Repetitive Nerve Stimulation Research Articles

What's in the Neuromuscular Junction Literature?

Four retrospective studies from the United States, Europe, and Asia address outcomes in juvenile myasthenia gravis. Common features include earlier onset with ocular myasthenia gravis (MG) and generally good outcomes overall. Patients who were seronegative, had equivocal acetylcholine receptor (AChR) antibodies, or had only clustered AChR antibodies had better outcomes. An article highlighting the utility of median nerve slow-repetitive stimulation is reviewed and another showing the high sensitivity of repetitive nerve stimulation in myasthenic crisis is covered. Two articles address the thymus and thymectomy in non-AChR antibody-positive autoimmune MG. Longer term data on eculizumab as well as studies of cyclophosphamide, rituximab, and tacrolimus are summarized. Other topics include the possible role of statins in MG and central nervous system autoimmune comorbidities.

Long-Term Safety and Usefulness of Mexiletine in a Large Cohort of Patients Affected by Non-dystrophic Myotonias.

Objective: The aim of our study was to evaluate the long-term efficacy and safety of mexiletine in 112 patients affected by genetically confirmed non-dystrophic myotonias. The study was performed at the Neurophysiologic Division of Fondazione Policlinico Universitario A. Gemelli Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), Rome and the Children's Hospital Bambino Gesù, Rome.Methods: The treatment was accepted by 59 patients according to clinical severity, individual needs, and concerns about a chronic medication. Forty-three patients were affected by recessive congenita myotonia, 11 by sodium channel myotonia, and five by dominant congenital myotonia. They underwent clinical examination before and after starting therapy, and Electromyography (EMG). A number of recessive myotonia patients underwent a protocol of repetitive nerve stimulations, for detecting and quantifying the transitory weakness, and a modified version of the Timed Up and Go test, to document and quantify the gait impairment.Results: Treatment duration ranged from 1 month to 20 years and the daily dosages in adults ranged between 200 and 600 mg. No patient developed cardiac arrhythmias causing drug discontinuation. Mexiletine was suspended in 13 cases (22%); in three patients, affected by Sodium Channel myotonia, because flecainide showed better efficacy; in one patient because of a gastric cancer antecedent treatment; in four patients because of untreatable dyspepsia; and five patients considered the treatment not necessary.Conclusions: In our experience, mexiletine is very useful and not expensive. We did not observe any hazarding cardiac arrhythmias. Dyspepsia was the most frequent dose-limiting side effect.

Office investigations for myasthenia gravis: comparative analysis

The purpose was to study the diagnostic yield of the various tests including lid fatigue test, Cogan twitch, Rest test, Ice test and Repetitive nerve stimulation (RNS) study in clinically diagnosed myasthenic patients. A prospective study of newly diagnosed myasthenic patients was done at tertiary eye - care centre. Totally, 58 patients underwent tests for the confirmation of myasthenia gravis. Fishers Exact test was used for comparative analysis. Average age of presentation was 44.13 years. Number of male and female were 33 (56.9%) and 25 (43.1%). 8 (13.8%) patients were under the age of 15 years. Variability was observed in 47/58 (81.04%) patients and Fatigue was seen in 40 /58(68.97%) patients. Cogan twitch was observed in 28/58(48.28%) patients. Sensitivity of Rest test was 50%. Sensitivity of Ice test was 72.4%. Ice test positivity was 90% (9/10) in mild, 75% (21/28) in moderate, 68.75% (11/16) in severe ptosis indicating that increasing severity decreases the sensitivity. Sensitivity of combined Rest test and ice test was 90 %. Sensitivity of RNS study was 90%. The difference between the RNS study and Ice test was not statistically significant (p- 0.583). However RNS study showed higher percentage of positivity. Ice test is more sensitive than rest test. Rest test and Ice test are simple, cost benefit bed side tests when combined, have sensitivity equivalent to RNS study. However RNS study is the gold standard confirmatory test.

