Objectives: To establish a reliable standardized technique for recording median H-reflexes from the flexor carpi radialis using surface electrodes; to establish normal values for H-reflex latency and side-to-side latency difference; to explore the effect of age and limb length on H-reflex latency; and to construct a three-variable nomogram to allow prediction of H-reflex latency, given age and limb length. Design: Quantitative, cross-sectional, descriptive, and normative study. Setting: Electromyography laboratory at a private outpatient office. Participants: Convenience sample of 123 healthy adult volunteers who met all inclusion and exclusion criteria. Intervention: The median H-reflex was obtained in 115 of 123 subjects. The mean median H-reflex latency was 15.88 � 1.56 ms. The mean side-to-side latency difference was 0.45 � .39 ms. Using two standard deviations, the upper limit of normal for latency was 19.00 ms, and the upper limit of normal for side-to-side difference was 1.23 ms. A weak correlation existed between H-refles latency and age, and a moderate correlation existed betwen H-relfex latency and arm length. Using the regression of H-reflex latency on age and arm length, a three-variable nomogram was constructed. Conclusions: The median H-relfex can be reliabley obtained from the flexor carpi radialis without facilitation. A normative value database was established, and a clinical prediction tool for calculating H-reflex latency was developed. Thus, the clinician is provided with a useful diagnostic technique in the assessment of radiculopathy and neuropathy.
