568-P: Pain Threshold of Intraepidermal Nerve Terminal Reflects Small Nerve Fiber Function and Rises in Early Phase of Diabetes

Abstract

We measured pain threshold of intra-epidermal nerve terminal (PINT) which is a simple and noninvasive method that can measure pain threshold of A delta fiber by intra-epidermal electrical stimulation. We aimed to investigate normal value, prevalence of abnormality and clinically associated factors to PINT and quantitative vibratory perception threshold (QVT). PINT and QVT were measured by a portable peripheral nerve testing device PNS-7000, and a vibration sensation meter AU 02-B in 656 Japanese regional health checkup examinees (40-75 years old; years old). Glucose tolerance; normal (N), pre-DM, newly diagnosed DM (NDM) and known DM (KDM), and neuropathic findings (pain, paresthesia, numbness in legs and reduced ATRs) were also determined. Relationship between age, glucose tolerance, neuropathic findings and PINT or QVT were investigated by simple and multivariate analyses. In 445 non-DM subjects without neuropathic findings, normal limit value of PINT (mA) was set by quantile regression method, and relationship between prevalence of PINT or QVT abnormalities and clinical factors were examined. As results, PINT was not changed under 70 years old, then somewhat elevated. QVT elevated from 50 years old. PINT was not associated with QVT. PINT was significantly elevated in NDM and KDM. QVT was elevated in diabetes and hypertension. Among the neuropathic findings, PINT was significantly associated with only pain. By multiple regression analyses, significant aggravating factors of PINT were aging and glucose intolerance. Normal values of PINT were > 0.4 (<69 years old) and >0.5 (70< years old) Prevalence of PINT abnormality were 3%, 4%, 13% and 9% in N, pre-DM, NDM and KDM, respectively. They were significantly increased with the deterioration of glucose tolerance. QVT abnormality was not significantly increased with glucose intolerance. In conclusion, PINT reflects small nerve fiber function, and associates with DM. So, PINT may be a useful for diagnosis and evaluation of small fiber neuropathy. Disclosure H. Sasaki: None. S. Kishimoto: None. K. Ogawa: None. S. Kurisu: None. K. Nanjo: None. Funding Japan Society for the Promotion of Science