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Barry J Sessle

Publications and source records attributed to Barry J Sessle.

At least 37 records · Page 2Linked to original sources
PubMed2003

The effect of glutamate-evoked masseter muscle pain on the human jaw-stretch reflex differs in men and women.

AIMS: To compare jaw-stretch reflex responses in male and female subjects and to determine whether injection of glutamate into the masseter muscle facilitates these responses in both sexes. METHODS: Jaw-stretch reflex responses were evoked with a muscle stretcher, and pain intensity was scored by 11 men and 13 women before and after the injection of glutamate (1.0 mol/L, 0.2 ml) into the masseter muscle. The subjects rated glutamate-evoked pain intensity on a visual analog scale. RESULTS: Baseline jaw-stretch reflex responses were larger and glutamate injections into the masseter muscle were significantly more painful in women than in men, however, glutamate significantly facilitated jaw-stretch reflex responses in men but not in women. CONCLUSION: These results suggest that there is a significant sex-related difference in human jaw-stretch reflex responses and their modulation by painful stimuli. Since one possible function of facilitated jaw-stretch reflex responses during jaw muscle pain may be to reduce jaw mobility and thus protect against further exacerbation of an existing injury, the finding of a sex-related difference in modulation of jaw-stretch reflex responses may prove to be important in clarifying why the prevalence of temporomandibular disorders is greater in women than in men.

Adult↗
PubMed2002

Influence of sex on reflex jaw muscle activity evoked from the rat temporomandibular joint.

Injection of glutamate into the rat temporomandibular joint (TMJ) evoked a concentration-dependent increase in jaw muscle activity. We investigated whether there are sex-related differences in glutamate-evoked jaw muscle activity that are mediated by sex hormones and whether prior injection of glutamate into the TMJ alters the magnitude of jaw muscle activity evoked by a subsequent injection of the algesic and inflammatory compound mustard oil (MO) into the TMJ. The magnitude of glutamate-evoked digastric and masseter muscle activity was significantly greater in female than male rats when 1000 mM glutamate was injected into the TMJ. Gonadectomy significantly reduced the magnitude of glutamate-evoked digastric muscle activity in female rats. Treatment of gonadectomized female rats with estrogen (20 microg/day) increased the magnitude of glutamate-evoked digastric muscle activity. Glutamate-evoked jaw muscle activity in gonadectomized and estrogen-treated gonadectomized males was not significantly different from intact males. Prior injection of glutamate over a concentration range of 10-1000 mM significantly increased digastric muscle activity evoked by MO injection into the TMJ 30 min later. In contrast, MO-evoked masseter muscle activity was significantly increased by prior injection of 250 mM glutamate only. There were, however, no sex-related differences in the enhancement of MO-evoked jaw muscle activity by prior injection of glutamate. These findings indicate that there are sex-related differences in glutamate-evoked jaw muscle activity that are dependent on female sex hormones, and increased glutamate concentrations sensitize the TMJ to noxious chemical stimuli.

Animals↗
PubMed2002

Effects of reversible bilateral inactivation of face primary motor cortex on mastication and swallowing.

The effects of reversible cold block-induced bilateral inactivation of the face primary motor cortex (face MI) on mastication and swallowing were studied in awake monkeys. A warm or cold alcohol-water solution was pumped through thermodes placed bilaterally on the dura overlying the intracortical microstimulation-defined face MI while the monkey chewed and swallowed food during pre-cool (thermode temperature 37 degrees C), cold block (4 degrees C), and post-cool (37 degrees C) sessions. Vertical and horizontal jaw movements and electromyographic (EMG) activity of several muscles were monitored. Each masticatory sequence was divided into three masticatory phases (i.e. food preparatory, rhythmic chewing, preswallow). The cold block markedly affected the ability of the monkey to carry out mastication although it did not prevent mastication from occurring. The masticatory deficit was characterized by a significant elongation of the total masticatory time, including in particular elongation of the food preparatory phase. The coordination of the jaw- and tongue-muscle activities was severely disrupted during the food preparatory phase. Face MI cold block also significantly affected the duration of some masticatory-related EMG activities and had some limited effects on the temporal relationships of the EMG activities during mastication. Although cold block significantly affected the duration and some EMG parameters of the preswallow phase, it had no significant effect on swallow duration or the EMG parameters during swallowing. These findings provide further evidence that the primate face MI plays a critical role in the regulation of mastication and that it plays a role in the preparation for swallowing.

