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PubMed1990

[Local alcoholisation treatment of spasmodic torticollis].

Idiopathic spasmodic torticollis is a type of focal dystonia. Major muscles which rotate the neck are M. sternocleidomastoideus (SCM) and M. splenius capitis (Spl) on both sides. In torticollis patients, its clinical characteristics could be understood as a vectorial summing up of tonus in bilateral SCM and Spl at rest. There is not any curative treatment for dystonia yet. A variety of medications and many types of surgical interventions have been tried without consistent or satisfactory results. In recent days local injection of botulinum-A toxin has shown to be effective in weakening focal dystonias. We used pure ethanol for local injection. Fourteen patients aged between 20-77 years (mean 48.9) were treated by alcoholisation. Disease duration ranged from 5 months to 12 years (mean 4.9 years). All had torticollis alone or had segmental dystonia containing spasmodic torticollis. Patients were recorded electromyographically using surface electrodes to make sure which neck muscles were hypertonic, and were rated before and after treatment according to the stages (0; normal-5; most severe). On the bases of these recordings the two most active muscles were selected for injection. Into the motor point of these muscles 1 ml of 1% lidocaine, and then the same dose of 99% ethanol were injected. This procedure was repeated on the mean ten times (6-14 times) every other week. The number of times of injection was decided in each case. Using the paired Student t test, there was a significant (p less than 0.01) improvement of the stage for the patients after injection, with a mean of 3.7 before treatment and 2.3 after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Reticular formation activity during wakefulness and sleep in a hibernator (Spermophilus lateralis).

This study examined ground squirrel reticular formation (RF) cell activity as a function of: (1) arousal state, and, (2) phasic alterations in neck muscle activity. A total of 37 neurons were recorded from 11 behaving squirrels (Spermophilus lateralis). Five cells were located in the midbrain RF, 15 were in the lateral pontine site implicated in inhibition of motor output, i.e. the subcoeruleus area, 11 were in the medial pontine RF, and 6 were in the medullary RF. Regardless of location, the majority of the cells (81%; 30 of 37) exhibited greatest activity when the animals were awake and/or in rapid-eye-movement (REM) sleep. However, the relationship between neuronal activity and phasic alterations in neck muscle activity differed as a function of location. The activity of 53% of cells (8 of 15) located in the subcoeruleus area increased with phasic decreases in electromyographic (EMG) activity, whereas the activity of cells (22 of 22) in other RF sites decreased or did not change with phasic decreases in EMG activity. The increased activity of subcoeruleus area cells during phasic decreases in neck muscle activity is further evidence suggesting that the lateral pontine RF is involved in promotion of muscle atonia during REM sleep and possibly wakefulness.

Animals↗

PubMed1981

Cardiovascular changes during arousal elicited by stimulation of amygdala, hypothalamus and locus coeruleus.

Experiments were performed in chronically operated cats first awake and thereafter anesthetized with pentobarbitone, 16-20 mg/kg i.v. Stimulation of the central amygdala in awake cats elicited an arousal reaction seen in cortical and hippocampal EEG, and in muscle activity of dorsal neck muscles. Concomitantly therewith were autonomic system reactions resulting in a decrease in aortic blood flow distal to the renal arteries, an increase in arterial blood pressure, a tachycardia during, and a short-lasting bradycardia at the end of stimulation. In slightly anesthetized cats the cardiovascular reactions were found to be qualitatively similar. If the postero-lateral hypothalamus or the locus coeruleus complex were stimulated in cats first awake and thereafter anesthetized, similar arousal reactions and similar cardiovascular changes were obtained as with amygdaloid stimulations. However, the onset and magnitude of the response were more abrupt and more marked than those obtained by amygdaloid stimulations. Recordings of single unit activity within the central amygdala during spontaneously occurring changes in the level of arousal showed that amygdaloid units (n = 10) discharged at a rate of 7-14 impulses/sec during wakefulness whereas during slow wave sleep (n = 5) the discharge was only 2-9 impulses/sec. The hypothesis is put forward that the amygdala integrates behavioral and cardiovascular changes during arousal.

