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PubMed1989

EMG cranial muscle levels in headache sufferers before and during headache.

It has long been assumed that the origin of pain in 'muscle-contraction headache' lies in the peri-cranial muscles, especially in the frontales. Pain, it is assumed, is experienced when the muscles are in spasm. It is further assumed that learned reductions in muscle tone between headache episodes will reduce the probability of future pain episodes. In this experiment, details are given of EMG measures made on the frontal, occipital, and neck muscles of separate groups of migraine and tension headache subjects. The measures were made before the onset of head pain and later when the same subjects reported pain. As part of the experiment, subjects were exposed to an experimental stressor during the pain-free period, and these results were compared with those of a group of non-headache subjects. Results showed that the headache groups did not differ on any of the pre-headache measures. Neck muscle levels varied markedly when compared with control subjects who had comparatively low levels reactive to an experimental stressor. When the data taken during the headache phase were analysed according to diagnosis, the occipital muscle output was found to be significantly lower in the migraine group and higher in the tension group.

Adult↗
PubMed1983

Speech production with flaccid paralysis of the rib cage, diaphragm, and abdomen.

Anteroposterior diameter changes of the rib cage and abdomen were measured during breathing maneuvers and utterance activities in an adult subject with flaccid paralysis of the rib cage, diaphragm, and abdomen. Data were charted to solve for lung volume, volumes of the rib cage and abdomen, chest wall configuration, and inferred neck muscle actions. Free breathing was accomplished through an alternate waxing and waning of neck muscle drive or through step-wise glossopharyngeal pumping. Connected speech was performed in breath groups begun by neck gestures that "cocked" the breathing apparatus and stored recoil energy in it for use during ensuing expirations. Some breath groups were also extended through intermittent glossopharyngeal pumping. Connected speech was characterized by frugal control of the air supply through compensatory adjustments in the larynx and upper airway. Compensations involved in the breathing maneuvers and utterance activities are described, and consideration is given to two understandings--the human potential for functional restoration and the clinical evaluation and management of individuals with neuromuscular impairment.

Abdomen↗
PubMed1963

[Contribution to the study of the effects of weightlessness on the central nervous system of the rat].

We have studied the effects of various states of acceleration on the physiological activity of white rats. Initial experimental trials were carried out in the course of a flight of the Veronique missile. In another series of experiments the trials took place in an airplane in the course of successive parabolic flights at several minutes intervals producing periods of weightlessness of 33 to 44 seconds. We recorded the electrical activity of a large area lying between one electrode located in the somesthesic area and another electrode located in the homolateral visual area. In addition, cardiac and respiratory rate and electrical activity of the mesencephalic reticular formation and of the muscles of the neck were recorded. We found an intense cortical activation during the entire duration of the missile flight. In the airplane during the periods of weightlessness basic electrical activity has not been modified. Recordings of electrical activity in the mesencephalic reticular formation do not show any modification during missile flight. Afterwards appeared a flattening with the reduction of frequency. In the course of periods of weightlessness in airplane flight we have observed no modification of background electrical activity. Recording of neck muscle potentials shows, during weightlessness in airplane flight, a distinct augmentation of background tone. These findings seem in favor of a facilitation of reticular origin as a result of the abrupt diminution of volume of sensory information following the disappearance of the stimulus of gravity.

Acceleration↗
PubMed1996

Morphology of single axons of tectospinal and reticulospinal neurons in the upper cervical spinal cord.

