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PubMed1988

Shoulder strain in keyboard workers and its alleviation by arm supports.

Keyboard work consists mostly of dynamic contractions of the small muscles of the forearms and hands. This is accompanied by continuous activity in the arm, shoulder and neck muscles keeping the head and hand in the correct position. Eliminating the weight from the arm by means of support and the position of the arms influences the electrical activity of shoulder muscles when working at a keyboard. We studied the influence of elbow angle; as well as that of different arm supports, on electrical activity of upper trapezius muscle during keyboard work in healthy workers and persons suffering from shoulder pains. The measurements were carried out in the laboratory. EMG activities, which where measured as mean square root (RMS)-values at every 100-millisecond period in trapezius muscle when working, were lower, the greater the elbow angle. Furthermore electrical activity decreased when subjects used arm supports while working. It is evident that the static load to shoulder muscles can be lowered significantly in keyboard work, when the forearms are at an angle of at least 100 degrees and by using arm supports. The most convienient and ergonomic working position can also be found individually be the method used here.

Adult↗

PubMed2006

Craniocentric body-sway responses to 500 Hz bone-conducted tones in man.

Whole-body responses evoked by bone-conducted sound, a stimulus known to activate vestibular afferents, were recorded in standing subjects deprived of vision. With the head facing forward, unilateral mastoid vibration (500 Hz, 2 s, 136 dB force level) produced an oblique body sway with a consistent lateral component away from the stimulated ear and an average forward component. The side of stimulation had a powerful influence on the direction but not the magnitude of sway. Individuals' mean response directions were significantly clustered between subjects, as well as within subjects for 12 of 16 subjects when tested on five occasions. Single trial analysis did not reveal any habituation of the response. To investigate whether muscle spindle activation might be responsible for the response, vibration was applied directly over posterior and anterior neck muscles and tendons. This generally produced responses that were smaller and with different direction characteristics than with mastoid vibration. In contrast, stimulation over the temporal fossa produced responses similar in magnitude and direction to mastoid stimulation. When the head was turned in yaw to face in different directions the sway response changed direction by the same amount but with no change in magnitude, suggesting response organization in a craniocentric reference frame. Whole-body sway evoked by 500 Hz vibration delivered over sites close to the ear is thus likely to represent a vestibular-evoked balance response. When compared with sway responses evoked by 500 Hz vibration of the left temporal fossa, responses to 1 mA left cathodal galvanic vestibular stimulation were of similar magnitude, yet significantly different in direction, suggesting differences in the end organ afferents activated by these two stimuli. This may enable investigation of previously inaccessible aspects of vestibular function in intact freely behaving human subjects.

Acoustic Stimulation↗

PubMed1980

Electrocorticographic activity of the prepyriform cortex during the sleep-wakefulness cycle of the freely-behaving rat.

The electrocorticographic (ECoG) behavior of prepyriform cortex (PPC) was studied during the spontaneous sleep-wakefulness cycle (SWC) of freely-behaving rats in which recording electrodes had been chronically implanted in PPC, neocortex (NEO), entorhinal area, olfactory bulb (OB), hippocampus, and dorsal neck muscles. The different phases of the SWC were discerned by taking into account the NEO, OB and neck musculature electrical activities, and criteria were set for the identification of various PPC ECoG patterns. The existence of rather regular associations between the PPC ECoG and the various SWC phases was demonstrated, but it was also seen that these associations defied simplistic generalizations. Thus, whereas the level of ECoG activity (in terms of synchronization vs. desynchronization) was, in the majority of instances, equivalent in PPC and NEO in some SWC phases (alert wakefulness, synchronized sleep and paradoxical sleep), the same was not true in the case of the relaxed wakefulness, drowsiness, intermediary and preparadoxical phases. In the same context, when the time relationships between the alternations of different SWC phases and PPC ECoG patterns were analyzed, it became clear that although only rarely the PPC transition occurred after the correspondent SWC one, the former could either precede, or be simultaneous with the latter, depending on the particular SWC transition being considered. The neural control mechanisms possibly responsible for the coupling of PPC and NEo EcoG activities are briefly discussed.

Animals↗

PubMed1998

[Contemporary postural and segmental modification of forced voice].

