喉返神经麻痹的肌电特点及相关研究

目的：研究喉返神经麻痹患者不同时间和损伤程度的喉肌电特点。方法：根据发病时间将87例喉返神经麻痹患者分为7组,分析其喉肌电特点,并与30例正常受试者进行对比研究。结果：①发病2周时,最早5d在受累甲杓肌、环杓后肌和环杓侧肌即可出现纤颤波和正锐波等失神经电位;2周-3个月失神经电位增多,可见再生电位;3个月后失神经电位渐少,再生电位渐多;36个月后失神经电位消失。②受累喉肌肌电募集减弱甚至无明显干扰相,干扰相波幅和转折数显著低于正常对照组,其中转折数减低更为明显,未受累喉肌募集电位明显增大。③部分患者受累喉肌诱发电位消失,其他患者可见波幅小、潜伏期长的诱发电位。结论：喉肌电图对于喉返神经麻痹的诊断和鉴别具有重要意义,失神经电位和再生电位特点与神经损伤的程度和时间相关,异常的诱发电位可提示神经损伤的程度。     

面瘫后口眼联带运动的肌电图研究及临床意义

目的探讨面瘫后口眼联带运动的电生理实质。方法对41例已有临床口眼联动现象的周围性面瘫患者做了肌电图检查,同心针电极放置在降口角肌内记录,嘱患者做眨眼和闭目动作,观察降口角肌肌电信号的变化,健、患侧对比分析,探讨联动现象的电生理实质。结果在做眨眼或闭目运动时,所有患者患侧降口角肌内均能记录到异常的联动电位,呈两种特征,闭目时为一种连续的、波幅较低的随意动作电位样的冲动,眨眼时表现为一种与眼睑运动同步的持续(30～350)毫秒的多相电位。在做健侧降口角肌检查时,发现8例患者肌电图异常,其中健侧有周围性面瘫病史的2例引出了异常联动电信号,另有6例引出了纤颤电位,这6例曾经历过健侧面部的针灸或小针刀治疗,其余健侧肌电图正常的33例健侧面部均无疾病、手术或有创治疗史。结论①面瘫后口眼联带运动的病理生理基础是神经错向再生,本应支配眼轮匝肌的面神经纤维与支配降口角肌的神经纤维产生了联系。②面部针灸、小针刀有可能损伤颅外段面神经分支或末梢。     

Evoked electromyographic test applied for recurrent laryngeal nerve paralysis

This study was performed to apply the evoked electromyographic (EMG) test to the larynx and to find out whether or not this test is useful for diagnosis of patients with recurrent laryngeal nerve paralysis. As a result, it was considered that the present test was useful for the following:

• 1 Diagnosis of the site of lesion: The decision is easily made whether the recurrent laryngeal nerve is damaged alone or together with the superior laryngeal nerve, and on the site of damages along the recurrent laryngeal nerve in some cases.
• 2 Determination of prognosis: The cases showing no evoked wave may not recover completely. For the cases showing an evoked wave, information on prognosis can be obtained from the degree of changes in latency and evoked wave form.
• 3 Indication of the state of nerve regeneration: The evoked EMG test is able to reveal the state of reinnervation of the paralyzed laryngeal nerve as well as and even earlier than the ordinary EMG test.

     

A new method for laryngeal electromyography

A new method of surface electromyography (EMG) is presented, for sampling the posterior crico-arytenoid, interarytenoid and crico-pharyngeal sphincter. The results obtained in normal volunteers are discussed and the indications for laryngeal electromyography (LEMG) outlined. It has the advantage of being non-invasive and safe, and can be done as an out-patient procedure with minimal discomfort to the patient, and unassociated complications. This has provided a new and fascinating field of investigation in neuromuscular disorders of the larynx. The same principles of surface EMG may also be applied to the muscles of the tongue, palate, pharynx … and surface EMG in the upper respiratory tract may become a valuable method of clinical investigation.     

