Sjögren’s Syndrome (SS) is a chronic autoimmune disorder primarily known for causing dryness by affecting the tear and salivary glands. As a systemic condition, the immune response can affect organs and systems throughout the body, including the brain and nervous system. Neurological involvement is a recognized complication of the disease, affecting both the central and peripheral nervous systems.
Understanding Neurological Involvement
Neurological manifestations are often termed “Neuro-Sjögren’s” and result directly from the underlying autoimmune process. The immune system mistakenly targets nerve tissues and the blood vessels that supply them. Damage occurs primarily through inflammation and vasculitis. Immune cells may directly attack nerve structures, similar to the process that damages the salivary glands. Inflammation of small blood vessels (vasculitis) can also compromise blood flow, leading to nerve tissue damage.
The nervous system is divided into the Central Nervous System (CNS), which includes the brain and spinal cord, and the Peripheral Nervous System (PNS), which comprises all nerves outside the CNS. Sjögren’s can affect both systems. Neurological symptoms can sometimes be the first manifestation of Sjögren’s Syndrome, appearing years before the characteristic dryness. Prevalence is variable, affecting up to 45% of patients over the disease course.
Central Nervous System Manifestations
CNS involvement leads to a wide spectrum of symptoms, from subtle cognitive changes to severe acute events. Cognitive dysfunction, often called “brain fog,” is a common complaint. This involves difficulties with memory, attention, and executive functions like planning and problem-solving. Chronic fatigue, often disproportionate to activity level, is another frequent manifestation. Patients may also experience severe headaches or migraines resistant to typical pain relievers, reflecting diffuse inflammation within the brain tissue.
Less frequently, severe focal CNS events occur. Transverse myelitis, inflammation of the spinal cord, can cause sudden or progressive weakness, sensory loss, or bladder/bowel dysfunction. This inflammation can sometimes mimic Multiple Sclerosis (MS) by causing demyelinating lesions in the white matter. Vasculitis (inflammation of brain blood vessels) can lead to stroke-like events or transient ischemic attacks (TIAs). These events cause sudden focal deficits, such as one-sided weakness or visual disturbances. Optic neuritis, inflammation of the optic nerve, can cause sudden, painful vision loss.
Peripheral Nervous System Effects
The Peripheral Nervous System (PNS) is affected more frequently than the CNS, with neuropathy being the most common complication. Neuropathy is damage to peripheral nerves, causing changes in sensation, movement, and involuntary functions. Sensory neuropathy is common, resulting in numbness, tingling, or pins-and-needles sensation, often in the hands and feet.
Small fiber neuropathy (SFN) is a prevalent and painful manifestation, affecting the small fibers responsible for pain and temperature. SFN causes intense burning or electrical pain and heightened sensitivity to light touch (allodynia). SFN often requires specialized testing because standard nerve conduction studies typically yield normal results.
Sensory ganglionopathy occurs when the immune system attacks the dorsal root ganglia. This leads to severe loss of joint position sense and balance, causing an unsteady gait (sensory ataxia). If motor nerves are involved, patients may experience muscle weakness, cramping, or loss of reflexes (sensorimotor polyneuropathy).
Autonomic neuropathy damages nerves regulating involuntary functions like heart rate, blood pressure, and digestion. Symptoms include orthostatic intolerance (lightheadedness or fainting upon standing), sometimes presenting as Postural Orthostatic Tachycardia Syndrome (POTS). Gastrointestinal issues and abnormal sweating patterns are also common.
Diagnosis and Treatment Approaches
Diagnosing neurological involvement requires coordination between rheumatologists and neurologists. Diagnostic tools confirm nerve damage, rule out other causes, and identify autoimmune activity. Magnetic Resonance Imaging (MRI) of the brain and spinal cord is routinely used to look for signs of inflammation, demyelination, or stroke-like lesions characteristic of CNS involvement.
A lumbar puncture (spinal tap) may analyze cerebrospinal fluid (CSF) for inflammation markers, such as elevated protein levels or immune cells. To diagnose peripheral nerve damage, specialized testing is often required beyond standard nerve conduction studies, which only assess large nerve fibers. A skin biopsy can measure intraepidermal nerve fiber density, which is a definitive way to confirm small fiber neuropathy.
Treatment strategies for Neuro-Sjögren’s are guided by the severity and location of the damage, with the primary goal being to suppress the overactive immune system. For severe, progressive, or acute manifestations like transverse myelitis or vasculitis, high-dose corticosteroids or intravenous cyclophosphamide may be used to rapidly reduce inflammation. Biologic agents, such as rituximab (which targets B-cells), are increasingly used for both CNS and PNS involvement that is resistant to traditional immunosuppressants.
For chronic symptoms, especially peripheral neuropathy, symptomatic treatment is a significant focus. This involves medications like anti-seizure drugs or certain antidepressants that can help manage nerve pain. While these medications provide relief, they do not target the underlying autoimmune cause, making immunosuppressive therapy an important consideration when the neuropathy is determined to be inflammatory.