The investigations of note in peripheral neuropathy include:
- ESR, CRP
- LFTs, GGT
- plasma B12 and folate
- serum protein electrophoresis and immunoelectrophoresis
Subsequently, EMG and peripheral nerve conduction; if these are normal and assuming symptoms and signs are confined to the legs, question whether there is a lesion in the cauda equina.
- other special investigations may include serum vitamin E concentrations, cryoglobulins, urinary heavy metals and porphyrins, antinuclear antibodies, rheumatoid factor, Sjogren's syndrome (SS) antibodies, (SS-A (anti-Ro) and SS-B (anti- La)), serology for Lyme disease and HIV, antiganglioside GM1 antibodies, Schirmer's test; if raised inflammatory markers and features of possible paraneoplastic peripheral neuropathy then further investigation for possible occult malignancy
- McLeod JG. Investigation of peripheral neuropathy. Journal of Neurology, Neurosurgery, and Psychiatry 1995;58:274-283.