Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease where the body’s immune system mistakenly attacks its own tissues and organs. This systemic attack can affect nearly any part of the body, including the nervous system. Neuropathy is damage to the peripheral nerves outside of the brain and spinal cord. As a recognized complication of SLE, this damage results in symptoms like weakness, numbness, and pain. Neuropathy interferes with the transmission of signals between the central nervous system and the rest of the body. Neuropathy is a manifestation of the underlying disease activity in lupus patients.
Mechanisms of Nerve Damage in Lupus
The primary way SLE causes damage to the peripheral nerves is through inflammation of the small blood vessels that supply the nerves. This process is a form of lupus vasculitis, where immune complexes—clumps of antibodies and antigens—deposit in the vessel walls. The inflammation and thickening of these tiny vessels, known as the vasa nervorum, restrict blood flow to the nerve tissue. This lack of oxygen and nutrients, or ischemia, directly causes nerve damage and dysfunction.
Another pathway involves the direct action of autoantibodies produced by the immune system. Certain lupus-related autoantibodies, such as anti-phospholipid antibodies, are implicated in nerve injury. These antibodies may directly target components of the nerve cells or the myelin sheath, the protective layer around the nerve fibers, causing an immune-mediated attack.
Anti-phospholipid antibodies can also contribute to nerve damage by promoting the formation of microthrombi, or tiny blood clots, within the small vessels supplying the nerves. The resulting damage can affect both the axon (the main nerve fiber) and the myelin sheath. This dual mechanism of inflammation and antibody-mediated attack explains how neuropathy presents in a lupus patient.
Recognizing Types of Lupus-Associated Neuropathy
Lupus-associated neuropathy can manifest in several patterns, with peripheral neuropathy (PN) being the most common form. This type primarily affects the nerves controlling sensation and movement in the limbs. Patients often experience tingling, numbness, or a sensation described as “pins and needles,” which typically starts in the feet and hands in a symmetrical, “stocking-glove” distribution. Sensory symptoms can escalate to burning or shooting pain, and motor involvement may lead to muscle weakness and difficulty with fine motor tasks or walking.
Autonomic Neuropathy (AN) involves damage to the nerves that regulate involuntary bodily functions like heart rate, blood pressure, digestion, and temperature control. Symptoms of AN can include dizziness or faintness, particularly when standing up quickly, a condition known as orthostatic intolerance. Patients may also experience unexplained digestive issues such as chronic diarrhea or constipation, or abnormal sweating patterns.
Mononeuritis Multiplex (MNM) represents a more severe manifestation of lupus vasculitis. It is characterized by damage to two or more separate, specific nerve areas. This condition is associated with highly active systemic inflammation and results in acute, asymmetric weakness or paralysis in the affected limbs. For example, a patient might experience sudden foot drop on one side and wrist weakness on the other.
Diagnosis and Management of Neuropathy in Lupus
Diagnosing neuropathy in lupus involves a detailed neurological examination and specific electrodiagnostic tests to confirm nerve damage and rule out other causes. A thorough history is taken to correlate symptoms with lupus disease activity and to identify potential contributing factors, such as coexisting diabetes or medication side effects. The physical exam focuses on assessing sensation, reflexes, and muscle strength.
Nerve Conduction Studies (NCS) and Electromyography (EMG) are the standard tools used to evaluate the function of the peripheral nerves and muscles. NCS measures how quickly electrical signals travel through the nerves, which can identify damage to the myelin sheath or the axon. EMG assesses the electrical activity in muscles, helping to determine if muscle weakness is due to nerve injury or a primary muscle disorder.
For management, the treatment strategy operates on two levels: controlling the underlying lupus disease activity and providing symptom relief. The first line of action involves suppressing the autoimmune response that is causing the nerve damage. High-dose corticosteroids, such as intravenous methylprednisolone, are often used to quickly reduce inflammation during acute flares.
Immunosuppressive drugs, including cyclophosphamide or azathioprine, may be initiated to maintain disease control and prevent further nerve injury. For patients experiencing pain, symptom relief is provided through medications targeting neuropathic pain, such as gabapentinoids or certain classes of antidepressants. Physical therapy is also recommended to help maintain muscle strength and mobility, assisting in managing the long-term effects of nerve damage.