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PubMed1987

Neuromuscular control of posture in the infant and child: is vision dominant?

This study explored the effects of vision and maturation on the characteristics of neuromuscular responses underlying balance control in both seated and standing children of five age groups (3 1/2-5 months, 8-14 months, 2-3 years, 4-6 years, and 7-10 years). A platform was used to unexpectedly disturb the child's balance in the anterior or posterior direction. Responses of the leg, trunk, and neck muscles were recorded using surface electromyograms. Vision was not required for the activation of these responses in any of the age groups tested. However, comparison of the muscle response latencies of standing children to posterior platform translation in the two visual conditions showed a significant reduction in latency for neck flexors in the 2- to 3-year-olds with vision removed and ann increase in the total number of monosynaptic reflexes. No reduction in latency was found in the older age groups. The hypothesis of a shift from an early long latency visual dominance to a shorter latency proprioceptive one during childhood is discussed. Postural control showed a cephalo-caudal developmental gradient with postural responses appearing first in the neck, then trunk, and finally, legs, as children developed from 3 to 14 months of age. A wide variety of response patterns was seen in the 3- to 5-month-olds, indicating that postural responses are not functional prior to experience with stabilizing the center of mass.

Journal Article↗
PubMed2003

GABAA receptor antagonism at the hypoglossal motor nucleus increases genioglossus muscle activity in NREM but not REM sleep.

The pharyngeal muscles, such as the genioglossus (GG) muscle of the tongue, are important for effective lung ventilation since they maintain an open airspace. Rapid-eye-movement (REM) sleep, however, recruits powerful neural mechanisms that can abolish GG activity, even during strong reflex respiratory stimulation by elevated CO2. In vitro studies have demonstrated the presence of GABAA receptors on hypoglossal motoneurons, and these and other data have led to the speculation that GABAA mechanisms may contribute to the suppression of hypoglossal motor outflow to the GG muscle in REM sleep. We have developed an animal model that allows us to chronically manipulate neurotransmission at the hypoglossal motor nucleus using microdialysis across natural sleep-wake states in rats. The present study tests the hypothesis that microdialysis perfusion of the GABAA receptor antagonist bicuculline into the hypoglossal motor nucleus will prevent the suppression of GG muscle activity in REM sleep during both room-air and CO2-stimulated breathing. Ten rats were implanted with electroencephalogram and neck muscle electrodes to record sleep-wake states, and GG and diaphragm electrodes for respiratory muscle recording. Microdialysis probes were implanted into the hypoglossal motor nucleus for perfusion of artificial cerebrospinal fluid (ACSF) or 100 microM bicuculline during room-air and CO2-stimulated breathing (7 % inspired CO2). GABAA receptor antagonism at the hypoglossal motor nucleus increased respiratory-related GG activity during both room-air (P = 0.01) and CO2-stimulated breathing (P = 0.007), indicating a background inhibitory GABA tone. However, the effects of bicuculline on GG activity depended on the prevailing sleep-wake state (P < 0.005), with bicuculline increasing GG activity in non-REM (NREM) sleep and wakefulness both in room air and hypercapnia (P < 0.01), but GG activity was effectively abolished in those REM periods without phasic twitches in the GG muscle. This abolition of GG activity in REM sleep occurred regardless of ACSF or bicuculline at the hypoglossal motor nucleus, or room-air or CO2-stimulated breathing (P > 0.63). We conclude that these data in freely behaving rats confirm previous in vitro studies that GABAA receptor mechanisms are present at the hypoglossal motor nucleus and are tonically active, but the data also show that GABAA receptor antagonism at the hypoglossal motor nucleus does not increase GG muscle activity in natural REM sleep.

Animals↗
PubMed1995

[Clinical features and factors related to the functional prognosis in Meige's syndrome].

To clarify the factors determining the amelioration of Meige's syndrome, changes of involuntary movements (IVMs) and functional disability, we examined 60 patients with Meige's syndrome during 5 years after the onset. On average, they showed gradual worsening of IVMs for approximately 2.1 years, then the IVMs ameliorated slowly. In many patients, blepharospasm appeared as the first symptom. Subsequent IVMs were seen in vicinity of the muscles of orbicularis oculi. Phasic involuntary contractions changed to tonic ones in some patients. Asynchrony of the IVMs in various facial or neck muscles may be originated from extensive pathological changes and high excitability in the brainstem. The factors determining the amelioration of functional disability are: (1) younger onset, (2) shorter duration from the onset to the period showing the worst symptoms, (3) mild IVMs when the symptoms were the worst, (4) shorter duration from the onset to the beginning of therapy, (5) synchrony of the IVMs between the muscles of orbicularis oculi and other muscles. Methylphenidate, trihexyphenidyl, and ceruletide showed a higher efficiency for IVMs than the other drugs. The drug therapy in Meige's syndrome should be started as early as possible.

