Nasal Muscle Research Articles

Striated muscle fiber crossings of the head and neck: a histological study using near-term human fetuses and elderly cadavers.

Striated muscle fiber crossings at almost right angle are known to exist in the face, soft palate, pharyngeal wall and tongue. We aimed to identify a specific interface tissue at the crossing. We observed histological sections from 22 half-heads of 12 near-term fetuses at 26-40 weeks (crown-rump length, 215-334 mm). For comparison, we also observed tongue frontal sections from 5 elderly cadavers (75-85 years old). At the angle of mouth as well as in the soft palate and pharyngeal wall, a solitary striated muscle fiber (e.g., levator) consistently crossed a fiber bundle of the antagonist muscle (e.g., depressor), but a solitary-to-solitary fiber interdigitation was unlikely with the antagonist muscle. Near the external nasal orifice as well as in the tongue intrinsic muscle layer, at every section, there was a crossing with an endomysium-to-endomysium contact: the nasalis and platysma muscles and; the vertical and transverse (or inferior longitudinal) tongue muscles. Therein, the functional vectors crossed at almost right angle. Also in adult tongue, the vertical and transverse muscle fibers sometimes (0-2 sites per section) crossed with an endomysium-to-endomysium contact. At the muscle crossing with an endomysium contact, the endomysium and basement membrane seemed to receive a friction stress between two muscles. Although some crossings might disappear due to high muscle activity after birth, not a few of them were likely to maintain. To minimize the mechanical stress, a minute nervous control of the timing, duration and strength of muscle contraction seemed to be necessary.

Electrophysiological Insights: Using Repetitive Nerve Stimulation to Monitor Clinical Status and Remission in Myasthenia Gravis

ABSTRACT Objective: Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disorder with a variable course that complicates the prediction of remission. This study aimed to evaluate the utility of repetitive nerve stimulation (RNS) in monitoring clinical status through the assessment of decremental response rates in the nasalis and trapezius muscles during treatment. Subjects and Methods: A prospective study was conducted with 52 patients diagnosed with generalized MG. Patients underwent clinical assessments, including tests for anti-acetylcholine receptor and anti-muscle-specific kinase antibodies, and were classified according to the Myasthenia Gravis Foundation of America classification. Electrophysiological testing through RNS and single-fiber electromyography was performed. Data analysis involved comparing the RNS decrement rates with clinical and demographic variables. Follow-up for assessing remission spans 2 years. Results: Among the 52 patients, 53.8% achieved clinical remission. In the remission group, 14.3% of the patients exhibited a decremental response compared with 70.8% in the nonremission group, particularly in the nasalis and trapezius muscles, in the follow-up RNS conducted 2 years after the initial assessment (P < 0.05). The remission group presented significantly lower rates of antibody positivity and less bulbar involvement. Interestingly, initial clinical severity did not correlate significantly with remission. Conclusion: This study demonstrated the usefulness of RNS in assessing the clinical status of MG patients and evaluating the effectiveness of current therapeutic strategies. These findings suggest that focusing on specific muscle responses in RNS can provide valuable information for patient management.

From masks to muscles: Mapping facial structure of Nycticebus.

Facial musculature in mammals underlies mastication and nonverbal communicative facial displays. Our understanding of primate facial expression comes primarily from haplorrhines (monkeys and apes), while our understanding of strepsirrhine (lemurs and lorises) facial expression remains incomplete. We examined the facial muscles of six specimens from three Nycticebus species (Nycticebus coucang, Nycticebus javanicus, and Nycticebus menagensis) using traditional dissection methodology and novel three-dimensional facial scanning to produce a detailed facial muscle map, and compared these results to another nocturnal strepsirrhine genus, the greater bushbaby (Otolemur spp.). We observed 19 muscles with no differences among Nycticebus specimens. A total of 17 muscles were observed in both Nycticebus and Otolemur, with little difference in attachment and function but some difference in directionality of movement. In the oral region, we note the presence of the depressor anguli oris, which has been reported in other primate species but is absent in Otolemur. The remaining muscle is a previously undescribed constrictor nasalis muscle located on the lateral nasal alar region, likely responsible for constriction of the nares. We propose this newly described muscle may relate to vomeronasal organ functioning and the importance of the use of nasal musculature in olfactory communication. We discuss how this combined methodology enabled imaging of small complex muscles. We further discuss how the facial anatomy of Nycticebus spp. relates to their unique physiology and behavioral ecology.

