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PubMed1994

Importance of cholinergic, GABAergic, serotonergic and other neurons in the medial medullary reticular formation for sleep-wake states studied by cytotoxic lesions in the cat.

Previous evidence has suggested that neurons in the medial medullary reticular formation play a critical role in the modulation of forebrain and spinal cord activity that occurs during the sleep-waking cycle and particularly in association with the state of paradoxical sleep. The importance of these neurons, including cholinergic, serotonergic and GABAergic cells [Holmes C. J. et al. (1994) Neuroscience 62, 1155-1178] for sleep-wake states was investigated after their destruction with the neurotoxin quisqualic acid injected into the medullary gigantocellular and magnocellular tegmental fields in cats. To assess the effects of the neuronal loss, polygraphic recording and behavioural observations were performed in baseline and for three weeks after the lesion, and the changes in these measures were correlated with the volume of destruction of medullary regions and the numbers of chemically identified cells within those regions. Following the cytotoxic lesions, which affected approximately 60% of the medullary gigantocellular and magnocellular tegmental fields, there was a significant reduction in the amount of paradoxical sleep (to a mean of 64% of baseline) during the first postlesion week, that recovered variably across cats in the second and third weeks. There was little to no change in the amount or organization of waking and slow wave sleep. The individually variable amounts of postlesion paradoxical sleep were correlated positively with the number of surviving cholinergic cells, negatively with the number of surviving serotonergic cells and positively with the ratio of surviving cholinergic or GABAergic cells to serotonergic cells. The most marked effect of the lesion was a substantial increase in the amplitude of the nuchal electromyogram during slow wave sleep (to 198%) and paradoxical sleep (to 378% of baseline in the first postlesion week). The increase in muscle tone was associated with movements of the head, neck or limbs during paradoxical sleep. Although, in some cats, the abnormal neck muscle tone decreased with time, limb movements continued to occur during paradoxical sleep for the duration of the experiment. The ratio of the total number of remaining cholinergic or GABAergic cells to serotonergic cells correlated negatively with the increased muscle tone and/or movements. It was concluded that the neurons of the medial medullary reticular formation contribute to, but are not necessary for, the generation of paradoxical sleep, and have particular importance for the regulation of muscle tone and inhibition of movement during this state.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1991

The validity and predictive value of four assessment instruments for evaluation of the cervical and stomatognathic systems.

Four assessment instruments--a 10-item cervical pain questionnaire, a 10-item TMJ pain questionnaire, the Cervical Range of Motion (CROM) instrument, and the Craniomandibular Index--were used to evaluate 25 consecutive patients presenting to a physical therapy clinic for evaluation and treatment of cervical hyperextension-hyperflexion injuries. The assessment tools were tested for internal consistency between the cervical and stomatognathic measures as well as between the two sets of measures. The cervical questionnaire was strongly correlated to the CROM measurements. Tenderness to palpation of the superficial neck muscles was not correlated to the cervical questionnaire nor to measures of cervical flexion-extension or lateral flexion. It was, however, correlated to cervical rotation. The TMJ questionnaire was a useful predictor of muscular tenderness and self-reported symptoms in the stomatognathic system, but it was not related to the intra-articular signs of TMD. The flexion-extension and rotation measures of cervical mobility were useful predictors of masticatory muscle tenderness. These assessment tools are valid indicators of cervical or stomatognathic status and, when used together, provide a comprehensive description of jaw and neck status.

Humans↗

PubMed1982

The cervical spine in fibrodysplasia ossificans progressiva.

Radiographs of the cervical spine in 11 patients with fibrodysplasia ossificans progressiva (FOP) have been examined, and abnormalities found in all. In 4, small cervical vertebral bodies with enlarged pedicles were seen in early childhood; later, variable fusion of the vertebrae was apparent in all patients. This fusion was first noted between adjacent neural arches in late childhood but also involved the vertebral bodies in some adult patients. It was only sometimes associated with ossification of the adjacent neck muscles, and appeared to be an important cause of neck stiffness in FOP. The radiological changes may be confused with those of Still's disease or of the Klippel-Feil syndrome.