The forced voice corresponds with increased peri-laryngeal tension during phonation caused by inappropriate muscle action. It is usually accompanied by a characteristic posture (the face thrust forwards, tension in the neck muscles etc...). This posture may cause dysfunction of the cords themselves, leading to dysphonia, and perhaps requiring laryngeal microsurgery. Our project aimed to put forward and validate a system of objective, non-invasive measurements of the postural features of the forced voice, in order to improve the management of these patients. The study was prospective, comparing a control group with no previous vocal problems with a group of patients with problems of laryngeal dysfunction. We carried out a number of simultaneous measurements of postural and segmental activity during phonation, using in parallel an accelerometer, a method of cine-analysis, and a postural platform. Recordings were made during phonation, but only analysed during the resting phase. It turned out that the speed of displacement of the centre of gravity was the most useful discriminating factor. The mean value was 0.07 (displacement type 0.126) for the control group, and 0.32 (displacement type 0.211) for the patient group. The discrimination between these two groups was significant (p < 0.001, Mann-Whitney test). The reliability of this measurement allows us to envisage the inclusion into the clinical investigation package of measurements of the postural and segmental changes in the forced voice.

Adolescent↗

PubMed1994

Reinnervation of the trapezius muscle after radical neck dissection.

Based on the observation, that the caudal parts of the trapezius muscle after radical neck dissection with complete loss of the spinal accessory nerve, are still innervated to an individually varying degree, and on recent anatomical findings relating to this fact, a method for completely reinnervating the trapezius muscle, despite uncompromising radicality of the dissection, is introduced. This procedure consists of identifying and dislodging a subfascial branch of the deep cervical plexus running to the caudal parts of the trapezius muscle in the lateral cervical triangle and anastomosing it to the distal stump of the accessory nerve, using microsurgical techniques, thereby connecting it to the whole innervation system of the muscle. Clinical and electromyographical examinations showed very good recovery of all three portions of the muscle, 15 months after the procedure, in 46 of 52 patients (85%), although these patients were preselected by temporarily blocking the accessory nerve prior to operation, as possessing very little additional nerve supply.

Accessory Nerve↗

PubMed1999

Characteristics of postradical neck pain syndrome: a report of 25 cases.

The postradical neck pain syndrome has been briefly described in the literature, but detailed characterization has not been reported. To further define this syndrome, 25 patients with persistent pain for at least 1 month following neck dissection were evaluated. The sample consisted of 13 men and 12 women with moderate to severe pain ranging from 1 month to 27 years in duration. All patients had at least one type of neuropathic pain: spontaneous, continuous burning pain (81%), shooting pain (69%), and/or allodynia (88%). Neuropathic pain sites were within the distribution of the superficial cervical plexus (SCP). Regional myofascial pain was also common (72%). Seventeen patients agreed to undergo diagnostic local anesthetic injections. Ten of these patients had both neuropathic and somatic (myofascial) pain. Local anesthetic injection of the SCP temporarily eliminated all neuropathic pain in the 17 patients who underwent the procedure. The 10 patients who also had myofascial pain reported temporary relief of their somatic pain following myofascial trigger point injections (TPI). Criteria for the postradical neck pain syndrome are proposed: (1) persistent, nonprogressive neuropathic pain involving one or more branches of the SCP, which may be accompanied by (2) regional nonprogressive somatic pain associated with myofascial pain trigger points in head and neck muscles.

Female↗

PubMed2001

Abnormal interaction between vestibular and voluntary head control in patients with spasmodic torticollis.

The functional status of vestibulo-collic reflexes in the sternocleidomastoid (SCM) muscles was investigated in 24 patients with spasmodic torticollis using small, abrupt 'drops' of the head. None had been treated with botulinum toxin injections during at least 4 months preceding the study. Eight of the patients, four of whom had been studied before surgery, were also studied after selective peripheral denervation of neck muscles. The reflex was of normal latency and duration in the 'passive drop' condition, in which subjects were instructed not to oppose the fall of the head. To study voluntary interaction with the reflex response, subjects were then asked to flex the neck as quickly as possible after onset of the head drop ('active drop'). In this condition, voluntary responses in patients were delayed, smaller and less effective in counteracting the head fall than in normal subjects. The same abnormalities were also found in patients after surgery when the head posture was improved. Somatosensory/auditory voluntary reaction times in SCM were normal, as was the latency of the startle reflex. We conclude that voluntary interaction with the vestibulo-collic reflex is disrupted in patients with spasmodic torticollis, a finding which corroborates the patients' aggravation of their symptoms by head or body perturbations. Lack of effective interaction between two major systems controlling head position may contribute to torticollis.