Insertions of the striated muscles in the skin and mucosa: a histological study of fetuses and cadavers.

Striated muscle insertions into the skin and mucosa are present in the head, neck, and pelvic floor. We reexamined the histology of these tissues to elucidate their role in transmission of the force. We examined histological sections of 25 human fetuses (gestational ages of ~11-19 weeks and ~26-40 weeks) and 6 cadavers of elderly individuals. Facial muscle insertion or terminal almost always formed as an interdigitation with another muscle or as a circular arrangement in which muscle fiber insertions were sandwiched and mechanically supported by other muscle fibers (like an in-series muscle). Our examination of the face revealed some limited exceptions in which muscle fibers that approached the dermis were always in the nasalis and mentalis muscles, and often in the levator labii superioris alaeque nasi muscle. The buccinator muscle was consistently inserted into the basement membrane of the oral mucosa. Parts of the uvulae muscle in the soft palate and of the intrinsic vertical muscle of the tongue were likely to direct toward the mucosa. In contrast, the pelvic floor did not contain striated muscle fibers that were directed toward the skin or mucosa. Although 'cutaneous muscle' is a common term, the actual insertion of a muscle into the skin or mucosa seemed to be very rare. Instead, superficial muscle insertion often consisted of interdigitated muscle bundles that had different functional vectors. In this case, the terminal of one muscle bundle was sandwiched and fixed mechanically by other bundles.

Advanced Injection of Botulinum Toxin in the Nasal Muscles: A Novel Dynamic Change in Facial Expression.

Among the nasal muscles, the levator labii superior alaeque nasi (LLSAN) acts as a transitional muscle that conjugates with other nasal and perinasal muscles. Thus, when treating the nasal region with Botulinum toxin (BTX), it is important to understand local nasal muscular dynamics and how they can influence the muscular dynamics of the entire face. This is a retrospective analysis of cases treated by an injection pattern encompassing the face, including nasal muscles. Photographs were taken at rest and during motion (frontal and oblique views), before and after treatment. A total of 227 patients have been treated in the last 18months with the following results: eyebrow tail lifting, softness of crow's feet, improvement of the drooping of the tip of the nose, and shortening of the lip philtrum when smiling. We present cases illustrating the use of this approach. Treating the facial muscles globally (including the frontal, corrugators, procerus, orbicularis oculi, platysma, DAO, and nasal muscles) can improve the smile and facial expressions. This is believed to occur because the elevated portion of the upper lip muscle becomes stronger as the nasal part of the LLSAN is paralyzed. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Unveiling Myasthenia Gravis: A Comprehensive Analysis of Diagnostic Tools and Clinical Insights

Objective: This research offers a comprehensive analysis of Myasthenia Gravis (MG), uncovering the remarkable accuracy of spinal accessory, ulnar, and facial nerve repetitive nerve stimulation (RNS), along with the precision of single fiber electromyography (SF-EMG) in MG diagnosis. We also embark on an exploration of clinical features and autoantibody test results in generalized MG patients.
 Methods: In this prospective study, we welcomed 31 individuals definitively diagnosed with generalized MG into our quest. The categorization of patients was conducted in accordance with the criteria set by the Myasthenia Gravis Foundation of America (MGFA). We examined patients' trapezius, nasalis, and abductor digiti minimi (ADM) muscles using RNS. We meticulously recorded the presence of MG autoantibodies, clinical subtypes based on affected muscle groups, and SF-EMG jitter rates.
 Results: The mean age of the 31 patients of whom 19 (61.3%) were male, was 64 ± 13.9 years. Among them, 20 showed positivity in the Anti-AChR antibody test. In 28 patients, accounting for 90.3% of the study group, single fiber electromyography (EMG) displayed increased jitter. There were 4 (12.9%), 24 (77.4%) and 12 (38.7%) patients featuring a decremental response of exceeding 10% in ADM, trapezius and nasalis muscles, respectivelyOur investigation revealed notable findings, such as the absence of substantial correlations between decremental response rates and age, gender, duration of complaints, antibody test results, thymus abnormalities, affected muscle types, familial history, or increased jitter rates in SF-EMG (p>0.05).
 Conclusion: As our findings clearly show, we can confidently attest to the remarkable sensitivity of RNS in MG diagnosis when muscle selection is precise. A gem discovered on our study is the high sensitivity of the spinal accessory nerve, a revelation that should guide the course of routine RNS studies, particularly for those facing ocular-onset myasthenia.

