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PubMed1996

Haloperidol-increased muscle tone in rats as a model of parkinsonian rigidity.

The aim of the present study was to find out whether haloperidol-induced rigidity was similar to that seen in parkinsonism. Simultaneous measurements of the muscle resistance (mechanomyogram, MMG) of the hind foot to passive flexion and extension in the ankle joint, as well as determination of the electromyographic (EMG) activity of the gastrocnemius and tibialis anterior muscles of rats were carried out. Haloperidol was injected in doses of 0.5-10 mg/kg 1 h before the start of measurements. Haloperidol increased, in a dose-dependent manner, the muscle resistance of the rat's hind leg to passive movements. Muscle rigidity was accompanied with an increase resting, as well as in the stretch-induced long-latency EMG activity (in which supraspinal reflexes are most probably involved) in both those muscles, whereas the short-latency EMG activity (first large bursts of EMG activity, beginning ca. 9 ms after the start of a movement, probably of a spinal origin) was significantly decreased. The obtained results suggest that the haloperidol-increased MMG/EMG activity might be a good model of parkinsonian rigidity.

Animals↗
PubMed1996

Alfentanil as procedural pain relief in newborn infants.

AIMS: To assess the need for, and the suitability of, alfentanil for pain relief during tracheal suction used in assisted ventilation in newborn infants. METHODS: In a randomised, controlled, double blind, crossover trial, placebo (10 micrograms/kg) and 20 micrograms/kg alfentanil were infused in random order two minutes before three separate endotracheal suctions, at least six hours apart, to 10 infants. Measurements were made of physiological variables, behaviour, and stress hormones. RESULTS: After placebo infusion heart rate significantly increased (median 14; interquartile range 12-16 beats/minute) as did behavioural pain score (5; 3-5). Alfentanil (20 micrograms/kg) attenuated the heart rate increase, normalised the pain score, and caused a decrease in plasma adrenaline activity (0.3; 0.2-0.7 nmol/l). Noradrenaline concentration showed a nonsignificant decreasing trend with increasing alfentanil dose and beta endorphin was unchanged. Rigidity was noted in the placebo (n = 2), 10 micrograms/kg (n = 2), and 20 micrograms/kg (n = 5) alfentanil groups, respectively. CONCLUSIONS: Tracheal suction is a painful procedure. The dose of alfentanil required for pain relief (20 micrograms/kg) causes a high incidence of rigidity and thus should be used only with muscle relaxant.

Alfentanil↗
PubMed1993

[A case of rigid spine syndrome--histological findings of muscles].

A 10-year-old boy with rigid spine syndrome was reported. He had mild weakness in the limb, and moderate weakness in the neck flexor and extensor muscles since early childhood. Because of limited flexion of the spine, he could not bend down. CT of the muscles revealed increased low density in the erector spine muscle, predominantly at the lumbar level. In the biopsy specimens obtained from the left biceps brachii and erector spine muscles, there was a variation in fiber size with scattered necrotic and regenerating fibers, and fibrosis, predominantly in the latter. Except for scattered fibers with rimmed vacuoles, the overall histopathological features were similar to those seen in progressive muscular dystrophies, suggesting that the dystrophic process is one of the major pathomechanisms for rigid spine syndrome.

Child↗
PubMed1986

The clinical recognition of subacute tetanus.

The clinical features of a modified form of tetanus, termed 'subacute tetanus', occurring in non-immune patients are presented as manifested in five patients. Subacute tetanus has a good prognosis and favourable outcome. Trismus and abdominal rigidity may be minimal or absent. Nocturnal, brief generalized muscle spasms, palpably contracted sternomastoid muscles and spastic limbs are common features of the disease. The pathophysiology of the nocturnal muscle spasms requires elucidation.

Adult↗
PubMedDate not supplied

Stiff-man syndrome with spinal cord lesion.

An autopsy case of stiff-man syndrome is presented. The patient was a 54-year-old man who had suffered from fluctuating rigidity and tonic spasm of the trunk and leg muscles for three years. These symptoms were induced by emotional stress, strain at voiding and other external stimuli. Physical examination revealed stiffness of the neck, trunk and legs without obvious muscle weakness or atrophy. Deep tendon reflexes were hyperactive, while sensation was normal. EMG showed the stiffened muscles to have continuous motor unit activity which was decreased by myoneural block, spinal anesthesia, diazepam or sleep. Administration of diazepam (60 mg daily) gave some relief of the stiffness for several days. However, respiratory arrest suddenly occurred. Although the patient was resuscitated, he died nine days after this episode. Examination of the spinal cord revealed loss and degeneration of nerve cells with marked gliosis in the medial motor nuclei of the anterior horns. A symmetric degeneration in the bilateral anterior columns which has never been described as a spinal cord lesion in the stiff-man syndrome was also seen.

