1,721,043 research outputs found
Fibrillatory activity and other membrane changes in partially denervated muscles
No full textRat soleus muscles were partially or totally denervated by sectioning the radicular nerve L5 or the radicular nerves L3 through L6, respectively. Three days after these procedures, fibrillation potentials were not observed in the case of partial denervation, whereas they were clearly detectable after total denervation. At later times, spontaneous spike activity also developed in the partially denervated muscles. The difference in time of onset of fibrillation between partially and totally denervated muscles was confirmed by a more gradual increase in the number of acetylcholine receptors and a greater sensitivity to tetrodotoxin of the former muscles. These differences between partially and totally denervated muscles are interpreted on the basis of the different amounts of nerve breakdown products generated in the two situations
Time and frequency domain analysis of surface myoelectric signals duringelectrically-elicited cramps
No full textOBJECTIVES: To examine if different frequencies of electrical stimulation trigger different sized cramps in the abductor hallucis muscle and to analyze their surface electromyographic (EMG) behaviour in both time and frequency domains. METHODS: Fifteen subjects were studied. Stimulation trains of 150 pulses were applied to the muscle motor point. Frequency was increased (starting from 4pps with 2-pps steps) until a cramp developed. Current intensity was 30% higher than that eliciting maximal M-waves. After the first cramp ("threshold cramp"), a 30-minute rest was provided before a second cramp ("above-threshold cramp") was elicited with a frequency increased by 50% with respect to that eliciting the first cramp. RESULTS: We found greater EMG amplitude and a compression of the power spectrum for above-threshold cramps with respect to threshold cramps. M-wave changes (ranging between small decreases of M-wave amplitude to complete M-wave disappearance) occurred and progressively increased throughout stimulation trains. Significant positive correlations were found between estimates of EMG amplitude during cramps and estimated reductions of M-wave amplitude. CONCLUSIONS: Varying frequencies of electrical stimulation triggered different sized cramps. Moreover, decreases in M-wave amplitude were observed during both threshold and above-threshold stimulations. The choice of the stimulation frequency has relevance for optimizing electrical stimulation protocols for the study of muscle cramps in both healthy and pathological subjects
Polyneuritis cranialis: clinical and electrophysiological findings
No full textA 13 year old boy, developed bilateral facial weakness, dysphonia and dysphagia acutely after a febrile illness. Neurological examination and MRI of the brain were normal. The CSF protein level increased. Blink reflex monitoring during clinical recovery was consistent with demyelination of the lower cranial nerves innervating the branchial arch musculature, a rare variant of Guillain-Barre syndrome
Successful botulinum toxin treatment of dysphagia in oculopharyngeal muscular dystrophy.
No full textnot availabl
The botulinum toxin treatment of lower facial muscles in patients affected by hemifacial spasm
No full textHypokalemic periodic paralysis: a single fiber electromyographic study
No full textThe neurophysiological findings obtained with standard electromyography (EMG) and single fiber EMG (SFEMG) in a case of hypokalemic periodic paralysis (HoPP) are reported. During the period between paralytic attacks the only abnormalities consisted of scanty fibrillation potentials and, with SFEMG, a fiber density increase. In the first stage of an induced paralytic attack the most striking feature was decrease in fiber density, slight increase in jitter with several blocks. These results indicate a failure of the membrane surface to propagate an action potential. In some fibers the block is likely to be permanent, thus explaining the decrease in fiber density. The jitter increase is due to a slight abnormality at the synaptic site or to a variation in the propagation velocity of the muscle fiber
Acute peroneal compartmental syndrome: report of a case
No full textAmong the compartmental syndromes the necrosis of peroneal muscles is unusual. We report a case in which the swelling of peroneal muscle causes a compression of the common peroneal nerve below the peroneal head. A disturbance of both the motility and sensibility of the deep and superficial peroneal nerve is present with different pathogenesis. In fact, EMG suggested a muscular damage of the peroneal compartment and a denervation of the pretibial muscle. Interfascicular neurolysis along the peroneal nerve was performed to decompress the common and the deep peroneal nerve. A recovery in the territory of the tibialis anterior deep peroneal nerve confirmed the different mechanisms of paralysis
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