Painful Immunoglobulin-G4 Related Neuropathy

Chronic sensorimotor neuropathies are the dominant clinical presentation of a variety of disorders. Newly recognized entities need to be appreciated in evaluation of these disorders. A 38-year-old male patient presented to our department with one year history ofprogressive numbness and severe pain starting from lower limbs accompanied with a significant weight loss, constipation, urinary retention, and dry mouth during the last six months. On examination a bilateral proptosis without eye movement restriction, normal cranial nerveexamination, decreased force and atrophy of the distal lower limb muscles were evident accompanied with abolished muscle stretch reflexes and decrease in pain and temperature sensation. Electrodiagnostic study was compatible with a chronic axonal sensorimotorneuropathic process. Laboratory evaluations revealed an increasing erythrocyte sedimentation rate up to 72 mm/hour and a positive c-reactive protein. Primary evaluations was negative for common vasculitic and paraneoplastic disorders. Lip minor salivary glandbiopsy showed a nonspecific inflammatory pattern not suggestive of the Sjogren’s disease. We performed a sural nerve biopsy which was indicative of a lymphocytic infiltration, however we did not observe a typical vasculitic pattern. An elevated high-titer immunoglobulin-G4 (IgG4) was found on follow-up laboratory evaluations. Considering the diagnosis of IgG4-related neuropathy, pulse corticosteroid treatmentwas initiated which was followed with a dramatic response. Conclusion: IgG4 related neuropathy are a recently recognized pathologic entity and should be considered as a differential diagnosis of probable immune-mediated neuropathic disorders with unknown etiology.