Animals↗
PubMed2002

Effects on mastication of reversible bilateral inactivation of the lateral pericentral cortex in the monkey (Macaca fascicularis).

It is known that intracortical microstimulation (ICMS) of the lateral pericentral cortex can evoke masticatory movements and swallowing in awake monkeys. The aim was to determine if the ability of monkeys to carry out mastication is affected by reversible bilateral cold block of the ICMS-defined cortical masticatory area/swallow cortex. A cranial chamber was implanted bilaterally in two monkeys and a warm or cold alcohol-water solution was pumped through thermodes placed bilaterally on the dura overlying the ICMS-defined cortical masticatory area/swallow cortex while monkeys chewed standardised amounts of fruit during pre-cool (thermode temperature, 37 degrees C), cool (0-4 degrees C), and post-cool (37 degrees C) trials. Electromyographic (EMG) activity was recorded from masseter, genioglossus, anterior digastric, geniohyoid and thyrohyoid or perilaryngeal muscles. Vertical and horizontal jaw movements were recorded with a photodiode position transducer, which monitored movements of a light-emitting diode fixed to the mandible. Each masticatory period was divided into a food-preparatory phase, a rhythmic chewing phase and a preswallow phase. Both monkeys could readily accept and ingest the foodstuffs during pre-cool and post-cool trials. In contrast, cold block was associated with masticatory deficits, reflected in both monkeys as impaired food intake or manipulation and difficulty in carrying out a sequence of masticatory cycles, alterations in of the food-preparatory phase, and alterations in masticatory-related EMG patterns of the jaw and tongue muscles. The cold block-induced changes included significant (P<0.05) prolongations of the total masticatory time, the food-preparatory phase duration, and burst durations of the jaw and tongue muscle EMG activities; furthermore, the amplitudes and temporal correlations of the EMG activities of the jaw and tongue muscles were significantly (P<0.05) changed by cold block. These findings provide further evidence that the lateral pericentral cortex has a critical role in the initiation and regulation of masticatory movements in the primate, and that the programming of masticatory muscle activities may be dependent upon corticofugal influences for engaging masticatory motor activities appropriate to the masticatory conditions.

Animals↗
PubMed2002

Effects of reversible cold block of face primary somatosensory cortex on orofacial movements and related face primary motor cortex neuronal activity.

Our previous studies have revealed that face primary somatosensory cortex (SI) as well as face primary motor cortex (MI) play important roles in the control of orofacial movements in awake monkeys, and that both face MI and face SI neurons may have an orofacial mechanoreceptive field and show activity related to orofacial movements. Since it is possible that the movement-related activity of face MI neurons could reflect movement-generated orofacial afferent inputs projecting to face MI via face SI, the present study used reversible cold block-induced inactivation of the monkey's face SI to determine if face MI neuronal activity related to a trained tongue-protrusion task, chewing or swallowing was dependent on the functional integrity of the ipsilateral face SI and if inactivation of face SI affects orofacial movements. The effects of face SI cold block were tested on chewing, swallowing and/or task-related activity of 73 face MI neurons. Both task and chewing and/or swallowing-related activity of most face MI neurons was independent of the functional integrity of the ipsilateral face SI since SI cold block affected the movement-related activity in approximately 25% of the neurons. Similarly, unilateral cold block of SI had very limited effects on the performance of the task and chewing, and no effect on the performance of swallowing. These findings suggest that movement-induced reafferentation via face SI may not be a significant factor in accounting for the activity of the majority of ipsilateral face MI neurons related to trained movements, chewing and swallowing.

Animals↗
PubMed2002

Central sensitization of nociceptive neurons in trigeminal subnucleus oralis depends on integrity of subnucleus caudalis.