Adult↗

PubMed1995

Application of a cervical stimulating apparatus for bilateral transcutaneous phrenic nerve stimulation.

Transcutaneous bilateral phrenic nerve stimulation (tPNS) is frequently used to assess diaphragmatic function in humans. Commonly, stimulation is performed with hand-held electrodes; however, these are unsuitable for studies requiring repeated PNS and where recruitment of rib cage and neck muscles may shift the probes in relation to the nerves. In this study we describe the design of a cervical neck brace and electrode probes that maintain stimulating electrodes in constant position relative to the phrenic nerves and facilitates studies requiring repeated maximal PNS. The effectiveness of the apparatus was examined by 1) reviewing the reproducibility of the transdiaphragmatic pressure response to 0.1 ms tPNS (PdiT) at relaxed functional residual capacity in four subjects studied on 25 +/- 8 (SD) occasions (> or = 24 h apart) over a 4-yr period, and 2) measuring peak-to-peak amplitude of the left and right diaphragmatic compound muscle action potentials (surface electrodes) during two prolonged studies (38 +/- 9 min) in each subject, when tPNS was performed during repeated submaximal and maximal inspiratory efforts. PdiT was reproducible in each subject when measured repeatedly within a single study [coefficient of variation (CV) of 3.8 +/- 0.8%] and over separate days (CV of 11.5 +/- 3.5%). The peak-to-peak amplitudes of the left and right compound muscle action potentials were also reproducible (CV of 8.4 +/- 4.3 and 8.4 +/- 2.9%, respectively) and independent of the degree of effort. The apparatus appears effective for the maintenance of maximal stimulation under varied conditions for long periods and provides reproducible measurements of PdiT both within and between studies.

Action Potentials↗

PubMed2005

Experimental induction of muscle tenderness and headache in tension-type headache patients.

The aim of the present study was to investigate the impact of static contraction of the shoulder and neck muscles on muscle tenderness and headache in patients with tension-type headache. Twenty patients with frequent episodic tension-type headache and 20 healthy age- and sex-matched controls were examined using a placebo-controlled cross-over design. The subjects performed static contraction of the trapezius muscles (active procedure) or the anterior tibial muscles (placebo procedure) with 10% of maximal force for 30 min. Total tenderness score, local tenderness score and headache intensity were evaluated before and after the static work. Changes in headache intensity were followed for 24 h. Pericranial tenderness increased significantly more in patients than in controls after the active procedure (P = 0.04). The increase in pericranial tenderness tended to be higher after the active procedure than after the placebo procedure in patients (P = 0.08) and in controls (P = 0.07). Sixty per cent of the patients and 20% of the healthy controls developed headache after the active procedure. Fifty per cent of the patients and none of the controls developed headache after the placebo procedure. There was no significant difference in headache development between the active and the placebo procedure in patients or controls. These findings demonstrate that tension-type headache patients are more liable to develop shoulder and neck pain in response to static exercise than healthy controls.

Adult↗

PubMed2001

Efficacy and safety of a standardised 500 unit dose of Dysport (clostridium botulinum toxin type A haemaglutinin complex) in a heterogeneous cervical dystonia population: results of a prospective, multicentre, randomised, double-blind, placebo-controlled, parallel group study.

