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PubMedDate not supplied

[Selective denervation of neck muscles in the treatment of spasmodic torticollis. Preliminary results].

The authors present a review of the methods of surgical treatment of spasmodic torticollis, particularly the selective denervation of cervical muscles. Based on the literature and own experience cases treated by means of this method are described. Using selective ramisectomy it is possible to attain permanent improvement in most patients suffering from spasmodic torticollis, with very low complication rate. Our preliminary cases indicates that this method of treatment allows to acquire improvement of quality of life in patients with this particular type of dystonia.

Adult↗
PubMed2001

Optimal signal bandwidth for the recording of surface EMG activity of facial, jaw, oral, and neck muscles.

Spontaneous pericranial electromyographic (EMG) activity is generally small and is contaminated by strong low-frequency artifacts. High-pass filtering should suppress artifacts but affect EMG signal power only minimally. In 24 subjects who performed a warned simple reaction time task, the optimal high-pass cut-off frequency was examined for nine different pericranial muscles. From four experimental conditions (visual and auditory reaction signals combined with hand and foot responses), 1-min EMG recordings were selected (bandwidth: 0.4-512 Hz) and divided into 60 1-s data segments. These segments were high-pass filtered, the -3-dB cut-off frequency varying from 5 to 90 Hz, and subjected to power spectral analysis. Optimal high-pass filter frequencies were determined for the mean power spectra based on visual estimation or comparison with a theoretical spectrum of the artifact-free EMG signal. The optimal frequencies for the different muscles varied between 15 and 25 Hz and were not influenced by stimulus or response modality. For all muscles, a low-pass filter frequency between 400 and 500 Hz was appropriate.

Adult↗
PubMed1993

Flight helmet weight, +Gz forces, and neck muscle strain.

The aim of this study was to investigate the effect of flight helmet weight on cervical erector spinae muscle strain under high +Gz forces. Two helmets of different weight were compared by recording inflight neck muscle activities with a portable surface-integrated EMG (IEMG) device. The obtained IEMG activities were normalized by comparing them with activities representing maximal voluntary contraction (MVC) of the muscles. Two test pilots carried out a total of 16 flights consisting of a series of different maneuvers. The results indicate that a lighter flight helmet may--at least in some pilots--cause less strain on neck structures than a heavier one. The effect of helmet weight was readily apparent only under high +Gz forces; changing from a heavier to a lighter helmet reduced the mean muscular strain from 9.5 to 8.8% and from 20.2 to 17.1% of the MVC under +4.0 and +7.0 Gz, respectively. Thus, some, but not all, acute inflight neck pain and related problems might be avoided by using lighter flight helmets.

Adult↗
PubMed1999

Reproducibility of isometric strength: measurement of neck muscles.

OBJECTIVE: To evaluate the repeatability of an advanced method of measuring the strength of functionally different groups of neck muscles using an isometric apparatus. DESIGN: A repeated measures design was used within and between sessions. BACKGROUND: Chronic neck pain has been associated with poor isometric neck strength. In rehabilitation, strength measurements may thus help to evaluate the basic condition and show whether or not treatments and exercises have been beneficial for improving strength. Previous tests have concentrated on testing strength while trying to bend forwards and backwards, but no biomechanics device, able to test rotator muscles, has been presented. METHOD: The new isometric measurement device was used to test flexion, extension and also rotation strengths of normal subjects (n = 33). RESULTS: Intratester repeatability was good with regard to all measured parameters. CONCLUSIONS: With both tests performed on the same day and test comparisons between days, intratest repeatability was good with regard to all measured parameters.

Adolescent↗
PubMed1986

[Vibration of neck muscles changes the apparent position of a visual target].

