From the Guidelines
For idiopathic severe axonal polyneuropathy, a comprehensive extended work-up is crucial, including nerve conduction studies/electromyography (NCS/EMG), complete blood count, comprehensive metabolic panel, and specialized testing such as anti-ganglioside antibodies and genetic testing for hereditary neuropathies, as recommended by recent guidelines 1.
Key Components of the Work-up
- Nerve conduction studies/electromyography (NCS/EMG) to assess nerve function and damage
- Complete blood count and comprehensive metabolic panel to evaluate for systemic abnormalities
- Specialized testing including anti-ganglioside antibodies, anti-MAG antibodies, paraneoplastic antibody panel, and genetic testing for hereditary neuropathies (particularly PMP22, MFN2, and GJB1 mutations) to identify potential causes
- Lumbar puncture for CSF analysis to evaluate protein levels, cell count, and oligoclonal bands
- Consider skin biopsy for small fiber evaluation and sural nerve biopsy in select cases
- Imaging, including chest/abdomen/pelvis CT, to screen for occult malignancy
- Toxin exposure history and medication review are essential to identify potential reversible causes
Importance of Comprehensive Evaluation
The comprehensive approach is necessary because axonal polyneuropathies have numerous potential causes, and identifying a treatable etiology is crucial for management, as highlighted in the management of immune-related adverse events 1. Even when no cause is found (truly idiopathic), this thorough evaluation helps exclude treatable conditions and guides symptomatic management with medications like gabapentin, pregabalin, duloxetine, or amitriptyline for neuropathic pain. Prompt recognition and management of symptoms are essential to prevent long-term morbidity and mortality, particularly in cases of severe axonal polyneuropathy, which may resemble immune-related Guillaine-Barré syndrome (GBS) with an incidence of approximately 0.2%-0.4% 1.
From the Research
Idiopathic Severe Axonal Polyneuropathy Extended Work-up
- The diagnosis and treatment of idiopathic severe axonal polyneuropathy can be challenging due to its unknown etiology and lack of response to classical treatments such as steroids, intravenous immunoglobulin, plasmapheresis, or immunosuppressant drugs 2.
- Some studies suggest that rituximab may be effective in treating chronic idiopathic axonal polyneuropathy, with patients showing dramatic improvement in weakness, muscle atrophy, numbness, and paresthesias after receiving intravenous rituximab 2.
- However, other studies have focused on the treatment of chronic inflammatory demyelinating polyneuropathy (CIDP), which is a different condition, and have found that intravenous immunoglobulin (IVIg) is effective in treating CIDP, with at least four randomized controlled trials demonstrating its efficacy in over 60% of CIDP patients 3.
- The use of IVIg in idiopathic autoimmune neuropathies, including Guillain-Barré syndrome, CIDP, and multifocal motor neuropathy, has been shown to be effective, with IVIg being the gold standard for treatment in multifocal motor neuropathy 3.
- A systematic review of chronic idiopathic axonal polyneuropathy found that it is a common type of polyneuropathy, but the least studied, and that increasing awareness and research into this entity may result in better understanding and the development of treatment strategies 4.
- Recent studies have investigated the changes in axonal and clinical function during intravenous and subcutaneous immunoglobulin therapy in CIDP, and have found that IVIg has a rapid clinical effect, but the relation to clinical improvement remains speculative 5.