Treatment of myasthenia gravis: focus on pyridostigmine

Beyond Motor Neurons in Spinal Muscular Atrophy: A Focus on Neuromuscular Junction

5q-Spinal muscular atrophy (5q-SMA) is one of the most common neuromuscular diseases due to homozygous mutations in the SMN1 gene. This leads to a loss of function of the SMN1 gene, which in the end determines lower motor neuron degeneration. Since the generation of the first mouse models of SMA neuropathology, a complex degenerative involvement of the neuromuscular junction and peripheral axons of motor nerves, alongside lower motor neurons, has been described. The involvement of the neuromuscular junction in determining disease symptoms offers a possible parallel therapeutic target. This narrative review aims at providing an overview of the current knowledge about the pathogenesis and significance of neuromuscular junction dysfunction in SMA, circulating biomarkers, outcome measures and available or developing therapeutic approaches.

Acetylcholinesterase inhibitors are ineffective in MuSK-antibody positive myasthenia gravis: Results of a study on 202 patients

BACKGROUND

Myasthenia gravis (MG) with MuSK antibodies (MuSK-MG) represents a distinct subtype with different responses to treatments compared to patients with AChR antibodies, especially in terms of tolerance to acetylcholinesterase inhibitors (AChEI). However, AChEI are often used as first line symptomatic treatment in MuSK-MG, despite reports that they are poorly tolerated, seldom effective or even deleterious.

METHODS

We analyzed demographic, clinical and therapeutic responses and side-effects in the large cohort of 202 MuSK-MG patients cared for at the MG Clinic of Azienda Ospedaliero-Universitaria Pisana.

RESULTS

165 patients had received AChEI at first evaluation. Only 7/165 patients (4.2%) reported an initial clinical benefit. Conversely, 76.9% of patients reported at least one side effect, most commonly neuromuscular hyperexcitability (68.4%), gastrointestinal (53.9%) and neurovegetative (35.8%) disturbances. 56 (33.9%) patients reported a concomitant worsening of muscle weakness and twelve patients (7.3%) suffered a cholinergic crisis. According to these patients, the severity of cholinergic side effects was greater at higher doses of AChEI, but side effects occurred regardless of the dose administered and ceased once the drug was discontinued.

CONCLUSIONS

This is the largest population of MuSK-MG patients reported for perceived responsiveness and tolerance to AChEI treatment. Our obervations strongly suggest avoiding this treatment in MuSK-MG.

[Myasthenia Gravis - Update]

Myasthenia gravis - still a challenge for sufferers and doctors in 2023. But which therapy is best suited? Our clinically experienced experts have summarized the current guidelines for diagnosis and treatment in order to provide optimal support for those affected. Find out how you can carry out a quick and targeted diagnosis and which treatment options are available to alleviate the course of the disease.

Potentially inappropriate drug use in myasthenia gravis: a real-world population-based cohort study in Italy

Introduction

To evaluate the use of pyridostigmine in presence of contraindications, and the use of concomitant potentially contraindicated drugs in a cohort of patients affected by Myasthenia Gravis (MG) in the Italian Regions of Lazio, Tuscany, and Umbria.

Methods

This is a retrospective cohort study. A multivariate logistic regression model was used to evaluate the determinants of pyridostigmine and of potentially contraindicated drugs use in MG patients.

Results

Among 591 incident pyridostigmine users affected by MG, 91 (15.4%) had at least one of the contraindications considered at the first prescription of pyridostigmine. Patients prescribed with pyridostigmine in presence of contraindications were more frequently affected by diabetes, obesity, and renal diseases. Age 75+ years (odds ratio, OR 4.94, 95% confidence interval, CI 1.60-15.22 for Latium; OR 3.78, 95%CI: 1.26-11.34 for Tuscany; OR 5.83, 95%CI 1.19-28.52 for Umbria), the presence of at least one specific comorbidity (OR 3.93; 95%CI 1.68-9.17 for Latium), and polytherapy (6+ drugs, OR 4.90, 95%CI: 1.35-17.85 for Tuscany) were found to be significantly associated with pyridostigmine use in presence of contraindications. Among patients affected by MG, 1,483 (62.6%) were treated with potentially contraindicated drugs in the first year of follow-up (67.06.9% in Latium; 59% in Tuscany; 57.6% in Umbria). Patients aged 75+ years, those with at least one specific complication or comorbidity, and those exposed to polytherapy were more likely to be treated with a potential contraindicated drug.

Conclusion

Among incident users of pyridostigmine, more than 15% of patients have at least one of the contraindications considered, and among patients diagnosed with MG, in the first year of follow-up >60% of subjects were treated with potentially contraindicated drugs.

Enhanced low-threshold motor unit capacity during endurance tasks in patients with spinal muscular atrophy using pyridostigmine

OBJECTIVE

To investigate the electrophysiological basis of pyridostigmine enhancement of endurance performance documented earlier in patients with spinal muscular atrophy (SMA).

