Contraction-induced upper extremity H reflexes: normative values.
OBJECTIVE
To determine the reliability of contraction-induced upper extremity H reflexes; to calculate normal values for latency, amplitude, and side-to-side variation; and to correlate latency to arm length.


METHODS
Case series.


METHODS
Electrophysiology laboratory of a tertiary care center.


METHODS
Twenty-three healthy volunteers (4 men, 19 women), aged 19 to 42.


METHODS
Volunteers were tested bilaterally for H reflexes in four to six upper extremity muscles during an isometric contraction.


METHODS
H reflex onset latency, onset to negative peak amplitude, side-to-side variation, normal ranges, and latency versus arm-length correlation.


RESULTS
H reflexes were found at all 264 sites tested. Mean latencies varied from 9.5 to 27 msec. Maximum normal side-to-side variation was 1.5 to 2.7 msec. Maximum normal amplitude ratios (larger to smaller) ranged from 2.06 to 4.80. Abductor pollicis brevis (APB) and abductor digiti minimi (ADM) H reflex latencies were strongly correlated to arm length. Correlation for APB = .64 (p<.0001) and for ADM = .70 (p<.0001).


CONCLUSIONS
Contraction-induced upper extremity H reflexes occur consistently in healthy adults, with latencies, amplitudes, and side-to-side variation occurring in predictable ranges.
D000328:Adult; D001132:Arm / Q000502:physiology; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D012016:Reference Values