Nasal muscle function using electromyography (EMG) and nerve conduction velocity (NCV) in sub- and supra-perichondrial rhinoplasty

Nasal muscle function using electromyography (EMG) and nerve conduction velocity (NCV) in sub- and supra-perichondrial rhinoplasty

Association between Serum Varicella-Zoster Virus IgM and IgG and Prognosis of Ramsay Hunt Syndrome.

Ramsay Hunt syndrome (RHS) has a poor prognosis because of varicella-zoster virus (VZV) infection. This is most closely related to severe inflammation in the geniculate ganglion of the facial nerve due to VZV infection or reactivation. This study investigated whether there were differences in the prognosis and accompanying symptoms of facial paralysis based on the presence or absence of VZV IgM and IgG antibodies. This study was conducted as a retrospective chart analysis of 105 patients with RHS who were admitted to our hospital between 2015 and 2021. The House-Brackmann (HB) grade and electroneurography (ENoG) was used to evaluate the degree of facial paralysis. Patients' subjective symptoms were evaluated by dividing them into dizziness, tinnitus, hyperacusis, and hearing loss. No difference was observed in the initial HB grade with or without IgM; however, the final HB grade was significantly higher in IgM-positive patients than in IgM-negative patients (p < 0.05). Further, when IgM was positive, the value of the orbicularis oculi muscle in the ENoG test results was significantly higher (p < 0.05), and symptoms of tinnitus and hyperacusis occurred more frequently (p < 0.05). The initial and final HB grades were significantly higher in IgG-positive patients than in IgG-negative patients (p < 0.05). When IgG was positive, the values of nasalis and oris muscles in the ENoG test results were significantly higher (p < 0.05), and symptoms of dizziness occurred more frequently (p < 0.05). This study confirmed that the more active the immunological action of the VZV in the body, the greater the damage to the facial and vestibulocochlear nerves, which are associated with the degree of facial paralysis and the accompanying otologic symptoms.

Comparison of 3 Grading Systems (House-Brackmann, Sunnybrook, Sydney) for the Assessment of Facial Nerve Paralysis and Prediction of Neural Recovery.

Currently, multiple classification systems exist for the assessment of facial nerve paralysis. This study was designed to choose the most practical system for use in a clinical setting depending on the clinician need. We compared the responsiveness of the 3 facial nerve grading systems, i.e., House-Brackmann, Sydney, and Sunnybrook, as the subjective method and compared the outcomes with the objective method, i.e., the nerve conduction study. The correlation between the subjective and objective assessments was determined. A total of 22 consented participants with facial palsy was assessed with photos and videography recordings where they performed 10 standard facial expressions. The severity of facial paralysis was evaluated with the House-Brackmann, Sydney, and Sunnybrook grading scales subjectively and with the facial nerve conduction study objectively. The assessments were repeated after 3 months. A Wilcoxon signed-rank test showed that there were statistically significant change in all three gradings after 3-month of assessment. The responsiveness of the nerve conduction study was significant for the nasalis and orbicularis oris muscles. It was not significant for the orbicularis oculi muscle. The nasalis and orbicularis oculi showed statistically significant correlation with the three classification systems except for the orbicularis oculi muscle. All three grading systems, House-Brackmann, Sydney, and Sunnybrook, showed statistically significant responsiveness after 3 months of evaluation. The nasalis and orbicularis oculi muscle can be used to predict facial palsy recovery because they showed strong positive and negative correlations with the extent of facial nerve degeneration from the nerve conduction study.

Myomodulation Using Botulinum Toxin in Septorhinoplasty for Crooked Noses: Introducing the Concept and Application of Nasal Muscle Imbalance Theory.