Repetitive ocular vestibular evoked myogenic potentials in myasthenia gravis.

To validate the repetitive ocular vestibular evoked myogenic potentials (RoVEMP) test for diagnostic use in myasthenia gravis (MG) and to investigate its value in diagnostically challenging subgroups. The RoVEMP test was performed in 92 patients with MG, 22 healthy controls, 33 patients with a neuromuscular disease other than MG (neuromuscular controls), 4 patients with Lambert-Eaton myasthenic syndrome, and 2 patients with congenital myasthenic syndrome. Mean decrement was significantly higher in patients with MG (28.4% ± 32.2) than in healthy controls (3.2% ± 13.9; p < 0.001) or neuromuscular controls (3.8% ± 26.9; p < 0.001). With neuromuscular controls as reference, a cutoff of ≥14.3% resulted in a sensitivity of 67% and a specificity of 82%. The sensitivity of the RoVEMP test was 80% in ocular MG and 63% in generalized MG. The RoVEMP test was positive in 6 of 7 patients with seronegative MG (SNMG) with isolated ocular weakness. Of 10 patients with SNMG with negative repetitive nerve stimulation (RNS) results, 73% had an abnormal RoVEMP test. The magnitude of decrement was correlated with the time since the last intake of pyridostigmine (B = 5.40; p = 0.019). The RoVEMP test is a new neurophysiologic test that, in contrast to RNS and single-fiber EMG, is able to measure neuromuscular transmission of extraocular muscles, which are the most affected muscles in MG. Especially in diagnostically challenging patients with negative antibody tests, negative RNS results, and isolated ocular muscle weakness, the RoVEMP test has a clear added value in supporting the diagnosis of MG. This study provides Class III evidence that RoVEMP distinguishes MG from other neuromuscular diseases.

Can the Large-Scale Decrement in Repetitive Nerve Stimulation Be Used as an Exclusion Criterion for Amyotrophic Lateral Sclerosis?

Objective: The objectives of this work were to identify the characteristics of repetitive nerve stimulation (RNS) in patients with amyotrophic lateral sclerosis (ALS) and further verify the electrophysiological exclusion criteria of ALS.Methods: A total of 150 patients with ALS who were admitted to the Department of Neurology of Renmin Hospital of Wuhan University from January 2015 to December 2018 were enrolled. Clinical and electrophysiological data of the enrolled patients were collected. The differences in the amplitudes of the compound muscle action potential (CMAP) between the trapezius muscle (Trap) and the abductor digiti minimi (ADM) in low-frequency RNS were compared. Furthermore, we analyzed the associations between decremental responses and gender, onset age, duration of disease, onset site, Amyotrophic Lateral Sclerosis Functional Rating Scale—Revised (ALSFRS-R), disease progression rate, and CMAP amplitude.Results: A significant decrement (≥20%) in at least one muscle was observed in 11.3% of the ALS patients, while decrements (≥10%) in at least one muscle were observed in 41.3%. The decremental percentage in the trapezius muscle was significantly higher than that in the abductor digiti minimi (P < 0.001). The onset age, duration of disease, onset site, and disease progression rate did not affect decremental responses. The decremental responses in RNS were more significant in ALS patients with low ALSFRS-R scores (P = 0.01). Moreover, there was a positive linear correlation between the CMAP amplitude and the decremental percentage of Trap and ADM in ALS patients.Conclusions: CMAP decremental responses in RNS were common in ALS patients, suggesting abnormalities of neuromuscular junctions (NMJs). It is worthy of further discussion whether to consider a decrement >20% in RNS as a diagnostic exclusion criterion for ALS.

Utility of Repetitive Nerve Stimulation in Myopathies.

Investigators from the Mayo Clinic, Rochester, MN, evaluated 157 patients with confirmed myopathy who had electrodiagnostic studies done between January 2007 and May 2017.