Results from a dose-ranging study in a selected group of de novo patients with rotational cervical dystonia (CD) suggest that 500 units of Dysport (Clostridium botulinum toxin type A haemaglutinin complex) is the optimal starting dose. The present study aimed to confirm the efficacy and safety profile of this dose in a population of CD patients more representative of those seen in a typical dystonia clinic. A total of 68 patients with moderate to severe CD (Tsui score > or = 9) were randomly assigned to receive placebo or Dysport 500 units. Treatment was administered according to the clinical pattern of head deviation, using a standardised injection protocol. A total of 21 patients (11 Dysport, 10 placebo) had not previously received botulinum toxin type A (BtxA) injections, and 47 patients (24 Dysport, 23 placebo) had received BtxA more than 12 weeks previously. Assessments were performed at baseline and weeks 4, 8 and 16. Patients defined as non-responders at week 4 were re-treated in an open phase with 500 units of Dysport at week 6, and were followed up at week 10. Significant between-group differences in Tsui scores were present at weeks 4 (p=0.001) and 8 (p=0.002). Similarly, there were significant between-group differences (p < 0.001) in patient and investigator assessments of response in favour of Dysport at weeks 4 and 8. Also, more Dysport (49%) than placebo (33%) patients were pain-free at week 4 (p=0.02). Overall, 30/35 (86 %) Dysport patients and 14/33 (42%) placebo patients were classified as responders at week 4. Adverse events were reported by 15/35 Dysport patients and 9/33 placebo patients. Open phase treatment produced improvements in Tsui (p < 0.001) and pain scores (p=0.011), and 23/24 patients were classified as responders. Although individual dose titration and muscle selection is desirable, this study demonstrated that a dose of 500 units of Dysport injected into clinically identified neck muscles without electromyographic guidance is safe and effective in the treatment of patients with the major clinical types of cervical dystonia.

Adolescent↗

PubMed2003

Homicidal and suicidal ligature strangulation--a comparison of the post-mortem findings.

Suicides by ligature strangulation are rare events. In Berlin (3.5 million inhabitants; ca. 500 suicides per year) approximately one case per year occurs. Here, we present the main findings of 19 cases investigated between 1978 and 1998, compared to 47 cases of homicidal ligature strangulation. Two of the 19 suicidal victims had single fractures of the upper thyroid horns and one victim a fracture of a lower thyroid horn; other types of laryngohyoid injuries were not observed. In the homicidal series, the laryngohyoid structures were unaffected in 26 cases (12 of these victims were children or adolescents), single thyroid horn fractures were present in three cases and more significant injuries in 18 cases. Macroscopic bleedings of the laryngeal muscles were found in 12 victims of the homicidal group and in none of the suicidal. Bleedings in the neck muscles seldom occurred in suicides. According to these findings, the laryngohyoid injuries can be helpful in the differentiation of suicide from homicide, if more than a single thyroid horn fracture or a laryngeal soft tissue trauma is present.

Adolescent↗

PubMed2000

Strain in the braincase and its sutures during function.

The skull is distinguished from other parts of the skeleton by its composite construction. The sutures between bony elements provide for interstitial growth of the cranium, but at the same time they alter the transmission of stress and strain through the skull. Strain gages were bonded to the frontal and parietal bones of miniature pigs and across the interfrontal, interparietal and coronal sutures. Strains were recorded 1) during natural mastication in conjunction with electromyographic activity from the jaw muscles and 2) during stimulation of various cranial muscles in anesthetized animals. Vault sutures exhibited vastly higher strains than did the adjoining bones. Further, bone strain primarily reflected torsion of the braincase set up by asymmetrical muscle contraction; the tensile axis alternated between +45 degrees and -45 degrees depending on which diagonal masseter/temporalis pair was most active. However, suture strains were not related to overall torsion but instead were responses to local muscle actions. Only the coronal suture showed significant strain (tension) during jaw opening; this was caused by the contraction of neck muscles. All sutures showed strain during jaw closing, but polarity depended on the pattern of muscle usage. For example, masseter contraction tensed the coronal suture and the anterior part of the interfrontal suture, whereas the temporalis caused compression in these locations. Peak tensile strains were larger than peak compressive strains. Histology suggested that the skull is bent at the sutures, with the ectocranial surface tensed and the endocranial surface predominantly compressed. Collectively, these results indicate that skulls with patent sutures should be analyzed as complexes of independent parts rather than solid structures.

Animals↗

PubMed1989

Radiocaesium from Chernobyl in Swedish moose.

The (137)Cs activity concentrations of muscle samples taken from moose collected from the central part of Sweden were determined. Pre-Chernobyl samples had a mean (137)Cs activity concentration of 23 Bq kg(-1). Samples collected during the hunting season (mainly October) had, on average, 760 Bq kg(-1) in 1986 and 664 Bq kg(-1) in 1987. No significant differences between various muscles (neck, thigh and leg) could be seen. The correlation between ground deposition of (137)Cs and activity concentration in moose muscle was significant. There seems, however, to be other important parameters. One is the percentage of farmland within the home range of the moose-less farmland gives higher (137)Cs activity concentrations.

