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At least 1,513 records · Page 84Linked to original sources
PubMed1993

Combined use of surface electromyography and 31P-NMR spectroscopy for the study of muscle disorders.

This article describes the use of combining spectral electromyographic signal techniques with phosphorus magnetic resonance (31P-NMR) spectroscopy for the purpose of studying muscle disorders. The quantification of muscle fatigue by electromyographic spectral variables such as the median frequency is summarized. Its development as a laboratory and clinical tool is presented, with an emphasis toward its potential as an assessment procedure. Similarly, the use of 31P-NMR spectroscopy for noninvasive measurement of phosphate metabolites and intracellular pH during fatigue are described. The limitations of this procedure are presented and compared with surface electromyographic techniques. Suggestions are made for combining these techniques for the purpose of monitoring muscle metabolic and electrophysiologic changes in situ during fatiguing exercises. A recent study in which these techniques were combined to evaluate the underlying mechanisms of fatigue in patients with fibromyalgia is described.

Adult↗
PubMed1998

Classification of paraspinal muscle impairments by surface electromyography.

The purpose of this article is to provide an overview of research to develop surface electromyographic (EMG) measurements for classification of paraspinal muscle impairments in persons with low back pain (LBP). The process of developing laboratory and clinically based protocols is described. Results of studies to evaluate the reliability of these measurements and their relationships with impairments and function are discussed. Research efforts to incorporate EMG spectral measurements, such as the median frequency, into a classification system to identify different types of muscle impairments are documented. Discriminant functions have been calculated based on case-control studies to identify 2 kinds of LBP impairments from constant-force isometric tasks: (1) excessive fatigue due to muscle deconditioning and (2) inhibition of muscle activation secondary to pain or pain-related behaviors. New areas of investigation designed to improve the classification accuracy of such functions using procedures other than discriminant analysis are described. Work in progress to extend the application of the technique to tasks other than those involving just isometric contraction, including those involving repetitive trunk movement, is also described.

Adult↗
PubMed2001

Intramuscular versus surface electromyography of the diaphragm for determining neuromuscular blockade.

We determined the neuromuscular blockade of 0.2 mg. kg(-1) mivacurium at the diaphragm by using two new methods of electromyographic (EMG) monitoring and compared it with acceleromyography of the orbicularis oculi (OO) and the corrugator supercilii (CS) muscle. After the induction of anesthesia in 15 patients undergoing gynecologic laparoscopic surgery, evoked EMG responses at the diaphragm were obtained by using skin electrodes at the back of the patient, placed lateral to T12/L1 or L1/L2, and a laparoscopically applied wire electrode inserted into the dorsolateral portion of the diaphragm. Acceleromyography at the right OO and the left CS was performed. The facial and phrenic nerves were stimulated transcutaneously (onset: every 10 s, offset: every 15 s, single twitch stimulation). Lag and onset time, peak effect, and clinical duration (time to reach 75% of control value and time to reach 90% of control value) were measured and the results were compared by using analysis of variance; P < 0.05 showed significant difference. Pearson's correlation test and the Bland-Altman test were used to compare the two diaphragmatic monitoring methods. Mean peak effects of >98% were reached at all sites. Onset times at diaphragm (skin, IM) were significantly (P < 0.005) shorter than at the CS or OO (100 +/- 14 s and 98 +/- 16 s vs 147 +/- 39 s, 185 +/- 38 s) without being statistically different between OO and CS. There was a good correlation of lag, onset time, time to reach 75% of control value, and time to reach 90% of control value (r = 0.8, 0.9, 0.8, and 0.75; P < 0.01) between the two diaphragmatic methods. Mean difference and limits of agreements are -2 +/- 15 s, 1 +/- 21 s, -1 +/- 2.3 min, and -2 +/- 3.4 min. We showed a shorter onset and clinical duration at the diaphragm in comparison with CS and OO. Two methods of EMG of the diaphragm correlated well and showed good comparability. The novel method of surface diaphragmatic EMG at the patient's back may be useful during routine clinical anesthesia.

Adolescent↗
PubMed1997

Quantitative electromyography-guided botulinum toxin treatment of cervical dystonia.

The purpose of this study was to investigate the clinical and electromyographic effect of turn/amplitude analysis (TAA)-guided botulinum toxin administration in patients with cervical dystonia. Involuntary electromyographic activity was recorded from both sternocleidomastoidei, both splenii capites, and both trapezii muscles of 13 torticollis patients, aged 34-73 years, before and after botulinum toxin A (Dysport) application. Dystonic muscles were selected for the injection if mean turns/s exceeded a level of 200. Four weeks after treatment with a mean dose of 223 mu/subject, clinical improvement was observed in 12 patients (92%) and only one patient reported no effect. Electromyographic improvement could be observed in 10 patients (77%). Both turns/s and the amplitude/turn decreased by 27% on the average after treatment. The electromyographic toxin effect showed a good correlation with the clinical toxin effect (r = 0.6). No dose dependency of the changes in turn/amplitude parameters could be observed. We found TAA a valuable modality for targeting and selecting dystonic muscles and for assessing the therapeutic benefit of the toxin.