Age of Onset↗
PubMed1993

A technique for diagnosing the individual patterns of innervation of the trapezius muscle prior to neck dissection.

Based on the techniques of regional anaesthesia, a method for simulating the effects of radical neck dissection on the innervation of the trapezius muscle by selectively and reversibly blocking the accessory nerve and its superficial cervical anastomoses, was developed and tested on 40 patients who were due to undergo radical neck dissection. Action potentials of the three portions of the muscle were recorded after this blockade as well as after radical neck dissection, and compared. It was found that the electromyograms were congruent in 92.5% of the cases. Four patterns of innervation were demonstrated, ranging from complete substitution of the resected or blocked nerves to a remaining muscle activity of less than 20% after blockade or radical neck dissection.

Accessory Nerve↗
PubMedDate not supplied

Essential blepharospasm and related dystonias.

Essential blepharospasm is an idiopathic disorder of progressive involuntary spasms of the orbicularis oculi and upper facial (corrugator, procerus) muscles. Blepharospasm literally means spasm of the eyelids; however, most patients with blepharospasm also have or will develop squeezing in the lower face and neck muscles (Meige's syndrome, orofacial dystonia, or oromandibular dystonia). Some patients develop dystonic, uncontrolled movements in areas outside the facial nerve distribution (segmental cranial dystonia or craniocervical dystonia). Chronic, forceful squeezing by the periocular muscles becomes debilitating for the patient and leads to functional and cosmetic eyelid deformities. Treatment has included a variety of modalities and oral medications that are of limited efficacy. Botulinum-A toxin injections have delivered the best temporary relief from this disorder, while the periorbital myectomy operation has been shown to give the best long-term results.

Blepharospasm↗
PubMed2004

Eye-neck coupling during optokinetic responses in head-fixed pigeons (Columba livia): influence of the flying behaviour.

The effects of the behavioural context on the properties of slow and fast phases of the horizontal optokinetic nystagmus (OKN) and on the electromyographic neck response (EMG) were investigated in head-fixed pigeons. Responses in two situations were compared: (i) animals were hung in a harness ('resting' condition); (ii) animals in harness were subjected to a frontal airflow that provoked a flight posture ('flying' condition). During optokinetic stimuli the neck muscles responded in synchrony and in synergy with the eye nystagmus in both the 'resting' and the 'flying' conditions. In the 'resting' condition the neck activity was essentially correlated to the slow phase velocity of the eyes (eye SPV) whereas in the 'flying' condition, the neck response was also correlated to the eye position. The neck response was independent of the retinal slip velocity during the OKN. The velocity of the slow and fast phases of the OKN was not modified by flight. However, the 'flying' condition provoked an increase of the neck response by augmenting both its velocity gain (neck EMG/eye SPV) and its position gain (neck EMG/eye position). These results show that although an optokinetic stimulation results in synchronised eye and head motor commands in head-fixed pigeons, only the head motor command is modified by the behavioural context ('flying' vs. 'resting'). This strategy could help pigeons in reorienting their gaze during the flight.

Animals↗
PubMed1996

Distinctive features of idiopathic inflammatory myopathies in French Canadians.