The role of septorhinoplasty for adequate correction of deviated nose is well documented, but the rationales and patterns for recurrences after proper rhinoplasty remain unclear. There has also been little attention given to the influence of nasal musculatures on the stability of nasal structures after septorhinoplasty. The aim of this article is to propose our nasal muscle imbalance theory, which may explain the potential reason for redeviation of the noses in the initial period after septorhinoplasty. We postulate that in a chronically deviated nose, the nasal muscles on the convex side will be stretched and develop hypertrophy after prolonged period of increased contractile activity. On the contrary, the nasal muscles on the concave side will undergo atrophy due to reduced load requirement. In the initial period of recovery after a septorhinoplasty to bring the nose back to midline, this muscle imbalance is still uncorrected with unequal pulling forces on the nasal structure because the stronger nasal muscles on the previously convex side is still hypertrophied and exert stronger forces compared with the previously concave side, therefore increasing the risk of redeviation of the nose back to the preoperative side until muscle atrophy occurs in the convex side and a balanced nasal muscle pull is achieved. We believe that postseptorhinoplasty botulinum toxin injections can be used as an adjunct in rhinoplasty surgery to effectively block the pulling actions of the stronger or overacting nasal muscles by speeding up the atrophy process while allowing patient's nose to heal and stabilize in the desired position. However, further studies to objectively confirm this hypothesis is required, which include comparing topographic measurements, imaging and electromyography signals before and after injections in postseptorhinoplasty patients. The authors have already planned a multicenter study to further evaluate this theory.

Assessment of Nerve Conduction in Patients With Lower Motor Neuron Facial Paralysis.

Introduction Bell's palsy (BP), a lower motor neuron facial paralysis, commonly causes dysfunction of muscles of facial expression. Nerve conduction electrodiagnostic studies differentiate early-stage minor conduction blocks from later-stage Wallerian degeneration. Nerve conduction studies (NCSs) assess facial nerve function by delivering supramaximal electrical stimulus at the stylomastoid foramen. The amplitude loss percentage of the affected side is calculated with reference to the normal side. Aim The study's aim was to characterize the ncs in BP cases and to evaluate the correlation between the Compound Muscle Action Potential (CMAP) of the muscles affected. Materials and methods One hundred and four NCS data of BP cases were retrospectively collected over the period of two years. Statistical analyses of variables were done using the Chi-square test, one-way ANOVA, and Pearson correlation coefficient. Result The greater amplitude loss was seen in the orbicularis oris muscle innervated by buccal and mandibular branches of the facial nerve. The bivariate correlation between the Right Nasalis versus Right Orbicularis Oculi and Left Orbicularis Oculi versus Left Nasalis showed a highly significant moderately Strong Positive Correlation with an R-value of 0.687 and 0.558, respectively. The amplitude drop percentage was statistically significant in the affected left and right sides with P values of 0.008 and 0.007 respectively (P value < 0.05). The amplitude drop between the nasalis, orbicularis oculi and orbicularis oris muscles of both sides was statistically significant with a P value of 0.001. Conclusion NCS should be mandatorily included as an assessment protocol in BP cases for quantification of nerve degeneration and as a prognostic tool during the course of treatment.

Decreased initial compound muscle action potential amplitudes in myasthenia gravis

Objective We aimed to investigate the hypothesis that amplitudes of compound muscle action potential (CMAP) elicited by single stimulation decrease by baseline neuromuscular blocking in myasthenia gravis (MG), and to examine correlation of CMAP amplitudes with baseline muscle weakness. Methods One hundred ninety-four consecutive patients who underwent repetitive 3 Hz nerve stimulation tests (RNST) at our laboratory were included in the study. Of these, 109 patients were diagnosed as suffering from MG, and the remaining 85 with other disease served as the non-MG controls. RNST was performed on the nasalis, trapezius, and abductor digiti minimi (ADM) muscles. CMAP amplitudes elicited by the first stimulation were compared between the two groups. In MG patients, we studied the correlation of CMAP amplitudes with MG Foundation of America (MGFA) class, total scores of manual muscle testing (MMT), and 4th decrement (%) of RNST. Results Compound muscle action potential amplitudes in MG were significantly lower than in controls (p < 0.05 in all muscles tested). Decreases in CMAP amplitudes were more prominent in generalized than in ocular MG (p < 0.05), and in patients with MGFA III–V classes than in those with 0–II (p < 0.01 in the trapezius and ADM). CMAP amplitudes partially correlated with total MMT scores and MG-ADL scale scores. Additionally, CMAP amplitudes elicited by the first stimulation correlated with the 4th decrement of RNST (p < 0.01 in all muscles tested). Conclusion Compound muscle action potential amplitudes are reduced in MG, presumably by baseline neuromuscular transmission block, and could reflect persistent muscle weakness, rather than fatigue, in MG patients.

