Lumbar sympathetic nerve blocks or lumbar sympathetic block injections are a diagnostic tool and a treatment modality for certain types of lower back pain and other forms of pain. A sympathetic nerve block targets a set of sympathetic nerves with a numbing agent to temporarily affect nerve function. This can help doctors determine if a specific set of nerves is responsible for a patient’s symptoms or should be looking elsewhere.
In cases of complex regional pain syndrome, for example, pain symptoms may be partially caused by the malfunction of sympathetic nerves, which are part of your autonomic nervous system. Certain viral infections, such as chickenpox or shingles, can affect your sympathetic nerves and cause pain symptoms and rashes.
In contrast to sensory nerves or motor nerves, the nerves of the autonomic nervous system work “behind the scenes” to help regulate everything from your breathing to the rate at which you sweat. Damaged sympathetic nerves or malfunctions in the sympathetic nervous system may cause peripheral inflammation and lower pain inhibition, activate nociceptive receptors, and trigger an array of pain symptoms and vascular problems, constricting the blood vessels and reducing blood flow to critical areas.
The sympathetic nerves surrounding your spine’s lumbar (lower back) region concentrate around the sympathetic ganglia, located between your lower vertebrae. A guided injection with an anesthetic or a corticosteroid can help doctors isolate the sympathetic nerves around your spine as the culprit of your symptoms and help you achieve short-term relief through a nerve block. Understanding how a nerve block works can give you a better insight into the nature of your pain and the difference between nociceptive pain and neuropathy.
Understanding Nerve Blocks
Nerve blocks utilize special imaging tools and techniques to guide a syringe into a portion of the body near a target nerve before temporarily or permanently disabling the nerve with a particular medication. Different types of nerve blocks use other medications depending on the target area and nerve, the intent behind the procedure, and the patient’s medical history. Some nerve blocks are carried out with a conventional painkiller (an opioid) or other anesthetics.
Sometimes, corticosteroids suppress inflammation if the problem at hand is swelling. In cases of intractable pain or cases where a nerve is damaged and is consistently sending false signals, a nerve block procedure is used to destroy a target peripheral nerve with a neurolytic agent (a cooling/heating agent or a neurolytic compound like ethanol), so it can regrow and heal back without the pain or eliminate pain for a long time.
Nerve blocks can last hours, days, or weeks. A doctor may prescribe multiple nerve blocks throughout a patient’s treatment. While they provide short-term relief, they are rarely used as a sole treatment. Many nerve blocks are used solely for diagnostic purposes, to identify a cause for a patient’s symptoms, or rule one out.
When Are Lumbar Sympathetic Nerve Blocks Needed?
A lumbar sympathetic nerve block may be called for if a doctor has reason to believe their patient is suffering from a condition involving their sympathetic nervous system, especially the nerves of the lower back. Lumbar sympathetic nerve blocks are often considered as a treatment tool or diagnostic tool in cases of:
- Reflex sympathetic dystrophy/complex regional pain syndrome (a chronic pain condition)
- Shingles (especially in the legs)
- Vascular insufficiency (poor blood flow, low blood pressure, severe circulation problems)
- Diabetic neuropathy and leg pain (damaged nerves)
If a patient’s symptoms improve, it may help confirm a diagnosis and provide much-needed pain relief. However, not all patients are candidates for lumbar sympathetic nerve blocks. There are contraindications that preclude people from a nerve block injection. These indications include:
- A recent/ongoing infection.
- Blood clotting problems.
- Being on specific medication (such as warfarin).
- Hypertension/high blood pressure.
- And more.
If a fluoroscopy and nerve block are being considered, ensure your doctor is entirely up to date on your medical history and any medication you take. Patients trying for a baby or in the early stages of pregnancy should beware that fluoroscopy involves x-rays, which may harm a fetus in the beginning stages of development.
Preparing for a Lumbar Sympathetic Nerve Block
Lumbar sympathetic nerve blocks or injections are minimally invasive and require little preparation. However, you can eat and drink normally. If you are on any blood-thinning medication, such as warfarin, you may need to stop for a few days before the procedure if your condition allows it. Certain over-the-counter drugs, like ibuprofen, should also be avoided before the nerve block.
In preparation for the injection, you may be asked to lie down. The preliminary injection site will be wiped down and disinfected, and an anesthetic cream might be applied to reduce the pressure of the needle. In most cases, a lumbar sympathetic injection involves either an analgesic (like an opioid) or a corticosteroid. The first injection will usually inject some contrast dye into the target area, which an x-ray can pick up to better outline the nerves of the lower back. Then, x-ray imaging is used to make sure the needle placement is precise for the medication being used.
After the injection is done, you will be monitored for adverse reactions. This takes no more than a few hours, while the procedure takes less than half an hour on average. Patients are usually permitted to go home the very day they’ve been injected. However, you should be driven home. Your doctor may advise you to avoid operating any heavy machinery (including cars) for at least 24 hours.
What To Expect After a Lumbar Sympathetic Nerve Block
Pain relief or symptom alleviation may occur as soon as mere minutes after the injection. The relief can last days, weeks, or hours. In some cases, it can take longer. There may be some bruising at the injection site. However, the risk for anything more than a bruise is shallow. If there is bleeding, or worse, call your doctor. Get emergency help if you develop a fever or other signs of infection after your injection. Lumbar sympathetic nerve blocks are safe, minimally invasive, and effective.