Brain↗
PubMed1996

Influence of 6-hydroxydopamine lesion of the dopaminergic nigrostriatal pathway on the muscle tone and electromyographic activity measured during passive movements.

The aim of the present study was to find out whether a 6-hydroxydopamine-induced lesion of the substantia nigra in rats would evoke muscular rigidity of the parkinsonian type. Simultaneous measurements of muscle resistance (mechanomyogram) of the hind foot to passive flexion and extension at the ankle joint, as well as of the electromyographic activity of the antagonistic muscles of the ankle joint--the gastrocnemius and tibialis anterior--in rats were carried out one, two and four weeks after bilateral injections of 6-hydroxydopamine (6.5 micrograms/microliter) into the substantia nigra. After immunohistochemical staining of brain sections for tyrosine hydroxylase, the rats were divided into two groups in which, on average, either 70% (63-80%) or 89% (81-96%) of nigral cells degenerated. Larger lesions increased the resistance (mechanomyogram) of the rat's hind leg to passive movements two weeks after 6-hydroxydopamine injection, whereas smaller lesions did not. Muscle rigidity was accompanied by an increase in the movement-induced reflex electromyographic activity in both muscles, mainly in long-latency components which are most probably influenced by supraspinal mechanisms. However, in spite of relatively large lesions of nigral dopamine cells, already four weeks after the lesion, muscle rigidity and the respective electromyographic activity diminished dramatically, which seems to result from very effective compensatory mechanisms operating in young lesioned rats. The results suggest that the muscle rigidity induced by the 6-hydroxydopamine nigral lesion seems to be a good model of parkinsonian rigidity.

Animals↗
PubMed1982

A mechanographic method for measurement of muscle tone in the conscious rat. The calf muscle stretch response in reserpine-induced rigidity.

A simple mechanographic method for the measurement of muscle tone in awake rats is presented. It utilizes principles corresponding to those in clinical assessment of tone and it has been applied to an animal model of Parkinson's disease: the reserpine-treated rat. The rat was restrained by a plastic cylinder and by metal cuffs at the ankles. The hind feet were repeatedly dorsiflexed by an electromechanical manipulator and the resulting calf muscle tension was indirectly measured with a strain-gauge system. The relative contributions to the stretch response from the different muscle groups acting on the ankle joint in the awake and untreated rat and during reserpine-induced rigidity are described. Very little active tension was found in the untreated rat. After treatment with reserpine, continuous activation of the muscle was found in EMG recordings and there was a sharp increase in the tension recorded during stretch. The static response to the increased isometric stretch was augmented. An additional, tonic response to ramp stretch was elicited at all stretch velocities. There was no evidence for phasic responses to rapid stretch in reserpine-induced rigidity. The amplitude of the myomechanogram was thus found to be independent of the ramp stretch velocity. Subsequent injection of apomorphine abolished the increased stretch response. It is demonstrated that changes in muscle tone could be followed during drug treatment and that the method can be used in investigations of the pathophysiological mechanisms behind the disorders of muscle tone.

Animals↗
PubMed1983

Reserpine-induced rigidity in rats: drug effects on muscle tone from corpus striatum and nucleus accumbens.

A study of the pathophysiological mechanisms of reserpine rigidity with the aid of a mechanographic method for the quantification of muscle tone. Apomorphine was used as a test substance to reduce reserpine rigidity by stimulation of dopamine receptors. Some experiments were made with additional drug treatment in an attempt to ascertain the dopaminergic specificity of the test. Apomorphine injected bilaterally to the corpus striatum has been shown to counteract the rigidity [6]. Microinjections of reserpine to corpus striatum induced rigidity with dominance in the hindleg ipsilateral to the side of injection. This rigidity was reduced by subcutaneous apomorphine. The effect of subcutaneous apomorphine on the rigidity was blocked by prior microinjection of trifluoperazine to the corpus striatum. Injections to nucleus accumbens were ineffective in all these respects. It is concluded that reserpine induces rigidity mainly by interference with the dopamine transmission in the corpus striatum.

5-Hydroxytryptophan↗