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Results for “Muscle Tonus”

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At least 271 records · Page 15Linked to original sources
PubMed1978

The syndrome of 'continuous muscle fiber activity.'.

A 7-year-old boy who suffered from increasing stiffness and contractures of the extremities had distally pronounced atrophy and absent tendon reflexes. Electromyography showed continuous electrical activity during rest, sleep, after intravenous injection of diazepam, and after peripheral nerve block. The H reflex was elicitable; the silent period after the reflex was absent. Histopathological examination of the peroneus muscle disclosed a marked preponderance of type I fibers and slight atrophy of the type II fibers. Electron microscopic examination of the endplates demonstrated a marked atrophy of the postsynaptic regions and widened synaptic clefts. After one year's treatment with phenytoin, 200 mg daily, the patient showed an almost normal muscle tone. As not all of these electrophysiological phenomena can be fully explained by disturbances of the nerve terminals or the endplates, a further anomaly proximal from the peripheral nerve block seems to have been present.

Child↗
PubMed1976

Sympathetic pupillary tone in old age.

In an attempt to determine whether autonomic neural factors might be involved in senile miosis, we tested pupillary responses to agents acting on the ocular sympathetic system in old subjects and compared them to responses in young adults. Our results suggest that sympathetic tone is decreased in the elderly. The dilator pupillae muscle does not lose its sensitivity to norepinephrine with age.

Adolescent↗
PubMed1988

Pseudoretraction of the eyelid in thyroid-associated orbitopathy.

Two patients with previously stable thyroid-associated orbitopathy presented with the fairly sudden onset of apparent upper eyelid retraction in their nondominant eye, accompanied by asymmetry of the eyebrows, with elevation on the side without the eyelid retraction. No other signs of worsening of the orbitopathy were present, and instillation of 2.5% phenylephrine hydrochloride in the contralateral, dominant eye relieved the eyelid retraction and normalized the eyebrow position. At surgery, both patients were found to have levator aponeurogenic ptosis in the eyelid that appeared to be "normal." This occurrence is explained by Hering's law and should be considered in planning surgery to reestablish palpebral fissure symmetry in such patients.

Blepharoptosis↗
PubMed1997

Selective laryngeal reinnervation with separate phrenic and ansa cervicalis nerve transfers.

OBJECTIVE: To perform selective reinnervation of the laryngeal abductor and adductor muscle groups after injury to the recurrent laryngeal nerve, recovering laryngeal function without impairment by synkinesis. DESIGN: Ten cats underwent the surgical procedure. To reinnervate the posterior cricoarytenoid muscle (abductor), a phrenic nerve graft was anastomosed to the main trunk of the recurrent laryngeal nerve. The adductor branch was severed, and the proximal stump was buried in the posterior cricoarytenoid muscle. The sternohyoid branch of the ansa cervicalis was anastomosed to the distal stump to reinnervate the adductor muscle group. After a period of 10 weeks, the laryngeal function was evaluated with videolaryngoscopy and electromyography of the posterior circoarytenoid and vocalis muscles. RESULTS: Of the 10 cats, 9 could be evaluated. Laryngeal abductor function was comparable with the unaffected side in the 9 cats. During respiratory distress conditions, a minor compromise of the maximal abduction was observed in 5 cats. Phonation was not tested, but spontaneous adduction during expiration was seen in all cats. Reflex closure on ipsilateral, supraglottic, tactile mucosal stimulation was seen in only 2 cats. In each cat, evidence of nerve regeneration and reinnervation of both muscle groups was established with electromyography, electrical stimulation, and histological examination. CONCLUSIONS: Using this selective reinnervation procedure, good laryngeal function can be achieved in the cat model, which may be applicable in humans. By reinnervation of the vocalis muscle, muscle tonus is achieved, which is expected to improve voice quality. Using this procedure, however, no active reflex closure may be expected.

Animals↗
PubMed1997

Distribution of nitric oxide synthase implies a regulation of circulation, smooth muscle tone, and secretory function in the human prostate by nitric oxide.