Effects of repetitive transcranial magnetic stimulation versus transcutaneous electrical nerve stimulation to decrease diabetic neuropathic pain

Background/Aims Repetitive transcranial magnetic stimulation and transcutaneous electrical nerve stimulation have been studied repeatedly to reduce diabetic neuropathic pain. The objective of this study was to compare the effects of aerobic training plus one of the treatment therapies on decreasing pain severity in patients with diabetic peripheral neuropathy. Methods A total of 30 patients with diabetic peripheral neuropathy were randomly assigned into two equal groups: group A and group B. Both groups received aerobic training exercises. Group A received repetitive transcranial magnetic stimulation, and Group B received transcutaneous electrical nerve stimulation for 5 consecutive days in 1 week. Outcome measures included pain severity assessment using the Visual Analogue Scale and the serum β-endorphin levels. Results There was a non-significant difference in pre-treatment (P=0.061) and post-treatment (P=0.652) in the Visual Analogue Scale scores between groups. However, β-endorphin levels were significantly different between groups in post- (P=0.015) rather than pre-treatment (P=0.459) levels. A significant moderate correlation between β-endorphin levels and Visual Analogue Scale scores was found in group A (r=−0.6783) at (P=0.008), while it was not significant in group B (r=0.043) at (P=0.883). Conclusions Adding transcutaneous electrical nerve stimulation or repetitive transcranial magnetic stimulation therapies to aerobic training showed similar effects in reducing pain severity in patients with diabetic peripheral neuropathy.

Clinical and electrophysiological evaluation of myasthenic features in an alpha-dystroglycanopathy cohort (FKRP-predominant)

A postsynaptic dysfunction of the neuromuscular junction has been reported in patients with alpha-dystroglycanopathy associated with mutations in guanosine diphosphate (GDP)-mannose pyrophosphorylase B gene (GMPPB), some of whom benefit from symptomatic treatment. In this study, we determine the frequency of myasthenic and fatigue symptoms and neuromuscular junction transmission defects in a fukutin-related protein (FKRP)-predominant alpha-dystroglycanopathy cohort. Thirty-one patients with alpha-dystroglycanopathies due to mutations in FKRP (n = 25), GMPPB (n = 4), POMGNT1 (n = 1), and POMT2 (n = 1) completed a six-question modified questionnaire for myasthenic symptoms and the PROMIS Short Form v1.0-Fatigue 8a survey, and they underwent 3 Hz repetitive nerve stimulation of spinal accessory nerve-trapezius and radial nerve-anconeus pairs. Results showed that fatigue with activity was common; 63% of the cohort reported fatigue with chewing. A defective postsynaptic neuromuscular junction transmission was not identified in any of the patients carrying FKRP mutations but only in one mildly affected patient with GMPPB mutations (c.79 G>C, p.D27H and c.402+1G>A, splice site variant). We conclude that symptoms of fatigue with activity did not predict abnormal neuromuscular junction transmission on electrodiagnostic studies in this cohort and that, unlike GMPPB subgroup, a defective neuromuscular junction transmission does not appear to be present in patients with FKRP-associated muscular dystrophies.

Brody myopathy demonstrates a pseudo-increment on repetitive nerve stimulation.

Brody myopathy (BM) is a recessive condition caused by mutations in the ATP2A1 gene and usually induces impaired muscle relaxation during and after exercise. Diagnosis relies on needle electromyography showing electrical silence, muscle biopsy with decreased sarcoplasmic reticulum calcium adenosine triphosphatase activity, and genetic analysis. Electrodiagnostic functional analyses are useful in the diagnosis of channelopathies, and thus may be impaired in BM. We performed exercise tests and repetitive nerve stimulation (RNS; 10 supramaximal stimuli at 3 Hz) in 10 patients with BM. All participants showed incremental responses on RNS. Compound muscle action potential amplitude was increased and duration was decreased, especially in the ulnar nerve (+30.2 ± 7.1% and - 30.3 ± 2.8%, respectively; both P < .001). Easily accessible, this sign, referred to as the Arzel sign, could prove to be a very useful tool in BM diagnosis and in broadening its phenotype.

