Surface vs intramuscular laryngeal electromyography

Surface Electromyography-Driven Therapeutic Gaming for Rehabilitation of Upper Extremity Weakness: A Pilot Study

SUMMARY

In patients with severe upper extremity weakness that may result from peripheral nerve injuries, stroke, and spinal cord injuries, standard therapy in the earliest stages of recovery consists primarily of passive rather than active exercises. Adherence to prescribed therapy may be poor, which may contribute to suboptimal functional outcomes. The authors have developed and integrated a custom surface electromyography device with a video game to create an interactive, biofeedback-based therapeutic gaming platform. Sensitivity of the authors' custom surface electromyography device was evaluated with simultaneous needle electromyography recordings. Testing of this therapeutic gaming platform was conducted with a single 30-minute gameplay session in 19 patients with a history of peripheral nerve injury, stroke, spinal cord injury, and direct upper extremity trauma, including 11 patients who had undergone nerve and/or tendon transfers. The device was highly sensitive in detecting low levels of voluntary muscle activation and was used with 10 distinct muscles of the arm, forearm, and hand. Nerve and tendon transfer patients successfully activated the donor nerve/muscle and elicited the desired movement to engage in gameplay. On surveys of acceptability and usability, patients felt the system was enjoyable, motivating, fun, and easy to use, and their hand therapists expressed similar enthusiasm. Surface electromyography-based therapeutic gaming is a promising approach to rehabilitation that warrants further development and investigation to examine its potential efficacy, not only for building muscle strength and endurance but also for facilitating motor relearning after nerve and tendon transfer surgical procedures.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Comparison of two electromyographical endotracheal tube systems for intraoperative recurrent laryngeal nerve monitoring: reliability and side effects

BACKGROUND

Recurrent laryngeal nerve (RLN) monitoring systems should be reliable and safe. Monitoring via electromyographical systems on an endotracheal tube (ETT) is widely spread. The MagStim™ system consists of an adhesive electrode to be fixed on an endotracheal tube. The Xomed™ endotracheal tube provides integrated electrodes. Reliability and side effects had never been compared. As both systems have very different morphological properties, we hypothesized that there might be differences in reliability and the incidence of side effects.

METHODS

In a retrospective quality management analysis of 118 patients (MagStim™ electrode, 57 patients; Xomed™ ETT, 61 patients), we compared laryngeal side effects according to the Chilla score and detection rate of the RLN.

RESULTS

Both systems had comparable detection rates of the RLN above 95%. Both electrode systems seemed to have similar reliability. Difficulties to detect the nerve were observed in seven patients (four with MagStim, three with Xomed). In the group with the Xomed™ ETT, significantly less mild laryngeal side effects were observed.

CONCLUSION

Both MagStim™ and Xomed™ ETT were reliable in detecting the RLN. The Xomed™ ETT, however, might cause milder laryngeal side effects compared with the MagStim™ electrode.

Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement

Intraoperative neural monitoring (IONM) during thyroid and parathyroid surgery has gained widespread acceptance as an adjunct to the gold standard of visual nerve identification. Despite the increasing use of IONM, review of the literature and clinical experience confirms there is little uniformity in application of and results from nerve monitoring across different centers. We provide a review of the literature and cumulative experience of the multidisciplinary International Neural Monitoring Study Group with IONM spanning nearly 15 years. The study group focused its initial work on formulation of standards in IONM as it relates to important areas: 1) standards of equipment setup/endotracheal tube placement and 2) standards of loss of signal evaluation/intraoperative problem-solving algorithm. The use of standardized methods and reporting will provide greater uniformity in application of IONM. In addition, this report clarifies the limitations of IONM and helps identify areas where additional research is necessary. This guideline is, at its forefront, quality driven; it is intended to improve the quality of neural monitoring, to translate the best available evidence into clinical practice to promote best practices. We hope this work will minimize inappropriate variations in monitoring rather than to dictate practice options.