Amygdala↗

PubMed2003

Endurance and performance during multiple intense high +Gz exposures with effective anti-G protection.

BACKGROUND: In many high-intensity wartime scenarios, pilots may be required to fly multiple, strenuous missions during the same day. HYPOTHESIS: New anti-G protection allows fighter pilots to endure multiple high +G, exposures during several sorties in a limited time interval. METHODS: Nine well-trained centrifuge subjects were exposed to tactical aerial combat maneuvers using balanced pressure breathing during G (PBG) and an extended coverage anti-G suit. The centrifuge exposures consisted of five simulated sorties during a 4-h period, each consisting of four engagements with rapid onset cycles (6 G x s(-1)) varying between +4 G, and -9 GC. The subjects executed a tracking task before, during, and after each engagement and verbally indicated their effort level. Neck muscle strength was measured before and after the test. RESULTS: Seven of the nine subjects could endure all five sorties during the 4-h period. On a scale from 0 (no effort) to 11 (maximum possible effort), highest effort level during runs varied from 5.5 to 11 units (mean 8.7). Maximal heart rate varied from 140-173 bpm (mean 159) and minimum finger oxygen saturation from 75-93% (mean 88). Maximal peripheral and central light-loss varied from 0 to 100% (mean 71 and 40, respeclively). Three G-LOCs (two in the same subject) and four cases of near loss of consciousness occurred. The general fatigue recovery time varied from 9 to 48 h (mean 21). The tracking tests showed that performance deteriorated significantly during all G exposures; the neck muscle contraction was impaired by 12% (p = 0.035) after the C exposures. CONCLUSION: It is possible to train subjects to withstand five simulated flight sorties during a 4-h period with a total of up to 80 peaks to +9 Gz and 80 peaks to +8 Gz using PBCG and an extended coverage anti-G suit.

Aerospace Medicine↗

PubMed2003

Trigemino-cervical-spinal reflexes in humans.

INTRODUCTION: Electrical stimulation of the supraorbital nerve (SON) induces late reflex responses in the neck muscles; these responses are hypothesised to be polysynaptic reflexes participating in a defensive withdrawal retraction of the head from facial nociceptive stimuli. Such responses may extend to the proximal muscle of the arms. OBJECTIVE: (1) to investigate reflexes in the upper limb muscles (trigemino-spinal responses, TSR) and their relationship with trigemino-cervical responses (TCR); and (2) to identify the nociceptive component of such reflexes and their functional significance. METHODS: Reflex responses were registered from the semispinalis capitis and biceps brachii muscles after electrical stimulation of the SON in 12 healthy subjects. The sensory (ST), painful (PT) and reflex thresholds, the latency and area of the responses, the effect of heterotopic painful stimulation (HTP), the recovery cycle as well as the effect of the expected and unexpected stimuli were measured. RESULTS: Stable reproducible TCR and TSR responses were identified at 2.5+/-0.4 x ST, which corresponded exactly to the PT in all the subjects. The TCR and TSR areas were markedly reduced after HTP. The recovery cycle of the TSR area was faster than that of the TCR. Repeated rhythmic stimulation failed to induce progressive reflex suppression. CONCLUSIONS: These results confirm the nociceptive nature of the TCR and indicate that the biceps brachii response (TSR) has the same nocifensive significance as the posterior neck muscle responses. TCR and TSR are mediated different polysynaptic pathways The presence of trigemino-cervical-spinal responses in our study clearly indicates that there is a reflex interaction between nociceptive trigeminal afferents and both upper and lower cervical spinal cord motoneurons.

Adult↗

PubMed1995

Short-latency trigemino-cervical reflexes in man.

