The masseter reflex: Postprocessing methods and influence of age and gender - Normative values of the masseter reflex

Objectives: Normative values of the masseter reflex are scarce. We studied the latencies, amplitudes and side differences of the masseter reflex in 10 5 healthy volunteers between the ages of 5 and 78 years. Methods: Latencies were calculated as the mean of 10 single sweeps and, simultaneously, measu red from the summation curve. Short-term reproducibility was determined in 33 volunteers by retesting the reflex after 1 week. Results: There was a po sitive correlation between age and latencies and a negative correlation bet ween age and amplitude. Maximal normal latencies were 8.3 ms for men and 7. 9 ms for women in the age group below 50 years and 9.1 and 9.2 ms for the a ge group above 50 years. Latency differences between the right and left sid es of >0.4 ms for subjects aged below 50 years and >0.5 ms for subjects age d above 50 years exceeded the 95% confidence interval. Amplitudes did not d epend on gender. Calculated as a percentage of the side with higher amplitu de, differences above one third could be accepted as abnormal. Conclusion: The masseter reflex appears to be a stable and robust clinical test, if age and gender differences are taken into account. Copyright (C) 2001 S. Karge r AG, Basel.