The discharge rate of muscle spindle afferents normally provides a precise signal of muscle length. Vibration of a muscle or its tendon induces an increase in afferent discharge which then no longer represents true muscle length; however, this increased proprioceptive input is interpreted in the central nervous system as a lengthening of the muscle. The incremented signal gives rise to illusions of displacement, or movement, of a fixed, vibrated limb. A visual target attached to such a vibrated limb also appears to move. We now report that vibration of the neck muscles influences visual localisation by inducing illusory movement of targets in visual space. Subjects were seated in a totally dark room and viewed a light-emitting diode (LED). The LED was placed at eye level approximately in the body midline at a distance of 70 cm. They held a physiotherapy vibrator in the left hand with its tip against the left side of the neck. When vibration was initiated the LED appeared to move rightward. The position of the tip of the vibrator was adjusted to produce the maximum apparent displacement to the right. In some subjects the illusion had a vertical component. Subjects maintained the vibrator in position and described the illusion when vibration began, during vibration and at its end. They reported that, initially, the target moved to the right but this displacement ceased after a second or two. The target then appeared to continue in motion without changing its position. When vibration ended the target returned to its initial position.(ABSTRACT TRUNCATED AT 250 WORDS)

Central Nervous System↗
PubMed1994

Neck muscle activity in patients with severe chronic obstructive pulmonary disease.

The present studies were designed to assess the pattern of activity and the frequency of activation of the neck muscles in patients with chronic obstructive pulmonary disease (COPD). Using concentric needle electrodes, we thus recorded the electromyograms of the scalene, sternocleidomastoid, and trapezius muscles during resting breathing in 40 stable patients with severe chronic airflow obstruction (FEV1 = 0.69 +/- 0.18 L) and hyperinflation (FRC = 228 +/- 40% of predicted); 17 patients were hypercapnic at rest. When breathing in the seated posture, all patients (100%) had strong inspiratory contraction of the scalenes. In contrast, no patient showed inspiratory activity in the trapezius, and only four patients (10%) showed definite, invariable inspiratory activity in the sternocleidomastoid. These two muscles were silent in the supine posture as well, even though the adoption of this posture was associated with an increase in dyspnea in most patients. We conclude, therefore, that in contrast to conventional thinking, most stable patients with severe COPD do not use the sternocleidomastoids or the trapezii when breathing at rest. Additional measurements indicated that the sternocleidomastoid inspiratory activity previously recorded in such patients was in general caused by a cross-contamination from surrounding muscles.

Adult↗
PubMed2006

Examination of EMG normalisation methods for the study of the posterior and posterolateral neck muscles in healthy controls.

The purpose of this study was to examine the reliability of normalisation methods used in the study of the posterior and posterolateral neck muscles in a group of healthy controls. Six asymptomatic male subjects performed a total of 12 maximum voluntary isometric contractions (MVIC) and 60%-submaximal isometric contractions (60%-MVIC) against the torque arm of an isokinetic dynamometer whilst surface and intramuscular electromyography (EMG) was recorded unilaterally from representative posterior and posterolateral locations. Reliability was calculated using intra-class correlation coefficient (ICC), relative standard error of measurement (%SEM) and relative coefficient of variation (%CV). Maximal torque output was found to be highly reliable in the directions of extension and right lateral bending when the first of three MVIC contractions was excluded. When averaged across contraction direction, high reliability was found for both surface (MVIC: ICC=0.986, %SEM=7.5, %CV=9.2; 60%-MVIC: ICC=0.975, %SEM=10, %CV=13.7) and intramuscular (MVIC: ICC=0.910, %SEM=20, %CV=19.1; 60%-MVIC: ICC=0.952, %SEM=16.5, %CV=13.5) electrodes. Intramuscular electrodes displayed the least reliability in right lateral bending. The use of visual feedback markedly increased the reliability of 60%-MVIC contractions.

Adult↗
PubMed1982

Neck muscles innervation patterns in the northern leopard frog (Rana P. pipiens).

The motor innervation patterns of neck and middle ear muscles were investigated in 24 northern leopard frogs (Rana p. pipiens) using the horseradish peroxidase retrograde tracing technique. The results show that various neck muscles were innervated by motoneurons in medial motor column of the ventral horn extending from the second to third spinal nerves, and positioned medially to the lateral motor column (LMC). Middle ear muscle, on the other hand, was innervated by motoneurons in LMC.