We describe a reflex evoked in neck muscles by stimulation of afferent fibres in the trigeminal nerve. The clearest responses were seen in averaged, unrectified, monopolar surface electromyographic (EMG) recordings from active sternocleidomastoid muscles after stimulation of the infraorbital nerve. They consisted of a bilateral positive/negative (p19, n31) wave with a mean onset latency of 12.9 ms which corresponded to a period of inhibition in the underlying motor unit activity. Responses also could be seen in splenius and trapezius, but not in arm muscles. Stimuli to other branches of the trigeminal nerve (supraorbital or mental) did not produce such clear effects. The threshold for the reflex was relatively low (2-4 times perceptual threshold) and its size scaled with the level of background EMG in an approximately linear fashion. Responses to infraorbital stimulation did not interact with other short-latency inhibitory responses in the sternocleidomastoid muscle evoked by loud acoustic clicks or stimulation of the median nerve at the wrist. We suggest that the infraorbital response is part of a head withdrawal reflex involving an oligosynaptic trigemino-cervical system similar to that described in the cat.

Acoustic Stimulation↗

PubMedDate not supplied

Effect of head rotation in whiplash-type rear impacts.

BACKGROUND CONTEXT: Knowledge is increasing about the electromyographic and kinematic response of the neck muscles to rear impact, and also recent information is available on the effect of a rear impact offset to the left (posterolateral). The effect of head rotation, however, at the time of rear impact is not known. PURPOSE: The purpose of this study was to examine the effects of head rotation to the left and right on the cervical muscle response to increasing low-velocity posterolateral impacts. STUDY DESIGN/SETTING: Twenty healthy volunteers were subjected to rear impacts of 4.7, 8.3, 10.9 and 13.7 m/s2 acceleration, offset by 45 degrees to the subject's left, with head rotation to right and left. METHODS: Bilateral electromyograms of the sternocleidomastoids, trapezii and splenii capitis were recorded. Triaxial accelerometers recorded the acceleration of the sled, torso at the shoulder level, and head of the participant. RESULTS: With the head rotated to the right, at an acceleration of 13.7 m/s2, the left sternocleidomastoid generated 59% and the right sternocleidomastoid 20% of their maximal voluntary contraction (MVC) electromyogram (EMG). Under these conditions, the remaining muscles (both splenii capitis and trapezius) generated 25% or less of their MVC. With the head rotated to the left, at an acceleration of 13.7 m/s2, the right sternocleidomastoid generated 65% and the left sternocleidomastoid only 11% of the MVC EMG. Under these conditions, again the remaining muscles had low EMG activity (27% or less) with the exception of the left trapezius which generated 47% of its MVC. Electromyographic variables were significantly affected by the levels of acceleration (p<.01). The time to onset and time to peak EMG for all muscles progressively decreased with increasing levels of acceleration, for both head rotation conditions. The kinetic variables and the electromyographic variables regressed significantly on the acceleration (p<.01). CONCLUSIONS: Direction of impact is a factor in determining the muscle response to whiplash, but head rotation at the time of impact is also important in this regard. More specifically, when a rear impact is left posterolateral, it results in increased EMG generation mainly in the contralateral sternocleidomastoid, as expected, but head rotation at the same time in this type of impact reduces the EMG response of the cervical muscles. Muscle injury seems less likely under these conditions in low-velocity impacts.

Acceleration↗

PubMed2000

Modulating active stiffness affects head stabilizing strategies in young and elderly adults during trunk rotations in the vertical plane.

Healthy young and elderly adults were asked to actively modulate neck muscle stiffness during random rotations of the trunk in the vertical plane. Angular velocity of head with respect to trunk and myoelectric activity of semispinalis capitis and sternocleidomastoid muscles were recorded. A MANOVA was performed on group, condition, and frequency variables. A gain and phase drop at 2.15 Hz in young adults indicated neural (i.e. reflex) damping of system mechanics. In the elderly, a steady rise in gain and drop in phase (P<0.0002) was indicative of a second order underdamped system. Even when instructed to not intervene elderly subjects exhibited cocontraction. Ineffective reflex mechanisms may underlie the emergence of this strategy.

Adult↗

PubMed1985

[Progressive supranuclear ophthalmoplegia--a clinical entity?].

The syndrome of progressive supranuclear ophthalmoplegia (Richardson-Steele-Olszewski-Syndrom) and its relation to other syndromes are discussed on the basis of a number of case histories and a survey of the pertinent literature. The validity of vertical ophthalmoplegia as a pathognomonic symptom is questioned. The main symptoms are as follows: the heightened tone of the neck muscles, as a rule combined with other indications of parkinsonism and an inclination to fall down. To varying degress there are also bulbar signs and subcortical dementia. Neuropathologically the syndrome can be classed with the "multiple system degeneration" group, on which little enough is known. It remains an open question whether the syndrom of Richardson-Steele-Olszewski is a syndrome of its own or whether it is just a variety of parkinsonism.