Ciliary Muscle Dimension Changes With Accommodation Vary in Myopia and Emmetropia.

PurposeThe purpose of this study was to determine whether accommodation-induced changes in ciliary muscle dimensions vary between emmetropes and myopes, and the effect of the image analysis method.MethodsSeventy adults aged 18 to 27 years consisted of 25 people with emmetropia (spherical equivalent refraction [SER] +0.21 ± 0.36 diopters [D]) and 45 people with myopia (−2.84 ± 1.72 D). There were 23 people with low myopia (>−3 D) and 22 people with moderate myopia (−3 to −6 D). Right eye ciliary muscles were imaged (Visante OCT; Carl Zeiss Meditec) at 0 D and 6 D demands. Measures included ciliary muscle length (CML), ciliary muscle curved length (CMLarc), maximum ciliary muscle thickness (CMTmax), CMT1, CMT2, and CMT3 (fixed distances 1–3 mm from the scleral spur), CM25, CM50, and CM75 (proportional distances 25%–75%). Linear mixed model analysis determined effects of refractive groups, race, and demand on dimensions. Significance was set at P < 0.05.ResultsMyopic eyes had greater CML and CMLarc nasally than emmetropic eyes. Myopic eyes had thicker muscles than emmetropic eyes at nasal positions, except CM25 and CMT3, and at CM75 temporally. During accommodation and only nasally, CML reduced in emmetropic and myopic eyes, and CMLarc reduced in myopic eyes only. During accommodation, both nasally and temporally, muscles thickened anteriorly (CMT1 and CM25) and thinned posteriorly (CMT3 and CM75) except for temporal CM75. Moderate myopic eyes had greater temporal CMLarc than low myopic eyes, and the moderate myopes had thicker muscles both nasally and temporally using fixed and proportional distances.ConclusionsPeople with myopia had longer and thicker ciliary muscles than people with emmetropia. During accommodation, the anterior muscle thickened and the curved nasal muscle length shortened, more in myopic than in emmetropic eyes. The fixed distance method is recommended for repeat measures in the same individual. The proportional distance method is recommended for comparisons between refractive groups.

ELECTROPHYSIOLOGIC PATTERN OF FACIAL MUSCLE INVOLVEMENT IN BELL'S PALSY

Introduction: Idiopathic Bell's Palsy is the commonest cause of Facial nerve palsy accounting for 45% to 71% of all causes of Facial Palsy. Electrophysiological evaluation comprises of Nerve conduction studies(NCS), Blink response and Electromyography(EMG) Methods: This was a prospective cross-sectional study done among 50 consecutive patients with Bell's Palsy who were evaluated and diagnosed within 1 week after onset of symptoms. Patients with facial palsy with a normal MRI and normal hematological and biochemical parameters were labelled as Bell's Palsy and were subjected to an NCS. Latency and CMAP recordings were obtained from Orbicularis Oculi, Nasalis and Orbicularis Oris. Results: Fifty patients were included in this study (27 male and 23 female). Most patients belonged to the age group of 41 - 60 years. One-Half(25) of the included patients had palsy of the Facial nerve on the right side and the others on the Left side. Forty-one(82%) of included patients had electrophysiological involvement of the orbicularis oculi as dened by a decrease in CMAP of more than 50% compared to the normal side. Similarly, 41(82%) patients had electrophysiological abnormality of the Nasalis muscle and 26(52%) patients had decreased CMAP of the Orbicularis Oris Muscle. The most frequent electrophysiologic pattern observed in this study in the rst week was involvement of all 3 muscles studied i.e., Orbicularis Oculi, Nasalis and Orbicularis Oris. Conclusion: In the rst week of illness, electrophysiological abnormality was most frequently seen in Orbicularis Oculi and Nasalis muscles. Follow-up electrophysiological studies are required to know the pattern of progression

Novel Anatomical Guidelines on Botulinum Neurotoxin Injection for Wrinkles in the Nose Region.