Our recent studies have shown that application to the tooth pulp of the inflammatory irritant mustard oil (MO) produces a prolonged (>40 min) "central sensitization" reflected in neuroplastic changes in the mechanoreceptive field (RF) and response properties of nociceptive brain stem neurons in subnuclei oralis (Vo) and caudalis (Vc) of the trigeminal spinal tract nucleus. In view of the previously demonstrated ascending modulatory influence of Vc on Vo, our aim was to determine whether the Vo neuroplastic changes induced by MO application to the tooth pulp depend on an ascending influence from Vc. In chloralose/urethan-anesthetized rats, MO application to the pulp produced significant increases in Vo nociceptive neuronal orofacial RF size and responses to mechanical noxious stimuli that lasted as long as 40-60 min. These changes were not affected by vehicle (saline) microinjected into Vc at 20 min after MO application, but 0.3 microl of a 5 mM CoCl(2) solution microinjected into the ipsilateral Vc produced a reversible blockade of the MO-induced Vo neuroplastic changes. A similar volume and concentration of CoCl(2) solution injected into subnucleus interpolaris of the trigeminal spinal tract nucleus did not affect the MO-induced neuroplastic changes in Vo. These findings indicate that inflammatory pulp-induced central sensitization in Vo is dependent on the functional integrity of Vc.

Animals↗
PubMed2002

Neuronal activity patterns in primate primary motor cortex related to trained or semiautomatic jaw and tongue movements.

The present study was undertaken to determine the firing patterns and the mechanoreceptive field (RF) properties of neurons within the face primary motor cortex (face-MI) in relation to chewing and other orofacial movements in the awake monkey. Of a total of 107 face-MI neurons recorded, 73 of 74 tested had activity related to chewing and 47 of 66 neurons tested showed activity related to a trained tongue task. Of the 73 chewing-related neurons, 52 (71.2%) showed clear rhythmic activity during rhythmic chewing. A total of 32 (43.8%) also showed significant alterations in activity in relation to the swallowing of a solid food (apple) bolus. Many of the chewing-related neurons (81.8% of 55 tested) had an orofacial RF, which for most was on the tongue dorsum. Tongue protrusion was evoked by intracortical microstimulation (ICMS) at most (63.6%) of the recording sites where neurons fired during the rhythmic jaw-opening phase, whereas tongue retraction was evoked by ICMS at most (66.7%) sites at which the neurons firing during the rhythmic jaw-closing phase were recorded. Of the 47 task-related neurons, 21 of 22 (95.5%) examined also showed chewing-related activity and 29 (61.7%) demonstrated significant alteration in activity in relation to the swallowing of a juice reward. There were no significant differences in the peak firing frequency among neuronal activities related to chewing, swallowing, or the task. These findings provide further evidence that face-MI may play an important role not only in trained orofacial movements but also in chewing as well as swallowing, including the control of tongue and jaw movements that occur during the masticatory sequence.

Animals↗
PubMed2002

P2X receptors in trigeminal subnucleus caudalis modulate central sensitization in trigeminal subnucleus oralis.

This study investigated the role of trigeminal subnucleus caudalis (Vc) P2X receptors in the mediation of central sensitization induced in nociceptive neurons in subnucleus oralis (Vo) by mustard oil (MO) application to the tooth pulp in anesthetized rats. MO application produced a long-lasting central sensitization reflected in neuroplastic changes (i.e., increases in neuronal mechanoreceptive field size and responses to innocuous and noxious mechanical stimuli) in Vo nociceptive neurons. Twenty minutes after MO application, the intrathecal (i.t.) administration to the rostral Vc of the selective P2X(1), P2X(3), and P2X(2/3) receptor antagonist, 2'-(or 3'-)O-trinitrophenyl-ATP (TNP-ATP), significantly and reversibly attenuated the MO-induced central sensitization for more than 15 min; saline administration had no effect. Administration to the rostral Vc of the selective P2X(1), P2X(3), and P2X(2/3) receptor agonist, alpha,beta-methylene ATP (alpha,beta-meATP, i.t.) produced abrupt and significant neuroplastic changes in Vo nociceptive neurons, followed by neuronal desensitization as evidenced by the ineffectiveness of a second i.t. application of alpha,beta-meATP and subsequent MO application to the pulp. Administration to the rostral Vc of the selective P2X(1) receptor agonist beta,gamma-methylene ATP (beta,gamma-meATP, i.t.) produced no significant neuroplastic changes per se and did not affect the subsequent MO-induced neuroplastic changes in Vo nociceptive neurons. These results suggest that P2X(3) and possibly also the P2X(2/3) receptor subtypes in Vc may play a role in the initiation and maintenance of central sensitization in Vo nociceptive neurons induced by MO application to the pulp.

