# When the nerve speaks first: IgG4-related disease unmasked by peripheral neuropathy

## TL;DR

This study explores how IgG4-related disease can first appear as nerve problems and responds well to steroid treatment.

## Contribution

The study highlights peripheral neuropathy as a rare initial sign of IgG4-related disease and its effective treatment with corticosteroids.

## Key findings

- Peripheral neuropathy can be the first symptom of IgG4-related disease.
- All patients showed improvement with corticosteroid therapy.
- Nerve damage in these cases often involves demyelination or axonal lesions.

## Abstract

IgG4-related disease (Immunoglobulin G4-related disease) is an immune-mediated condition characterized by elevated serum IgG4 levels, clinically presenting as multi-organ enlargement. However, only case reports exist of IgG4-related disease presenting initially with peripheral neuropathy. This study aims to elucidate the clinical features of IgG4-related disease with prominent peripheral neuropathy manifestations.

We reviewed 16 cases of IgG4-related disease with peripheral neuropathy as the initial presentation, including 15 cases from the literature and one case from our institution. Patient data were extracted and analyzed, encompassing clinical characteristics, pathological features, electrophysiological findings, and treatment information.

The median age of onset was 64.5 years, with 3 female and 13 male patients. Initially, 15 patients presented with limb numbness and weakness, while 1 exhibited hoarseness. All 16 patients demonstrated organ enlargement in addition to peripheral nerve damage. Peripheral nerve electrophysiology revealed demyelination and/or axonal lesions. All cases received oral corticosteroids, with immunosuppressants added in 3 cases. All patients responded well to corticosteroid therapy.

Peripheral neuropathy may present as the initial manifestation of IgG4-related disease. Such neuropathy demonstrates favorable response to corticosteroid therapy, and the indication for adding immunosuppressive agents should be evaluated based on individual circumstances.