Table 5.

Conditions in the Differential Diagnosis of SCN9A Small Fiber Neuropathy

CauseComment/Characteristics
Diabetic peripheral
neuropathy		History of diabetes; ↑ hemoglobin A1C
Rheumatologic
disease		Rheumatoid arthritis, systemic lupus erythematosus, Sjogren syndrome; positive autoimmune antibodies
Monoclonal
gammopathy		Occurs at older ages; IgM monoclonal gamma globulins
AmyloidosisA group of disorders characterized by amyloid protein deposition → neuropathy & cardiac or renal dysfunction
  • Amyloid light chain amyloidosis is a plasma cell dyscrasia assoc w/monoclonal protein in urine or serum.
  • Senile amyloidosis is caused by deposition of wild type transthyretin → heart failure, carpal tunnel, & spinal stenosis.
  • Inherited amyloidoses incl: hereditary transthyretin amyloidosis, gelsolin amyloidosis, & others
Paraneoplastic
sensory neuropathy		More common w/lung cancer; may precede cancer diagnosis; anti-Hu antibodies

From: SCN9A Neuropathic Pain Syndromes

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