A novel physiological investigation of the functional residual capacity by the bias flow nitrogen washout technique in infants

The dynamic functional residual capacity (FRC(dyn)), the lung volume most routinely measured in infants, is an unreliable volume landmark. In addition to the FRC(dyn), we measured the (passive) static FRC (FRC(st)) by inducing a brief post-hyperventilation apnea (PHA) in 33 healthy infants aged 7.4-127.2 weeks. A commercial system for nitrogen (N2) washout to measure FRC, and a custom made system to monitor and record flow and airway opening pressure signals in real-time were used in unison. Infants were manually hyperventilated to induce a PHA. After the last passive expiration, FRC(st) was estimated by measuring the volume of N2 expired after end-passive expiratory switching of the inspired gas from room air to 100% oxygen during the post-expiratory apneic pause. Repeatable intrasubject FRC(st) and FRC(dyn) measurements overlapped in most infants including the younger ones (P = 0.2839). Mean (95% confidence interval [CI]) FRC(st) was 21.1 (20.0-22.3), and error-corrected FRC(dyn) was 21.4 (20.4-22.4) ml/kg. Mean (washout time [t]) tFRC(st) was longer than tFRC(dyn) 60 sec (95% CI 55-65) versus 47 sec (95% CI 43-51) (P < 0.0001). The FRC and washout time were dependent on body length, weight and age. We conclude that the FRC(st) is not different from the FRC(dyn) in infants. The FRC(st) is a reliable volume landmark because the PHA stabilizes the end-expiratory level by potentially abolishing the sedated infant's breathing strategies. The FRC(st) lacks potential sources of errors and disadvantages associated with measuring the FRC(dyn). The findings cast significant doubt on the traditional physiology of air trapping in healthy infants' lungs.

Primingtechnik mit Cisatracurium

OBJECTIVE

Priming can significantly shorten the onset of nondepolarizing neuromuscular blocking agents (NNBA) measured at the adductor pollicis muscle (APM). In spite of the known risks, priming is very popular especially in cases where NNBAs with a long onset time are used. However, there are no data regarding the onset of action for a priming technique measured at the laryngeal muscles although these muscles are of great importance for conditions of intubation and patient safety. The aim of this study was to compare a bolus application and a priming technique with respect to the laryngeal onset time and peak effect.

PATIENT AND METHODS

After approval of the local ethics committee and written informed consent, 36 patients undergoing elective thyroid surgery were enrolled in the study. Anesthesia was induced and maintained with a target controlled infusion of propofol (target concentration 2.7-6.0 microg/ml) and infusion of remifentanil (0.25-0.75 microg/kgbw/min). After loss of consciousness, a tube with a surface electrode was placed into the trachea without the application of any neuromuscular blocking agent. Neuromuscular monitoring consisted of evoked electromyography (EMG) of the laryngeal adductor muscles via the surface electrode and evoked acceleromyography (TOF Guard) of the right adductor pollicis muscle (APM). After transcutaneous stimulation of the recurrent laryngeal nerve and ulnar nerve, either 0.9% NaCl followed by 0.1 mg/kgbw cisatracurium after 3 min (bolus group, n=12), a priming dose of 0.01 mg/kgbw cisatracurium followed by 0.09 mg/kgbw 3 min later (low dose priming group, n=12) or a priming dose of 0.015 mg/kgbw cisatracurium followed by cisatracurium 0.085 mg/kgbw 3 min later (high dose priming group, n=12) were injected. Lag time, onset time and peak effect of NMB were recorded and compared between the groups.

RESULTS

Demographic data, lag time and peak effect were comparable between the three groups. Onset time at the laryngeal muscles was significantly shorter in the high dose priming group (80+/-17 s), when compared to the low dose priming group (128+/-23 s) and bolus group (142+/-29 s). Onset time at the APM was also significantly shorter in the high dose priming group (154+/-35 s), when compared with the bolus group (226+/-76 s). The recovery of the neuromuscular function measured at the APM showed no differences between the groups.