History of Myasthenia Gravis Revisited.

The first description of myasthenia gravis (MG) was given by Thomas Willis in 1672. MG was the focus of attention after mid-nineteenth century and a great amount of information has been accumulated in a span of 150 years. The aim of this review is to convey this information according to a particular systematic and to briefly relate the experience of Istanbul University. MG history was examined in four periods: 1868-1930, 1930-1960, 1960-1990, and 1990-2020. In the first period (1868-1930), all the clinical characteristics of MG were defined. Physiological/pharmacological studies on the transmission at the neuromuscular junction were initiated, and the concept of repetitive nerve stimulation emerged. A toxic agent was believed to be the cause of MG which appeared to resemble curare intoxication. Association of MG with thymus was noticed. No noteworthy progress was made in its treatment. In the second period (1930-1960), acetylcholine was discovered to be the transmitter at the neuromuscular junction. Repetitive nerve stimulation was used as a diagnostic test. The autoimmune nature of MG was suspected and experiments to this end started to give results. The hallmark of this period was the use of anticholinesterases and thymectomy in the treatment of MG. The third period (1960-1990) can probably be considered a revolutionary era for MG. Important immunological mechanisms (acetylcholine receptor isolation, discovery of anti-acetylcholine receptor antibodies) were clarified and the autoimmune nature of MG was demonstrated. Treatment modalities which completely changed the prognosis of MG, including positive pressure mechanic ventilation and corticosteroids as well as plasma exchange/IVIg and azathioprine, were put to use. In the fourth period (1990-2020), more immunological progress, including the discovery of anti-MuSK antibodies, was achieved. Videothoracoscopic thymectomy reduced the morbidity and mortality rate associated with surgery. New drugs emerged and clinical trials were performed. Valuable guidelines were published. In the last part of the review, the experience in MG of Istanbul University, a pioneer in Turkey, is related.

Noninvasive Ventilation in Myasthenia Gravis.

Myasthenic crisis (MC) is mainly managed by invasive ventilation (IV) which is associated with prolonged intubation and ventilation and respiratory complication. To report the characteristics of patients who can be managed by noninvasive ventilation (NIV) and also predictors of NIV in myasthenia gravis (MG). In a retrospective study at tertiary care hospital in India during 2013-2015, patients with MG were evaluated. MG was diagnosed by clinical, repetitive nerve stimulation, and acetylcholine receptor antibodies. Patients were intubated based on arterial blood gas criteria. Demographic variables, Myasthenia Gravis Foundation of America (MGFA) score, and clinical examination were done. NIV success was defined if patient did not need mechanical ventilation (MV) in the management or for 72 h after extubation and was considered unsuccessful if patients required MV during this period. Twenty three out of 68 MG patients had MC, 16 patients were given NIV, and 16 IV. Median intensive care unit stay was 18 (4-94) days. Predictors of crisis were infection, bulbar weakness, MGFA > 2b, and history of crisis. NIV was the only respiratory support in 7 patients and reintubation was prevented in 3 patients. NIV failed in 9 patients. Comparison of NIV success and failure did not reveal any difference. With NIV, intubation was prevented in 7 and reintubation in 3 patients. NIV has lower incidence of complications. NIV should be tried in patients with impending MC.

Respiratory Assessment of Myasthenia Gravis Patients Using Repetitive Nerve Stimulation of Phrenic and Intercostal Nerves.