This is the first report on idiopathic inflammatory myopathies (IIM) in French Canadians. We reviewed retrospectively 30 French Canadian adults (20 women and 10 men) with IIM seen consecutively over 12 years. The median age at diagnosis was 45 years. The IIM were 8 (27%) primary polymyositis (PM), 9 (30%) primary dermatomyositis (DM), 5 (17%) IIM with neoplasia (lymphoma, breast, esophageal, colonic, and skin cancer) and 8 (27%) IIM with a connective tissue disease (4 with systemic sclerosis, 2 with mixed connective tissue disease, and 2 with rheumatoid arthritis). The most common presenting symptom was proximal muscle weakness (n = 10,33%). Of the remaining 20 patients, 6 (20%) had the onset of their weakness within 1 month of the presenting symptom. Only 3 (10%) patients did not have proximal muscle weakness. Twenty-six (87%) patients had weakness in the pelvic girdle, 25 (83%) in the shoulder girdle, and 7 (23%) in the neck muscles. Other common symptoms included dyspnea on exertion and dysphagia, each present in 13 (43%) patients. Gottron's papules and the heliotrope rash were the most common skin lesions documented in 11 (37%) and 10 (33%) patients, respectively. The serum creatine kinase (CK) level was between 171 and 1,000 U/L in 13 (43%) patients and between 1,001 and 6,000 U/L in 13 (43%) patients. Antinuclear antibodies (ANA) on HEp-2 cells were positive in 16 (53%) patients, of which 2 (13%) expressed autoantibodies to nuclear pore complexes. Autoantibody specificities were anti-La (n = 4, 13%), anti-U1RNP (n = 3, 10%), and anti-Ro (n = 2, 7%). None of the patients expressed anti-Jo-1, anti-topoisomerase I, or anticentromere antibodies. Twenty-eight (93%) patients received corticosteroid therapy, and 8 (27%) patients responded to prednisone alone. Thirteen (43%) patients were treated with methotrexate, and 9 (69%) responded. The mean follow-up was 62 months: 23 (77%) had their disease controlled, 3 (10%) patients were lost to follow-up, and 4 (13%) died (no death occurred because of IIM or its treatment). Therapy was discontinued because of remission in 5 (17%) patients. Cumulative survival rates at 2, 5, and 10 years were 89%, 89%, and 85%, respectively. The presence of autoantibodies to nuclear pore complexes and anti-La autoantibodies, the rare occurrence of anti-Jo-1 autoantibodies, the response to conventional therapies, and a high survival rate may distinguish IIM in French Canadians from that of other reported series.

Adult↗
PubMed2000

Shoulder muscle activity in young and older people during a computer mouse task.

OBJECTIVE: Assessment of the age effect in relation to computer work. BACKGROUND: Increasingly, more older people are using computers, while hardware and software are not designed with special consideration of their needs. METHODS: Eight young and nine older females performed different computer mouse tasks. Shoulder muscle activity was recorded from the right deltoid muscle, right and left upper trapezius muscle, and the neck extensor muscles. RESULTS: Mean trapezius muscle activity was significantly higher in the older people (2.8%/3.7% EMG(max) for R/L) compared to the young (1.1%/1.2% EMG(max)). There was a tendency to a higher activity in the older people for the deltoid muscle and the neck extensor muscles. There were small differences in shoulder muscle activation levels between mouse actions, target directions, and between precision demands. CONCLUSIONS: Shoulder muscle activity during computer work is affected by age, but only to a minor extent by the type of computer mouse task. The deltoid and the trapezius muscle activities are low during computer mouse use when there is efficient forearm support by the table. RelevanceAn increasing number of people use computers for hours every day. Intensive use of computers increases the risk of development of work-related musculoskeletal symptoms in the shoulder region.

Adult↗
PubMed1984

Organization and sensory properties of small myelinated fibres in the dorsal cervical rami of the cat.

A study using both anatomical dissection and electrophysiological recording has been made to analyse sensory components of the cervical dorsal rami in the cat. Particular attention has been paid to the physiological properties of Group III muscle afferents. The dorsal rami from C2 to C4 are composed of many nerve bundles that contain afferents from both muscle and skin. Bundles containing only cutaneous and only muscle afferents were identified and found to follow a relatively consistent pattern of organization within the ramus. In nerve bundles serving the biventer cervicis muscle, a population of Group III afferent fibres was identified that responded to strong localized pressure or localized stretch. Their receptive fields were generally small and situated on the muscle borders or in tendinous inscriptions. Such units comprised 73% of those with conduction velocities less than 20 m/s. Group III afferent fibres from neck muscles fired readily to intramuscular 6% sodium chloride, but were mostly not sensitive to bradykinin injected locally or intra-arterially.

Action Potentials↗
PubMed1997

Cervical magnetic stimulation of the phrenic nerves in bilateral diaphragm paralysis.

