Peripheral neuropathy (PN) is frequent in patients with
monoclonal gammopathy due to
plasma cell dyscrasia, but little is known about the comparative impact of nerve dysfunction in different disorders. We compared clinical and laboratory results between two diagnostic groups. We recruited 76 untreated
multiple myeloma (MM) and 27
AL amyloidosis (ALA) patients for evaluation of symptoms, clinical findings and nerve conduction studies (NCS). We diagnosed significant PN using total neuropathy scores (TNS > 7) in 17.6% of MM and 48.1% of ALA patients and in 27.7% of MM and 35.7% of ALA patients using NCS findings.
TNS score grades were significantly higher in the
AL amyloidosis patients (Fisher's exact test: P = .02) but a NCS based PN diagnosis was not significantly different (Fisher's exact test: P = .13). A significantly higher
TNS vibration (P = .04) and pin (P = .02) sensory sign and
TNS reflex (P = .04) sign score was found in
amyloidosis patients. Likewise, quantitative sensory thresholds for vibration was higher in
amyloidosis patients (Welsh ANOVA: P = .01). NCS revealed signs of more frequent axonal
tibial neuropathy with significantly lower motor response amplitudes (P = .02) and resulting higher
TNS scores (P = .002), while sural nerve sensory response amplitudes were without significant difference (P = .86). We found more severe
TNS grades of PN in
AL amyloidosis patients compared with MM patients. We also found higher sensory symptoms scores and higher thresholds for vibration but similar sensory involvement using NCS. The NCS exclusively showed signs of an axonal neuropathy.