Systemic Lupus Erythematosus (SLE), commonly known as lupus, is a chronic autoimmune disease where the immune system mistakenly produces autoantibodies that attack healthy tissues and organs. While lupus is often recognized for its effects on the joints, skin, and kidneys, it can also significantly target the nervous system. This involvement, known as neuropsychiatric lupus, frequently manifests as nerve pain, or neuropathic pain. Lupus mechanisms directly cause damage to nerves that relay sensations and control movement.
The Direct Link Between Lupus and Nerve Damage
The underlying cause of nerve pain in lupus is the systemic inflammation that characterizes the disease, leading to a direct assault on nerve structures. One primary mechanism involves autoantibodies and inflammatory cells targeting the nerve fibers themselves. These components can attack the nerve cell bodies or the myelin sheath, the protective fatty layer that insulates nerves and allows for rapid signal transmission. Damage to this insulation disrupts electrical signals, resulting in abnormal firing patterns interpreted as pain, tingling, or numbness.
Another significant mechanism is vasculitis, the inflammation of blood vessels. Nerves require a constant supply of oxygen and nutrients delivered by small blood vessels, often called the vasa nervorum. When lupus causes inflammation in these tiny vessels, blood flow is restricted or interrupted, leading to ischemia (a lack of oxygen). This oxygen deprivation causes nerve injury and eventual death of the nerve tissue, resulting in the persistent, often burning sensation characteristic of neuropathic pain. Antiphospholipid antibodies, which promote blood clotting, can further exacerbate this process by physically blocking these small vessels.
Specific Types of Nerve Involvement
The most common form of nerve damage causing pain in lupus patients is Peripheral Neuropathy, which affects nerves outside the brain and spinal cord. This damage typically presents as a symmetric, distal sensorimotor polyneuropathy, affecting both sensation and movement. It usually starts in the feet and hands in a classic “stocking-and-glove” distribution. Patients often describe sensations of burning, electric shock, or deep aching pain, alongside tingling or persistent numbness. Sensory nerves are particularly vulnerable.
A specific, often under-recognized form is Small-Fiber Neuropathy, which damages the small, unmyelinated nerve fibers responsible for pain and temperature sensation. This condition causes severe, burning pain, particularly in the lower extremities. It is sometimes overlooked because standard nerve conduction studies (NCS) may appear normal, as these tests only assess the function of larger, myelinated nerve fibers. The damage is instead confirmed by a reduced density of these small fibers upon a skin biopsy.
A more severe, though less frequent, manifestation is Mononeuritis Multiplex, characterized by damage to two or more separate nerve areas. This condition often results in localized, intense pain, muscle weakness, and paralysis in the affected regions. Lupus can also affect the Central Nervous System (CNS), causing issues like headaches, seizures, or cognitive dysfunction (“lupus brain fog”). However, these CNS symptoms are distinct from neuropathic pain felt in the limbs, as CNS involvement stems from inflammation and blood flow issues within the brain and spinal cord.
Confirming the Diagnosis
Diagnosing neuropathic pain in a lupus patient requires a careful clinical assessment to ensure symptoms are directly attributable to the autoimmune disease and not a secondary cause. A physician begins with a detailed patient history and a thorough physical and neurological exam to identify the pattern and distribution of pain, weakness, or loss of reflexes. Since lupus patients may have co-existing conditions that cause neuropathy, such as diabetes or medication side effects, a key part of the process is exclusion. The doctor must rule out these other potential causes before linking the nerve pain to lupus activity.
Specialized tests are used to assess nerve function and pinpoint the location and type of damage. Nerve Conduction Studies (NCS) measure the speed and strength of electrical signals passing through large, myelinated nerves. NCS helps differentiate between damage to the myelin sheath (demyelinating) or the nerve fiber itself (axonal). These studies are often paired with Electromyography (EMG), which assesses the electrical activity of muscles at rest and during contraction. The EMG helps determine if muscle weakness is due to nerve damage or a primary muscle problem. For suspected small-fiber neuropathy, where NCS and EMG results are typically normal, a skin punch biopsy may be necessary to microscopically measure the density of small nerve fibers. Imaging techniques, such as MRI or CT scans, may also be employed to rule out structural issues or central nervous system involvement that could mimic peripheral nerve pain.
Managing Neuropathic Pain in Lupus
Management of lupus-related neuropathic pain requires a dual approach: controlling the underlying autoimmune activity and alleviating painful symptoms. The most important step is treating the active lupus that is causing the nerve damage. This typically involves high-dose corticosteroids, such as glucocorticoids, often followed by long-term immunosuppressive therapies. Medications are used to calm the immune system, halting the inflammatory attack on the nerves and preventing further injury. These include cyclophosphamide, azathioprine, or mycophenolate mofetil.
While the underlying disease is being treated, symptomatic pain management is necessary to improve the patient’s quality of life. Standard over-the-counter pain relievers are generally ineffective for true neuropathic pain, which responds better to medications that modulate nerve signals.
Pharmacological Management
Anti-seizure medications, such as gabapentin and pregabalin, are commonly prescribed as they slow the excessive firing of damaged nerve cells. Tricyclic antidepressants, including amitriptyline and nortriptyline, are also frequently used at lower doses to interfere with pain signals sent to the brain. Topical pain relievers, such as lidocaine patches or creams, can provide localized relief for specific areas of burning or tingling.
Supportive Therapies
Beyond medication, supportive therapies like physical therapy help maintain muscle strength and function. Lifestyle adjustments, including gentle exercise and stress reduction, contribute to overall pain management.