Animals↗
PubMed2005

Pain effects of glutamate injections into human jaw or neck muscles.

AIMS: To document and compare the intensity, localization, and quality of pain evoked by glutamate injections into the human masseter or splenius muscles and to determine the effect of glutamate-evoked pain on the pressure pain thresholds (PPTs) in both jaw and neck muscles. METHODS: Twenty-six healthy men were given painful injections of glutamate (1.0 mol/L) and control injections of isotonic saline (0.165 mol/L) into the masseter and splenius muscles. The subjects rated the perceived intensity of pain on a visual analog scale (VAS), drew the area of the pain on maps of the face and neck, and filled out a Danish version of the McGill Pain Questionnaire (MPQ). PPTs were used to assess the sensitivity of the masseter and splenius muscles to mechanical stimuli (n = 11). RESULTS: Glutamate injection into the masseter or splenius evoked pain lasting almost 10 minutes. Peak pain intensity usually occurred within 2 minutes of the injection, and VAS scores of peak pain were significantly higher for the masseter muscle compared with the splenius muscle (paired t test, P = .003). The pain area from the masseter injections did not extend into the neck region, although in some subjects the pain from the neck region extended into the temporal region. There were no significant relationships between the area of perceived pain and the VAS pain scores (Pearson correlation, P > .297). Glutamate-evoked pain in either the masseter or splenius muscles was associated with significant decreases in masseter or splenius PPTs, respectively (2-wayANOVAs, P < .016). Isometric saline injections were almost pain-free and caused no PPT changes. CONCLUSION: The data suggest that the masseter muscle is more sensitive to glutamate injections and mechanical stimuli than the splenius muscle. The relatively limited overlap between the sensory manifestations of pain from masseter and splenius muscles may have potential implications for diagnosis and management of myofascial pain complaints in the craniofacial and neck region.

Adult↗
PubMed1994

Short-latency neck muscle responses to vertical body tilt in normal subjects and in patients with spasmodic torticollis.

EMG responses in the sternocleidomastoid (SCM) and dorsal neck muscles (DNM) to vertical head acceleration were studied in normal subjects and in patients with spasmodic torticollis, standing on a platform that could be tilted upwards. The vertical body displacement and the induced changes in the head-neck angle (a flexion-extension sequence) were recorded. Excitatory responses, symmetrical on the two sides, were elicited in normal subjects in both muscle groups, at a latency of about 60 msec (DNM) and 90 msec (SCM). With the head initially extended, the latency of DNM response increased, leaving that of SCM unchanged. During an isometric rotatory effort, an early inhibitory period was recorded in the active muscles at a latency of about 40 msec. Downward tilt did not evoke the responses. The DNM excitatory responses appeared to be related to muscle stretch, while those in SCM, as well as the inhibitory responses in both muscles, were thought to originate in the vestibular receptors. During active head rotation the response increased in amplitude in the active SCM and decreased in the lengthened antagonist; decreased responses in the lengthened muscle persisted during passive head rotation. This was attributed to an influence from the tonic neck receptors. In the patients, SCM responses had normal latency, but were reduced in amplitude or absent in the dystonic muscle, in spite of tilt-induced head movements comparable to those recorded in normals. The diminution was even bigger if compared to normal subjects with the head actively rotated to a similar extent. It persisted when the head was returned to normal position by the "geste antagoniste." The inhibitory responses were unaffected in the active normal and dystonic muscles. The possible role of a deficit of the central vestibular connections in the decreased excitatory SCM response in dystonic patients is considered.

Adult↗
PubMed2006

Reliability of normalisation methods for EMG analysis of neck muscles.