Adolescent↗

PubMed1975

Adrenergic and cholinergic receptors in the human prostate, prostatic capsule and bladder neck.

The adrenergic and cholinergic receptors of the human prostatic capsule, prostatic "adenoma", and bladder neck, were investigated by the in-vitro isometric technique. The prostatic capsule was found to be very rich in both alpha-adrenergic receptors and cholinergic receptors. The prostatic adenoma was moderately rich in alpha-adrenergic receptors, but cholinergic receptors were absent. Beta-adrenergic receptors were absent in the prostatic adenoma, and there was an equivocal response in less than half the specimens of the prostatic capsule. An attempt was made to distinguish between the trigonal component at the posterior bladder neck, and the true bladder neck muscle both posteriorly and antero-laterally. The results indicat that the "posterior bladder neck" seen at operation is predominantly trigonal muscle, and is poor in cholinergic receptors. The adrenergic response is variable in the true bladder neck muscle, but is present and strong in the trigonal muscle. This response is characteristically gradual in its development. In view of the findings in this investigation, it is suggested that certain instances of acute retention of urine in prostatic patients are due to over-stimulation of the alpha-adrenergic receptors, particularly those in the prostatic capsule. Similarly, the accepted clinical contraindication to the use of cholinergic drugs for retention in the prostatic patient is supported by the distribution of the cholinergic receptors in the tissues examined.

Acetylcholine↗

PubMed1999

From balance regulation to body orientation: two goals for muscle proprioceptive information processing?

This study was based on the assumption that the central processing of proprioceptive inputs that arise from numerous muscles contributes to both awareness and control of body posture. The muscle-spindle inputs form a "proprioceptive chain" which functionally links the eye muscles to the foot muscles. Here, we focused on the specific contribution of two links in the control of human erect posture by investigating how proprioceptive messages arising from ankle and neck muscles may be integrated by the central nervous system. Single or combined mechanical vibrations were applied to different muscle tendons at either one (ankle or neck) or both (ankle plus neck) body levels. The amplitude and the specific direction of the resulting oriented body tilts were analyzed by recording the center of foot pressure (CoP) through a force platform with four strain gauges. The results can be summarized as follows: (1) the vibration-induced whole-body tilts were oriented according to the muscles stimulated; furthermore, the tilts were in opposite directions when neck or ankle muscles on the same side of the body were stimulated; (2) except for the ankle antagonist muscles, co-vibrating adjacent or antagonist muscles at the same body level (ankle or neck) resulted in body sways, whose orientation was a combination of those obtained by stimulating these muscles separately; and (3) likewise, co-vibrating ankle and neck muscles induced whole-body postural responses, whose direction and amplitude were a combination of those obtained by separate vibration. We conclude that the multiple proprioceptive inputs originating from either one or both body levels may be co-processed in terms of vector-addition laws. Moreover, we propose that proprioceptive information from ankle and neck muscles may be used for two tasks: balance control and body orientation, with central integration of both tasks.

Adult↗

PubMed2006

Eye movements cannot explain vibration-induced visual motion and motion aftereffect.

Eye movements are thought to account for a number of visual motion illusions involving stationary objects presented against a featureless background or apparent motion of the whole visual field. We tested two different versions of the eye movement account: (a) the retinal slip explanation and (b) the nystagmus-suppression explanation, in particular their ability to account for visual motion experienced during vibration of the neck muscles, and for the visual motion aftereffect following vibration. We vibrated the neck (ventral sternocleidomastoid muscles, bilaterally, or right dorsal muscles) and measured eye movements in conjunction with perceived illusory displacement of an LED presented in complete darkness (N=10). To test the retinal-slip explanation, we compared the direction of slow eye movements to the direction of illusory motion of the visual target. To test the suppression explanation, we estimated the direction of suppressed slow-phase eye movements and compared it to the direction of illusory motion. Two main findings show that neither actual nor suppressed eye movements cause the illusory motion and motion aftereffect. Firstly, eye movements do not reverse direction when the illusory motion reverses after vibration stops. Secondly, there are large individual differences with regards to the direction of eye movements in observers who all experience a similar visual illusion. We conclude that, rather than eye movements, a more global spatial constancy mechanism that takes into account head movement is responsible for the illusion. The results also argue against the notion of a single central signal that determines both perceptual experience and oculomotor behaviour.