Adenosine Triphosphate↗
PubMed2002

Integration of basic sciences into the predoctoral curriculum to study temporomandibular disorders and orofacial pain.

This paper outlines several aspects of the integration of basic sciences into the predoctoral dental curriculum. It addresses a number of the points or questions posed by the organizers of the Third Educational Conference to Develop the Curriculum in Temporomandibular Disorders and Orofacial Pain. The importance of the basic sciences for a comprehensive overview of knowledge bearing on temporomandibular disorders and orofacial pain is first emphasized, followed by considerations of what material should be taught and by whom. The paper concludes by considering at what stage of the curriculum this material should be included, how the pertinent basics sciences should be taught, and under what circumstances. Under the term "basic sciences" are included not only relevant biomedical or biologic sciences such as physiology and anatomy, but also the behavioral sciences such as psychology and cognitive science.

Behavioral Sciences↗
PubMed2002

Recent insights into brainstem mechanisms underlying craniofacial pain.

This article briefly highlights some of the recent advances in knowledge of the neural processes underlying pain in the face and mouth. It particularly focuses on those mechanisms operating in the brainstem that are involved in the transmission and modulation of nociceptive signals and that reveal a remarkable degree of plasticity following injury or inflammation of craniofacial tissues. Insights into these processes hold promise of the development of new or improved therapeutic procedures for the relief of pain.

Afferent Pathways↗
PubMed1995

Parabrachial area and nucleus raphe magnus-induced modulation of electrically evoked trigeminal subnucleus caudalis neuronal responses to cutaneous or deep A-fiber and C-fiber inputs in rats.

The aim of this study was to determine whether trigeminal subnucleus caudalis (Vc) neurons show differential inhibitory effects produced by parabrachial area (PBA) or nucleus raphe magnus (NRM) conditioning stimulation (CS) on their A-fiber versus C-fiber inputs electrically evoked from cutaneous and deep tissues. A total of 55 Vc neurons in urethane/chloralose-anesthetized rats were functionally classified as low-threshold mechanoreceptive (LTM; n = 12), nociceptive (wide-dynamic-range, WDR, and nociceptive-specific, NS; n = 11), deep (D; n = 6), or nociceptive convergent neurons receiving skin and deep inputs (S+D; n = 26). Most neuronal responses were tested for both PBA and NRM CS (20-40 microA) delivered 50 msec prior to test stimulation (1.1-1.5 x threshold) of their mechanoreceptive field (RF) or the hypoglossal nerve (XII). Inhibition of responses to both cutaneous and deep A-fiber and C-fiber inputs occurred in over two-thirds of the Vc neurons tested in each neuronal class, and facilitation of responses was only occasionally found. In general, both PBA (ipsi- and contralateral) and NRM CS produced profound inhibition of electrically evoked responses in all neuron types, e.g., responses reduced to mean values of 50-53% of control in LTM neurons, 35-46% in WDR, NS, and S+D neurons, and 61-63% in D neurons. No significant difference in the magnitude of their inhibitory effects was found between PBA and NRM, and between Vc neuronal responses to A- and C-fiber inputs irrespective of their origin from skin or deep tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Pain and personality profiles in burning mouth syndrome.

The McGill Pain Questionnaire (MPQ) and the Minnesota Multiphasic Personality Inventory (MMPI) were administered to 72 subjects with burning mouth syndrome (BMS) who were also requested to match the levels of their clinical pain to line lengths on a visual analogue scale (VAS) and to experimentally induced warm and painful thermal stimuli. The responses of 102 toothache pain subjects and 43 asymptomatic age- and sex-matched control subjects were used to compare the responses of the BMS subjects on the MPQ and MMPI, respectively. The results indicated that BMS pain is quantitatively similar to, but qualitatively different from, toothache pain, that self-reports of BMS pain appear to be valid, that when compared to the asymptomatic control subjects, BMS subjects show elevations in certain personality characteristics which are similar to those seen in other chronic pain patients, and that these personality disturbances tend to increase with increased pain. Therefore, our findings indicate that the pain of BMS is more severe than has previously been suggested and that the severity of this pain may explain some of the personality changes which occur in the BMS subjects.

Adult↗
PubMed1987

Psychophysical assessment of tactile, pain and thermal sensory functions in burning mouth syndrome.