Cervical magnetic stimulation (CMS) produces a greater twitch transdiaphragmatic pressure (TwPdi) than electrical stimulation. This may be because CMS produces rib cage muscle activation, thus producing an inspiratory action independent of the diaphragm. Alternatively, CMS could merely stiffen the rib cage, allowing the diaphragm to act efficiently, by contracting against a stable rib cage. To examine these two hypotheses we studied five patients with isolated bilateral diaphragm paralysis using CMS and bilateral electrical phrenic stimulation (BES). TwPdi, twitch esophageal pressure (TwPes), and twitch gastric pressure (TwPgas) were measured. We also assessed maximal sniff esophageal and transdiaphragmatic pressures (SnPes) (SnPdi), maximal inspiratory and expiratory mouth pressures (MIP) (MEP), and fall in VC on moving from an upright to a supine position. Respiratory muscle strength tests were consistent with bilateral diaphragm paralysis, and the MEPs confirmed normal expiratory muscle function. The patients were able to generate a mean SnPes of -30 cm H2O, mainly because of inspiratory activity of rib cage and neck muscles. However, TwPdi and TwPes during both CMS and BES were close to zero. We conclude that in our patients with diaphragm paralysis caused by neuralgic amyotrophy, CMS stiffens the rib cage but does not have an inspiratory action independent of the diaphragm.

Adult↗
PubMed1994

Myotonic dystrophy: relative sensitivity of symptoms signs and abnormal investigations.

Twenty-five symptoms, signs, and abnormal investigations were looked for in 20 patients with clinically-definite myotonic dystrophy. Weakness of facial muscles, neck flexors, and arm external rotators was found in all patients (sensitivity = 100%). Arm external rotation has not been reported as a frequently involved muscle in previous clinical studies on myotonic dystrophy. Careful examination of muscle strength may therefore predict which patients may or may not carry the abnormal gene for myotonic dystrophy.

Adolescent↗
PubMed2007

Anti-MuSK-positive myasthenia gravis: neuromuscular transmission failure in facial and limb muscles.

The presence of antibodies against muscle-specific receptor tyrosine kinase (MuSK) appears to define a subgroup of patients with myasthenia gravis (MG) characterized by weakness predominant in bulbar, facial and neck muscles compared with anti-acetylcholine receptor (AChR) antibody-positive MG. To investigate the patterns and severity of neuromuscular transmission failure in different muscles in MuSK-positive MG, we performed single fiber electromyography (SFEMG) in the facial (frontalis) and limb (extensor digitorum communis, EDC) muscles in three anti-Musk-positive patients, and compared results with those of 11 anti-AChR-positive patients. Only one of the three MuSK-positive patients had abnormal jitter in EDC, but all the three showed clearly increased jitter in the frontalis. By contrast, the AChR-positive patients showed similarly abnormal jitter for the two muscles. These results suggest that when the diagnosis of anti-MuSK-positive MG is suspected, SFEMG should be performed in most prominently affected muscles.

Antibodies↗
PubMedDate not supplied

Edentulousness and neuroleptic-induced neck and trunk dyskinesia.

Edentulousness, by disrupting trigeminal propioceptive input from the oral cavity to the basal ganglia, may increase the risk for neuroleptic-induced orofacial dyskinesia. Since lesions of the globus pallidus alter trigeminal sensory-induced reflexive neck muscle activity in rats and the putamen-caudate complex regulates vestibular and propioceptive mechanisms, edentulousness could facilitate also the expression of neuroleptic-induced neck and trunk dyskinesias. In a sample of 131 neuroleptic-treated chronic schizophrenic patients, we found that edentulous patients exhibited significantly more neck and trunk dyskinesias as compared to nonedentulous patients (p less than 005). By contrast, dyskinesias of the face, tongue, and extremities did not differ between the two cohorts of patients. Our findings imply that edentulousness may increase the risk of neck and trunk dyskinesias and highlight the importance of the dental status in tardive dyskinesia.

Adolescent↗
PubMed2001

[Relation between neck accessory inspiratory muscle electromyographic activity and lung volume].

Years ago it was reported that, as lung volume increased, there was a corresponding increase in scalene EMG activity (Raper et al. J Appl Physiol 21: 497-502, 1966). Otherwise, the relationship between changing lung volume and the EMG of the respiratory muscles has not been defined. We therefore inserted fine wire electrodes into the scalene (SCLN), sternocleidomastoid (STERNO), and trapezius (TRAPEZ) muscles in 6 healthy subjects under direct vision using high-resolution ultrasound. Maximum EMG activity (EMGmax) was obtained for each muscle by a variety of respiratory and postural maneuvers. Then, in the standing posture, air flow, raw and moving average EMG signals were sampled and input to a computer during quasi-static inspiration from functional residual capacity (FRC) to total lung capacity (TLC). We found that the relationship between EMG and lung volume for SCLN, but not for STERNO or TRAPEZ, was expressed by exponential curves. The onset of SCLN, STERNO and TRAPEZ EMG occurred at 13.3 +/- 7.4 (mean +/- SE), 67.8 +/- 14.6, and 89.2 +/- 3.9% of inspiratory capacity. The EMG of SCLN, STERNO, TRAPEZ, reached 85.7 +/- 2.6, 60.7 +/- 8.6, and 11.8 +/- 5.2% of EMGmax, respectively, at TLC. We conclude that: 1) SCLN is the most, and TRAPEZ the least, active neck accessory inspiratory muscle, while STERNO is intermediate, and 2) there is a lung volume dependency of the neck accessory muscle EMG activity.