BACKGROUND: Nitric oxide (NO) is suggested as a mediator involved in the regulation of smooth muscle tone, blood flow, and secretory function of the genitourinary tract and originates from different NO synthase (NOS) isoforms located in endothelial, neuronal, and epithelial structures. The aim of the present study was to determine the location of endothelial and neuronal NOS in the human prostate. METHODS: Histochemical NADPH-diaphorase (NADPH-d) staining, ultrastructural NADPH examination, and NOS immunohistochemistry were performed on histologically verified nonmalignant prostate tissue from normal nonobstructive and hyperplastic obstructive human prostates. RESULTS: In the prostatic tissue, NADPH-d staining and immunohistochemistry with bNOS antibody revealed the existence of a dense nitrinergic innervation of glandular epithelium, fibromuscular stroma, and blood vessels. NADPH-d reaction in glandular epithelium was not confirmed by ecNOS or bNOS immunohistochemistry. In benign prostatic hyperplasia (BPH), the nitrinergic innervation is reduced. The vascular distribution of ecNOS provides evidence for a segmental differentiation of the NO-mediated vascular regulation. CONCLUSIONS: NO plays an important role in the autonomic innervation of all compartments of prostatic tissue. In obstructive BPH, the nitrinergic innervation is reduced compared to that in normal prostate tissue. Further studies are necessary to elucidate the complex role of NO in the prostate.

Aged↗
PubMed1998

A new congenital muscular dystrophy with mitochondrial structural abnormalities.

We report a new form of congenital muscular dystrophy (CMD) in 4 patients from three unrelated families with probable autosomal-recessive inheritance. All patients had the clinical characteristics of merosin-positive congenital muscular dystrophy, but had marked mental retardation. The disease was slowly progressive and 1 patient died from dilated cardiomyopathy at the age of 13 years. In addition to dystrophic changes with necrosis and regeneration in muscle, the most striking finding was mitochondrial depletion in the center of the sarcoplasm. Mitochondria at the periphery of fibers were markedly enlarged ("megaconial" appearance) with complicated cristae, and contained a normal amount of mitochondrial DNA by in situ hybridization. Mitochondrial enlargement may represent functional compensation for mitochondrial depletion in the central sarcoplasm, where myofibrillar degeneration occurred.

Adolescent↗
PubMed1998

Activity of phasic motor neurons partially transforms the neuronal and muscle phenotype to a tonic-like state.

We present a model preparation, the crayfish, to investigate chronic stimulation effects in muscle fiber type and neuronal conversion from fast to slow. The results show a presynaptic alteration in transmitter release after 1 week of stimulation at 5 Hz for a 2-h daily regime. With the same stimulation paradigm, the muscle proteins displayed on a polyacrylamide gel only start to show changes after 3 weeks. The original phasic motoneurons within 1 week display an enhanced ability to resist synaptic depression, as do tonic motoneurons. The results show that identified phasic motoneurons and muscle fibers in the crayfish can be transformed to a toniclike state, and that the nerve terminals convert prior to the muscle fibers. Electrophysiological clinical measures indicating a change in transmitter release properties may not necessarily mean that the muscle fibers have fully adapted for long-lasting effects. This preparation allows stimulation conditions to be examined with ease.

Action Potentials↗
PubMed1999

The effects of training through high-frequency electrical stimulation on the physiological properties of single human thenar motor units.

The relative impact of training on motor units (MUs) with differing physiological characteristics remains controversial. To examine this issue, we longitudinally tracked the contractile and electrical characteristics of six human thenar MUs in 2 young healthy subjects before, during, and following an intermittent, high-frequency electrical stimulation program. Responses of MUs with differing baseline physiological characteristics varied widely. While the twitch and maximal tetanic tensions of the slower and fatigue-resistant MUs increased, tensions of the faster and more fatigable MUs declined. The fatigue resistance of the faster and more fatigable MUs, on the other hand, increased while that of the slower MUs remained unchanged. Although electrical stimulation of individual MUs allowed their training to be precisely controlled, it will be of practical importance to determine whether similar divergent MU contractile changes also occur with voluntary training.

Action Potentials↗