METHODS

We recorded surface electromyography (sEMG) in four upper extremity muscles of 31 patients with SMA types 2 and 3 performing endurance shuttle tests (EST) and maximal voluntary contraction (MVC) measurements during a randomized, double blind, cross-over, phase II trial. Linear mixed effect models (LMM) were used to assess the effect of pyridostigmine on (i) time courses of median frequencies and of root mean square (RMS) amplitudes of sEMG signals and (ii) maximal RMS amplitudes during MVC measurements. These sEMG changes over time indicate levels of peripheral muscle fatigue and recruitment of new motor units, respectively.

RESULTS

In comparison to a placebo, patients with SMA using pyridostigmine had fourfold smaller decreases in frequency and twofold smaller increases in amplitudes of sEMG signals in some muscles, recorded during ESTs (p < 0.05). We found no effect of pyridostigmine on MVC RMS amplitudes.

CONCLUSIONS

sEMG parameters indicate enhanced low-threshold (LT) motor unit (MU) function in upper-extremity muscles of patients with SMA treated with pyridostigmine. This may underlie their improved endurance.

SIGNIFICANCE

Our results suggest that enhancing LT MU function may constitute a therapeutic strategy to reduce fatigability in patients with SMA.

Myasthenia Gravis: Novel Findings and Perspectives on Traditional to Regenerative Therapeutic Interventions

The prevalence of myasthenia gravis (MG), an autoimmune disorder, is increasing among all subsets of the population leading to an elevated economic and social burden. The pathogenesis of MG is characterized by the synthesis of autoantibodies against the acetylcholine receptor (AChR), low-density lipoprotein receptor-related protein 4 (LRP4), or muscle-specific kinase at the neuromuscular junction, thereby leading to muscular weakness and fatigue. Based on clinical and laboratory examinations, the research is focused on distinguishing MG from other autoimmune, genetic diseases of neuromuscular transmission. Technological advancements in machine learning, a subset of artificial intelligence (AI) have been assistive in accurate diagnosis and management. Besides, addressing the clinical needs of MG patients is critical to improving quality of life (QoL) and satisfaction. Lifestyle changes including physical exercise and traditional Chinese medicine/herbs have also been shown to exert an ameliorative impact on MG progression. To achieve enhanced therapeutic efficacy, cholinesterase inhibitors, immunosuppressive drugs, and steroids in addition to plasma exchange therapy are widely recommended. Under surgical intervention, thymectomy is the only feasible alternative to removing thymoma to overcome thymoma-associated MG. Although these conventional and current therapeutic approaches are effective, the associated adverse events and surgical complexity limit their wide application. Moreover, Restivo et al. also, to increase survival and QoL, further recent developments revealed that antibody, gene, and regenerative therapies (such as stem cells and exosomes) are currently being investigated as a safer and more efficacious alternative. Considering these above-mentioned points, we have comprehensively reviewed the recent advances in pathological etiologies of MG including COVID-19, and its therapeutic management.

A multilevel screening pipeline in zebrafish identifies therapeutic drugs for GAN

Giant axonal neuropathy (GAN) is a fatal neurodegenerative disorder for which there is currently no treatment. Affecting the nervous system, GAN starts in infancy with motor deficits that rapidly evolve toward total loss of ambulation. Using the gan zebrafish model that reproduces the loss of motility as seen in patients, we conducted the first pharmacological screening for the GAN pathology. Here, we established a multilevel pipeline to identify small molecules restoring both the physiological and the cellular deficits in GAN. We combined behavioral, in silico, and high-content imaging analyses to refine our Hits to five drugs restoring locomotion, axonal outgrowth, and stabilizing neuromuscular junctions in the gan zebrafish. The postsynaptic nature of the drug's cellular targets provides direct evidence for the pivotal role the neuromuscular junction holds in the restoration of motility. Our results identify the first drug candidates that can now be integrated in a repositioning approach to fasten therapy for the GAN disease. Moreover, we anticipate both our methodological development and the identified hits to be of benefit to other neuromuscular diseases.

Pharmacological and nutritional therapy of children and adults with chronic intestinal pseudo-obstruction

INTRODUCTION

Chronic intestinal pseudo-obstruction (CIPO) is a rare, heterogeneous and severe form of gastrointestinal dysmotility.

AREAS COVERED

Pertinent literature on pediatric and adult CIPO management has been assessed via PubMed, Scopus, and EMBASE from inception to June 2022. Prokinetics, aimed at restoring intestinal propulsion (e.g. orthopramides and substituted benzamides, acetyl cholinesterase inhibitors, serotonergic agents and others), have been poorly tested and the available data showed only partial efficacy. Moreover, some prokinetic agents (e.g. orthopramides and substituted benzamides) can cause major side effects. The CIPO-related small intestinal bacterial overgrowth requires treatment preferably via poorly absorbable antibiotics to avoid bacterial resistance. Apart from opioids, which worsen gut motility, analgesics should be considered to manage visceral pain, which might dominate the clinical manifestations. Nutritional support, via modified oral feeding, enteral or parenteral nutrition, is key to halt CIPO-related malnutrition.

