Human Current Perception Threshold Objective Test Methods

Quantitative Sensory Testing (QST) has been used to detect and characterize sensation alteration in human being. Most clinical conditions come with neuropathies and cause the disorder of sensory function, including diabetic mellitus, uremia and so on. QST is easy and simple to perform, and mostly not painful. It is an important auxiliary method to diagnose the peripheral neuropathies and is particularly suited for screening and longterm evaluation of sensory function.An objective method to measure human current perception threshold (CPT) is discussed in this dissertation. Galvanic skin responses (GSR) of subject are sampled to reflect his/her responses to quantitative stimuli. The new method can exclude the subjective factors and is more objective in comparison with conventional quantitative sensory testing methods.Existing clinical studies indicate that sinusoidal percutaneous stimuli of 5Hz, 250Hz and 2000 Hz activate C fibers, Aδ fibers and Aβ fibers, respectively. Thus, the current stimuli of these frequencies can be used to assess the function of different nerve fibers. Skin conductance responses to discrete 5Hz and 250Hz sinusoidal electric current stimuli are recorded with a CPT testing system. Stimuli with large magnitudes can evoke GSR while weak stimuli evoke no GSR. The average of intensities of the maximum stimulus not causing arousal and the minimum stimulus causing arousal is considered as current perception threshold.CPT of ten healthy subjects using both GSR method and forced-choice method are obtained. Results of two methods are compared and analyzed. Experimental results show that new method is easy to operate, reliable and objective.