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Inhibitory Jaw Reflex (inhibitory + jaw_reflex)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Characteristics of a jaw reflex in humans with temporomandibular disorders: a preliminary report

JOURNAL OF ORAL REHABILITATION, Issue 5 2007
P. MAILLOU
summary, Electromyography was used to compare characteristics of an inhibitory jaw reflex in 10 temporomandibular disorder patients and 10 age- and sex-matched healthy controls. The methodology was novel in that the reflex was that evoked in the active masseter muscle, by electrical stimulation of perioral skin. This response has advantages over those previously studied as it avoids problems associated with stimulating in the moist intra-oral environment and it is monophasic, thus permitting easy quantification. The results have shown that (i) with the stimulation parameters employed, the reflex was present in all 10 control subjects, but in only eight of 10 temporomandibular disorder patients. (ii) When stimulation intensities were expressed as multiples of sensory threshold, there was no significant difference in the minimum level of stimulation required to evoke the reflex between the groups, although there was a trend for the patients with temporomandibular disorders to require higher intensities. (iii) Comparison of data from subjects giving responses at the same stimulus intensity (6 × sensory threshold: seven temporomandibular disorder patients, eight controls), showed no significant differences in the latencies or magnitudes of the reflex between the groups. However, the overall duration of the reflex was significantly shorter for the patients with temporomandibular disorders, with the reflex finishing significantly earlier. Thus even within the limitations of this study, it appears that an inhibitory jaw reflex evoked from stimulation around the mouth, may be weaker in temporomandibular disorder patients. This conclusion is consistent with previous studies on more complex jaw reflexes evoked by intra-oral stimuli. [source]

The inhibitory effect of a chewing task on a human jaw reflex

MUSCLE AND NERVE, Issue 6 2010
Pauline Maillou BDS
Abstract This study was undertaken to investigate whether an inhibitory jaw reflex could be modulated by experimentally controlled conditions that mimicked symptoms of temporomandibular disorders. Reflecting on previous work, we anticipated that these conditions might suppress the reflex. Electromyographic recordings were made from a masseter muscle in 18 subjects, while electrical stimuli were applied to the upper lip. An inhibitory reflex wave (mean latency 47 ms) was identified and quantified. Immediately following an accelerated chewing task, which in most cases produced muscle fatigue and/or pain, the size of the reflex wave decreased significantly by about 30%. The suppression of inhibitory jaw reflexes by fatigue and pain may result in positive feedback, which may contribute to the symptoms of temporomandibular disorders. Future studies of temporomandibular disorder sufferers will help to determine whether such reflex changes reflect the underlying etiology and/or are a result of the temporomandibular disorder itself. Muscle Nerve, 2010 [source]

Possible gender-related differences in a jaw reflex evoked by stimulation of the human lip

JOURNAL OF ORAL REHABILITATION, Issue 9 2002
M. F. LYONS
It has been reported that the latency of the jaw jerk reflex in symptom-free human female subjects is significantly shorter than in male subjects (Kossioni et al., 1994). In the present study, we have begun to investigate whether there are any gender-related differences in other jaw reflexes. The EMG recordings were made from an active masseter muscle in 16 young adult age-matched subjects (eight male, eight female; aged 20,43 years). Inhibitory reflexes were evoked in the muscle by applying stimuli through bipolar electrodes clipped over the lower lip with the cathode placed intraorally on the oral mucosa. While the stimuli were being applied, the subjects maintained the EMG level at around 10% of maximum with the aid of visual feedback. The presence or absence of reflex responses was determined as previously described (Louca et al., 1996). Wilcoxon Rank Sum tests were used to compare the properties of the short- (,10,15 ms) and long- (,40,50 ms) latency inhibitory reflexes evoked by the stimuli in the two groups. There was no significant difference between the male and female groups in the threshold or latency of either reflex. However, the duration of the long-latency inhibition was significantly shorter in females than in males (median values: 29·0 versus 44·0 ms, P=0·015). These preliminary findings suggest that, at least in young human subjects, there is a gender-related difference in the strength but not in the presence of long-latency inhibitory jaw reflexes. [source]