EXPERT OPINION

There have been significant roadblocks preventing the development of CIPO treatment. Nonetheless, the considerable advancement in neurogastroenterology and pharmacological agents cast hopes to test the actual efficacy of new prokinetics via well-designed clinical trials. Adequate dietary strategies and supplementation remain of crucial importance. Taken together, novel pharmacological and nutritional options are expected to provide adequate treatments for these patients.

Case report: Immune remission from generalized myasthenia gravis in a dog with a thymoma and cholangiocellular carcinoma

A 9-year-old male neutered Cockapoo was presented with an acute and progressive history of exercise induced weakness involving all limbs, and bilateral decreased ability to blink. Investigations revealed generalized myasthenia gravis alongside the presence of a thymoma and a cholangiocellular carcinoma. Symptomatic treatment through pyridostigmine bromide was used to control clinical signs, and complete surgical removal of the thymoma and cholangiocellular carcinoma was performed. Serum acetylcholine receptor antibody concentration was measured serially. Clinical remission defined as resolution of clinical signs alongside discontinuation of treatment was achieved by day 251 (8.2 months). Immune remission defined as normalization of serum acetylcholine receptor antibody concentration alongside resolution of clinical signs and discontinuation of treatment was achieved by day 566 (18.5 months). Neurological examination was normal, and the owners did not report any clinical deterioration during the final follow-up appointment on day 752 (24 months), hence outcome was considered excellent. This is the first report describing the temporal evolution of serum acetylcholine receptor antibody concentration in a dog with thymoma-associated myasthenia gravis which achieved immune remission following thymectomy. Treatment was successfully discontinued without any evidence of clinical deterioration thereafter despite serum acetylcholine receptor antibody concentration not normalizing for another 315 days (10 months).

Ryanodine receptor 1 related myasthenia like myopathy responsive to pyridostigmine

Disease causing variants in the Ryanodine receptor 1 (RYR1) gene are a common cause for congenital myopathy and for malignant hyperthermia susceptibility. We report a 17 year old boy with congenital muscle weakness progressing to a myasthenia like myopathy with muscle weakness, fatigability, ptosis, and ophthalmoplegia. Muscle biopsy showed predominance and atrophy of type 1 fibers. Whole-exome trio sequencing revealed three variants in the RYR1-gene in the patient: c.6721C > T,p.(Arg2241*) and c.2122G > A,p.(Asp708Asn) in cis position, and the c.325C > T,p.(Arg109Trp) variant in trans. Treatment with pyridostigmine improved symptoms. This case supports that a myasthenia like phenotype is part of the phenotypic spectrum of RYR1 related disorders, and that treatment with pyridostigmine can be beneficial for patients with this phenotype.

Design, synthesis and biological evaluation of light-driven on-off multitarget AChE and MAO-B inhibitors

Neurodegenerative diseases are multifactorial disorders characterized by protein misfolding, oxidative stress, and neuroinflammation, finally resulting in neuronal loss and cognitive dysfunctions. Nowadays, an attractive strategy to improve the classical treatments is the development of multitarget-directed molecules able to synergistically interact with different enzymes and/or receptors. In addition, an interesting tool to refine personalized therapies may arise from the use of bioactive species able to modify their activity as a result of light irradiation. To this aim, we designed and synthesized a small library of cinnamic acid-inspired isomeric compounds with light modulated activity able to inhibit acetylcholinesterase (AChE) and monoamine oxidase B (MAO-B), with remarkable selectivity over butyrylcholinesterase (BChE) and MAO-A, which have been investigated as the enzyme targets related to Alzheimer's disease (AD). The inhibitory activities were evaluated for the pure E-diastereomers and the E/Z-diastereomer mixtures, obtained upon UV irradiation. Molecular docking studies were carried out to rationalize the differences in the inhibition potency of the E and Z diastereomers of the best performing analogue 1c. Our preliminary findings may open-up the way for developing innovative multitarget photo-switch drugs against neurodegenerative diseases.

Pharmacotherapy of Generalized Myasthenia Gravis with Special Emphasis on Newer Biologicals

Myasthenia gravis (MG) is a chronic, fluctuating, antibody-mediated autoimmune disorder directed against the post-synaptic neuromuscular junctions of skeletal muscles, resulting in a wide spectrum of manifestations ranging from mild to potentially fatal. Given its unique natural course, designing an ideal trial design for MG has been wrought with difficulties and evidence in favour of several of the conventional agents is weak as per current standards. Despite this, acetylcholinesterases and corticosteroids have remained the cornerstones of treatment for several decades with intravenous immunoglobulins (IVIG) and therapeutic plasma exchange (PLEX) offering rapid treatment response, especially in crises. However, the treatment of MG entails long-term immunosuppression and conventional agents are viable options but take longer to act and have a number of class-specific adverse effects. Advances in immunology, translational medicine and drug development have seen the emergence of several newer biological agents which offer selective, target-specific immunotherapy with fewer side effects and rapid onset of action. Eculizumab is one of the newer agents that belong to the class of complement inhibitors and has been approved for the treatment of refractory general MG. Zilucoplan and ravulizumab are other agents in this group in clinical trials. Neisseria meningitis is a concern with all complement inhibitors, mandating vaccination. Neonatal Fc receptor (FcRn) inhibitors prevent immunoglobulin recycling and cause rapid reduction in antibody levels. Efgartigimod is an FcRn inhibitor recently approved for MG treatment, and rozanolixizumab, nipocalimab and batoclimab are other agents in clinical trial development. Although lacking high quality evidence from randomized clinical trials, clinical experience with the use of anti-CD20 rituximab has led to its use in refractory MG. Among novel targets, interleukin 6 (IL6) inhibitors such as satralizumab are promising and currently undergoing evaluation. Cutting-edge therapies include genetically modifying T cells to recognise chimeric antigen receptors (CAR) and chimeric autoantibody receptors (CAAR). These may offer sustained and long-term remissions, but are still in very early stages of evaluation. Hematopoietic stem cell transplantation (HSCT) allows immune resetting and offers sustained remission, but the induction regimens often involve serious systemic toxicity. While MG treatment is moving beyond conventional agents towards target-specific biologicals, lack of knowledge as to the initiation, maintenance, switching, tapering and long-term safety profile necessitates further research. These concerns and the high financial burden of novel agents may hamper widespread clinical use in the near future.