Adult↗

PubMed1996

[Study of the elimination of residues and local tissue injury following intramuscular injection of a solution of the combination trimethoprim/sulfatroxazole in pigs].

Two different studies are described. The first study deals with the elimination of residues of trimethoprim (TMP), sulfatroxazole (STX) and its main metabolite N4-acetyl-sulfatroxazole (N4-acetyl-STX) in pigs. Thirty -six pigs were treated with trimethoprim/sulfatroxazole IM in the nec k at a dosage of 16 mg/kg body weight for five days. Groups of four pig s were slaughtered at different time intervals. The study showed that concentration of STX, N4-acetyl-STX and TMP in edible tissues and at the injection sites were below 0.1 ppm on day nine after the last injection. S TX was eliminated the slowest, and STX can therefore be selected as a marker for residues of the trimethoprim/sulfatroxazole formulation in the tissues. The second study deals with irritation aspects of this trimethoprim /sulfatroxazole formulation. Four pigs of 32-35 kg were treated IM w with trimethoprim/sulfatroxazole and benzylpenicillin sodium. Each pig received the same injection volume, namely four trimethoprim/sulfatroxazole injections (16 mg/kg body weight per injection site), two in the back and two in the neck muscle, and two benzylpenicillin sodium injections (20,000 I.U./kg body weight per injection site), in the back muscle. All pigs were slaughtered 14 days after treatment and the extent of the irritation was compared. There were no differences between trimethoprim/sulfatroxazole and benzylpenicillin sodium with regard to irritation at the injection site in the back muscle. The irritation in the neck site was statistically less prominent than that in the back muscle and was considered not to affect the quality of the meat.

Animals↗

PubMedDate not supplied

Indicators of the influence a peripheral vestibular deficit has on vestibulo-spinal reflex responses controlling postural stability.

For a controlled sway stabilization task, the areas underlying EMG responses in ankle and neck muscles, as well as amplitudes of ankle torque responses, were shown to be significantly correlated with the clinically defined extent of a patient's peripheral vestibular deficit. The responses, elicited by ankle dorsiflexion of the support surface on which the subject stood, were statistically examined in order to select those measurements which would best indicate differences between a normal, a patient with a unilateral deficit, or one with a bilateral deficit. For this purpose, a stepwise discriminant analysis was performed on measurements of head and trunk angular accelerations in addition to muscle EMG and ankle torque signals. The primary measurements selected to optimally assign a subject to a population were the periods of ankle torque and neck extensor activity associated with correcting for the imposed body displacement backwards and maintaining upright head position respectively. The resulting division into populations was 100% correct. However, within the population of unilateral deficit patients, the technique failed to correctly identify those with acute from those with compensated deficit. This technique of investigating vestibulo-spinal reflex responses is more specific and sensitive than Romberg tests, because it will quantify and specify the underlying cause of the patient's balance and ambulatory disorder.

Adult↗

PubMed2005

A comparison of symptomatic and asymptomatic office workers performing monotonous keyboard work--1: neck and shoulder muscle recruitment patterns.

