Less is More in Diabetic Neuropathy Diagnosis: Comparison of Quantitative Sudomotor Axon Reflex and Skin Biopsy
To compare the frequency of abnormalities in epidermal nerve fiber density (ENFD) and quantitative sudomotor axon reflex (QSART) in patients with diabetic distal symmetric polyneuropathy (DSPN).Methods:
Nerve conduction studies, ENFD, and QSART data were obtained pre- and postexercise, in patients enrolled in a prospective diabetic neuropathy study. McNemar's test was applied to compare the yield of ENFD and QSART.Results:
Eighteen patients (58 ± 4 years) were enrolled, with 36 data collection points. In diabetic DSPN and diabetic large fiber DSPN (DSPN-L), abnormal ENFD (77% and 100% respectively) is more frequent than abnormal QSART (39% and 35%, respectively) (P value = 0.001 in diabetic DSPN and P value = 0.0002 in diabetic DSPN-L), whereas in diabetic small fiber DSPN (DSPN-S), both tests have similar yields (47%).Conclusions:
ENFD has a high diagnostic yield in diabetic DSPN and DSPN-L. Including QSART data adds little to the sensitivity of EFND in DSPN-S.