Novel treatment strategies for acetylcholine receptor antibody-positive myasthenia gravis and related disorders

The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG). These antibodies damage the postsynaptic membrane of the neuromuscular junction and cause muscle weakness by depleting AChRs and thus impairing synaptic transmission. As one of the best-characterized antibody-mediated autoimmune diseases, AChR-MG has often served as a reference model for other autoimmune disorders. Classical pharmacological treatments, including broad-spectrum immunosuppressive drugs, are effective in many patients. However, complete remission cannot be achieved in all patients, and 10% of patients do not respond to currently used therapies. This may be attributed to production of autoantibodies by long-lived plasma cells which are resistant to conventional immunosuppressive drugs. Hence, novel therapies specifically targeting plasma cells might be a suitable therapeutic approach for selected patients. Additionally, in order to reduce side effects of broad-spectrum immunosuppression, targeted immunotherapies and symptomatic treatments will be required. This review presents established therapies as well as novel therapeutic approaches for MG and related conditions, with a focus on AChR-MG.

Antibody Therapies in Autoimmune Neuromuscular Junction Disorders: Approach to Myasthenic Crisis and Chronic Management

Myasthenia gravis (MG) is a neurological autoimmune disorder characterized by muscle weakness and fatigue. It is a B cell-mediated disease caused by pathogenic antibodies directed against various components of the neuromuscular junction (NMJ). Despite the wide range of adverse effects, current treatment is still based on non-specific immunosuppression, particularly on long-term steroid usage. The increasing knowledge regarding the pathogenic mechanisms of MG has however allowed to create more target-specific therapies. A very attractive therapeutic approach is currently offered by monoclonal antibodies (mAbs), given their ability to specifically and effectively target different immunopathological pathways, such as the complement cascade, B cell-related cluster of differentiation (CD) proteins, and the human neonatal Fc receptor (FcRn). Up to now, eculizumab, a C5-directed mAb, has been approved for the treatment of generalized MG (gMG) and efgartigimod, a FcRn inhibitor, has just been approved by the U.S. Food and Drug Administration for the treatment of anti-acetylcholine receptor (AChR) antibody positive gMG. Other mAbs are currently under investigation with encouraging preliminary results, further enriching the new range of therapeutic possibilities for MG. This review article provides an overview of the present status of mAb-based therapies for MG, which offer an exciting promise for better outcomes by setting the basis of a precision medicine approach.

Discovery of Novel Acetylcholinesterase Inhibitors by Virtual Screening, In Vitro Screening, and Molecular Dynamics Simulations

Alzheimer's disease is the most common neurodegenerative disease and currently poses a significant socioeconomic problem. This study describes the uses of computer-aided drug discovery techniques to identify novel inhibitors of acetylcholinesterase, a target for Alzheimer's disease. High-throughput virtual screening was employed to predict potential inhibitors of acetylcholinesterase. Validation of enrichment was performed with the DUD-E data set, showing that an ensemble of binding pocket conformations is critical when a diverse set of ligands are being screened. A total of 720 compounds were submitted for in vitro screening, which led to 25 hits being identified with IC₅₀ values of less than 50 μM. The majority of these hits belonged to two scaffolds: 1-ethyl-3-methoxy-3-methylpyrrolidine and 1H-pyrrolo[3,2-c]pyridin-6-amine both of which are noted to be promising compounds for further optimization. As various possible binding poses were suggested from molecular docking, molecular dynamics simulations were employed to validate the poses. In the case of the most active compounds identified, a critical, stable water bridge formed deep within the binding pocket was identified potentially explaining in part the lack of activity for subsets of compounds that are not able to form this water bridge.