Physiologic features of vocal fatigue: electromyographic spectral-compression in laryngeal muscles

OBJECTIVES: This study addresses the problem of defining observable attributes of "vocal fatigue" as a physiologic condition. The aim was to determine the applicability of electromyography (EMG) spectral compression in observing fatigue in laryngeal muscles arising from prolonged vocal effort. STUDY DESIGN: Single institution, nonrandomized, prospective analysis of subjects evaluated in an academic, tertiary care center. METHODS: In adapting EMG techniques, we report pretest observations that bear on the choice of voicing tasks serving to induce and estimate muscle fatigue and the selection of muscles that are particularly involved in effortful vocalization. On this basis, an experiment was designed where intramuscular EMG was used to record lateral cricoarytenoid potentials of seven subjects at regular intervals across a 12 to 14 hour period (50 samples per subject). Between each of these samples, the participants were required to produce loud speech for 3 minutes with peaks of 74 dBA at 1 meter. RESULTS: The results show fatigue-related spectral compression for all subjects and nonlinear changes across time indicating critical values beyond which fatigue is persistent. CONCLUSION: Spectral compression appears to present a robust attribute of fatigue-related changes in muscles involved in vocalization. There are several implications with respect to research on the prevention of acquired voice pathologies.     

Intraoperative laryngeal electromyographic assessment of patients with immobile vocal fold.

The differential diagnosis of laryngeal ankylosis versus paralysis is occasionally difficult in patients with immobile vocal folds. Eight patients with acute and chronic evidence of vocal fold immobility were investigated by intraoperative electromyography (IEMG) during planned microlaryngoscopy. Bipolar hook wire electrodes were inserted into the thyroarytenoid muscle, of which the electrical activity was monitored during neuromotor blockade and emergence from anesthesia. The normal side and the side with ankylosis or stenosis showed normal IEMG activity. There was progressive recruitment of larger motor units during recovery from muscle relaxation. Patients with laryngeal paralysis failed to show such recruitment patterns. Thus, IEMG can be used as a diagnostic tool during operative laryngoscopy to differentiate neuromotor injury from anatomic causes of vocal fold immobility. The advantages of IEMG are its ease of application and certainty of electrode position. It can also be used to monitor recurrent nerve integrity and detect early laryngospasm. Further IEMG clinical study is warranted.     

Mechanisms of synkinesis

When the facial nerve is injured, changes occur in muscle, proximal nerve, distal nerve, and the cell body in the nucleus. All of these changes contribute to the quality of regeneration and repair. This paper describes the usual processes of neuronal regeneration with the objective of a better understanding of why some injuries inevitably result in poor return of motion and synkinesis, while others recover completely. The possible mechanisms of synkinesis include: imperfect regeneration due to axonal misdirection, demyelination, microglial scarring in the facial nucleus, neuron depopulation, multiple axon sprouting, and misdirection of regenerating axons via vertical anastomotic filaments.     

An electromyographic study of recurrent laryngeal nerve conduction and its clinical applications

Electromyographic techniques were used to study laryngeal nerve conduction in dogs and in man. The data obtained confirmed that there is a 2–5 msec difference in latency between the left and right recurrent laryngeal nerve. Conduction velocities were determined by actual measurement in dogs and calculated from known anatomic data in humans. Conduction velocity in both species was the same bilaterally. The actual value varied, depending upon the site of stimulation. It is slower the more distal the stimulating cathode is placed. Proximal conduction velocity is approximately 65 M/sec. Distal conduction velocity approximately 30 M/sec. Study of bilateral activity indicated that the onset of electrical activity is simultaneous ± 5 msec. Following simultaneous bilateral vagus nerve stimulation there is a time lag of 3 msec, in the onset of electrical activity in the right and left recurrent laryngeal muscles. Since vocalization does not occur until 350–400 msec after onset of electrical activity in the laryngeal muscle, it is felt that, in comparison, 3 msec is an insignificant difference in symmetry. In addition phonation is a function of subglottic pressure and tension in the vocal cord and not muscular vibration; therefore, there is no physiologic reason for nerve impulses to arrive simultaneously in the adductor muscles. Electromyography and nerve conduction studies can lead to greater precision in diagnosis and treatment of laryngeal disorders. The study can be done with little or no morbidity and the equipment is easily available. It is recommended for studying patients with disorders of voice that could have a neurologic basis.     

