How is the nervous system affected by primary Sjogrens Syndrome?
• Central nervous system: includes focal and diffuse patterns of involvement that may lead to multiple sclerosis-like brain lesions, sensory/motor deficits, seizures, encephalopathy or cognitive impairment. Longitudinally extensive transverse myelitis (LETM; ≥4 vertebral segments) and optic neuritis have been described in patients with SS alongside serum anti-aquaporin-4 antibodies, representing an overlap with neuromyelitis optica. Pulse-dose corticosteroids in addition to rituximab or cyclophosphamide represent induction therapy, followed by maintenance immunosuppression with mycophenolate mofetil, azathioprine or rituximab. Any patient presenting with LETM and/or optic neuritis should have occult SS ruled out.
• Peripheral nervous system: peripheral neuropathy can be motor (mononeuritis multiplex), pure sensory, or sensorimotor. Patients with burning paresthesias and pain, but normal nerve conduction velocities, may have a small fiber neuropathy. Up to 50% of patients with a small fiber neuropathy have findings of dysautonomia as well. These patients have selective loss of pinprick and temperature sensation (small fibers) while having normal vibratory sensation and deep tendon reflexes (large fibers). Small fiber neuropathy is diagnosed by a skin biopsy showing a reduction in epidermal nerve fibers. Initial treatment is conservative and includes medications to reduce neuropathic pain (gabapentin, pregabalin, topical lidocaine, or capsaicin) as well as counseling on patient self-management strategies (similar to the treatment approach for widespread pain in fibromyalgia). In patients with severe symptoms despite conservative therapy, limited data suggests that SS-related small fiber neuropathy and/or dysautonomia may respond to intravenous immunoglobulin therapy.