Work-related neck and upper limb disorders (WRNULD) are common problems among office workers who use computers intensively and maintain prolonged static postures. These disorders have often been attributed to result from sustained muscle activity in the neck-shoulder musculature. The present study examined whether symptomatic subjects exhibited the same muscle activity patterns as asymptomatic controls when they performed a prolonged computer task under the same conditions. Surface electromyography (EMG) of four major neck-shoulder muscles were compared between a Case Group (n=23) and a Control Group (n=20) of female office workers. The Case Group had higher activity in the right upper trapezius (UT) while the Control Group had more symmetrical muscle activity between left and right UT. The Case subjects could also be differentiated into "High Discomfort" and "Low Discomfort" sub-groups based on their discomfort scores. The High Discomfort Group had significantly higher right UT activity compared to the Low Discomfort and Control Groups. Results suggested that symptomatic individuals had altered muscle recruitment patterns that persisted throughout the sustained occupational task, while discomfort increased with time-at-task. These findings indicate that altered muscle recruitment patterns observed in the symptomatic subjects preceded the onset of task discomfort, and this finding may have important implications for the etiology of WRNULD.

Adult↗

PubMed2006

Occlusion, sternocleidomastoid muscle activity, and body sway: a pilot study in male astronauts.

The modifications induced by microgravity on the coordinated patterns of movement of the head, trunk, and limbs are reported on extensively. However, apparently there is little data on the masticatory muscles. In normal gravitational conditions, information from the neck and stomatognathic apparatus play a role in maintaining the body's balance and equilibrium. The current pilot study used normal gravity conditions to investigate the hypothesis of a functional coupling between occlusion and neck muscles and body postural oscillations. The immediate effect of modified occlusal surfaces on the contraction pattern of the sternocleidomastoid muscles during maximum voluntary clenching and on the oscillation of the center of foot pressure was analyzed in 11 male astronauts (aged 31-54 yrs). All subjects were healthy and free from pathologies of the neck and stomatognathic apparatus. Occlusal splints were prepared using impressions of their dental arches. The splints were modeled on the mandibular arch, had only posterior contacts, and were modified to obtain a more symmetric, standardized contraction of the masseter and temporalis muscles during teeth clenching. Surface EMG activity of the sternocleidomastoid muscles was recorded during a maximal voluntary clench with and without the splint. Sternocleidomastoid potentials were standardized as percent of the mean potentials recorded during a maximum contralateral rotation of the head, and the symmetry of the EMG waves of left- and right-side muscles was measured. Body sway was assessed with and without the splint, either with eyes open or closed. The variations of the center of foot pressure were analyzed through bivariate analysis, and the area of the 90% standard ellipse was computed. Within each visual condition (eyes open or closed), the difference between the areas of oscillation measured with and without the splint was computed. Muscular activity was more symmetric with the splint. The area of oscillation of the center of foot pressure was larger without the splint than with the splint, both with eyes open and eyes closed. The modifications, induced by the occlusal splint in the sternocleidomastoid muscles' symmetry, and center of foot pressure differential area with closed eyes, were significantly related (p < 0.05): the larger the increment in muscular symmetry, the smaller the area of oscillation with the splint as compared to without the splint. A functionally more symmetric maxillo-mandibular position resulted in a more symmetric sternocleidomastoid muscle contraction pattern and less body sway. Modifications in the contraction of the masticatory muscles may therefore affect the whole body.

Adult↗

PubMed2001

Polymyography combined with time-locked video recording (video EMG) for presurgical assessment of patients with cervical dystonia.

We assessed 26 patients with cervical dystonia, in whom botulinum toxin (BT) injections had failed, before selective peripheral denervation. We decided to base the decision which muscle should be denervated on both clinical information and EMG data and focussed on the following features: activity at onset or during 'dystonic spasms' (according to the concept of the 'leading' dystonic muscle), paradoxical activity during voluntary head movements causing restriction of head movements opposite the side of head turn or tilt and activity when symptoms deteriorated during walking. To identify these muscles we developed a new recording system that integrates simultaneous video-taping and polymyography (video EMG) by means of a digital counter, driven by the recording software (resolution 0.1 s), that was fixed in view of the video camera. This system time-locked clinical signs with relevant EMG activity thus allowing demonstration of the above features. These were found in 68% of dystonic muscles with each of them being present in approximately 40%. Video EMG allows an integrated approach to identify overactive neck muscles in patients with cervical dystonia taking into account both relevant clinical findings and EMG data.