Evoked electromyographic technique for quantitative assessment of the innervation status of laryngeal muscles

OBJECTIVES: The purpose of this study was to develop a minimally invasive, noninjurious evoked electromyographic technique that could accurately quantitate the level of innervation of laryngeal muscles with recurrent laryngeal nerve stimulation. METHODS: A four-phase study was conducted in 24 canines, including 1) identification of the best stimulation-recording configuration, 2) statistical analysis of sensitivity and accuracy, 3) evaluation of safety, and 4) identification of the laryngeal muscle(s) that contribute to the evoked response. RESULTS: The results demonstrated that an entirely noninvasive technique is not feasible. The stimulating cathode must be invasive to ensure discrete activation of the recurrent laryngeal nerve, whereas both recording electrodes should remain on the surface with one overlying the thyroid ala. This configuration proved to be highly accurate, with an error rate of only 6% to 7%, and with sensitivity sufficient to detect a signal in a nerve with fewer than 1% of the axons intact. There was no evidence of nerve injury in any animal over the course of 350 stimulus needle penetrations. By use of neuromuscular blockade to identify those muscles generating the surface response, the thyroarytenoid muscle was found to be the primary contributor, whereas the posterior cricoarytenoid muscle was uninvolved. CONCLUSIONS: This evoked electromyographic technique could provide quantitative information regarding the extent of muscle innervation during denervation and regeneration in case of laryngeal paralysis.     

Changes of extremity and laryngeal muscle electromyographic amplitudes after intravenous administration of vecuronium

Objectives: To compare electromyographic (EMG) amplitude changes in extremity and laryngeal muscles after vecuronium administration and study the effects of topical lidocaine on laryngeal EMG in a swine model. Study Design: Prospective animal study. Methods: Electrically evoked EMG activities were recorded from the vocalis muscles (directly and via an EMG endotracheal tube) and from the flexor digitorum muscles before and after intravenous vecuronium administration. EMG amplitudes were followed for 30 minutes after vecuronium injection together with monitoring of limb twitches to train‐of‐four stimulation. The testing was repeated after a 30‐minute wash‐out period and with topical lidocaine. Results: EMG amplitude recovery occurred sooner and more quickly in flexor digitorum muscle than in vocalis muscles. Reappearance of four twitches corresponded to EMG amplitude recovery to about 80% of the baseline in flexor digitorum muscles and to about half‐baseline size in vocalis muscles. EMG amplitudes were generally lower at the start of the second round testing than the first round, with somewhat slower recovery in vocalis muscles. Conclusions: In contrast to reports by others in human studies, extremity muscles seem to be more resistant to vecuronium at 0.1 mg/kg than laryngeal muscles in the swine. Reappearance of four twitches corresponds to 50% of laryngeal EMG recovery and indicates adequate condition for monitoring electrically evoked laryngeal EMG activities. This study is inconclusive regarding the effects of topically applied lidocaine on laryngeal EMG amplitudes. Translation of these data to humans should be done with caution.     

A new mouse laryngeal transplantation rejection grading system

Objectives/Hypothesis:

Development of a rat laryngeal transplantation model allowed for the first total human laryngeal transplantation by the senior author in 1998. In an effort to further our knowledge of the immune system's role in laryngeal rejection, a change to the mouse model was required. Prior to initiating immunosuppressive research protocols, a reliable mouse larynx rejection classification had to be established.

Study Design:

Animal study.

Methods:

Thirty‐one mouse laryngeal transplants (C57 BL/6 donors to C3H recipients) were performed and allowed to reject. Six time points were evaluated histologically: 1, 3, 5, 7, 9, and 15 days post‐transplant. Eight anatomic sites were evaluated and assigned a point value. A linear regression model was constructed using the group number as the response and the scores from the eight histological criteria as predictors. Severity classifications were determined by observing patterns in the sum of scores of variables found to be significant contributors. Group 1 was normal; group 2, minimal rejection; groups 3, 4, and 5, moderate rejection; and group 6, severe rejection.

Results:

All mice survived the transplants. Of the observed histological changes, cartilage, fat, muscle, and magnitude of lymphocytic infiltration significantly correlated with rejection severity. The rejection model created demonstrated 100% accuracy in predicting the severity classification for the 31 specimens in the study.

Conclusions:

The model established provides an accurate and reliable way to classify rejection severity in mice receiving laryngeal allografts. This sets the stage for future advanced study of manipulating the immune system as a mechanism for establishing allograft tolerance. Laryngoscope, 2010