The Importance of Thermal Threshold Testing in Detecting of Small Fiber Neuropathy in Type 1 Diabetes Mellitus
Abstract
Background: Thermal threshold testing represents an integral part of neurophysiological diagnostics of small fiber neuropathy. Diabetes mellitus is the most common cause of SFN.
The aim of our study was to evaluate changes of thermal thresholds depending on the duration of diabetes. Material and methods: 45 patients with type 1 diabetes mellitus (27 women, 18 men, mean age 45,1 years) were enrolled in the study.
The group was divided into two subgroups according to the duration of diabetes ( 25 years). We used a thermal stimulator (Somedic) and determined cold detection thresholds (CDT) and warm detection thresholds (WDT) in thenar, tibia and dorsum of the foot.
Non-randomized method of reaction time was used as an investigative algorithm. Results: We demonstrated a statistically significant difference between the thermal thresholds in lower extremities/tibia (CDT p < 0.001, WDT p = 0.002), dorsum of the foot (CDT, WDT p < 0.001).
In diabetics, CDTs are lower and WDTs are higher in comparison with controls. An abnormality of CDT occurs earlier and more frequently.
We proved statistically significant difference for the mean values of CDT (p = 0.024) and for the mean values of WDT (p = 0.049) in the dorsum of the foot between the two subgroups. Linear regression demonstrated a statistically signifi cant relationship between the thermal thresholds in the dorsum of the foot and the duration of diabetes and determined individual regression equations.
Conclusion: Thermal threshold testing in the distal part of the leg appears to be a good screening tool for detection of small fiber neuropathy in type 1 diabetic patients, especially in diabetics with neuropatic symptoms and normal nerve conduction studies and needle electromyography.