Tactile, two-point discrimination, thermal change detection and heat pain thresholds as well as oral stereognostic ability, warmth scaling and heat pain tolerance were compared in a group of 72 subjects with burning mouth syndrome (BMS) and 43 age- and sex-matched control subjects. No differences were found between the BMS and control subjects for any of the sensory modalities tested except for heat pain tolerance. Pain tolerance was significantly decreased for the BMS subjects at the tongue tip, a site of clinical pain in approximately 85% of the subjects tested in this study, but not at the cutaneous lower lip which was a site of pain only in approximately 17% of the subjects tested in this study. In addition, no differences in heat pain tolerance were found at the cutaneous lower lip between the control subjects and the BMS subjects who reported pain on the mucosal lower lip (approximately 49% of subjects), but heat pain tolerance was significantly decreased at this site for those BMS subjects tested without pain on the mucosal lower lip (approximately 51% of subjects). These findings do not suggest a psychogenic origin for the alteration of heat pain tolerance in the BMS subjects, but suggest instead specific changes in their peripheral or central sensory functions.

Adult↗
PubMed1984

Applicability of the McGill Pain Questionnaire to the differentiation of 'toothache' pain.

The McGill Pain Questionnaire (MPQ) was administered to 102 'toothache' patients to determine whether it was sufficiently sensitive to distinguish between dental patients whose pain was clinically diagnosed as originating from a reversibly inflamed tooth pulp (group I) and those whose pain was diagnosed as originating from an irreversibly inflamed or necrotic pulp (group II). Scores for Total Pain Rank Index (PRI(T)), Sensory Pain Rank Index (PRI(S)), Evaluative Pain Rank Index (PRI(E)), Miscellaneous Pain Rank Index (PRI(M)), and Number of Words Chosen (NWC) were significantly higher (p less than 0.05) for group II patients. The PRI differences between both groups were attributed mainly to the more frequent selection by group II patients of 8 of the 20 subclasses of words and/or of words with higher rank values within the 8 subclasses. A significantly greater degree of sleep disturbance, nausea, headache, drowsiness and/or dizziness was also found in group II patients. Discriminant analysis using the 20 subclasses and 4 supplementary questions related to sleep disturbance, changes in food intake or activity levels, and accompanying symptoms, indicated that the MPQ, when used alone, correctly predicted diagnosis and treatment outcome in 73% of patients. Therefore, our findings indicate that the MPQ can distinguish between the two types of toothache and suggest that, especially when used along with other standard diagnostic tests, it may be a useful clinical adjunct in the diagnosis of dental pain.

Adolescent↗
PubMed1981

Raphe-induced suppression of the jaw-opening reflex and single neurons in trigeminal subnucleus oralis, and influence of naloxone and subnucleus caudalis.

(1) The effects of stimulation of the nucleus raphe magnus (NRM) and the periaqueductal gray (PAG) were tested on the digastric (jaw-opening) reflex and on the activity of functionally identified single neurons recorded in trigeminal (V) subnucleus oralis in the brain stem. Reflex and neuronal responses evoked by tooth pulp stimulation could be readily suppressed for 250--1000 msec by PAG and NRM conditioning stimuli. The effects were not specific for tooth pulp afferent inputs, however, since suppression was also apparent in jaw-opening reflex responses evoked by low-intensity electrical or tactile stimulation of oral-facial sites, and in the mechanically or electrically evoked responses of oralis neurons with localized low-threshold mechanoreceptive fields. (2) The modulatory effects on the jaw-opening reflex and oralis neuron activity were not altered by reversible cold block of synaptic transmission in V subnucleus caudalis. Thus it appears that the PAG- and NRM-induced effects on the reflex and oralis neurons are not dependent on relays via caudalis. (3) Some of the suppressive influences on responses to oral-facial stimuli could be reversed by the administration of the opiate antagonist naloxone. This suggests that some of the modulatory influences involve endogenous opiate-related mechanisms. (4) Many of the oralis neurons were identified as trigeminothalamic relay neurons on the basis of their antidromic response to ventrobasal thalamic stimulation; PAG and NRM conditioning produced not only a suppression of their orthodromic responses to oral-facial stimuli but also caused a decrease in the antidromic excitability of the relay neurons. This decrease may be indicative of raphe-induced postsynaptic inhibition of oralis neurons, and/or presynaptic facilitation of their thalamic endings.

Animals↗