Objective: The purpose of this study was to establish the normal values of tendon reflexes (T-reflex) in upper extremities of normal Korean adults.

Method: T-reflex responses were recorded in 30 normal volunteers by delivering tendon taps with a hand operated electric reflex hammer. From 5 repeated trials of each subject, the shortest onset latency and duration, the largest peak to peak amplitude of compound muscle action potentials were chosen for representative values.

Results:

1) There was no significance in the side-to-side differences for all values.

2) Mean values of latency were 13.8⁑1.1 msec in males, 12.4⁑0.9 msec in females for biceps T-reflex and 13.0⁑1.1 msec in males, 11.3⁑1.0 msec in females for triceps T-reflex and there were significant differences between males and females.

3) Height and upper arm length showed a significant positive correlation with biceps and triceps T-reflex latency (p＜0.001).

Conclusion: We believe that our results can be used as a guideline researching the tendon reflexes in upper extremities.

Early onset cerebellar ataxia with retained tendon reflexes is distinctive clinical syndrome characterized by progressive cerebellar ataxia of unknown etiology with an onset within the first two decades. This disorder was distinguished from Friedreich's ataxia by the preservation of the deep tendon reflexes. There is 22-year-old male with 13 year history of slowly progressive cerebellar ataxia and dysarthria. His elder brother, also, has milder clinical manifestations, electrophysiological and radiological abnormalities. We experienced two cases of early onset cerebellar ataxia with retained tendon reflexes developed in brothers which was diagnosed by clinical manifestations, electrophysiologic, radiologic studies and report with brief review of related literatures.