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PubMed2004

Non-invasive transabdominal uterine electromyography correlates with the strength of intrauterine pressure and is predictive of labor and delivery.

OBJECTIVE: The study was conducted to investigate whether the strength of uterine contractions monitored invasively by intrauterine pressure catheter could be determined from transabdominal electromyography (EMG) and to estimate whether EMG is a better predictor of true labor compared to tocodynamometry (TOCO). STUDY DESIGN: Uterine EMG was recorded from the abdominal surface in laboring patients simultaneously monitored with an intrauterine pressure catheter (n = 13) or TOCO (n = 24). Three to five contractions per patient and corresponding electrical bursts were randomly selected and analyzed (integral of intrauterine pressure; integral, frequency, amplitude of contraction curve on TOCO; burst energy for EMG). The Mann-Whitney test, Spearman correlation and receiver operator characteristics (ROC) analysis were used as appropriate (significance was assumed at a value of p < 0.05). RESULTS: EMG correlated strongly with intrauterine pressure (r = 0.764; p = 0.002). EMG burst energy levels were significantly higher in patients who delivered within 48 h compared to those who delivered later (median [25%/75%]: 96,640 [26,520-322,240] vs. 2960 [1560-10,240]; p < 0.001), whereas none of the TOCO parameters were different. In addition, burst energy levels were highly predictive of delivery within 48 h (AUC = 0.9531; p < 0.0001). CONCLUSION: EMG measurements correlated strongly with the strength of contractions and therefore may be a valuable alternative to invasive measurement of intrauterine pressure. Unlike TOCO, transabdominal uterine EMG can be used reliably to predict labor and delivery.

Abdomen↗
PubMed1988

Assessment of organophosphorus-induced delayed neuropathy in chickens using needle electromyography.

The adult chicken provides the generally accepted animal model for organophosphorus-induced delayed neuropathy, exhibiting both clinical signs and histopathological damage after exposure. In this study, noninvasive electrodiagnostic methods were used for assessment of the development of neuropathy after administration of a single dose of protoxicant tri-ortho-tolyl phosphate (TOTP, 360 and 500 mg/kg po) and active congener phenyl saligen phosphate (PSP, 2.5 and 6 mg/kg im). Onset and severity of clinical signs were dose-related for both organophosphorus compounds. Extensive peripheral nerve lesions consistent with advanced stages of organophosphorus-induced delayed neuropathy were noted in selected chickens examined 19 d after TOTP administration. Needle electromyographic examinations of gastrocnemius, anterior tibialis, semitendinosus, and semimembranosus muscles were done before exposure and on d 8, 15, and 19 after exposure to TOTP and on d 8, 15 and 17 after exposure to PSP. Untreated chickens (negative controls) were also examined at each session. An untreated chicken with a transected sciatic nerve (positive control) was examined on d 13, 20, and 23 posttransection. Prolonged insertional activities were found in both treated and untreated chickens. Denervation potentials were found in only 2 of the 20 chickens administered organophosphates. Denervation potentials were, however, easily visible 13 d following transection of the sciatic nerve of a normal chicken. Needle electromyography could not evaluate organophosphorus-induced delayed neuropathy in chickens of this study.

Animals↗
PubMed2004

Surface electromyography apparatus as a measurement device for biofield research: results from a single case study.

OBJECTIVES: The objective of this preliminary investigation was to determine if surface electromyography (EMG) equipment is capable of detecting electrical signals that can be used as a measure in biofield research. DESIGN: These preliminary data were collected from one subject (a member of the research team), using the subject as his own control. Resting state data are compared to data collected during a specific Healing Touch (HT) intervention. SETTINGS/LOCATION: The setting was in an electromagnetically shielded room (a modular enclosure utilizing two separate conductive electromagnetic barriers, which were electrically isolated, attached by a single-point ground connection) at the University of Wisconsin-Milwaukee, Milwaukee, WI. INTERVENTION: Data were collected during a resting state, and subsequently during a partial "HT back sequence." The back sequence is a standard HT procedure consisting of "Connecting the Lower Body," "Open Spinal Energy Flow," a "Vertebral Spiral Technique," and other techniques taught in HT level 2. MEASURES: Electrodes were attached to the back of the subject at eight acupoints. The Model 544 EMG System (amplifier and electrode assembly) (Therapeutics Unlimited, Inc. Iowa City, IA) was used to acquire data. The raw data were divided into discrete time segments and converted from the time domain into the frequency domain by performing a fast Fourier transform. Integer frequency averaging was conducted to allow for ease of interpretation. Using the voltages at each frequency, the signal strength was calculated in decibels. RESULTS: A 0-65 Hz frequency spectrum was obtained from the surface EMG apparatus. An averaged baseline, "resting state" frequency spectrum was definable for the subject that was stable with time for signal strengths >0 dB. When the HT practitioner attuned with the subject, higher frequency components of the spectrum increased in amplitude, peaked, then decreased throughout the intervention. CONCLUSIONS: The conclusions drawn from these results is that the surface EMG apparatus has potential as a measurement device for biofield research. Further experimentation using this device for biofield measurement is encouraged.