We evaluated decremental response from phrenic and intercostal nerves using slow repetitive nerve stimulation test (RNST) to look for its diagnostic significance in sero-negative predominantly bulbar myasthenia gravis (MG) with normal peripheral or cranial nerve RNST. RNST from phrenic and intercostal nerves was performed along with standard RNST from abductor digiti minimi (ADM), trapezius, nasalis and orbicularis oculi muscles in 10 normal individuals (group I), 10 patients with neurological disorders other than MG (group II) and 10 patients with MG (group III). We evaluated the presence of positive response in first two groups (group I and II) and absence of negative response in group III. Spirometry was also performed in MG patients. Mean baseline decrement in I/C RNST in three groups was -2.06±1.33 %, -2.5±2.18% and -27.1±17.9 % respectively. One minute post exercise decrement in I/C RNST in three groups was -2.9±1.36%,-2.9±1.36% and -32.9±17.9% respectively. RNST of phrenic nerve showed mean baseline decrement of -2.1±2.3%, -3.2±2.6 % and -18.3±30.3% in three groups respectively. One minute post exercise decrement percentage were -2.2±1.18% in group I, -4.8±2.18% in group II and -29.2±19.2% in group III. RNST of peripheral nerves were negative in two patients who were bulbar sero-negative MG, however, significant decrement was seen in intercostal and phrenic nerve RNST. Intercostal and phrenic nerve RNST are a better test for assessing respiratory involvement specially in patients presenting with bulbar symptoms and having negative RNST of peripheral nerves.

Occurrence of Guillain-Barr\xe9 syndrome and Myasthenia Gravis in an elderly male

IntroductionThe occurrence of both Guillain-Barré syndrome(GBS) and myasthenia gravis (MG) in the same individual is rare. The underlying pathophysiology was assumed to be autoimmune humoral mechanisms and molecular mimicry with a cross-reaction between autoantibodies and myelin sheath of peripheral nerves and acetylcholine receptors of the neuromuscular junction (NMJ).Case descriptionA 68-year-old male known diabetic and hypertensive with good drug compliance presented with acute onset quadriparesis with bulbar involvement for 1 day. On examination, he had mild neck flexion weakness and bulbar weakness. He had flaccid quadriparesis with absent deep tendon reflexes and negative Babinski. The rest of the neurological examination was normal.Discussion and evaluationBlood and electrophysiological studies showed evidence of demyelinating polyradiculoneuropathy with temporal dispersion suggestive of Guillain-Barré syndrome. He was treated with intravenous immunoglobin and complete resolution of symptoms. Two months later, he presented with new-onset asymmetrical ptosis and bulbar symptoms for 3 days. On further evaluation, repetitive nerve stimulation showed postsynaptic neuromuscular disorder pattern typical of myasthenia gravis, which was further confirmed by positive acetylcholinesterase receptor antibodies (AChR). Thymoma was ruled out by imaging. He was treated with anticholinesterases, low dose steroids, and immunosuppressants (azathioprine) following which he had improvement of symptoms.ConclusionOur patient, who was initially diagnosed with Guillain-Barré syndrome and recovered, presented 2 months later with a new-onset illness suggestive of myasthenia gravis. This existence of two different neurological entities in the same individual is a rarity, and early recognition is essential for treatment decision and prognostic strategies.

Paediatric myasthenia gravis: Prognostic factors for drug free remission

Our aim was to identify clinical outcomes, serological features and possible prognostic indicators of paediatric myasthenia gravis (MG). We collected 74 MG patients with disease onset before the age of 16 years (73% pre-pubertal onset defined as ≤10 years), seen regularly at two UK specialist centres, over a period of 11 years. The cohort was multi-ethnic, with a high number of non-Caucasians (52%). Ocular presentation was seen in 38 (51%) and only 8 (21%) of these generalised. Fifty-two (70%) patients had antibodies to the acetylcholine receptor (AChR) measured by radioimmunoprecipitation, 10 (14%) had antibodies only to clustered AChRs detected by a cell based assay, 3 (4%) had muscle-specific kinase and one (1%) low-density lipoprotein receptor-related protein 4 antibody. Only 8 (11%) had no detectable antibodies. Seventeen patients attained drug free remission (Kaplan Meyer survival curve estimates 25% by 7 years). Several factors were associated with a higher likelihood of free remission: onset age ≤10 years, Asian and Caucasian races, lack of AChR antibodies on RIA, and normal repetitive nerve stimulation at diagnosis. However, in a multifactorial regression analysis, the antibody status was the only significant predictor for drug free remission, with 60% of patients with antibodies only to clustered AChR achieving this outcome. Complete drug free remission is not uncommon in paediatric MG and several factors appear to influence this outcome with antibody status being the most important. These factors can be easily evaluated at diagnosis, and may help to determine whose patients are likely to require more intensive treatments.