Adult↗
PubMed1999

Fluorine-18 fluorodeoxyglucose imaging using dual-head coincidence positron emission tomography without attenuation correction in patients with head and neck cancer.

PURPOSE: An accurate, preoperative assessment of tumor extent and lymph node involvement is necessary to plan and tailor therapy for patients with head and neck cancer. Metabolic imaging with fluorine-18 fluorodeoxy-glucose (FDG) is a good method to detect primary tumors in the head and neck and to assess the involvement of lymph nodes, but it is not widely available because of the high cost of positron emission tomography (PET). Recently, an alternative method for using FDG was developed: coincidence detection PET (CoDe PET) using a gamma camera. The aim of this study was to evaluate the clinical utility of FDG CoDe PET using a gamma camera in patients with head and neck cancer. MATERIALS AND METHODS: Thirty FDG CoDe PET studies without attenuation correction were performed in seven patients before therapy and in 19 patients after therapy (ages: 25-79 years, mean, 50 +/- 13 years; 18 men, 8 women) with various head and neck cancers. All patients had fasted for 6 to 12 hours and were injected with 111 to 370 MBq F-18 FDG 1 hour before imaging. Visually detectable focal FDG uptake in the primary tumor site or in the neck was considered positive except for physiologic uptake. The FDG CoDe PET studies were correlated with MRI. The gold standard for the presence of disease was the combination of repeated MRIs, endoscopic examination, and 3 months of follow-up clinical evaluation. RESULTS: FDG CoDe PET had a detection rate that was comparable to that of MRI in the pretherapy group. However, in the posttherapy group, FDG CoDe PET could differentiate residual tumor or tumor recurrence from radiation change more accurately than could MRI. However, it had a less accurate detection rate for cervical node metastases because of asymmetric neck muscle uptake. CONCLUSIONS: FDG CoDe PET is a sensitive and cost-effective method to detect primary tumor and lymph node involvement in primary head and neck cancers. It is also useful in differentiating residual tumor or tumor recurrence from posttherapy changes in patients with head and neck tumors.

Adult↗
PubMed2001

Characteristics of tone burst-evoked myogenic potentials in the sternocleidomastoid muscles.

HYPOTHESIS: Optimum stimulus parameters for tone burst-evoked myogenic responses can be defined. These optimized responses will be similar to those evoked by clicks in the same subjects. BACKGROUND: Loud tones give rise to myogenic responses in the anterior neck muscles, similar to click-evoked potentials, and are likely to be saccular in origin. METHODS: Tone burst-evoked and click-evoked myogenic potentials were measured from the sternocleidomastoid muscles of 12 normal subjects (6 men, 6 women) during tonic activation. The effects of tone burst frequency and duration were systematically investigated. Thresholds were measured and compared with click thresholds for the same subjects. Patients with specific lesions were studied using both stimuli. RESULTS: Tone burst-evoked responses showed frequency tuning, with the largest reflex amplitudes at either 500 Hz or 1 kHz. As the stimulus duration was increased, using a constant repetition rate, there was an increase in the reflex amplitudes followed by a decline. The overall optimum stimulus duration was 7 milliseconds. The mean tone burst threshold was 114.4-dB sound pressure level. Stimulus thresholds for click-evoked and tone burst-evoked responses were significantly correlated. Tone burst-evoked and click-evoked responses were present after stimulation of the affected ears of subjects with profound sensorineural hearing loss. Four subjects who had previously undergone vestibular neurectomy had an absence of click and tone burst-evoked responses on the side of the lesion, confirming their vestibular dependence. CONCLUSION: Tone burst-evoked myogenic responses are similar to click-evoked responses but require lower absolute stimulus intensities. To be certain of an optimum response, a stimulus duration of 7 milliseconds, an adequate intensity, and frequencies of both 500 Hz and 1 kHz should be used.

Acoustic Stimulation↗