Botulinum neurotoxin injection surrounding the nose area is frequently used in aesthetic settings. However, there is a shortage of thorough anatomical understanding that makes it difficult to treat wrinkles in the nose area. In this study, the anatomical aspects concerning the injection of botulinum neurotoxin into the nasalis, procerus, and levator labii superioris alaeque muscles are assessed. In addition, the present knowledge on localizing the botulinum neurotoxin injection point from a newer anatomy study is assessed. It was observed that, for the line-associated muscles in the nose region, the injection point may be more precisely defined. The optimal injection sites are the nasalis, procerus, and levator labii superioris alaeque muscles, and the injection technique is advised. We advise the best possible injection sites in association with anatomical standards for commonly injected muscles to increase efficiency in the nose region by removing the wrinkles. Similarly, these suggestions support a more precise procedure.

Nose Reconstruction Using Bilobed Flap: A Case Report

This document illustrates the formatting process for authors, who would be preparing their papers for publication in the International Journal of Scientific Advances (IJSCIA). It behooves the prospective authors the skillset, scientific or scholarly acumen and wherewithal to ensure that their manuscript contents are original and have never been submitted to other journals while under review in the IJSCIA. Background: Basal cell carcinoma (BCC) is a slow-growing, locally destructive malignant skin tumor. The nasal location is considered a high-risk feature of BCC because of its anatomical features and problems in identifying the tumor preoperatively. Surgery is the cornerstone of nasal BCC treatment and various techniques have been developed to combine full 3D tumor removal with good aesthetic and functional results. Case Presentation: We report a circular black discoloration of a 64-year-old male patient on the left side of the nose within 2 years. The patient was scheduled for surgical removal and reconstruction of the defect using a bilobed flap. The flap consists of two lobes with a common semicircular base marked around the transverse portion of the nasalis muscle and its aponeurosis. The flap then removes the skin from the triangular peninsula at the base of the defect. After removal, the flap is moved into the defect and placed with 5-0 Prolene with a simple suture. Conclusion: The bilobed flap has multipurpose in all ways. The main benefit of this flap include the similarity color and texture relative to the defect site, ease of reproducibility, low complication rates, and the ability to design it in different sizes and tissue compositions.

1578 Advances in Facial Nerve Monitoring Parameters During Vestibular Schwannoma Surgery

Abstract Aim To evaluate the effectiveness of multi-channel electromyographic monitoring of the facial nerve in improving the detection of mechanically elicited EMG activity and providing new predictive criteria for post-operative facial nerve function. Method The Study was conducted on 20 patients undergoing vestibular schwannoma resection in a tertiary referral cerntre. All patients were subjected to facial nerve monitoring during the surgery by a 5-channel setup monitoring the frontalis, O.oculi, nasalis, O.oris, and mentalis muscle. Mechanically elicited EMG activities of the monitored facial muscles were recorded for analysis. After tumour removal, the facial nerve was stimulated proximal to the tumour site using two different types of probes: Prass and flush-tip. Post-operative facial nerve function was assessed using House-Brackmann scale immediately post-operatively and after six months and correlated to the study tested parameters. Results The use of 5-channel montage led to significantly higher sensitivity in detecting mechanically elicited EMG activity than would have been possible with the ordinary 2-channel one. Mentalis muscle showed significantly higher number and amplitude of spontaneous EMG activities than other facial muscles. Positive correlation was found between the proximal threshold and the post-operative facial nerve outcome. The Prass stimulator showed significantly lower threshold than the ball-tip probe. Conclusions The use of multi-channel facial nerve monitoring allowed earlier and more efficient monitoring of the facial nerve. The use of the Prass stimulator is more accurate and correlates more with the real threshold needed for post-resection stimulation of the facial nerve than the ball-tip.

Value of intraoperative monitoring of the trigeminal nerve in detection of a superiorly displaced facial nerve during surgery for large vestibular schwannomas.