Central Apneas Due to the CLIFAHDD Syndrome Successfully Treated with Pyridostigmine

NALCN mutations lead to complex neurodevelopmental syndromes, including infantile hypotonia with psychomotor retardation and characteristic facies (IHPRF) and congenital contractures of limbs and face, hypotonia, and developmental delay (CLIFAHDD), which are recessively and dominantly inherited, respectively. We present a patient in whom congenital myasthenic syndrome (CMS) was suspected due to the occurrence of hypotonia and apnea episodes requiring resuscitation. For this reason, treatment with pyridostigmine was introduced. After starting the treatment, a significant improvement was observed in reducing the apnea episodes and slight psychomotor progress. In the course of further diagnostics, CMS was excluded, and CLIFAHDD syndrome was confirmed. Thus, we try to explain a possible mechanism of clinical improvement after the introduction of treatment with pyridostigmine in a patient with a mutation in the NALCN gene.

The impact of acetylcholinesterase inhibitors on ileus and gut motility following abdominal surgery: a clinical review

Postoperative ileus is a common complication in the days following colorectal surgery occurring in up to 50% of patients. When prolonged, this complication results in significant morbidity and mortality, doubling the total costs of hospital stay. Postoperative ileus (POI) results from the prolonged inflammatory phase that is mediated in part by the cholinergic anti-inflammatory pathway. Acetylcholinesterase inhibitors, such as neostigmine and pyridostigmine, delay the degradation of acetylcholine at the synaptic cleft. This increase in acetylcholine has been shown to increase gut motility. They have been effective in the treatment of acute colonic pseudo-obstruction, but there is limited evidence for the use of these medications for reducing the incidence of POI. This review was conducted to summarise the evidence of acetylcholinesterase inhibitors' effect on gut motility and discuss their potential use as part of an enhanced recovery protocols to prevent or treat POI.

Common Pathogenic Mechanisms in Centronuclear and Myotubular Myopathies and Latest Treatment Advances

Centronuclear myopathies (CNM) are rare congenital disorders characterized by muscle weakness and structural defects including fiber hypotrophy and organelle mispositioning. The main CNM forms are caused by mutations in: the MTM1 gene encoding the phosphoinositide phosphatase myotubularin (myotubular myopathy), the DNM2 gene encoding the mechanoenzyme dynamin 2, the BIN1 gene encoding the membrane curvature sensing amphiphysin 2, and the RYR1 gene encoding the skeletal muscle calcium release channel/ryanodine receptor. MTM1, BIN1, and DNM2 proteins are involved in membrane remodeling and trafficking, while RyR1 directly regulates excitation-contraction coupling (ECC). Several CNM animal models have been generated or identified, which confirm shared pathological anomalies in T-tubule remodeling, ECC, organelle mispositioning, protein homeostasis, neuromuscular junction, and muscle regeneration. Dynamin 2 plays a crucial role in CNM physiopathology and has been validated as a common therapeutic target for three CNM forms. Indeed, the promising results in preclinical models set up the basis for ongoing clinical trials. Another two clinical trials to treat myotubular myopathy by MTM1 gene therapy or tamoxifen repurposing are also ongoing. Here, we review the contribution of the different CNM models to understanding physiopathology and therapy development with a focus on the commonly dysregulated pathways and current therapeutic targets.

ABCpred: a webserver for the discovery of acetyl- and butyryl-cholinesterase inhibitors

Alzheimer's disease (AD) is one of the most common forms of dementia and is associated with a decline in cognitive function and language ability. The deficiency of the cholinergic neurotransmitter known as acetylcholine (ACh) is associated with AD. Acetylcholinesterase (AChE) hydrolyses ACh and inhibits the cholinergic transmission. Furthermore, both AChE and butyrylcholinesterase (BChE) plays important roles in early and late stages of AD. Therefore, the inhibition of either or both cholinesterase enzymes represent a promising therapeutic route for treating AD. In this study, a large-scale classification structure-activity relationship model was developed to predict cholinesterase inhibitory activities as well as revealing important substructures governing their activities. Herein, a non-redundant dataset constituting 985 and 1056 compounds for AChE and BChE, respectively, was obtained from the ChEMBL database. These inhibitors were described by 12 sets of molecular fingerprints and predictive models were developed using the random forest algorithm. Evaluation of the model performance by means of Matthews correlation coefficient and consideration of the model's interpretability indicated that the SubstructureCount fingerprint was the most robust with five-fold cross-validated MCC of [0.76, 0.82] for AChE and BChE, respectively, and test MCC of [0.73, 0.97]. Feature interpretation revealed that the aromatic ring system, heterocyclic nitrogen containing compounds and amines are important for cholinesterase inhibition. Finally, the model was deployed as a publicly available webserver called the ABCpred at http://codes.bio/abcpred/ .

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

Drugs That Induce or Cause Deterioration of Myasthenia Gravis: An Update

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder which is characterized by presence of antibodies against acetylcholine receptors (AChRs) or other proteins of the postsynaptic membrane resulting in damage to postsynaptic membrane, decreased number of AChRs or blocking of the receptors by autoantibodies. A number of drugs such as immune checkpoint inhibitors, penicillamine, tyrosine kinase inhibitors and interferons may induce de novo MG by altering the immune homeostasis mechanisms which prevent emergence of autoimmune diseases such as MG. Other drugs, especially certain antibiotics, antiarrhythmics, anesthetics and neuromuscular blockers, have deleterious effects on neuromuscular transmission, resulting in increased weakness in MG or MG-like symptoms in patients who do not have MG, with the latter usually being under medical circumstances such as kidney failure. This review summarizes the drugs which can cause de novo MG, MG exacerbation or MG-like symptoms in nonmyasthenic patients.