CONCLUSION

Our results show that only high dose priming of cisatracurium can significantly shorten the laryngeal onset time. However, clinical routine use is not recommended due to possible side-effects.

Update on neuromuscular pharmacology

Since the introduction of d-tubocurarine into clinical practice, neuromuscular relaxants have been widely used in anaesthesia. Although their clinical use is easy, several points still require further attention and research. There is still a need for a drug with the clinical profile of succinylcholine but fewer unwanted side-effects. A better understanding of the effects of muscle relaxants on different muscles could help in their clinical use during the perioperative period. Much knowledge is needed about residual neuromuscular block and its detection in order to improve the quality of recovery from neuromuscular blockade. If some questions remain to be answered, several recent articles have increased our knowledge and should improve our clinical practice.

Brief review: Neuromuscular monitoring: an update for the clinician

PURPOSE

To review established techniques and to provide an update on new methods for clinical monitoring of neuromuscular function relevant to anesthesia.

SOURCE

A PubMed search of relevant article for the period 1985-2005 was undertaken, and bibliographies were scanned for additional sources.

PRINCIPAL FINDINGS

There is no substitute for objective neuromuscular monitoring; for research purposes, mechanomyography (MMG) is the gold standard; however, the most versatile method in the clinical setting is acceleromyography since it can be applied at various muscles and has a long track record of clinical utility. Kinemyography is valid to monitor recovery of neuromuscular transmission at the adductor pollicis muscle (AP), whereas phonomyography is easy to apply to various muscles and shows promising agreement with MMG. Monitoring of the corrugator supercilii muscle (CS) may be used to determine the earliest time for tracheal intubation as it reflects laryngeal relaxation better than monitoring at the AP. Recovery of neuromuscular transmission is best monitored at the AP, since it is the last muscle to recover from neuromuscular blockade (NMB). If train-of-four (TOF) stimulation is used, a TOF-ratio > 0.9 should be the target before awakening the patient. If surgery or the type of anesthesia necessitates NMB of a certain degree, e.g., TOF-ratio = 0.25, monitoring of muscles which best reflect the degree of NMB at the surgical site is preferable.

CONCLUSION

Objective methods should be used to monitor neuromuscular function in clinical anesthesia. Acceleromyography offers the best compromise with respect to ease of use, practicality, versatility, precision and applicability at various muscles. The CS is the optimal muscle to determine the earliest time for intubation, e.g., for rapid sequence induction.

An external monitoring site at the neck cannot be used to measure neuromuscular blockade of the larynx

Using phonomyography, a new monitoring technique of neuromuscular blockade (NMB), we compared NMB after mivacurium 0.1 mg/kg at the lateral cricoarytenoid muscle (LCA) with a possible external monitoring site of the larynx. In 12 patients, data were obtained at both sites using phonomyography. Anesthesia was induced with remifentanil 0.25-0.5 microg . kg(-1) . min(-1) followed by propofol 2-3 mg/kg. A small piezo-electric microphone was positioned beside the vocal cords into the muscular process at the base of the arytenoid cartilage to record acoustic signals from the contraction of the LCA. A second microphone was positioned at an external site, lateral to the trachea, just below the thyroid notch. The recurrent laryngeal nerve was stimulated supramaximally using train-of-four (TOF) stimulation every 12 s. Onset, maximum effect, and offset of NMB were measured and compared. Peak effect, time to reach (T) 25%, 75%, and 90% of control twitch response, and TOF recovery to TOF ratios 0.5-0.8 were significantly longer at the external site. The onset time was not significantly different between the two sites. We used phonomyography with a microphone placed at the neck to evaluate the possibility to externally monitor NMB at the larynx. When compared with LCA, we found a more pronounced peak effect and longer offset of NMB. The acoustic signals recorded at this external site are unlikely to stem from laryngeal muscle contraction but are rather a result of contraction of the strap muscles of the neck.