Adult↗

PubMed1988

Axonal trajectories of posterior canal-activated secondary vestibular neurons and their coactivation of extraocular and neck flexor motoneurons in the cat.

Unit activities of 148 secondary vestibular neurons related to the posterior semicircular canal were recorded extracellularly in anesthetized cats. Axonal projections of these neurons were examined by their antidromic responses to stimulation of the excitatory target motoneurons of the contralateral (c-) inferior rectus muscle (IR) and bilateral (bi-) motoneuron pools of longus capitis muscles, neck flexors, in the C1 segment (C1LC). The neurons were classified into 4 groups according to their axonal projections. The first group of neurons, termed vestibulo-oculo-collic (VOC) neurons, sent axon collaterals both to the c-IR motoneuron pool and to the c-C1LC motoneuron pool. The majority of them (72%) were located in the descending nucleus. The second group of neurons were termed vestibuloocular (VO) neurons and sent their axons to the c-IR motoneuron pool but not to the cervical cord. Most of them (86%) were located in the medial nucleus. The third group of neurons, termed vestibulo-collic (contralateral) (VCc) neurons, sent axons to the c-C1LC motoneuron pool via the contralateral ventral funiculus but not to the oculomotor nuclei. They were mostly (75%) found in the descending nucleus. The last group of neurons were vestibulo-collic (ipsilateral) (VCi) neurons, which gave off axons to the ipsilateral (i-) C1LC motoneuron pool via the ipsilateral ventral funiculus but not to the oculomotor nuclei. One of them also sent an axon collateral to the c-C1LC motoneuron pool. The majority of them (74%) were located in the ventral part of the lateral nucleus. It was also observed in some of the VOC and VCi neurons that they produced unitary EPSPs in the c-C1LC and i-C1LC motoneurons, respectively. Their synaptic sites were estimated to be on the cell somata and/or proximal dendrites of the motoneurons.

Animals↗

PubMed2002

Effect of mental and physical demands on muscular activity during the use of a computer mouse and a keyboard.

OBJECTIVES: This study explores the effects of mental and physical demands on muscular activity in the use of the mouse and keyboard in computer work in a time-pressed situation. METHODS: Twelve female subjects performed a computer task with four combinations of two forms of input device (computer mouse and keyboard) and two levels of mental demand (with and without a color word test). The time available for response was limited. Performance and electromyography (EMG) were recorded for the forearm, shoulder, and neck muscles. RESULTS: The mean static muscular activity was 2-7% of the maximum EMG for the forearm and neck extensor muscles. All the muscles for which recordings were made showed increased muscular activity in the mentally demanding condition. The increase in the static muscular activity level varied from 0.3% of the maximum EMG for the right trapezius muscle to 2.6% for the extensor carpi ulnaris muscle. Significant differences in muscular activity between the use of a computer mouse and a keyboard were only found for the neck extensors; in the computer mouse condition there was a static EMG level of 3.5% for the maximum EMG, compared with 2.8% for the keyboard. CONCLUSIONS: Mental demands during computer work increased muscular activity in all of the recorded muscles. Increased muscular activity was found in the neck during the use of the mouse in comparison with the use of the keyboard; this phenomenon may be related to higher visual demands during the use of a mouse than with a keyboard. These findings may help explain the adverse effects of psychosocial work factors on the musculoskeletal system.

Adult↗

PubMed2000

Co-ordinated mandibular and head-neck movements during rhythmic jaw activities in man.

