The value of fourth finger sensory median-ulnar nerve latency difference test in grading carpal tunnel sydrome

Purpose: fourth finger sensory median-ulnar nerve latency difference test is a frequently used method in detecting carpal tunnel syndromes of especially beginning stage. the objective of this study was to show the value of fourth finger sensory median-ulnar nerve latency difference test in grading carpal tunnel syndrome and to find out which value second finger sensory median nerve latency should exceed in order to make a comparative study with fourth finger sensory median-ulnar nerve study.materials and methods: if routine nerve conduction studies were normal and the fourth finger sensory medianulnar nerve latency difference was 0.5 msec and above, cts was considered to be very mild; if only median nerve sensory latency extension (over 3.5 msec) was present cts was considered to be mild; if in addition to median sensory latency extension there was median sensory amplitude decrease and/or median nerve motor distal latency extension, cts was considered to be moderate. 86 women, 35 men, 189 hands with diagnosis of carpal tunnel syndrome were evaluated in this study.results: latency difference and age in the moderate cts group was statistically significantly higher when compared with other groups (p<0.001). the cases whose median-ulnar sensory nerve fourth finger latency difference was 0.5 msec and the cases above this had median sensory nerve distal latency values of 3.0 msec and above.conclusion: while 1.9 msec and above fourth finger sensory median and ulnar nerve latency difference was helpful in making a diagnosis of moderate cts, it did not have a contribution to making very mild and mild cts diagnosis. in addition, we recommend this test to be used in cases with cts clinic, normal emg examination and a median sensory latency value of 3.0 msec and over.