Acupuncture Points↗
PubMed2000

Comparison of succinylcholine with two doses of rocuronium using a new method of monitoring neuromuscular block at the laryngeal muscles by surface laryngeal electromyography.

We compared the onset of neuromuscular block with succinylcholine (1 mg kg-1) and two doses of rocuronium (0.6 and 0.9 mg kg-1) at the adductor pollicis muscle using electromyography (EMG) and acceleromyography (AMG), and at the adductor laryngeal muscles with a new electromyographic method using a disposable surface electrode attached to the cuff of a tracheal tube. At the larynx, the mean (+/- SD) time to 90% block and the onset time of succinylcholine (38 +/- 15 and 47 +/- 19 s, respectively) were significantly shorter (P < 0.01) than for rocuronium 0.6 mg kg-1 (92 +/- 42 and 106 +/- 38 s) and rocuronium 0.9 mg kg-1 (52 +/- 31 and 64 +/- 30 s). We found that, with comparable degrees of neuromuscular block, the onset time of succinylcholine at the adductor pollicis was significantly shorter (P < 0.01) than for rocuronium 0.6 mg kg-1 and 0.9 mg kg-1 (EMG, 80 +/- 39 vs 145 +/- 48 s and 99 +/- 31 s; AMG, 90 +/- 39 vs 124 +/- 53 s and 106 +/- 38 s). Clinical duration at the adductor pollicis (AMG) was significantly longer (P < 0.01) for both rocuronium groups than for succinylcholine (T4:T1 = 0.7, 54 +/- 18 and 77 +/- 21 vs 8 +/- 6 min). The surface laryngeal electrode proved non-invasive, easy to use and reliable in measuring onset of the neuromuscular block at the larynx.

Adult↗
PubMed1992

No posterior mandibular displacement in Angle Class II, division 2 malocclusion as revealed with electromyography and sirognathography.

The activity of the anterior and posterior temporal, and of the masseter muscles was studied by electromyography and the position of the mandible by sirognathography. The recordings were made in 22 children, aged 8-13 years, with Angle Class II, division 2 malocclusion before and during treatment of their malocclusion. The treatment comprised two phases: proclination of the upper incisors and bite raising with a removable plate, and the subsequent correction of the distal occlusion with an activator. The aim of the study was to reveal signs of anterior mandibular positioning during the treatment. The electromyographic recordings were made in the rest position of the mandible, and during maximal biting, chewing, and swallowing. The sirognathographic recordings comprised the positions of the mandible at rest, at intercuspation, and during tooth contact during chewing and maximal mandibular movements. The muscle activity at rest was unchanged during the period of observation. The activity during maximal biting, chewing, and swallowing decreased during the phase of proclination, which was interpreted as a result of occlusal instability. The positions of the mandible at rest, at intercuspation, and during chewing were stable during the treatment. Neither the electromyographic recordings nor the recordings of mandibular positions revealed any signs of anterior mandibular positioning during the treatment of the Class II, division 2 malocclusion.

Child↗
PubMed1991

An outbreak of soft-tissue infections due to Mycobacterium fortuitum associated with electromyography.

An outbreak of infections due to Mycobacterium fortuitum associated with electromyography (EMG) is described. During a 6-week period, six patients who received EMG at one facility developed soft-tissue infections manifested by slowly expanding suppurative nodules at sites of needle electrode insertion. M. fortuitum was isolated from five patients; four isolates that were evaluated further were M. fortuitum biovariant fortuitum. EMG procedures were done in one laboratory by one physician and assistant. Standard procedures included use of reusable needle electrodes disinfected with 2% glutaraldehyde and then rinsed with tap water. On recognition of the outbreak, the procedure was changed to include autoclaving of needle electrodes. Active surveillance for 1 year revealed no further cases. M. fortuitum could not be isolated from the laboratory, EMG equipment and reagents, or skin of the medical personnel. The outbreak demonstrates that nontuberculous mycobacterial infection may be associated with EMG.