The aim of this study was to investigate the role of trigeminal and facial nerve monitoring in the early identification of a superiorly (anterior and superior (AS)) displaced facial nerve. This prospective study included 24 patients operated for removal of large vestibular schwannomas (VS). The latencies of the electromyographic (EMG) events recorded from the trigeminal and facial nerve innervated muscles after mapping the superior surface of the tumor were analyzed. The mean latency of the recorded compound muscle action potential (CMAP) from the masseter muscle was 3.6 ± 0.5ms and of the peripherally transmitted responses by volume conduction from the frontalis, o. oculi, nasalis, o. oris, and mentalis muscles was 4.6 ± 0.9, 4.1 ± 0.7, 3.9 ± 0.4, 4.3 ± 0.8, and 4.5 ± 0.6ms, respectively, after trigeminal nerve stimulation in 24 (100%) patients (pattern I response). In 6 (25%) patients, the mean latency of CMAP on the masseter was 3.3 ± 0.3ms, and the latencies of the CMAP from the frontalis, o. oculi, nasalis, o. oris, and mentalis muscles were 6.5 ± 1.3, 5.0 ± 1.5, 7.5 ± 1.3, 7.4 ± 0.6, and 7.0 ± 1.5ms, respectively, longer than those of the peripherally transmitted responses (p = 0.002, p = 0.001, p < 0.001, and p = 0.015, respectively) indicating simultaneous stimulation of both nerves (pattern II response). All patients with this response were later confirmed to have an AS-displaced facial nerve. Recognizing the response resulting from simultaneous stimulation of both the facial and trigeminal nerves is important to help early identification of an AS-displaced facial nerve before it is visible in the surgical field and to avoid misleading information by confusing this pattern for a pure trigeminal nerve response.

Effects of diaphragmatic control on multiparametric analysis of the sniff nasal inspiratory pressure test and inspiratory muscle activity in healthy subjects.

BackgroundWe investigated the influence of diaphragmatic activation control (diaphC) on the relaxation rate, contractile properties and electrical activity of the inspiratory muscles of healthy subjects. Assessments were performed non-invasively using the sniff inspiratory pressure test (SNIP) and surface electromyography, respectively.MethodsTwenty-two subjects (10 men and 12 women) performed 10 sniff maneuvers in two different days: with and without diaphC instructions. For the SNIP test with diaphC, the subjects were instructed to perform intense activation of the diaphragm. The tests with the best SNIP values were used for analysis.ResultsThe maneuver with diaphC when compared to the maneuver without diaphC exhibited significant lower values for: SNIP (p <0.01), maximum relaxation rate (MRR) (p <0.01), maximum rate of pressure development (MRPD) (p <0.01), contraction times (CT) (p = 0.02) and electrical activity of the sternocleidomastoid (SCM) (p <0.01), scalene (SCL) (p = 0.01) and intercostal (CI) (p = 0.03) muscles. In addition, the decay constant (tau, τ) and relaxation time (½ RT) did not present any changes.ConclusionThe diaphragmatic control performed during the SNIP test influences the inspiratory pressure and the contractile properties of inspiratory muscles. This occurs due to changes in the pattern of muscle recruitment, which change force velocity characteristics of the test. Thus, instruction on diaphC should be encouraged for better performance of the SNIP test and for evaluation targeting the diaphragm muscle activity.

Electrophysiological studies in patients with seropositive/seronegative myasthenia gravis

Background: Myasthenia gravis (MG) affects the neuromuscular transmission, causing fluctuating muscle weakness and fatigue. This study is carried out with the aim to study the electrophysiologic findings of different subtypes of MG referred to our center in Tehran, Iran. Methods: All patients with MG presenting to neurology department of Shariati Hospital, Tehran University of Medical Sciences were enrolled. Clinically, patients with MG were categorized as ocular vs. generalized. The acetylcholine receptor (Ach-R) and muscle-specific receptor tyrosine kinase (anti-MuSK) antibodies were performed. Repetitive Nerve Stimulation (RNS) was performed using the standard method, with supramaximal stimulation of muscles at the 3 Hz frequency by surface electrode at rest. Abductor pollicis brevis (APB) (median nerve), anconeus (radial nerve), trapezius (accessory nerve), and nasalis (facial nerve) muscles were studied in all patients. Single fiber electromyography (SFEMG) was performed by standard method. Results: 196 seropositive patients with MG were included in the study. In electrophysiological studies, RNS was performed for 146 patients of Ach-R-Ab positive MG, with positive results in 110 patients. In addition, SFEMG was conducted for 8 patients with negative RNS, which resulted in 7 positive tests. Among 23 patients with anti-MuSK-positive MG, RNS was performed for 16 patients, with positive results in 11 patients. The 5 remaining patients with negative RNS test were studied by SFEMG, 4 of whom had positive results. APB compound muscle action potential (CMAP) decrementation significantly correlated with Ach-R-Ab positive MG (P < 0.03). Conclusion: This finding can support the hypothesis that the selection of muscles in electrodignostic study would be important. The electrodiagnostic studies are a good and non-invasive diagnostic tool for MG, and a combination of different distal, proximal, and facial muscles can increase the overall sensitivity of the test.