Quantification of Cover Test Prior and Post Pyridostigmine in Diagnosis of Myasthenia Gravis

Objective: To assess the value of measuring diplopia before and after pyridostigmine intake to differentiate myasthenia gravis from sagging eye syndrome.To establish a threshold for a positive response to pyridostigmine in the diagnosis of myasthenia gravis.Methods: 15 patients with myasthenia gravis and 15 with sagging eye syndrome diplopia were evaluated. Diplopia was measured in five positions (upgaze, downgaze, right gaze, left gaze, and primary position). After baseline measurements, the patient received a single dose (60 mg) of pyridostigmine. After 60 minutes the prism measure was performed again in five positions. Horizontal deviation, vertical deviation at distance was compared before and after a single dose of pyridostigmine in each gaze. Ocular deviations were compared between the two groups to identify the threshold with the highest sensitivity and specificity.Results: Differences between pretest deviations and posttest deviations in any gaze were found to be statistically significant only in the MG group. The optimum threshold for a positive response to pyridostigmine was a reduction of 2 prism diopters in any component in any gaze. Sensitivity for the detection of myasthenia diplopia was 80.00% and specificity was 86.67%.Conclusions: Our results suggest that measuring diplopia with prisms before and after pyridostigmine administration can help to detect patients with suspected myasthenia.

Motoneuron-specific loss of VAChT mimics neuromuscular defects seen in congenital myasthenic syndrome

Motoneurons (MNs) control muscle activity by releasing the neurotransmitter acetylcholine (ACh) at the level of neuromuscular junctions. ACh is packaged into synaptic vesicles by the vesicular ACh transporter (VAChT), and disruptions in its release can impair muscle contraction, as seen in congenital myasthenic syndromes (CMS). Recently, VAChT gene mutations were identified in humans displaying varying degrees of myasthenia. Moreover, mice with a global deficiency in VAChT expression display several characteristics of CMS. Despite these findings, little is known about how a long-term decrease in VAChT expression in vivo affects MNs structure and function. Using Cre-loxP technology, we generated a mouse model where VAChT is deleted in select groups of MNs (mnVAChT-KD). Molecular analysis revealed that the VAChT deletion was specific to MNs and affected approximately 50% of its population in the brainstem and spinal cord, with alpha-MNs primarily targeted (70% in spinal cord). Within each animal, the cell body area of VAChT-deleted MNs was significantly smaller compared to MNs with VAChT preserved. Likewise, muscles innervated by VAChT-deleted MNs showed atrophy while muscles innervated by VAChT-containing neurons appeared normal. In addition, mnVAChT KD mice had decreased muscle strength, were hypoactive, leaner and exhibited kyphosis. This neuromuscular dysfunction was evident at 2 months of age and became progressively worse by 6 months. Treatment of mutants with a cholinesterase inhibitor was able to improve some of the motor deficits. As these observations mimic what is seen in CMS, this new line could be valuable for assessing the efficacy of potential CMS drugs.

Effects of Pyridostigmine on Esophageal and Pharyngeal Motility in Dysphagic Patients Undergoing High-Resolution Manometry

Weak or absent peristalsis of the esophageal musculature is a common finding in ambulatory patients suffering from dysphagia and frequently associated with gastroesophageal reflux. There is currently no pharmacologic intervention that reliably improves esophageal contractility in patients suffering from various esophageal motility disorders. Our objective was to evaluate the acute effects of pyridostigmine on high-resolution manometry parameters in patients suffering from dysphagia with evidence of esophageal dysmotility. Pyridostigmine is an acetylcholinesterase inhibitor which increases effective concentrations of acetylcholine at the neuromuscular junction of both striated and smooth muscle cells. We conducted a prospective crossover study of five patients with dysphagia and proven esophageal dysmotility. Three patients had baseline ineffective esophageal motility and two had achalasia. Patients underwent pharyngeal and esophageal manometry before and after pyridostigmine administration. The median distal contractile integral (DCI), a marker of esophageal contractile vigor, was significantly higher post pyridostigmine administration 3001 (1950.3-3703.2) mmHg × s × cm compared to pre-pyridostigmine DCI of 1229.9 (956.2-2100) mmHg × s × cm; P < 0.001. Pre-pyridostigmine 18/25 (72%) of the patient's swallows was peristaltic compared to 25/25 (100%) post-pyridostigmine; P < 0.005. No other pharyngeal or esophageal high-resolution manometry parameter differed significantly after pyridostigmine administration. The results of this pilot study demonstrate that pyridostigmine acutely improves esophageal contractile vigor in patients suffering from dysphagia with esophageal dysmotility. Further investigation with larger sample size, longer follow-up, side effect profile, and patient-reported outcome measures is still needed to determine the clinical usefulness of pyridostigmine in specific disorders of esophageal motility.