NCMP-02. MYASTHENIA GRAVIS INDUCED BY AVELUMAB

Abstract Monoclonal antibodies targeting PD- 1 (nivolumab and pembrolizumab) and PD-L1 (avelumab, atezolizumab, and durvalumab) are FDA approved for the treatment of metastatic cancers. Immune-related adverse events (irAEs) are autoimmune diseases which occur following treatment with PD-1 and PD-L1 inhibitors. Neurological irAEs following PD-L1 blockade are rarely reported, and mainly consist of Myasthenia Gravis (MG) and myositis. MG induced by avelumab has not been previously reported. We present a 74-year-old female with stage IV ovarian adenocarcinoma who entered a clinical trial involving avelumab and entinostat after disease progression following extensive resection, chemotherapy with doxorubicin, then docetaxol and cisplatin. She developed progressive generalized weakness and fatigue two months after entering the trial, leading to respiratory weakness and hypoventilation, and resulting in intubation and mechanical ventilation. Exam showed head-drop, diplopia, and proximal &gt; distal upper and lower limb weakness. Antibodies to acetylcholine receptors, muscle specific tyrosine kinase, and voltage-gated calcium channels (P/Q and N type) were negative, and serum creatine kinase was normal. Repetitive nerve stimulation showed significant decrement in the left spinal accessory nerve motor response with recording at trapezius. She was diagnosed with seronegative MG and was treated with IVIG, 2 grams/kg divided over 4 days, prednisone 60 mg daily, and pyridostigmine, which resulted in successful extubation, followed by gradual resolution of MG symptoms over a period of 3 months. At approximately 2 year follow-up, she remains on maintenance IVIG at 0.5 grams/kg every 3 weeks, as she develops proximal lower limb and neck extension weakness at the end of each IVIG cycle. We conclude that MG is a potentially life threatening but treatable irAE associated with avelumab. Our case also adds to the accumulating literature of the role of PD-1 signaling in the pathogenesis of autoimmune diseases of the muscles and neuromuscular junctions.

Distribution characteristics and correlation analysis of antibody detection value in myasthenia gravis

Objective: To determine the factors affecting distribution and magnitude of antibody detection value in myasthenia gravis (MG). Methods: A total of 406 MG patients diagnosed at Department of Neurology, Peking University First Hospital from May 2015 to November 2017 were included.All of them exhibited muscle fatigue with decreased response in repetitive nerve stimulation test. There were 200 males and 206 females whose ages ranged from 2 to 85 years old. According to clinical classification of MG recommended by Myasthenia Gravis Foundation of America (MGFA), patients assigned to class I to class V included 200,140, 46, 15 and 5 cases, respectively. There were 33 cases of thymic hyperplasia and 63 cases of thymoma confirmed by radiological or pathological findings. Quantile plots and quantile regression model were used to determine the effects of age, gender and MGFA classification, thymus disease on acetylcholine receptors (AChR)antibody, acetylcholinesterase (AChE) antibody, Titin antibody, ryanodine receptor (RyR) antibody and muscle-specific tyrosine kinase (MuSK) antibody detection values detected by enzyme-linked immunosorbent assay (ELISA). Results: MGFA classification had effects on distribution of AChR antibody level. There was a positive correlation between age and AChR antibody level(P<0.05). Negative correlation was found between age and AChE, Titin and RyR antibody level (P<0.05). No significant correlation was shown between any factors and MuSK antibody level(P≥0.05). MGFA classification had a positive correlation with AChR antibody level (P<0.05) and no correlation with other antibody levels (P>0.05). Gender and thymus disease had no correlation with any tested antibody levels (P>0.05). Conclusion: MGFA classification has significant effects on distribution of AChR antibody level. Age and MGFA classification have positive correlation with AChR antibody level.

