetic is applied before the needle is placed in the spine. The needle is very small and thin. The doctor will use the imaging to guide its placement into the specific area of the sympathetic nerve fiber. A dye is injected first, to ensure proper placement. Medication is then added, including anesthetics and steroids. An increase in the surface temperature of the legs is a good indicator that the block has been administered correctly.

Most patients notice an immediate change that can include pain relief or a warming sensation in the legs. After the procedure, patients should take it easy for the remainder of the day but can return to normal, working activities the next day. The anesthetic effects will wear off within a day. If a steroid has been administered it will take about 2-3 days before the patient is able to feel effects from it. Most patients need multiple rounds of the nerve block before reaching sufficient pain relief.

Conditions that may warrant a Lumbar Sympathetic Nerve Block

A nerve block may be necessary for conditions that involve pain or swelling in the legs. Additionally, conditions involving issues with blood circulation and oxygen delivery to tissues (vascular insufficiency) may benefit from a nerve block. Typically the earlier in the disease that a nerve block can be utilized, the more effective the intervention is.

• Reflex sympathetic dystrophy (RSD) and Complex regional pain syndrome (CRPS) are used interchangeably to describe the same condition. This is a rare condition where patients experience severe, chronic pain and swelling in one or multiple limbs. It is not yet fully understood although it seems to be triggered by an initial event (such as a traumatic injury, surgery or stroke). It is thought to be a consequence of inflammation and overstimulation of the sympathetic nervous system.
• Shingles (also called herpes zoster) is caused by the varicella-zoster virus (VZV), the same virus that causes chickenpox. After an episode of chickenpox, the virus remains in the body and can become reactivated later in life. This involves a very painful rash. If the rash is localized to regions on of the legs, a nerve block can help alleviate some of the pain associated with the rash. It may also help with residual pain after the rash has cleared (indicating overstimulated nerve damage).
• Vascular Insufficiency occurs when blood flow is reduced to a specific area. Blood carries oxygen to tissues and when the circulation is limited, tissues will eventually become damaged. The blood flow reduction can have a variety of causes including Raynaud syndrome, frostbite or diabetes.
• Peripheral neuropathy (PN) involves damage to peripheral nerves. Pain, numbness or tingling sensations accompany weakness and can potentially affect balance and gait, as PN most often affects the hand and feet. This nerve damage has a variety of potential causes including diabetes, immune issues, trauma, viral infections and side effects of medication, among others.
• Phantom Limb Pain occurs when an arm or leg is amputated but the patient continues to feel sensations (pain) at though it is still there. While it was once thought to be psychological, it is now understood that nerve impulses originating from the spinal cord are being sent to the brain and are interpreted as pain. It’s is also theorized that the brain undergoes some chemical alterations as a result of coping with an amputation and this can contribute to the phantom pain.

Lumbar Sympathetic Neurolysis

Neurolysis involves intentionally damaging the nerves to inhibit pain signals from reaching the brain. This should only be considered if nerve blocks are ineffective and an alternative procedure (such as surgery) is not a viable option. The setup is similar to a lumbar sympathetic nerve block; however, neurolysis involves multiple injections between each L1-L4 vertebrae. Instead of injection an anesthetic/steroid, absolute alcohol or phenol is administered. Alternatively, and seemingly more effectively, radiofrequency or heating with a laser are used to damage the nerve fibers.

Conditions that may warrant Neurolysis

• Ischemia is caused by issues with blood vessels that can then limit blood flow to various tissues. This oxygen deficiency often causes damage to the tissues around it. If it is not treated efficiency it can lead to tissue death. It can often cause pain before the tissue is destroyed.
• Vasospastic diseases are a result of the tightening of arteries or capillaries. These include Raynaud’s syndrome, acrocyanosis, and livedo reticularis.

Patients that should not have either procedure include those:

• Allergic to the type of medications used
• Using blood thinners as they are at increased risk of internal or extensive bleeding
• With any active bacterial or viral infection
• Experiencing an uncontrolled chronic condition such as diabetes or heart disease

Possible Side Effects

As with any medical procedure, there are possible side effects to consider. Most are mild and the more severe side effects are extremely rare.

• Pain at the injection site
• Infection at the injection site
• Internal infection in the surrounding tissue
• Bleeding
• Bruising
• Misplacement of the injection (blocking or damaging the wrong nerve)
• Overdose of anesthetic
• Unintentional damage to nerves
• Permanent nerve damage or paralysis

Conclusion

A lumbar sympathetic nerve block (or neurolysis) is a treatment option available for those suffering from various pain and vascular issues affecting the legs. While minimally invasive, these procedures are not generally used as the first-tier treatment option in pain management.

Treatment options for neuropathic extremity pain is best achieved through a combination of injection in conjunction with graded rehabilitative exercise.  Individual programs may include nerve blocks, physical therapy, occupational therapy and other modalities which may boosts the body’s natural ability to heal.

If your pain does not resolve after a brief period, contact us so that we may help diagnose the problem and treat the underlying cause.  Do not let pain persist or else it may become chronic.