Recent observations in man of concomitant mandibular and head movements during single maximal jaw-opening/-closing tasks suggest a close functional relationship between the mandibular and the head-neck motor systems. This study was aimed at further testing of the hypothesis of a functional integration between the human jaw and neck regions. Spatiotemporal characteristics of mandibular and associated head movements were evaluated for 3 different modes of rhythmic jaw activities: self-paced continuous maximal jaw-opening/-closing movements, paced continuous maximal jaw-opening/-closing movements at 50 cycles/minute, and unilateral chewing. Mandibular and head-neck movements were simultaneously recorded in 12 healthy young adults, by means of a wireless opto-electronic system for 3-D movement recordings, with retro-reflective markers attached to the lower (mandible) and upper (head) incisors. The results showed that rhythmic mandibular movements were paralleled by head movements. An initial change in head position (head extension) was seen at the start of the first jaw-movement cycle, and this adjusted head position was retained during the following cycles. In addition to this prevailing head extension, the maximal jaw-opening/-closing cycles were paralleled by head extension-flexion movements, and in general the start of these head movements preceded the start of the mandibular movements. The results support the idea of a functional relationship between the temporomandibular and the cranio-cervical neuromuscular systems. We therefore suggest a new concept for human jaw function, in which "functional jaw movements" are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital, and cervical spine joints.

Adult↗

PubMed2004

Different patterns of blood flow response in the trapezius muscle following needle stimulation (acupuncture) between healthy subjects and patients with fibromyalgia and work-related trapezius myalgia.

Needle stimulation (acupuncture) has recently been shown to increase blood flow in the tibialis anterior muscle and overlying skin in healthy subjects (HS) and patients with fibromyalgia (FM). The aim of the present study was to examine the effect of needle stimulation on local blood flow in the trapezius muscle and overlying skin in HS and two groups of patients suffering from chronic pain in the trapezius muscle, i.e., FM and work-related trapezius myalgia (TM) patients. Two modes of needling, deep muscle stimulation (Deep) and subcutaneous needle insertion (SC), were performed at the upper part of the shoulder and blood flow was monitored for 60 min post-stimulation. Blood flow changes were measured non-invasively by using a new application of photoplethysmography. Increased blood flow in the trapezius muscle and overlying skin was found in all three groups following both Deep and SC. In HS, Deep was superior to SC in increasing skin and muscle blood flow, whereas in FM, SC was as effective as, or even more effective, than Deep. In the severely affected TM patients, no differences were found between the stimuli, and generally, a lesser blood flow response to the stimuli was found. At Deep, the muscle blood flow increase was significantly larger in HS, compared to the two patient groups. Positive correlations were found between muscle blood flow at Deep and pressure pain threshold in the trapezius muscle, neck movement and pain experienced at the stimulation, and negative correlations were found with spontaneous pain-related variables, symptom duration and age, pointing to less favorable results with worsening of symptoms, and to the importance of nociceptor activation in blood flow increase. It was hypothesized that the different patterns of muscle blood flow response to the needling may mirror a state of increased sympathetic activity and a generalized hypersensitivity in the patients. The intensity of stimulation should be taken into consideration when applying local needle stimulation (acupuncture) in order to increase the trapezius muscle blood flow in chronic pain conditions.

Acupuncture↗

PubMed2005

Slow-tonic muscle fibers and their potential innervation in the turtle, Pseudemys (Trachemys) scripta elegans.