Single axons of tectospinal (TS) and reticulospinal (RS) neurons were stained with intraaxonal injection of HRP after electrophysiological identification, and their axonal trajectory was reconstructed at C1-C3 of the cat. TS neurons were located in the intermediate or deep layers of the caudal two-thirds of the superior colliculus (SC) and had multiple axon collaterals (up to seven collaterals) per stem axon). Collaterals had a simple structure, ramified several times mainly in the transverse plane, and terminated in the lateral parts of laminae V-VIII. More than half also had terminals in lamina IX. Terminals of TS neurons did not appear to make contacts with either the somas or proximal dendrites of retrogradely-labeled motoneurons in lamina IX, but clear contacts were found on counterstained interneurons in the lateral part of laminae V-VIII. Here, we examined three stained spinal interneurons receiving monosynaptic excitation from the SC. These interneurons had multiple axon collaterals mainly in laminae VII-IX, and made extensive contacts with retrogradely-labeled motoneurons of multiple neck muscles. Stem axons of single RS neurons receiving input from the contralateral SC ran in the ventromedial funiculus and gave off multiple axon collaterals to laminae VII-IX over at least several cervical segments. Their terminal boutons appeared to make contact with both the somas and proximal dendrites of retrogradely-labeled neck motoneurons. Single RS neurons made contacts with motoneurons of different neck muscles. These results provide evidence for functional synergies at the level of single RS neurons and spinal interneurons for neck movements. The present finding indicates that the direct TS projection to the spinal cord may influence the activity of multiple neck muscles mainly via spinal interneurons, and plays an important role in control of head movement in parallel with the tecto-reticulospinal system.

Animals↗
PubMed1991

An empirical note on tonic neck reflexes: control of the upper limb's proprioceptive sensation.

The effect of asymmetrical tonic reflexes on the upper limb in man was studied by analyzing errors in reproducing a targeted movement in right elbow extension following head rotation and vibration of the neck muscles. Overshoot of reproduction was observed only when the head was rotated to the left in contrast to no rotation or with rotation to the right. However, there was no influence on errors of reproduction after vibration of the neck muscles. These observations suggest that the proprioception in the rotated head controls the kinesthetic input by peripheral sensory receptors, namely, vestibular input plays a greater role in the accurate positioning of the upper limb, especially in inhibiting sensory input from the opposite side of the rotated head.

Adult↗
PubMed1997

Arm-movement-related neurons in the primate superior colliculus and underlying reticular formation: comparison of neuronal activity with EMGs of muscles of the shoulder, arm and trunk during reaching.

Neuronal activity was recorded from the superior colliculus (SC) and the underlying reticular formation in two monkeys during an arm reaching task. Of 744 neurons recorded, 389 (52%) clearly modulated their activity with arm movements. The temporal activity patterns of arm-movement-related neurons often had a time course similar to rectified electromyograms (EMGs) of particular muscles recorded from the shoulder, arm or trunk. These reach cells, as well as the muscles investigated, commonly exhibited mono- or biphasic (less frequently tri- or polyphasic) excitatory bursts of activity, which were related to the (pre-)movement period, the contact phase and/or the return movement. The vast majority of reach cells exhibited a consistent activity pattern from trial to trial as did most of the muscles of the shoulder, arm and trunk. Similarities between the activity patterns of the neurons and the muscles were sometimes very strong and were especially notable with the muscles of the shoulder girdle (e.g. trapezius descendens, supraspinatus, infraspinatus or the anterior and medial deltoids). This high degree of co-activation suggests a functional linkage, though not direct, between the collicular reach cells and these muscles. Neuronal activity onset was compared with that of 25 muscles of the arms, shoulders and trunk. The majority of cells (78.5%) started before movement onset with a mean lead time of 149+/-90 ms, and 36.5% were active even before the earliest EMG onset. The neurons exhibited the same high degree of correlation (r=0.97, Spearman rank) between activity onset and the beginning of the arm movement as did the muscles (r=0.98) involved in the task. The mean neuronal reach activity (background subtracted) ranged between 7 and 193 impulses/s (mean 40.5+/-24.2). The mean modulation index calculated [(reach activity background activity)/reach activity+background activity)] was 0.75+/-0.23 for neurons (n=358) and 0.87+/-0.14 for muscles (n=25). As the monkeys fixated the reach target constantly during an arm movement, neuronal activity which was modulated in this period was not related to eye movements. The three neck muscles investigated in the reach task exhibited no reach-related activity modulation comparable to that of either the reach cells or the muscles of the shoulder, arm and trunk. However, tonic neck muscle EMG was monotonically related to horizontal eye position. The clear skeletomotor discharge characteristics of arm-movement-related SC neurons revealed in this study agree with those already known from other sensorimotor regions (for example the primary motor, the premotor and parietal cortex, the basal ganglia or the cerebellum) and are consistent with the possible role of this population of reach cells in the control of arm movements.