Adult↗
PubMed2001

Rotationplasty type B IIIa according to Winkelmann: electromyography and gait analysis.

After resection of a malignant bone tumor of the femur, rotationplasty is considered a treatment option in addition to other limb salvage procedures such as endoprosthetic replacement, allograft, or autograft reconstruction. A Type B IIIa rotationplasty is indicated when the tumor involves the total femur or when skip lesions are detected. After the total femur is resected, the lateral tibial plateau is placed into the acetabulum after rotating the tibia and foot segment 180 degrees. Eight patients at an average age of 5.9 years underwent a rotationplasty Type B IIIa at the authors' institution. After a median followup of 59.6 months (range, 24-86 months) the clinical results were excellent and the functional status according to the criteria of the Musculoskeletal Tumor Society was good (23 of 30 points). In electromyographic analysis the muscle activity of the affected leg revealed good function of the stance and the swing phase muscles according to their new function with comparable amplitudes to the unaffected limb. The kinematics (range of motion of the hip and knee) were slightly assymmetric. Gait analysis showed a slight lateral trunk lean over the ipsilateral limb with reduced joint moment. All patients had full weightbearing ability. Remodeling of the tibial plateau into a round form mimicking a new femoral head is confirmed by radiographs and magnetic resonance imaging scans. In young children with a tumor of the total femur, rotationplasty Type B IIIa is a good treatment modality with excellent clinical and good functional results. The electromyographic and gait analysis data underscore a good functional restoration of gait after rotationplasty.

Bone Transplantation↗
PubMed1996

Intraoperative identification of laryngeal nerves with laryngeal electromyography.

The laryngeal nerves are at risk during thyroid surgery, and several techniques have been described for their intraoperative identification to minimize potential damage. Nerve protection is based on the electromyographic recording from the muscles innervated by the laryngeal nerves, and that electrical activity is picked up by various techniques. We evaluated an electrode attachment to the endotracheal tube that provides a stable method for continuous recording of the laryngeal electromyogram. In addition, we tested various modalities of electrical stimulation in the region where the nerves are located, identified the most reliable evoked electromyographic activity, and characterized the wave form and latency. The results, obtained in 28 patients scheduled for thyroid and parathyroid surgery, indicate that the technique of recording from electrodes attached to the endotracheal tube is safe and reliable. Insulated bipolar forceps or a monopolar electrode was used to deliver low-voltage pulses (1 to 3 V) at 1 to 2 pulses/s generated by either battery-operated or optically isolated stimulators. The most unequivocal recordings were obtained with the monitoring equipment set to the nerve-conduction velocity modality, with the sweep set at 2 msec/cm. The technique clearly differentiated the evoked electromyographic responses obtained from the superior or recurrent laryngeal nerve and was easily performed with no perioperative complications.

Adult↗
PubMed1999

Intraoperative electromyography for predicting facial function in vestibular schwannoma surgery.

OBJECTIVE: To assess the validity of intraoperative minimal stimulation threshold (MST) for predicting long-term facial function after vestibular schwannoma surgery. STUDY DESIGN: Prospective blinded study. METHODS: MST after tumor dissection and postoperative clinical facial function, assessed using the House Brackmann grading system (HB), were used to predict long-term clinical facial function, recorded at least 6 months after surgery. RESULTS: Two hundred and nine consecutive patients fulfilled selection criteria and 184 had successful intraoperative electrophysiologic monitoring and were eligible for further study. MST of 0.05 mA had moderate accuracy for predicting good long-term facial function, with 94% sensitivity, 91% positive predictive value (PPV), 60% specificity, and 70% negative predictive value (NPV). A more relevant group of 77 patients with poor postoperative facial function (HB III-VI) were assessed for predicting good long-term function. Applying this criteria, test accuracy fell, with 83% sensitivity, 64% PPV, 60% specificity, and 75% NPV. Postoperative clinical facial function had a greater accuracy for predicting good long-term function, with 83% sensitivity, 79% PPV, 75% specificity, and 79% NPV. A model of predicted probabilities of good outcome (HB I and II) was derived from a logistic regression with two additive predictors (postoperative HB and MST). This demonstrated that for patients with postoperative HB grade V, MST aided prediction. CONCLUSIONS: Intraoperative stimulation thresholds, when assessed against a relevant group of patients with poor postoperative facial function, had poor predictive accuracy. The severity of immediate postoperative clinical facial function was the most accurate predictor of long-term outcome. MST aided long-term prediction in a small but relevant group of patients with postoperative HB grade V facial function.

Cerebellar Neoplasms↗