Journal Article↗

PubMed1980

A patient with reflex myoclonus and muscle rigidity: "jerking stiff-man syndrome".

A patient with progressive muscular rigidity associated with reflex myoclonus is described. The muscular rigidity was predominantly axial, and the myoclonic jerks affected axial and leg muscles. Jerks occurred either spontaneously, or in response to touch to the perioral region, or to stretch of head and neck muscles. Physiological investigations suggested that the myoclonus originated in the medulla and was mediated by fast-conducting pathways upwards through the brainstem and down the spinal cord. The relationship of this condition to other types of muscular rigidity with and without myoclonus is discussed.

Adult↗

PubMed1990

Botulinum A toxin treatment for eyelid spasm, spasmodic torticollis and apraxia of eyelid opening.

Botulinum-A toxin (botAtox) was used in the treatment of blepharospasm (BS), idiopathic hemifacial spasm (HFS), idiopathic spasmodic torticollis (ST) and apraxia of eyelid opening (AEO). The injection of 7.5-30 U botAtox per eye spread over 3 or 4 sites in the palpebral part of orbicularis palpebrae (OP) reduced palpebral spasm in 12/13 cases of BS and in 7/8 cases of HFS. The effect lasted for 14.5 weeks on average (range 4-30 weeks). Palpebral ptosis (lasting 1-3 weeks) was the most frequent side effect (16/107 eyes treated) but was not related to dose of botAtox or number of inoculation sites. Injection of 60-160 U botAtox into the sternocleidomastoid, trapezius and splenius capitis muscles reduced ST objectively in 1/4 patients for about 4 weeks. In the other patients the reduction or abolition of the hypertrophy of the previous hyperactive muscles was accompanied by persistence or rearrangement of the dystonia pattern, suggesting a change in the pattern of activity of the neck muscles after botAtox. 5 U botAtox per eye spread over 4 sites in the OP significantly reduced the frequency of the episodes of involuntary eyelid closure in 2 patients with AEO but not BS. The therapeutic effect lasted for 7 months after the first treatment and for 8 months after the second in a 46 year old woman with a 6 month history while the second patient (72 year old parkinsonian) has now completed her 3rd month of treatment.

Adult↗

PubMed2004

Relation between activities of the cortex and vibrissae muscles during high-voltage rhythmic spike discharges in rats.

Paroxysmal 5- to 12-Hz high-voltage rhythmic spike (HVRS) activities, which are accompanied by whisker twitching (WT), are found in Long Evans rats, but the function of these HVRS activities is still debated. In four major functional hypotheses of HVRS discharges, i.e., alpha tremor, attention/mu rhythm, idling/mu rhythm, and absence seizure, the first two hypotheses emphasize WT behavior in HVRS bouts. Whisker movement is primarily determined by activation of intrinsic and extrinsic muscles. To clarify the role of WT in HVRS activities, simultaneous recording of the activities from the cortex and intrinsic/extrinsic and neck muscles were performed. Most HVRS bouts (68.8%) revealed no time-locked WT behavior in a 2-h recording session. In addition, WT primarily arose from active protraction due to activation of intrinsic muscles followed by passive retraction. A small portion of WT resulted from activation of both vibrissae muscles with dynamic frequency-dependent phase shifts. Onset of the rhythmic vibrissae EMG significantly lagged behind HVRS onset, and the mean duration of vibrissae muscle activity was one-third to a one-half of a HVRS bout. Moreover, a greater number of HVRS bouts were associated with a longer HVRS duration and higher oscillation frequency. Oscillation frequencies of HVRS activities without WT behavior were significantly lower than those with WT. Under peripheral sensory/motor blockade by xylocaine injection, oscillation frequencies of HVRS bouts significantly decreased, but no remarkable changes in the number or duration of HVRS bouts were observed. Compared with vibrissa muscle activity during WT and exploratory whisking, the duration of muscular activity in each cycle was apparently longer during whisking bouts. Based on these results, overemphasis of the role of WT on HVRS activities might not be appropriate. Instead, HVRS discharges may be associated with absence seizure or idling state. In addition, peripheral inputs, including WT, may elevate the oscillation frequency of HVRS bouts. Moreover, different muscular controls may exist between WT and whisking.