Adult↗
PubMed2001

Selectivity and sensitivity of intramuscular and transcutaneous electromyography electrodes.

We evaluated the differences in selectivity and sensitivity of intramuscular fine-wire electrodes and transcutaneous electrodes in detecting dynamic electromyography (EMG) signals from extensor digitorum (EDC) and extensor carpi radialis (ECR) muscles during isolated EDC and ECR contractions in two able-bodied subjects. Intramuscular fine-wire electrodes differentiated EDC and ECR EMG activities better than transcutaneous electrodes, and intramuscular fine-wire electrodes recorded higher amplitude signals than transcutaneous electrodes. Data suggest that intramuscular fine-wire electrodes are more selective and sensitive than transcutaneous electrodes in detecting EMG signals from adjacent forearm muscles.

Electric Stimulation↗
PubMed1996

Applications of electromyography in the throwing shoulder.

In the complex movement that makes up the baseball pitch, shoulder motion is a single link in an orderly chain of events. It can be argued, though, that herein lies the weakest link and by far the most commonly affected cog in the spectrum of overuse injuries in pitchers. Just why the shoulder receives the brunt of the stress has been the subject of numerous studies in the past several years. The tools of choice in many of these articles have been electromyography and high speed photography which have enabled researchers to study dynamically the phases of the pitch and the sequential firing of the muscles involved. With this information and the knowledge gained from studies looking at muscle activity during specific exercises, the clinician should be able to tailor a rehabilitation program that meets the needs of his or her patient. What has been learned from these articles as applied to the biomechanics of the pitch and the rehabilitation of the athlete who throws and the limitations of this form of study need to be clarified.

Biomechanical Phenomena↗
PubMed2001

Surface electromyography for noninvasive characterization of muscle.

Surface electromyography for noninvasive characterization of muscle. Exerc. Sport Sci. Rev., Vol. 29, No. 1, pp 20-25, 2001. Linear electrode arrays are used for noninvasive muscle characterization to study individual motor unit properties and the myoelectric manifestations of muscle fatigue during sustained contractions. The location of an electrode pair with respect to the innervation zone(s), the deterministic rather than stochastic nature of the signal, and the possibility of noninvasive fiber typing are discussed.

Electrodes↗
PubMed1998

Facial nerve electromyography and other cranial nerve monitoring.

Cranial nerves can be damaged during a variety of surgical procedures. The function of the cranial nerves can be monitored during surgery with electromyography (EMG), compound nerve and muscle action potentials (MAP), and auditory evoked potentials (AEP). We report important technical considerations that allow reliable recordings of these modalities during surgery, the criteria for determining a significant change in these electrophysiologic measures of function, the application of these techniques to specific surgical procedures, and the data that support the utility of cranial nerve monitoring.

Cranial Nerve Injuries↗
PubMed2002

Intraoperative electromyography.

Intraoperative electromyography (EMG) provides useful diagnostic and prognostic information during spine and peripheral nerve surgeries. The basic techniques include free-running EMG, stimulus-triggered EMG, and intraoperative nerve conduction studies. These techniques can be used to monitor nerve roots during spine surgeries, the facial nerve during cerebellopontine angle surgeries, and peripheral nerves during brachial plexus exploration and repair. However, there are a number of technical limitations that can cause false-positive or false-negative results, and these must be recognized and avoided when possible. The author reviews these basic electrophysiologic techniques, how they are applied to specific surgical situations, and their limitations.

Cranial Nerve Injuries↗
PubMed2000

Electromyography monitoring for percutaneous placement of iliosacral screws.

OBJECTIVE: To report our experience with the use of continuous electromyography (EMG) for placement of iliosacral screws. DATA SOURCES: Concurrently acquired data as well as patient charts, intraoperative EMG records, x-rays, and pelvic computed tomography (CT) scans. DESIGN: The monitored group of twenty-nine patients was studied prospectively. The control group consisted of twenty-two patients studied retrospectively. SETTING: Level One trauma center. METHODS: Continuous electromyograms were recorded for twenty-nine patients and compared with those from a group of twenty-two antecedent patients who were not monitored. The primary parameter of interest of this study was the presence or absence of neurologic change after iliosacral screw placement. This information was obtained prospectively in the study group and by retrospective review in the historical control. RESULTS: Four patients in the control group had postoperative and/or sensory motor changes prompting a postoperative CT scan; in each of these patients, a misdirected screw was identified and subsequently removed in a second procedure. There were no neurologic changes subsequent to placement in the twenty-nine patients who were monitored (7.5 percent versus 0 percent; p = 0.029, Fisher's exact test). All monitored patients had postoperative CT scans and showed the screw in a safe position with no significant violations of the S1 tunnel. CONCLUSION: Continuous EMG monitoring during iliosacral screw placement may be a useful neuroprotective tool.

