The conventional nerve conduction study measures only the maximal conduction velocity, which represents a minority of the fastest conducting fibers in human peripheral nerve. Therefore, it is unable to detect pathology of majority of nerve fibers with submaximal conduction velocities. To evaluate the diagnostic value of minimal conduction velocity in early phase of diabetic neuropathy, we measured the maximal and minimal motor conduction velocities of ulnar and peroneal nerves on 20 normal adults(Control group), 20 diabetic patients(GroupⅠ) who revealed normal findings in conventional electrodiagnostic procedures, and 40 diabetic patients(GroupⅡ) who revealed abnormal findings.

The results were as follows;

1) The fasting blood sugar and blood sugar level of PC2hours were not significantly different between group Ⅰ and group Ⅱ. The HbAlC level was significantly higher in group Ⅱ.

2) The mean maximal and minimal conduction velocity of ulnar nerve were 69.00±6.21 m/sec, 51.49±4.23 m/sec in control group, 61.84±6.06 m/sec, 45.22±6.34 m/sec in group Ⅰ and 54.53±6.68 m/sec, 39.80±6.74 m/sec in group Ⅱ.

3) The mean maximal and minimal conduction velocity of peroneal nerve were 59.71±6.23 m/sec, 44.76±1.94 m/sec in control group, 52.34±5.88 m/sec, 38.26±5.08 m/sec in group Ⅰ and 45.23±4.82 m/sec, 32.59±4.01 m/sec in group Ⅱ.

4) In comparison of group Ⅰ and group Ⅱ, the maximal and minimal conduction velocities were significantly slower in group Ⅱ in ulnar & peronel nerves(P<0.01).

In comparison of control and group Ⅰ, the maximal & minimal conduction velocities were significantly slower in group Ⅰ in ulnar nerve and only the minimal conduction velocity was signigicantly slower in group Ⅰ in peroneal nerve(P<0.01).

Thus, only the minimal conduction velocity revealed significant differences in two nerves in group comparisons.

5) In group Ⅱ, the maximal and minimal conduction velocities were not significantly different according to the abnormal findings of conventional nerve conduction study.

These findings indicate that the measurement of minimal conduction velocities using Hopf's collision technique is valuable in detecting early stage of polyneuropathy which is not detected by conventional nerve conduction study.

Keywords :Collision method, Maximal motor conduction velocity, Minimal motor conduction velocity, Diabetic neuropathy