Action Potentials↗

PubMed2006

[Recent progress in diagnosis and treatment of the injury to the peripheral nerve].

OBJECTIVE: To investigate the latest development in diagnosis and treatment of the injury to the peripheral nerve. METHODS: The literature at home and abroad was reviewed, and the research findings with clinical experience in diagnosis and treatment for the injury to the peripheral nerve were summarized. RESULTS: The treatment for the total brachial plexus avulsion injury was successfully performed by the extra-plexus nerve transfer. The avulsion of the brachial plexus could be directly repaired by the healthy C7 nerve root transfer through the anterior spinal approach. The forearm flexors could be reinforced by the neurovascularized gracilis transplantation. MRI and CTM were the best methods of early diagnosis for the brachial plexus injury. The pure upper or lower root avulsion of the brachial plexus injuries could be repaired by the intra-plexus nerve transfer, which involved a transfer of part of the ulnar nerve in the arm to the motor nerve of the biceps for C5-C6 avulsion of the brachial plexus,and a transfer of selective fascicles of the healthy C7 nerve root or brachial muscle branch to the flexors muscle fascicles of the median nerve or anterior interosseous nerve. The thoracic outlet syndrome always occurred in this position when the neck muscle fatigue occurred in the typists or the game-players after their longstanding looking forwards. The C5 and C6 roots were rolled by the tendenofibrotic tissue at the origin of the scalenus. After a procaine block, the symptom subsided. Radiation neuropathy was a series of pathological changes caused by overdoses of the radiation therapy. The pathologic findings consisted of a series of vessel damages and final coagulation necrosis, which induced clusters of abnormally-dilated, thin-walled telangiectasias. Radiation neuropathy could be detected by MRI and could be differentiated from tumor. Once the diagnosis was established, the therapy should be begun early, including the systemic use of steroids, anticoagulation, and hyperbaric oxygen. CONCLUSION: Great progress has been made in diagnosis and treatment of the injury to the peripheral nerve, but a further study should be performed to promote regeneration of the nerves and reconstruction of the related functions.

Brachial Plexus↗

PubMed1999

Myotube heterogeneity in developing chick craniofacial skeletal muscles.

Avian skeletal muscles consist of myotubes that can be categorized according to contraction and fatigue properties, which are based largely on the types of myosins and metabolic enzymes present in the cells. Most mature muscles in the head are mixed, but they display a variety of ratios and distributions of fast and slow muscle cells. We examine the development of all head muscles in chick and quail embryos, using immunohistochemical assays that distinguish between fast and slow myosin heavy chain (MyHC) isoforms. Some muscles exhibit the mature spatial organization from the onset of primary myotube differentiation (e.g., jaw adductor complex). Many other muscles undergo substantial transformation during the transition from primary to secondary myogenesis, becoming mixed after having started as exclusively slow (e.g., oculorotatory, neck muscles) or fast (e.g., mandibular depressor) myotube populations. A few muscles are comprised exclusively of fast myotubes throughout their development and in the adult (e.g., the quail quadratus and pyramidalis muscles, chick stylohyoideus muscles). Most developing quail and chick head muscles exhibit identical fiber type composition; exceptions include the genioglossal (chick: initially slow, quail: mixed), quadratus and pyramidalis (chick: mixed, quail: fast), and stylohyoid (chick: fast, quail: mixed). The great diversity of spatial and temporal scenarios during myogenesis of head muscles exceeds that observed in the limbs and trunk, and these observations, coupled with the results of precursor mapping studies, make it unlikely that a lineage based model, in which individual myoblasts are restricted to fast or slow fates, is in operation. More likely, spatiotemporal patterning of muscle fiber types is coupled with the interactions that direct the movements of muscle precursors and subsequent segregation of individual muscles from common myogenic condensations. In the head, most of these events are facilitated by connective tissue precursors derived from the neural crest. Whether these influences act upon uncommitted, or biased but not restricted, myogenic mesenchymal cells remains to be tested.

Animals↗