Consideration of repetitive nerve stimulation of the median nerve in patients being evaluated for myasthenia gravis.

Repetitive nerve stimulation (RNS) of the median nerve is rarely studied in myasthenia gravis (MG). We performed a retrospective analysis of RNS studies performed on 448 patients at our center between 2010 and 2016. Among 95 patients with MG, an abnormal decrement of the compound muscle action potential amplitude was seen in 40.7% of median, 38.4% of spinal accessory, and 57.1% of facial nerve RNS studies. Median nerve RNS was abnormal in 10 patients with normal spinal accessory and 5 patients with normal facial nerve RNS. MG patients with abnormal median nerve RNS were more likely to be seropositive and have limb weakness. No differences were observed in the incidence of abnormal median nerve RNS in patients with and without a median neuropathy at the wrist. Median nerve RNS is easy to perform, reproducible, and should be considered in the electrodiagnostic evaluation of MG.

Concomitant synaptic impairment of neuromuscular junction and axonal polyneuropathies

Peripheral axonal neuropathy (PAN) is a progressive axonopathy marked by loss of motor, sensory and autonomic fibers with reduced stability of neuromuscular transmission. In a previous work in demyelinating neuropathies, we showed that repetitive nerve stimulation (RNS) induced significant decremental responses in amplitude and area of muscle action potentials (CMAPs). In this work we studied prospectively, 111 diagnosed patients (clinically and electrophysiologically) with PAN, by performing RNS to assess the degree of weakened synaptic transmission at the NMJ and find out whether it is one of the aspects of PAN. Males constituted 61 patients while females are 50 with a mean age of 56 years. Nerve conduction study (NCS) and Electromyogram (EMG) revealed that patients with sensorimotor axonal neuropathy (n75), motor (n28) and the least (n8) were those with pure axonal sensory neuropathy. RNS of both axillary, musculocutaneous and Left Ulnar nerves, showed 87%, 80% and 28% decrements in amplitude and 91%, 84% and 43% in area for axillary, musculocutaneous and Left Ulnar nerves, respectively in 85 patients. This would suggest lower safety factors in neuromuscular transmission. The proximal nerves were significantly more sensitive in revealing the deficit than the distal ulnar nerve. The highly significant decrements of CMAPs in this study, could be attributed to disorders of peripheral nerves at the presynaptic level, induced by axonal loss. This leads to deficient exocytosis of Acetylcholine at the NMJ. Hence, this lack of availability of neurotransmitter would not be secure enough to stimulate the nicotinic postsynaptic receptors.

A rare case of musk myasthenia gravis in a HIV patient

Autoimmune disorders have been frequently described in HIV patients but there has been little research on the association between HIV and myasthenia gravis. MuSK myasthenia gravis coexisting with HIV is an even rarer entity. 50 years old lady with HIV and baseline CD4 count of 170, on antiretroviral therapy from 1.5 years, presented with complaints of difficulty swallowing, change in voice and intermittent double vision since 10 months. There was a history of fluctuations. On examination she had bilateral mild lateral gaze palsy with mild asymmetric bifacial weakness. Her gag reflex was weak on both sides. Her CD4 count done 6 months back had increased to 477 and her MRI brain was normal. Myasthenia gravis was strongly suspected. Repetitive Nerve Stimulation showed a decremental response in bilateral median innervated muscles. Her MuSK antibody was positive and Ach receptor antibody was negative, which confirmed the diagnosis of MuSK myasthenia gravis. There was improvement with addition of pyridostigmine and she was later discharged on Pyridostigmine, Prednisolone and Azathioprine. On follow up, the patient is showing sustained improvement. Autoimmune disorders are being increasingly reported with HIV infection since the advent of HAART. MuSK myasthenia gravis with HIV has been reported in very few case reports. The use of immunosuppressants in the treatment of these conditions should be carefully evaluated.