Slow-binding reversible inhibitor of acetylcholinesterase with long-lasting action for prophylaxis of organophosphate poisoning

Organophosphorus (OP) compounds represent a serious health hazard worldwide. The dominant mechanism of their action results from covalent inhibition of acetylcholinesterase (AChE). Standard therapy of acute OP poisoning is partially effective. However, prophylactic administration of reversible or pseudo-irreversible AChE inhibitors before OP exposure increases the efficiency of standard therapy. The purpose of the study was to test the duration of the protective effect of a slow-binding reversible AChE inhibitor (C547) in a mouse model against acute exposure to paraoxon (POX). It was shown that the rate of inhibition of AChE by POX in vitro after pre-inhibition with C547 was several times lower than without C547. Ex vivo pre-incubation of mouse diaphragm with C547 significantly prevented the POX-induced muscle weakness. Then it was shown that pre-treatment of mice with C547 at the dose of 0.01 mg/kg significantly increased survival after poisoning by 2xLD50 POX. The duration of the pre-treatment was effective up to 96 h, whereas currently used drug for pre-exposure treatment, pyridostigmine at a dose of 0.15 mg/kg was effective less than 24 h. Thus, long-lasting slow-binding reversible AChE inhibitors can be considered as new potential drugs to increase the duration of pre-exposure treatment of OP poisoning.

A Practical Approach to Managing Patients With Myasthenia Gravis-Opinions and a Review of the Literature

When the diagnosis of myasthenia gravis (MG) has been secured, the aim of management should be prompt symptom control and the induction of remission or minimal manifestations. Symptom control, with acetylcholinesterase inhibitors such as pyridostigmine, is commonly employed. This may be sufficient in mild disease. There is no single universally accepted treatment regimen. Corticosteroids are the mainstay of immunosuppressive treatment in patients with more than mild MG to induce remission. Immunosuppressive therapies, such as azathioprine are prescribed in addition to but sometimes instead of corticosteroids when background comorbidities preclude or restrict the use of steroids. Rituximab has a role in refractory MG, while plasmapheresis and immunoglobulin therapy are commonly prescribed to treat MG crisis and in some cases of refractory MG. Data from the MGTX trial showed clear evidence that thymectomy is beneficial in patients with acetylcholine receptor (AChR) antibody positive generalized MG, up to the age of 65 years. Minimally invasive thymectomy surgery including robotic-assisted thymectomy surgery has further revolutionized thymectomy and the management of MG. Ocular MG is not life-threatening but can be significantly disabling when diplopia is persistent. There is evidence to support early treatment with corticosteroids when ocular motility is abnormal and fails to respond to symptomatic treatment. Treatment needs to be individualized in the older age-group depending on specific comorbidities. In the younger age-groups, particularly in women, consideration must be given to the potential teratogenicity of certain therapies. Novel therapies are being developed and trialed, including ones that inhibit complement-induced immunological pathways or interfere with antibody-recycling pathways. Fatigue is common in MG and should be duly identified from fatigable weakness and managed with a combination of physical therapy with or without psychological support. MG patients may also develop dysfunctional breathing and the necessary respiratory physiotherapy techniques need to be implemented to alleviate the patient's symptoms of dyspnoea. In this review, we discuss various facets of myasthenia management in adults with ocular and generalized disease, including some practical approaches and our personal opinions based on our experience.

Celebrating the 70 years of pyridostigmine on therapy of Myasthenia Gravis: historical aspects of the preliminary trials

Currently, pyridostigmine bromide is an indispensable anticholinesterase agent used worldwide to treat patients with Myasthenia Gravis (MG). However, pyridostigmine bromide was unsuccessful in its "pioneering trials" to treat a series of MG patients. There are important historical landmarks before pyridostigmine bromide becomes useful, safe and indispensable for MG therapy. After 70 years of these "pioneering trials", this article reviews some historical aspects related to them, as well as other preliminary trials using pyridostigmine bromide as therapy for MG patients.

IL-37 Represses the Autoimmunity in Myasthenia Gravis via Directly Targeting Follicular Th and B Cells

IL-37 is a newly identified immune-suppressive factor; however, the function, cellular sources, and mechanism of IL-37 in humoral immunity and Myasthenia gravis (MG) are still unclear. In this study, we found IL-37 were substantially downregulated in the serum and PBMCs of MG patients compared with healthy controls. The lower IL-37 was associated with severer disease (quantitative MG score) and higher follicular Th (Tfh)/Tfh17 and B cell numbers. Flow cytometry analysis revealed that IL-37 was mainly produced by CD4⁺ T cells without overlapping with Th1, Th17, and Tfh subsets in MG patients. Regulatory IL-37⁺ T cell rarely expressed Foxp3 and CD25 but produced numerous IL-4. Tfh and B cell expressed high levels of SIGIRR, the receptor of IL-37, in MG patients. Mechanically, IL-37 directly bond to SIGIRR, repressed the proliferation, cytokine production of Tfh and B cells, and the secretion of autoantibody via inhibition of STAT3 signaling in Tfh and B cells.