Animals↗
PubMed1996

Effect of acute head-down tilt on skeletal muscle cross-sectional area and proton transverse relaxation time.

This study investigated changes in skeletal muscle cross-sectional area (CSA) evoked by fluid shifts that accompany short-term 6 degrees head-down tilt (HDT) or horizontal bed rest, the time course of the resolution of these changes after resumption of upright posture, and the effect of altered muscle CSA, in the absence of increased contractile activity, on proton transverse relaxation time (T2). Average muscle (CSA and T2 were determined by standard spin-echo magnetic resonance imaging. Analyses were performed on contiguous transaxial images of the neck and calf. After a day of normal activity, 24 h of HDT increased neck muscle CSA 19 +/- 4(SE)% (P < 0.05) while calf muscle CSA decreased 14 +/- 3% (P < 0.05). The horizontal posture (12 h) induced about one-half of these responses: an 11 +/- 2% (P < 0.05) in the neck muscle CSA and an 8 +/- 2% decrease (P < 0.05) in the calf. Within 2 h after resumption of upright posture, neck and calf muscle CSA returned to within 0.5% (P > 0.05) of the values assessed after a day of normal activity, with most of the change occurring within the first 30 min. No further change in muscle CSA was observed through 6 h of upright posture. Despite these large alterations in muscle CSA, T2 was not altered by more than 1.1 +/- 0.6% (P > 0.05) and did not relate to muscle size. These results suggest that postural manipulations and subsequent fluid shifts modeling micro-gravity elicit marked changes in muscle size. Because these responses were not associated with alterations in muscle T2, it does not appear that simple movement of water into muscle can explain the contrast shift observed after exercise.

Adult↗
PubMed2005

Capsaicin-induced effects on c-fos expression and NADPH-diaphorase activity in the feline spinal cord.

The distribution of c-fos expression and NADPH-diaphorase reactivity in the cervical and lumbar segments after stimulation of the vanilloid receptors in the dorsal neck muscles with capsaicin was studied in cats anaesthetized with alpha-chloralose. After the unilateral intramuscular injection of capsaicin, the mean number of Fos-immunoreactive neurons detected with an avidin-biotin-peroxidase technique was significantly increased in the superficial laminae (I), neck of the dorsal horn (V), and area around the central canal (VII) within both the cervical and lumbar spinal cord. Most Fos-immunoreactive neurons in the cervical spinal cord were giant and small cells. The widespread distribution of Fos-immunoreactive cells throughout the cervical cord within the intermediate zone (VII) coincided with the sites of localization of last-order premotor interneurons and cells of origin of inter-segmental crossed and uncrossed descending propriospinal pathways to the lumbar spinal cord. Fos-immunoreactive neurons were co-distributed with nitric oxide-generating cells at both levels of the spinal cord, although the double-labeled cells were not observed. In conclusion, the analysis of c-fos expression and NADPH-diaphorase reactivity shows that stimulation of vanilloid receptors in the neck muscles can initiate distinctive neuronal plasticity in the cervical (C1-C8) and lumbar (L1-L7) segments, and confirms the anatomical and functional coupling of both regions during processing of nociceptive signals from the dorsal neck muscles.

Animals↗
PubMed2004

Effects of neck extensor muscles fatigue on balance.