MYASTHENIA GRAVIS LAMBERT EATON OVERLAP SYNDROME AFTER ROCURONIUM ADMINISTRATION

SESSION TITLE: Tuesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM INTRODUCTION: Myasthenia Gravis Lambert Eaton Overlap Syndrome (MLOS) is a rare and debated entity with less than 50 cases reported to our knowledge. We present a case of MLOS that surfaced after receiving a neuromuscular blocking agent for rapid sequence induction and intubation (RSII). CASE PRESENTATION: 72 year old female with a history of chronic right foot drop was admitted with acute cholecystitis. Rocuronium was used for RSII. Cholecystectomy had no intraoperative complications. Two days after the procedure the patient was found to be lethargic, dysphonic complaining of diffuse musculoskeletal weakness, dysphagia, and dyspnea at rest. Vital signs were stable. Neurological exam showed oculo-bulbar weakness with dry mucus membranes. Lower extremity strength was 1/5 and upper extremity strength was 3/5 bilaterally. Deep tendon reflexes were absent. Sensation was diffusely intact. MRI brain, spine and lumbar puncture were negative. CXR showed normal lung parenchyma with bilateral elevated hemidiaphragms. Vital capacity and maximal inspiratory pressures were significant for weak respiratory muscle function with MIP -35cmH20 and vital capacity of 1L. She was started on positive pressure non-invasive ventilation to reduce the work of breathing. Pending lab results returned positive for AchR antibodies. Furthermore, EMG studies showed chronic denervation and repetitive nerve stimulation revealed pronounced facilitation of 75%. Pyridostigmine and IVIG therapy was initiated. Voltage gated calcium channel antibodies sent after treatment returned negative. Pan-CT was negative for malignancy. After two weeks of therapy, her respiratory muscle function improved, speech and swallow returned to baseline, and muscle strength mildly improved. DISCUSSION: There is controversy as to whether Myasthenia Gravis and Lambert Eaton can occur at the same time. Our patient had impressive oculo-bulbar weakness, AchR antibodies, followed by a good therapeutic response to pyridostigmine to support the diagnosis of Myasthenia Gravis. Whereas, the extreme fatigue, autonomic symptoms, and proximal muscle weakness primarily in the lower extremities along with the pronounced facilitation on EMG supported the diagnosis of Lambert Eaton syndrome. Furthermore, competitive neuromuscular blocking agents, like Rocuronium, are known to have a prolonged effect in patients with neuromuscular junction diseases such as Lambert Eaton and Myasthenia Gravis. The administration of Rocuronium in this patient was the inciting factor that led to her underlying diagnosis of MLOS. Therefore, this is a unique case that demonstrates the co-existence of these two neuromuscular disorders. CONCLUSIONS: It may be beneficial to avoid neuromuscular blocking agents for RSII in patients with a history of underlying neurological or musculoskeletal disorder as literature has shown that these agents can exacerbate the disease process. Reference #1: Jia R, Chen J, Ge R, Zeng Q, Chen F, Zhao Z. Coexistence Of Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome in a small cell lung cancer patient. Medicine. 2018. 97(23): 1-5. Reference #2: Shin, O. Myasthenia Gravis Lambert Eaton Overlap Syndrome. Muscle Nerve. 2016. 53:20-26. DISCLOSURES: No relevant relationships by Jagadish Akella, source=Web Response No relevant relationships by Theresa Henson, source=Web Response No relevant relationships by Santosh Kale, source=Web Response No relevant relationships by Sarah Malik, source=Web Response No relevant relationships by Elyana Matayeva, source=Web Response No relevant relationships by Asmat Ullah, source=Web Response