Degree and pattern of nerve enlargement in upper extremity nerves in chronic polyneuropathies
| Type of polyneuropathy | Degree of nerve enlargement | Pattern of nerve enlargement |
| CIAP | Normal nerve size or mild nerve enlargement | Focal Relatively symmetric Mainly at sites of entrapment |
| CIDP | Moderate-to-severe nerve enlargement | Mainly regional or diffuse, occasionally multifocal Relatively symmetric Mainly proximal nerve segments (upper arm, brachial plexus) |
| CMT: type 1A | Severe nerve enlargement | Predominantly diffuse or occasionally regional Symmetric Along full length of nerves (including brachial plexus) |
| CMT: other types | Normal nerve size or mild nerve enlargement | Focal Relatively symmetric Mainly at sites of entrapment, only mild enlargement outside sites of entrapment possible |
| GBS | Normal nerve size or mild nerve enlargement | Focal Relatively symmetric Mainly at cervical nerve roots, only mild or no enlargement in arm and leg nerves |
| HNPP | Moderate-to-severe nerve enlargement | Focal At sites of entrapment, usually multiple involved |
| IgM neuropahy | Moderate-to-severe nerve enlargement | Regional or diffuse Relatively symmetric Proximal and distal segments of arm nerves and brachial plexus |
| Leprosy | Moderate-to-severe nerve enlargement | Focal Commonly asymmetric Several centimetres proximal to sites of entrapment |
| LSS | Moderate-to-severe nerve enlargement | (multi)focal or regional Asymmetric Mainly proximal nerve segments (upper arm, brachial plexus) |
| MMN | Moderate-to-severe nerve enlargement | (multi)focal, occasionally regional Asymmetric Mainly proximal nerve segments (upper arm, brachial plexus) |
| Vasculitic neuropathy | Mild-to-moderate nerve enlargement | (multi)focal or regional Commonly asymmetric At sites of entrapment, proximal and distal arm, brachial plexus spared |
This table shows the degree and pattern of distribution of nerve enlargement frequently found in different types of chronic polyneuropathy. The pattern of nerve enlargement found may be an additional clue to the diagnose in a patient of suspected neuropathy, but further studies are necessary to determine the specificity and diagnostic value of these specific patterns.
.CIAP, chronic idiopathic axonal polyneuropathy; CIDP, chronic inflammatory demyelinating polyneuropathy; ; CMT, Charcot-Marie-Tooth disease; GBS, Guillain-Barré Syndrome; HNPP, hereditary neuropathy with liability to pressure palsies; LSS, Lewis-Sumner syndrome; MMN, multifocal motor neuropathy.