Polyneuropathy is the disease of the nerves, which can be diagnosed by various investigations and it becomes even more important to determine the underlying cause of polyneuropathy once the diagnosis of polyneuropathy has been made. Following are the investigations that are usually carried out to diagnose and determine the underlying cause of polyneuropathy:
1. Routine Blood Investigations:
These investigations give a wild guess about the type and cause of polyneuropathy:
These include following investigations:
I. Full Blood Count
II. Erythrocyte Sedimentation Rate
III. C-Reactive Protein
IV. Serum urea, creatinine and electrolytes
V. Liver Function Tests
VI. Thyroid Function Tests
VII. S. Glucose level
VIII. Vitamin B12 level
2. Specialized Blood Tests:
Specialized blood tests for polyneuropathy include:
I. Antinuclear Antibody
II. Extractable Nuclear Antigen.
III. Antineutrophil Cytoplasmic Antibodies.
IV. Heavy Metals
VI. Genetic Testing
3. Nerve Conduction Studies (NCS) and Electromyography (EMG):
This investigation helps differentiate focal/multifocal neuropathy, sensory and/or motor neuropathy and axonal or sensory neuropathy.
4. Cerebrospinal Fluid (CSF) Examination:
CSF examination can yield very important information especially regarding inflammatory neuropathies with proximal origin. Elevated proteins could be a hint towards paraneoplastic neuropathies while an elevated white cell count in a patient of inflammatory neuropathy could be pointing towards HIV associated neuropathy.
5. Nerve Biopsy:
Nerve biopsy does not have very high diagnostic yield and should only be attempted if it is expected to affect the decisions regarding management.