Aged↗

PubMed1995

Which structures are sensitive to painful transcranial electric stimulation?

Electric transcranial stimulation (TCS) is useful for clinical studies. It is, however, painful and not generally used for awake subjects. By means of topical anaesthesia and nerve blockades we wanted to find out which structures of the scalp and cranium are sensitive to electric TCS. Altogether 21 subjects participated in the present study. Our data show that pain experienced by the subjects during electric TCS is brought about by activation of the pain receptors in the scalp under the stimulating electrodes. Topical anaesthetic cream is incapable of attenuating this pain. The periosteum does not seem to be much more sensitive electric stimulation than rest of the scalp. Furthermore, contractions of facial and neck muscles do not seem to have a significant role in pain generation in electric TCS. Pain can be prevented if sufficiently large areas of the scalp are properly anaesthetized before stimulation by e.g. blockade of the major nerves responsible for the sensation of the stimulus area.

Adult↗

PubMed1996

[Lessons from experience of bertrand's selective peripheral denervation for splenius type torticollis].

A 23-year-old male with splenius type torticollis underwent selective denervation of C1 and C2 roots and C3-C6 spinal posterior rami, with excellent results. Based on this experience, we stress the importance of dynamic EMG and thorough review of video recording for identifying the involved neck muscles. In the operative procedures, the nerve rami are identified under the semispinalis muscle. To dissect the correct plane under the semispinalis muscle, the key point to keep in mind is to follow the great occipital nerve to the proximal part. An ultrasonic blood flow meter is useful to locate the vertebral artery in the spaces between the occiput and the C1 lamina and between C1-C2 laminae. Because fine nerve branches run in the soft tissues over the laminae, to avoid transient neuroapraxia, dissection around the C1, C2 arches should not be carried out under the periosteum, as is usually done in case of laminectomy. Dissection of C1 and C2 rami as far as the very medial part is rather difficult because of bleeding from the venous plexus and the presence of the vertebral artery. Therefore, the intradural approach might be easier for sectioning the C1 and C2 roots. We would like to add these points to the original description by Bertrand.

Adult↗

PubMed1994

Effects of chemical deactivation of the interstitial nucleus of Cajal on the vertical vestibulo-collic reflex induced by pitch rotation in alert cats.

The basic circuitry for the vestibulo-collic reflex (VCR) is a three-neuron arc, and this reflex requires the temporal and spatial transformation of vestibular signals to activate the appropriate neck muscles. Signals carried by vestibulo-collic neurons are insufficient to explain the responses of neck muscles. However, it is still unknown as to where the additional signal conversion is performed in the vertical VCR. We examined the effects of chemical deactivation of the interstitial nucleus of Cajal (INC) on the responses of biventer cervicis EMG induced by pitch rotation in the dark in alert head-fixed cats, and compared the results with the vertical vestibulo-ocular reflex (VOR) and also with the VCR and VOR induced by horizontal rotation. Muscimol infusion into the bilateral INC resulted in phase advance and gain drop in both the vertical VCR and the VOR, although the change was smaller in the VCR. The response phases of the horizontal VCR and VOR were not affected. Muscimol infusion outside the INC did not affect the phase of the vertical VCR or VOR. These results suggest that the INC is partially involved in temporal conversion of vestibular signals in the vertical VCR as well as in the VOR evoked by pitch rotation in alert cats.

Animals↗

PubMed1989

Androgen and estrogen receptors in bovine skeletal muscle: relation to steroid-induced allometric muscle growth.