Adolescent↗
PubMed2001

Near-infrared spectroscopy versus compartment pressure for the diagnosis of lower extremity compartmental syndrome using electromyography-determined measurements of neuromuscular function.

BACKGROUND: Compartmental syndrome (CS) is difficult to diagnose in intensive care unit patients. Compartment perfusion pressure (CPP) is an invasive, indirect measure of ischemia. Near-infrared spectroscopy is noninvasive, and directly measures ischemia by transmitting light through tissues at wavelengths that react with hemoglobin to provide percent tissue oxygen saturation (Sto(2)). Animal studies demonstrate that Sto(2) is superior to CPP for detecting CS. However, there are no studies in humans comparing Sto(2) with CPP. We hypothesized that Sto(2) can reliably detect CS, and is superior to CPP. METHODS: CS was induced in 15 human volunteers using a standard calf compression model. At 30-minute intervals, compression was increased to reduce Sto(2) from baseline (86% +/- 4%) to 60%, 40%, 20%, and < 10%, with simultaneous recording of CPP. Outcome variables included deep peroneal nerve conduction assessed by electromyography, cutaneous peroneal nerve sensitivity using Semmes-Weinstein monofilaments, and pain (visual analog scale). RESULTS: Both Sto(2) and CPP significantly correlated with all ischemia outcome variables (p < 0.001). Receiver operating characteristic curves of deep peroneal nerve conduction demonstrated that Sto(2) had higher sensitivity than CPP for detecting > 50% block. For example, when specificity was 83% for Sto(2) and 84% for CPP, sensitivity was 85% versus 56%, respectively (p = 0.02). When specificity for both was 72%, sensitivity was 94% for Sto(2) versus 76% for CPP (p = 0.04). CONCLUSION: In intensive care unit patients who cannot alert physicians to symptoms, near-infrared spectroscopy may help clinicians to avoid delayed or unnecessary prophylactic fasciotomy, and provides the benefits of a continuous, noninvasive monitoring technique.

Adolescent↗
PubMed1999

Comparison of Abshaper and conventionally performed abdominal exercises using surface electromyography.

PURPOSE: Many commercially available pieces of abdominal exercise equipment have been introduced to facilitate endurance training of the abdominal musculature. One of the latest devices is the Abshaper. The aim of this study was to investigate whether there is any difference between abdominal exercises performed while using the Abshaper compared with those performed conventionally. METHODS: Using surface electromyography (EMG), the upper and lower regions of rectus abdominis (RA), the external oblique (EO), and sternocleidomastoid (SCM) muscles of 22 first-year physical therapy students were assessed. Each participant performed five straight trunk curls and five side trunk curls both with the Abshaper and conventionally. To test for differences in relative peak and mean EMG activity between the two modes of exercise execution, paired t-tests (alpha = 0.05) were performed. Differences in the average time percentile at which peak EMG activity occurred were assessed by repeated measures ANOVA (alpha = 0.05). RESULTS: Exercises performed while using the Abshaper resulted in significantly greater relative peak and mean EMG activity within the upper portion of RA. For both the lower portion of RA and the EO muscles, no differences were found between the two modes of exercise execution. For SCM, Abshaper exercises resulted in significantly lower relative peak and mean EMG activity. In respect to the timing of peak EMG activity, no difference was found between the two modes of exercise execution for either the upper portion of RA, the EO, or SCM muscles. For lower RA, peak EMG activity occurred significantly earlier during conventional abdominal exercises in comparison with those performed while using the Abshaper. CONCLUSIONS: The Abshaper has a role in exercising the abdominal musculature.

Abdominal Muscles↗
PubMed2002

Perceived exertion, electromyography, and blood lactate during acute bouts of resistance exercise.