OBJECTIVE: Measure the effects of cervical extensor muscle isometric contraction on cervical surface electromyographic spectral shift and balance in healthy subjects. DESIGN: Experimental within-subject design. BACKGROUND: Postural instability can be induced by mechanically stimulating cervical muscle spindles. Postural changes are also observed in individuals who suffer from chronic neck pain or whiplash injury. Furthermore these subjects appear to experience neck musculature fatigue more quickly, which in turn not only affects the neck function but also seems to affect the balance in a standing posture. METHODS: Using a force platform, balance was measured, in 10 blindfolded college students before and after isometric voluntary contraction in neck extension at 5% and 25% maximum voluntary isometric contraction for a period of 5, 10 and 15 min. Paired posturographic data were analysed for differences. Control measurements were performed on the same subjects by measuring balance before and after subjects sitting quietly for 5, 10 and 15 min without performing isometric contraction. RESULTS: The results indicate that a 25% maximal isometric contraction of the neck extensors for 10 and 15 min duration produced significant changes in some posturographic parameters in young healthy males. Furthermore, this contraction also produced a significant cervical muscle electromyography median frequency spectrum shift of the lower frequencies. CONCLUSIONS: Balance was affected by 15 min of 25% maximal isometric contraction of the extensor cervical muscles. Posturographic parameters affected are similar to parameters observed in subjects that have suffered a whiplash injury. RELEVANCE: This study contributes to our understanding of functional aspects of cervical muscle fatigue. The similarity of results with other studies performed on subjects suffering from chronic neck pain and from whiplash injuries may suggest a similar cause for loss of postural control. Ultimately, this may help us in developing objective evaluation procedures for subjects suffering from neck complaints.

Adult↗
PubMed1994

Innervation of multiple neck motor nuclei by single reticulospinal tract axons receiving tectal input in the upper cervical spinal cord.

Axons of reticulospinal neurons (RSNs) activated monosynaptically by stimulation of the contralateral superior colliculus (SC) were stained with intraaxonal injection of horseradish peroxidase in the cat upper cervical spinal cord. Stem axons of single RSNs gave rise to multiple axon collaterals to laminae IX, VIII and VII over a few cervical segments. Single RSNs made contacts with retrogradely labeled neck motoneurons of different neck muscles. Therefore, RSNs were regarded as mediating output of the SC to functionally different groups of neck muscles simultaneously. The result gave evidence of neural implementation of a functional synergy for a neck movement at a single neuron level.

Animals↗
PubMed1980

Bladder neck dysfunction: the effect of the alpha-adrenergic blocking agent phentolamine on bladder neck dysfunction and a fluorescent histochemical study of bladder neck smooth muscle.

Urodynamic examinations and fluorescent histochemical studies suggest that patients with bladder neck obstruction can be divided into two main groups (responders and nonresponders) based on the response of their urinary flow rate to phentolamine and that the adrenergic nervous system of the bladder neck has an important effect on the response in responders.

Adrenergic Fibers↗
PubMed2005

Reflex muscle contraction in the unaware occupant in whiplash injury.

STUDY DESIGN: Computer modeling and parametric analysis were used to determine the effect of reflex contraction of the neck muscles in the unaware occupant in whiplash. OBJECTIVE: To delineate effects of reflex contraction on spinal segmental kinematics during the retraction phase. SUMMARY OF BACKGROUND DATA: The ability of reflex neck muscle contraction to mitigate whiplash injury in the unaware occupant remains unclear. Analyzing relative timing between electromyographic and head-neck kinematics, previous investigators theorized that muscle contraction alters spinal kinematics, decreasing injury likelihood. Other investigators suggested that injury occurs during the initial (retraction) phase of head-neck kinematics, before significant muscle force generation. METHODS: Computer modeling was used to determine reflex contraction effects on segmental angulations, implementing parametric analysis techniques to vary reflex delay and impact severity. RESULTS: Shorter reflex delays had a greater effect on segmental angulations later in the event and at lower impact severities. However, the magnitude of this effect, particularly at higher impact severities and during maximum cervical S-curvature (factors implicated in the whiplash injury mechanism) was minimal, altering segmental angulations by a maximum of 19%. CONCLUSIONS: Because reflex contraction did not substantially alter spinal kinematics, muscle contraction likely does not initiate in sufficient time to mitigate whiplash injuries that may occur during the retraction phase.

Cervical Vertebrae↗
PubMed1991

Eye and neck proprioceptive messages contribute to the spatial coding of retinal input in visually oriented activities.