The presence of free androgen (AR) and estrogen receptors (ER) was demonstrated in bovine skeletal muscle. Androgen receptor concentrations in neck muscle from cattle of different sexes and stages of development were related to hormonal status. In mature bulls (mean weight 600 kg), no free AR was detectable. Highest AR concentrations were measured in mature bulls (517 kg) castrated 24 h prior to slaughter (.85 +/- .21 fmol/mg protein). In female calves (155 kg), AR concentrations (.56 +/- .14 fmol/mg) were greater (P less than .01) than in male calves (.20 +/- .08 fmol/mg) of the same weight. Androgen receptors and ER in skeletal muscle of neck, shoulder, abdomen and hind leg of female and male calves were compared. There was no significant difference between AR concentrations in the neck, shoulder and hind leg, but concentrations were lower (P less than .05) in abdominal muscle. Estrogen receptor concentrations in neck, shoulder, abdomen and hind leg were not different between sexes (P less than .05). In male calves, ER content was lower (P less than .05) in abdominal than in other muscles. Estrogen receptor concentrations in muscles of female calves did not differ (P less than .05). The pronounced sensitivity to estrogens and androgens in the neck, shoulder, and hind leg of calves, being free of the respective hormone, may partly explain the characteristic conformation in calves treated with estrogenic and androgenic steroids and the sexual dimorphism of muscle growth.

Androgens↗

PubMed1996

Influences of the physical parameters on the risk to neck injuries in low impact speed rear-end collisions.

The current state of neck injuries sustained in car-to-car rear-end collisions were investigated according to recent automobile accident statistical data in Japan. To clarify the neck injury mechanisms for low impact speed car collisions, the newly developed impact sled experiment which simulates actual car impact acceleration was performed using human subjects. In order to measure and analyze the physical parameters such as human head rotational acceleration, neck bending moment, shearing and axial forces, the component measurement method with six-degrees of freedom was applied and demonstrated. Furthermore, relationships among the physical parameters, impact speeds, sitting positions, headrest heights and neck muscle tones applied on the subject's head and neck system were analyzed. These analyses would enable us to comprehend the conditions of the neck muscle tone and the effects of the sitting postures including headrest height, factors which are of vital importance to the understanding of neck injury mechanisms.

Acceleration↗

PubMed1995

Mechanisms controlling human head stabilization. II. Head-neck characteristics during random rotations in the vertical plane.

1. In this study we have tested the hypothesis that the mechanisms controlling stabilization of the head-neck motor system can vary with both the frequency and spatial orientation of an externally applied perturbation. Angular velocity of the head with respect to the trunk (neck) and myoelectric activity of two neck muscles (semispinalis capitis and sternocleidomastoid) were recorded in eight seated subjects during pseudorandom rotations of the trunk in the vertical (pitch) plane. Subjects were externally perturbed with a random sum-of-sines stimulus at frequencies ranging from 0.35 to 3.05 Hz. Four instructional sets were presented. Voluntary mechanisms were examined by having the subjects actively stabilize the head in the presence of visual feedback as the body was rotated (VS). Visual feedback was then removed, and the subjects attempted to stabilize the head in the dark as the body was rotated (NV). Reflex mechanisms were examined when subjects performed a mental arithmetic task during body rotations in the dark (MA). Finally, subjects performed a voluntary head tracking task while the body was kept stationary (VT). 2. In VS and NV, gains and phases of head velocity indicated good compensation for the perturbation at frequencies up to 2 Hz. Between 2 and 3 Hz, gains dropped slowly and then steeply descended above 3 Hz as phases became scattered. 3. In MA, gains were lower and exhibited more scatter than in VS and NV at frequencies < 1 Hz. Phases around -180 degrees indicated that compensatory activity was occurring even with these low gains. Between 1 and 2 Hz, response gains steeply ascended, implying that reflex mechanisms were becoming the predominant mechanism for compensation in this frequency range. Above 2 Hz, gains dropped off to 0.5 and lower, but phases remained close to -180 degrees, suggesting that the reflex mechanisms were not dominant in this frequency range, but that they were still contributing toward compensation for the trunk perturbation. 4. Neck muscle electromyographic (EMG) responses were similar in VS, NV, and MA, demonstrating decreasing gains between 0.35 and 1.5 Hz, and then increasing beyond the previous high level of activation. This U-shaped response pattern implies an enhanced participation of neural mechanisms, probably of reflex origin, in the higher frequency range. 5. Patterns observed during external perturbations of the trunk were not apparent in the response dynamics of voluntary head tracking. In VT, subjects successfully tracked the stimulus only at the lowest frequencies of head movement.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1998

Inactivation of the pons blocks medullary-induced muscle tone suppression in the decerebrate cat.

