[Electrostimulation-induced stapedius reflex. Presentation of a standardized procedure and results of clinical...

The electro-tactile elicitation of the stapedius muscle reflex is well known but not used in clinical practice. Despite a complex reflex pathway in the brainstem, correlations between reflex parameters and neurological impairments are still possible. We have developed a method for eliciting the electro-tactile stapedius muscle reflex and automatic analysis of different reflex parameters by using an analog-digital converter and a personal computer-integrated signal analysis system. Clinical investigations were carried out with a group of 55 healthy persons (control group), 13 patients with central facial palsies, 51 patients with multiple sclerosis (MS group) and 24 patients with absent acoustic-stapedius muscle reflexes. Findings demonstrated that the latency between stimulus and beginning of the reflex (L1) was significantly longer in the MS group compared with the control group. The best parameter for dividing the MS group into groups with different disability scores was S, which was the parameter for the increase in the L1 growth curve at different stimulus levels. Reproduction of the parameter S in repeated tests with different locations of the stimulus-electrode was excellent.