Neuromuscular blockade at the larynx, the diaphragm and the corrugator supercilii muscle: a review

PURPOSE

To review recent findings concerning neuromuscular blockade and monitoring at the larynx, the diaphragm, and the corrugator supercilii muscle.

SOURCE

This narrative review is based on recent publications.

PRINCIPAL FINDINGS

Neuromuscular blockade at the larynx and the diaphragm is less intense than at the adductor pollicis muscle; the onset and offset of neuromuscular blockade is more rapid. The corrugator supercilii muscle reflects better the time course of neuromuscular blockade of the larynx than the adductor pollicis muscle, is better suited to monitor the onset of neuromuscular blockade for intubation, and should give a better reflection of the time course and degree of neuromuscular blockade of the larynx or the diaphragm. Recovery of neuromuscular function at the end of any procedure is best reflected at the adductor pollicis muscle where neuromuscular transmission is last restored. Clinical monitoring of the larynx or the diaphragm is still limited by the absence of a simple method. Acceleromyography of the corrugator supercilii muscle is prone to artifacts that do not occur during monitoring of the adductor pollicis muscle. Phonomyography, a new method of monitoring that is currently being tested, is based on the phenomenon that muscle contraction creates low-frequency sound waves, which can be detected using special microphones to quantify neuromuscular blockade. This method seems promising because it can be easily used on all muscles of interest.

CONCLUSION

Research during the last 15 years has greatly enhanced our knowledge about how muscles react differently to muscle relaxants and has enabled us to achieve better surgical conditions with safer use of muscle relaxants. Interesting technologies have been developed to reliably monitor neuromuscular blockade at the larynx and the diaphragm, but are currently restricted to research settings. Our increased understanding should help us in ongoing efforts to develop the "ideal" muscle relaxant and the "ideal" method of neuromuscular monitoring.

Neuromuscular monitoring

This review summarizes recent reports on the techniques and the use of methods for monitoring neuromuscular function during anaesthesia. The latest news on the use of acceleromyography in the face and hand, on laryngeal and diaphragmal surface electromyography, on acoustic myography, on evaluation of intense neuromuscular block, and on postoperative residual curarization is presented and discussed. It is concluded that available evidence suggests that more attention should be paid by the anaesthetist to the problems of residual curarization and hence to proper monitoring of neuromuscular function using objective methods.

The lumbar paravertebral region provides a novel site to assess neuromuscular block at the diaphragm

PURPOSE

We evaluated a novel, paravertebral site for assessment of neuromuscular block at the diaphragm. The neuromuscular blocking effect of 0.1 mg x kg(-1) cisatracurium at the adducting laryngeal muscles, the diaphragm and the adductor pollicis (AP) were compared.

METHODS

In 24 patients undergoing thyroid surgery, evoked responses from the adducting laryngeal muscles and the AP muscle were obtained using surface electromyography (EMG). Skin electrodes were placed paravertebrally near T12/L1 or L1/L2 (novel position; n = 12) or conventionally (n = 12). After stimulation of the recurrent laryngeal, phrenic and ulnar nerves, the lag, onset time and maximum effect were measured (0.1 Hz, single twitch) as well as the time to reach 25% of T1/T0 (T 25%) using train-of-four stimulation every 20 sec.

RESULTS

A mean maximum block of more than 94% was reached at all sites. Lag, onset time and T 25% at the adducting laryngeal muscles and the diaphragm were significantly (P <0.005) shorter than at the AP muscle and did not differ significantly between the two diaphragmatic monitoring sites (conventional: 64 +/- 21 sec, 166 +/- 41 sec and 20 +/- 3 min vs novel: 60 +/- 16 sec, 161 +/- 40 sec and 22 +/- 2 min respectively).

CONCLUSION

Onset and duration of action of 0.1 mg x kg(-1) cisatracurium was shorter at the larynx and the diaphragm than at the AP muscle. EMG results obtained from the novel, paravertebral site did not differ from the conventional monitoring site at the seventh or eighth intercostal space and suggest this alternative site is appropriate for monitoring of the diaphragm.