The egocentric localization of objects in extrapersonal space requires that the retinal and extraretinal signals specifying the gaze direction be simultaneously processed. The question as to whether the extraretinal signal is of central or peripheral origin is still a matter of controversy, however. Three experiments were carried out to investigate the following hypotheses: 1) that the proprioceptive feedback originating in eye and neck muscles might provide the CNS with some indication about the gaze direction; and 2) that the retinal and proprioceptive extraretinal inputs might be jointly processed depending on whether they are of monocular or binocular origin. Application of low amplitude mechanical vibrations to either the extraocular or neck muscles (or both) of a subject looking monocularly at a small luminous target in darkness resulted in an illusory movement of the target, the direction of which depended on which muscle was stimulated. A slow upward target displacement occurred on vibrating the eye inferior rectus or the neck sterno-cleido-mastoidus muscles, whereas a downward shift was induced when the dorsal neck muscles (trapezius and splenius) were vibrated. The extent of the perceptual effects reported by subjects was measured in an open-loop pointing task in which they were asked to point at the perceived position of the target. These results extend to visually-oriented behavior the role of extraocular and neck proprioceptive inputs previously described in the case of postural regulation, since they clearly show that these messages contribute to specifying the gaze direction. This suggests that the extraretinal signal might include a proprioceptive component.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Eye-head coupling in humans. II. Phasic components.

A tonic coupling between the horizontal component of eye position and dorsal neck muscle activity has been demonstrated in animals and humans. In addition, a transient saccade related coupling has been found in animals. In order to investigate such a phasic component of the eye-head synergy in humans, we have recorded the activity of isolated motor units in the splenius muscle during large horizontal eye movements in head fixed subjects. Eye movement recording was achieved by conventional binocular electro-oculography and the activity of the right splenius muscle was recorded with Bronks coaxial electrodes inserted manually at the C4-C5 intervertebral level. We found two main types of motor unit discharge patterns in the splenius (SPMU), the first type (type A, 14 SPMUs) shows a phasic modulation of firing rate during saccades with a triphasic profile composed of a pre-saccadic suppression, a per-saccadic burst and a post saccadic tonic discharge proportional to eye position. The second type (type B, 6 SPMUs) exhibits little, if any, modulation of firing rate with either fixation or saccades. These results suggest that eye-head coupling is present not only during the fixation period but also during saccades and that a phasic activity or suppression related to saccadic eye velocity is present in dorsal neck muscle EMG.

Adult↗
PubMed2005

A randomized clinical trial of TENS and exercise for patients with chronic neck pain.

OBJECTIVE: To investigate the effect of transcutaneous electrical nerve stimulation (TENS) on acupuncture points and neck exercise in chronic neck pain patients. DESIGN: A randomized clinical trial. SETTING: Hospital-based practice. SUBJECTS: Two hundred and eighteen patients with chronic neck pain. INTERVENTIONS: Subjects were randomized into three groups, receiving either (1) TENS over the acupuncture points plus infrared irradiation (TENS group); (2) exercise training plus infrared irradiation (exercise group); or (3) infrared irradiation alone (control); twice a week for six weeks. OUTCOME MEASURES: The values of verbal numeric pain scale, Northwick Park Neck Pain Questionnaire, and isometric neck muscle strength were assessed before, at the end of the six-week treatment, and at the six-month follow-up. RESULTS: Results demonstrated that after the six-week treatment, significant improvement in the verbal numerical pain scale was found only in the TENS group (0.60+/-2.54, p = 0.027) and the exercise group (1.57+/-2.67, p < 0.001). Though significant reduction in Northwick Park Neck Pain Questionnaire score was found in all three groups, post-hoc tests showed that both the TENS and the exercise group produced better improvement (0.38+/-0.60% and 0.39+/-0.62% respectively) than the control group (0.23+/-0.63%). Significant improvement (p = < 0.001 to 0.03) in neck muscle strength was observed in all three groups, however, the improvement in the control group was not clinically significant and it could not be maintained at the six-month follow-up. CONCLUSIONS: After the six-week treatment, patients in the TENS and exercise group had a better and clinically relevant improvement in disability, isometric neck muscle strength, and pain. All the improvements in the intervention groups were maintained at the six-month follow-up.