Acceptable reliability of normalisation contractions in electromyography (EMG) is paramount for testing conducted over a number of days or if normal laboratory strength testing equipment is unavailable. This study examined the reliability of maximal voluntary isometric contractions (MVIC) and sub-maximal (60%) isometric contractions for use in neck muscle EMG studies. Surface EMG was recorded bilaterally from eight sites around the neck at C4/5 level from five healthy male subjects. Subjects performed MVIC and sub-maximal normalisation contractions using an isokinetic dynamometer (ID) and a portable cable dynamometer with attached strain gauge (PCD) in addition to a MVIC against a manual resistance (MR). Subjects were tested in flexion, extension, left and right lateral bending and were retested by the same tester within a two-week period. Intra class correlation co-efficients (ICC) were calculated for each testing method and contraction direction and a mean ICC was calculated across all contraction directions. All normalisation methods produced excellent within-day reliability (mean ICC >0.80) but only the MVICs using the ID and PCD had acceptable reliability when assessed between-days. This study confirmed the validity of using MVICs elicited using the ID and PCD as reliable reference contractions for the normalisation of neck EMG.

Adult↗
PubMed1989

[Electromyographic study on the effects of head position to head and neck muscles].

The purpose of this study is to reveal the relationship between the head position, and the neck and head muscles. At 4 head positions, the activities of masseter, anterior temporal, anterior digastric, sternocleidomastoid and trapezius muscle of ten normal subjects standing straight were investigated electromyographically with surface electrodes during voluntary maximal clenching in centric occlusion. Head positions were right tilting, left tilting, up-right and natural head position. The results obtained were as follows; 1. During head tilting, the activities of anterior digastric and sternocleidomastoid muscle on the tilting side were increased, the activities of masseter and trapezius muscle on the opposite side of the tilting side were increased, the activity of the anterior temporal muscle did not vary from the activity during up-right head position. 2. During natural head position, only the activity of sternocleidomastoid muscle on the natural tilting side was increased.

Electromyography↗
PubMed2003

Rapid neck muscle adaptation alters the head kinematics of aware and unaware subjects undergoing multiple whiplash-like perturbations.

To examine whether habituation confounds the study of whiplash injury using human subjects, we quantified changes in the magnitude and temporal development of the neck muscle electromyogram and peak linear and angular head/torso kinematics of subjects exposed to sequential whiplash-like perturbations. Forty-four seated subjects (23F, 21M) underwent 11 consecutive forward horizontal perturbations (peak sled acceleration=1.5 g). Electromyographic (EMG) activity was recorded over the sternocleidomastoid (SCM) and cervical paraspinal (PARA) muscles with surface electrodes, and head and torso kinematics were measured using linear and angular accelerometers and a 3D motion analysis system. EMG onset occurred at reflex latencies (67-75 ms in SCM) and did not vary with repeated perturbations. EMG amplitude was significantly attenuated by the second perturbation in PARA muscles and by the third perturbation in SCM muscles. The mean decrement in EMG amplitude between the first trial and the mean of the last five trials was between 41% and 64%. Related kinematic changes ranged from a 21% increase in head extension angle to a 29% decrease in forward acceleration at the forehead, and were also significantly different by the second exposure in some variables. Although a wider range of perturbation intensities and inter-perturbation intervals need to be studied, the significant changes observed in both muscle and kinematic variables by the second perturbation indicated that habituation was a potential confounder of whiplash injury studies using repeated perturbations of human subjects.

Acceleration↗
PubMed1990

Method of quantitative anatomical study of the dorsal neck muscles. Preliminary study.

Biomechanical models of the cervical spine require knowledge of the position, size and orientation of the individual muscles that act on the cervical spine. We have developed a technique to stereometrically measure anatomical specimens. The apparatus is composed of three graduated metallic rods, which slide along a fixed support. This method is accurate to map the anatomy of individual muscles and provides quantitative data on their lines of action. Results are obtained from one specimen. The computer processing of the collected data allows formulation of a three-dimensional model of the neck muscles in man.

Biomechanical Phenomena↗