A description is provided of the ratio of slow-tonic vs. slow- and fast-twitch fibers for five muscles in the adult turtle, Pseudemys (Trachemys) scripta elegans. The cross-sectional area of each fiber type and an estimation of the relative (weighted) cross-sectional area occupied by the different fiber types are also provided. Two hindlimb muscles (flexor digitorum longus, FDL; external gastrocnemius, EG) were selected on the basis of their suitability for future motor-unit studies. Three neck muscles (the fourth head of testo-cervicis, TeC4; the fourth head of retrahens capitus collique, RCCQ4; transversalis cervicis, TrC) were chosen for their progressively decreasing oxidative capacity. Serial sections were stained for myosin adenosine triphosphatase (ATPase), NADH-diaphorase, and alpha-glycerophosphate dehydrogenase (alpha-GPDH). Conventional fiber-type classification was then performed using indirect markers for contraction speed and oxidative (aerobic) vs. glycolytic (anaerobic) metabolism: i.e., slow oxidative (SO, including slow-twitch and possibly slow-tonic fibers), fast-twitch, oxidative-glycolytic (FOG), and fast-twitch glycolytic (Fg) fibers. Slow-tonic fibers in the SO class were then revealed by directing the monoclonal antibody, ALD-58 (raised against the slow-tonic fiber myosin heavy chain of chicken anterior latissimus dorsi), to additional muscle cross sections. All five of the tested muscles contained the four fiber types, with the ATPase-stained fibers including both slow-tonic and slow-twitch fibers. The extreme distributions of SO fibers were in the predominately glycolytic TrC vs. the predominately oxidative TeC4 muscle (TrC-SO, 9%; FOG, 20%; Fg, 71% vs. TeC4-SO, 58%: FOG, 16%; Fg, 25%). Across the five muscles, the relative prevalence of slow-tonic fibers (4-47%) paralleled that of the SO fibers (9-58%). TeC4 had the highest prevalence of slow-tonic fibers (47%). The test muscles exhibited varying degrees of regional concentration of each fiber type, with the distribution of slow-tonic fibers paralleling that of the SO fibers. In the five test muscles, fiber cross-sectional area was usually ranked Fg > FOG > SO, and slow-twitch always > slow-tonic. In terms of weighted cross-sectional area, which provides a coarse-grain measure of each fiber type's potential contribution to whole muscle force, all five muscles exhibited a higher Fg and lower SO contribution to cross-sectional area than suggested by their corresponding fiber-type prevalence. This was also the case for the slow-twitch vs. slow-tonic fibers. We conclude that slow-tonic fibers are widespread in turtle muscle. The weighted cross-sectional area evidence suggested, however, that their contribution to force generation is minor except in highly oxidative muscles, with a special functional role, like TeC4. There is discussion of: 1) the relationship between the present results and previous work on homologous neck and hindlimb muscles in other nonmammalian species, and 2) the potential motoneuronal innervation of slow-tonic fibers in turtle hindlimb muscles.

Animals↗

PubMed2001

Botulinum toxin for the treatment of cervical dystonia.

Cervical dystonia (CD) manifests clinically through involuntary spasms of neck muscles, producing abnormal head and neck movements and postures, which is often associated with pain. CD is the most common form of focal dystonia presenting to movement disorders clinics. Chemodenervation with botulinum toxin (BTX) has become the first-line treatment for CD, producing satisfactory relief of symptoms in > 80% of cases. Unresolved issues that may impact on the overall results include the method of selection for injection sites (clinical vs. electromyography), dosing, dilution and the role and relative efficacy of the different BTX serotypes. A guiding therapeutic principle of BTX injections is to achieve optimal results with the lowest possible dosage and frequency of administration. This strategy is critical in order to keep the risk of immunoresistance at a minimum. Development of antibodies that block the effects of BTX, usually associated with frequent injections of high doses, is the main reason for secondary unresponsiveness to this treatment. Although the mechanism of denervation at the neuromuscular junction by BTX is relatively well understood, the role of changes in muscle spindles and myopathic pain mechanisms, as well as secondary changes at the level of the basal ganglia, thalamus and cortex and their role in response to BTX, all need further exploration.

Anti-Dyskinesia Agents↗

PubMed1985

[Cervical and oculomotor reflexes induced by electrical stimulation of the semicircular canals of the pigeon].

The ampullae of horizontal, anterior and posterior canals of the alert pigeon were stimulated with short electrical pulses. The double pulses evoke synchronized biphasic short-latency disynaptic responses in neck muscles, their amplitudes depending on interpulse delay. Facilitation occurred between 80-100 mcsec and 3-4 msec. The amplitudes of contralateral responses were higher. The short-latency responses are under control of the otolithic input. The angular acceleration or short pulse trains evoke eye movements in the plane of the stimulated canal, as well as their neck correlates the polysynaptic responses that form the nystagmic rhythm. Changing of the stimuli parameters induce di- and polysynaptic neck responses as different components of the reaction. The eye nystagmus evoked with electrical stimulation of ampullae in the wide frequency band of stimulation, depended on stimuli parameters. The data obtained are discussed using concept of central vestibulo-oculomotor integrator.

Animals↗