The pontomedullary region is responsible for the reduction of muscle activity in rapid-eye-movement sleep and contributes to the control of muscle tone in waking. This study sought to clarify the nature of the interaction between the pontine and medullary reticular formation in mediating muscle tone suppression. The degree of medullary-induced neck muscle tone suppression in the decerebrate cat was assessed before and after microinjection of lidocaine into the pontine reticular formation. Medullary stimulation-induced suppression of neck muscle tone was blocked after pontine lidocaine microinjection. The maximum blockade was observed at 16.6 minutes on average after the injection, and recovery occurred within 45 minutes. We conclude that descending mechanisms from the medulla are not sufficient for the triggering of muscle tone suppression. A two-way interaction between the medulla and pons is hypothesized to play a crucial role in the control of muscle tone.

Anesthetics, Local↗

PubMed2001

Influences on the fusimotor-muscle spindle system from chemosensitive nerve endings in cervical facet joints in the cat: possible implications for whiplash induced disorders.

The aim of the present study was to establish if there exists reflex connections from ligamentous structures in cervical facet joints and the fusimotor system of dorsal neck muscles. In seven cats, anaesthetized with alpha-chloralose, bradykinin (BK) of concentrations between 12 and 50 microg was injected into the facet joint between C1 and C2. Recordings were made from single muscle spindle afferents (MSA) originating in contralateral trapezius and splenius muscles (TrSp). Fusimotor induced changes in the sensitivity of the muscle spindle afferents were assessed by recording the responses to sinusoidal stretches of the TrSp muscles. The mean rate of discharge and the depth of modulation of a fitted sine were taken as quantitative estimates of the response. A total of 25 MSAs were recorded, and 21 of these showed clear-cut alterations in their responses to the sinusoidal stretches following Bk. injections into contralateral facet joint. The majority of the responding afferents (13/21) showed changes in their responses indicating an increased activity of static fusimotoneurones, although responses of dynamic and mixed static and dynamic nature were also seen. Local anaesthetics applied to the intraarticular receptors abolished the effects. Injection (i.v.) of a general anaesthetic (pentobarbital) abolished the effects. The results show that there exist reflex connections between receptors in cervical facet joints and fusimotoneurones of dorsal neck muscles, and this might be of importance in the pathophysiology behind whiplash associated disorders (WAD).

Animals↗

PubMed1997

Quantitative assessment of botulinum toxin treatment in 43 patients with head tremor.

We treated 43 patients who had head tremor as the major complaint with local botulinum toxin type A (Btx A) injections into neck muscles: 29 patients were classified as suffering from tremulous cervical dystonia (TCD), and 14 had head tremor without dystonia (HT). All patients were clinically assessed by means of the Tsui scale and a 4-point pain scale at baseline and follow-up visit. Quantitative recordings of head tremor with a bidirectional accelerometer system (horizontal and vertical planes) placed on the forehead were obtained before and 2-3 weeks after Btx A injections. Muscle selection for an injection was based on the visible and palpable tremor oscillation in the involved neck muscles and on analysis of standardized simultaneous electromyographic recordings of six cervical muscles. Patients with HT received mean total doses of 400 units (U) of Dysport (Btx A) (range, 160-560 U) distributed between the two splenius capitis muscles. Patients with TCD received a mean total dose of 500 U Dysport (range, 320-720 U) injected into a mean of 3 muscles (range, 2-4 muscles). The condition of all patients with HT and of 26 of the 29 patients with TCD improved subjectively. The total on the Tsui scale as well as pain scores decreased significantly (p < 0.05) following treatment. Latency of onset, duration of improvement, and side effects showed no significant difference in HT and TCD. Amplitude of HT decreased significantly for both groups following treatment. The mean dominant peak frequency in TCD and HT was slightly less than 5 Hz and did not change significantly after treatment.

Adult↗