Acupuncture Points↗
PubMed1990

Neural organization in the brainstem circuit mediating the primary acoustic head startle: an electrophysiological study in the rat.

In awake rats the latency of auditory startle recorded electromyographically in the neck is about 5 ms, suggesting that the primary component of this brainstem reflex is mediated by a neural circuit with only a few synapses. In the present work, neural relays on acoustic head startle circuit are studied in alpha-chloralose-anesthetized rats by means of precise measurements, at putative brainstem relays, of the click-evoked potential latency and of the latency of nuchal EMG startle-like response elicited electrically from each recorded site using the same bipolar electrode. Allowing 0.6 ms for total synaptic transmission time in every relay nuclei, systematic comparisons of the shortest latencies of evoked potentials and shock-elicited startle, as well as estimations of conduction velocities in pathways from cochlea to C1-C5 spinal cord, suggest that one primary acoustic head startle circuit consists of ventral cochlear nucleus (postsynaptic evoked potential: 1.4 ms; startle: 3.6-4.0 ms), ventral nucleus of the lateral lemniscus (evoked potential: 2.3 ms; startle: 2.7-2.8 ms), medial bulbar reticular formation (evoked potential: 3.2-3.6 ms; startle: 2.1 ms), spinal interneuron and motoneuron. The nucleus reticularis pontis caudalis (NRPC) cannot be considered as an head startle relay intercalated between the ventral nucleus of the lateral lemniscus (VNLL) and the medial bulbar reticular formation (MBRF) because mean latencies of field potentials in the pontine RF and the LL nucleus are the same (2.3 ms). Moreover, startle-like responses in neck muscles are elicited through the three brainstem regions with latency differentials which exclude the possibility of a classical synaptic delay either between VNLL (2.8 ms) and NRPC (2.5 ms) or between NRPC and bulbar RF (2.1 ms). Nevertheless, NRPC probably remains a main primary relay on the acoustic startle circuitry; very short latency auditory responses (2.3 ms) are evoked in NRPC by clicks, and low current stimulations of this reticular region produce startle-like activity in neck muscles with a latency of only 2.5 ms. Two other alternative paths consisting of the VCN and NRPC which then would project directly, or through an unknown bulbar site, upon the spinal motor center are hypothetically proposed in conclusion.

Animals↗
PubMedDate not supplied

Postural changes of the cervical spine in patients with nontoxic goiter.

PURPOSE: To investigate differences in cervical spine posture and range of motion and self-reported neck pain and headache between patients with nontoxic goiter compared with a matched control group. DESIGN: An observational, controlled, blinded study. SETTING: The ambulatory outpatient facility of a university hospital. PARTICIPANTS: Twenty-five nontoxic goiter patients and 25 matched nongoiterous control subjects from the Department of Endocrinology. INTERVENTION: Participants were X-rayed from a lateral position in neutral, full flexion and full extension, and the radiographs were evaluated by a blinded examiner for anterior head carriage, maximal flexion, maximal extension and the extent and severity of any degenerative changes in the cervical spine. The degree of postural neck muscle tenderness was evaluated by a blinded rheumatologist using a validated Total Tenderness Score system. In addition, the two groups were compared for their self-reported frequency of neck pain and headaches. RESULTS: A significant increase in anterior head carriage was found among the goiter patients (p = .01), together with a corresponding decrease in flexion (p = .01), whereas the corresponding increase in extension was not statistically significant (p = .16). A higher prevalence of headaches was found in the goiter group (p = .06), but there was no difference in neck muscle tenderness (p = .40) or frequency of neck problems (p = .40) between the groups. The severity of degenerative changes in the cervical spine (p = .22) and the number of vertebral levels with degenerative changes (p = .13) were similar in the two groups. CONCLUSIONS: Goiters of > 100 g seem to alter the posture of the cervical spine, possibly resulting in a tendency for more frequent headaches. The changes do not seem to cause more neck pain, muscle tenderness or degeneration of the cervical spine.

Adolescent↗