PURPOSE: This study examined ratings of perceived exertion (RPE) during resistance exercise in women. In addition, changes in blood lactic acid and biceps muscle activity assessed using electromyography (EMG) were investigated as potential mediators of RPE during resistance exercise. METHODS: Twenty female volunteers (age, 25 +/- 4 yr) performed one set of biceps curl exercise at 30%, 60%, and 90% of their one-repetition maximum (1-RM). Total work was held constant by varying the number of repetitions during each of the three intensities. The three intensities were performed in random order. RPE responses were assessed for both the active muscle (RPE-AM) and the overall body (RPE-O) following each intensity. EMG data were collected from the biceps brachii muscle during each intensity. Blood samples were taken before and following the intensities and analyzed for blood lactic acid concentration. RESULTS: A two-factor repeated-measures ANOVA showed a significant RPE (region) x intensity interaction (P < 0.02). Both RPE-AM and RPE-O increased as the intensity of exercise increased. EMG activity increased significantly (P < 0.01) as the intensity of exercise increased. A two-factor repeated measures ANOVA performed on the blood lactate data showed a significant (P < 0.04) time x intensity interaction. Postexercise [Hla] was significantly greater (P < 0.01) at 90% 1-RM than at 30% 1-RM. No significant differences were found in [Hla] between 30% and 60% 1-RM, or between 60% and 90% 1-RM. CONCLUSION: These results indicate that monitoring RPE may be a useful technique for regulating resistance exercise intensity. Moreover, blood lactate and activity of the involved muscle may mediate the relation between RPE and resistance exercise intensity.

Adult↗
PubMed1994

A noninvasive functional evaluation following peripheral nerve repair with electromyography in a rat model.

A new bipolar surface electrode array was designed and constructed for a noninvasive "closed" functional evaluation with electromyography following sciatic nerve transection in a rat model. This "closed" method was compared with a conventional one-shot "open" measurement. Nerve conduction velocity and distal latency were calculated. Data obtained from the recordings from different animals as well as from the same animal at different points in time yielded excellent reproducibilities. There is no difference in the mean values whether nerve conduction velocity and distal latency are obtained by "closed" or "open" measurements. Correlation was significant (p < 0.01; rNCV = 0.77, rDL = 0.63) between these two methods. The results lead to the conclusion that the noninvasive functional evaluation with the parameters of nerve conduction velocity and distal latency introduced in the present study could be employed as a reliable method for serial functional evaluations following nerve transection in a long-term study in a rat model.

Animals↗
PubMed2000

The role of corpus cavernosum electromyography.

Although corpus cavernosum electromyography presents great theoretical appeal as a possible direct clinical measure of penile neurogenic function, it has still not been adopted as a routine diagnostic test in the evaluation of patients with erectile dysfunction. This is because of the considerable technical and interpretative problems associated with the method. This review covers some of the more important research and clinical papers published since its first description in 1989, with a special focus on recent advances in this field.

Animals↗
PubMed2004

Quantitative electromyography of the anal sphincter after uncomplicated vaginal delivery.

OBJECTIVE: Fecal incontinence in women is thought to be associated with sphincter laceration or pudendal nerve damage. A prolonged pudendal nerve terminal motor latency is evidence of profound nerve damage, but pudendal nerve terminal motor latency can be normal even when nerve injury has been sustained. We performed quantitative electromyography (EMG) to compare multiple motor unit action potential parameters between recently postpartum women and nulliparous women. METHODS: Standardized examinations were prospectively performed on 2 groups: 1) healthy nulliparous women without pelvic floor disorders (n = 28) and 2) asymptomatic women who were postpartum following vaginal delivery of their first child (n = 23). The examinations included pelvic organ prolapse quantification measurements, endoanal ultrasonography, pudendal nerve terminal motor latency, sacral reflexes, and concentric needle EMG using multiple motor unit action potential analysis. RESULTS: A mean of 11.5 (standard deviation [sd] 1.1) weeks had elapsed since first vaginal deliveries in the postpartum group. The mean fetal weight at delivery was 3,495 (sd 458) grams. There were no sphincter defects seen by ultrasonography. Compared with the nulliparous women, pudendal nerve terminal motor latency and sacral reflexes (clitoral-anal reflex, urethral-anal reflex) were not increased in the postpartum group. Each of the quantitative parameters (duration, amplitude, area, turns, and phases), measured from motor unit action potentials in the postpartum group, were larger than in the nulliparous group (P < or =.004, nested analysis of variance [ANOVA]). CONCLUSION: Quantitative EMG using multiple motor unit action potential analysis can detect the presence after vaginal childbirth of subtle nerve injury not demonstrable by pudendal nerve terminal motor latency. Even asymptomatic women show evidence of pelvic floor nerve injury after uncomplicated deliveries.

Action Potentials↗