A field method for blink reflex latency R-1 (BRL R-1) and prediction equations for adults and children.
OBJECTIVE
To develop a field worthy apparatus for blink reflex latency R-1 (BRL R-1), to compare mechanical and electrical stimulation, to define a standardized measurement of BRL R-1, to test a field worthy procedure and to produce population-based prediction equations.


METHODS
A special low voltage electromyographic (EMG) recording system was constructed which is uninfluenced by electrical and magnetic field. The supraorbital notches were stimulated mechanically using a small hammer and electrically using a stimulus of 2.0 ms duration and 2-5 mA 13. A computer program was developed which substracts the baseline for all data points and sums R-1 for 10 tests by identifying the noise floor or baseline of the EMG recording and the noise envelope. The beginning of R-1 and R-2 is defined as 2 times the noise amplitude of this envelope. BRL R-1 was compared after tap and after electrical stimulation in 16 subjects. Prediction equations were developed from data of 240 adults and 163 children unexposed to chemicals.


RESULTS
Mechanically and electrically elicited mean BRL R-1 in 16 subjects was identical at 12.6 ms on the right and 12.7 ms vs 12.5 on the left. In adults, BRL R-1 depended on age. In children BRL R-1 was age, weight and height dependent.


CONCLUSIONS
BRL R-1 elicited by supraorbital tap is field worthy, computer defined and identical to electrical BRL.
Kilburn
K H
KH
Environmental Sciences Laboratory, University of Southern California School of Medicine, Los Angeles, USA.
Thornton
J C
JC
Hanscom
B
B
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001767:Blinking / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D004558:Electric Stimulation; D004576:Electromyography; D004781:Environmental Exposure / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D010812:Physical Stimulation; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results