Pyridostigmine in Pediatric Intestinal Pseudo-obstruction: Case Report of a 2-year Old Girl and Literature Review

Pediatric chronic intestinal pseudo-obstruction is a rare disorder characterized by a severe impairment of gastrointestinal motility leading to intestinal obstruction symptoms in the absence of mechanical causes. The diagnosis is usually clinical and diagnostic work is usually aimed to rule out mechanical obstruction and to identify any underlying diseases. Treatment is challenging and requires a multidisciplinary effort. In this manuscript we describe the youngest child successfully treated with the orally administrable, long-acting, reversible anti-cholinesterase drug, pyridostigmine. Like other drugs belonging to cholinesterase inhibitors, pyridostigmine enhances gut motility by increasing acetylcholine availability in the enteric nervous system and neuro-muscular junctions. Based on the direct evidence from the reported case, we reviewed the current literature on the use of pyridostigmine in severe pediatric dysmotility focusing on intestinal pseudo-obstruction. The overall data emerged from the few published studies suggest that pyridostigmine is an effective and usually well tolerated therapeutic options for patients with intestinal pseudo-obstruction. More specifically, the main results obtained by pyridostigmine included marked reduction of abdominal distension, reduced need of parenteral nutrition, and improvement of oral feeding. The present case and review on pyridostigmine pave the way for eagerly awaited future randomized controlled studies testing the efficacy of cholinesterase inhibitors in pediatric severe gut dysmotility.

Metabolite Profiling by Hyphenated Liquid Chromatographic Mass Spectrometric Technique (HPLC-DAD-ESI-Q-TOF-MS/MS) and Neurobiological Potential of Haplophyllum sahinii and H. vulcanicum Extracts

In the current study, the ethanol extracts of flower, stem, and root parts of two endemic Turkish species, e. g., Haplophyllum sahinii O. Tugay & D. Ulukuş and H. vulcanicum Boiss. & Heldr., were screened against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) associated with Alzheimer's disease as well as tyrosinase (TYR) linked to Parkinson's disease using ELISA microplate assay at 200 μg/mL. Among the extracts, the highest inhibition was caused by the stem extract of H. sahinii against BChE (IC₅₀ =64.93±1.38 μg/mL). Consistently, all of the extracts were found to exert a selective inhibition towards BChE to some extent. It was only the root extract of H. vulcanicum that could inhibit AChE at low level (IC₅₀ =203.18±5.33 μg/mL). None of the extracts displayed an inhibition over 50 % against TYR. Metabolite profiling of the extracts was achieved by a highly hyphenated liquid chromatographic mass spectrometric technique (HPLC-DAD-ESI-Q-TOF-MS/MS), which revealed the presence of furoquinoline (β-fagarine, γ-fagarine) and amide (tubasenicine, tubacetine) alkaloids; furano- (rutamarin), pyrano- (xanthyletine), and geranyloxy coumarins; phenylpropanoid (secoisolariciresinol), arylnaphthalene (mono-O-acetyldiphyllin apioside), and dibenzylbutyrolactone (kusunokinin, haplomyrfolin) lignans. Several important differences were observed between the extracts analyzed. β-Fagarine was the major alkaloid in H. vulcanicum, whereas γ-fagarine was present only in the roots of both Haplophyllum species; moreover, secoisolariciresinol and secoisolariciresinol dimethyl ether were the main lignans in the stems and flowers. This is the first study identifying ChE and TYR inhibitory effect and metabolic profiles of H. vulcanicum and H. sahinii.

The effect of pyridostigmine on small intestinal bacterial overgrowth (SIBO) and plasma inflammatory biomarkers in HIV-associated autonomic neuropathies

Small intestinal bacterial overgrowth (SIBO) is common among patients with HIV-associated autonomic neuropathies (HIV-AN) and may be associated with increased bacterial translocation and elevated plasma inflammatory biomarkers. Pyridostigmine is an acetylcholinesterase inhibitor which has been used to augment autonomic signaling. We sought preliminary evidence as to whether pyridostigmine could improve proximal gastrointestinal motility, reduce SIBO, reduce plasma sCD14 (a marker of macrophage activation and indirect measure of translocation), and reduce the inflammatory cytokines IL-6 and TNFα in patients with HIV-AN. Fifteen participants with well-controlled HIV, HIV-AN, and SIBO were treated with 8 weeks of pyridostigmine (30 mg PO TID). Glucose breath testing for SIBO, gastric emptying studies (GES) to assess motility, plasma sCD14, IL-6, and TNFα, and gastrointestinal autonomic symptoms were compared before and after treatment. Thirteen participants (87%) experienced an improvement in SIBO following pyridostigmine treatment; with an average improvement of 50% (p = 0.016). There was no change in gastrointestinal motility; however, only two participants met GES criteria for gastroparesis at baseline. TNFα and sCD14 levels declined by 12% (p = 0.004) and 19% (p = 0.015), respectively; there was no significant change in IL-6 or gastrointestinal symptoms. Pyridostigmine may ameliorate SIBO and reduce levels of sCD14 and TNFα in patients with HIV-AN. Larger placebo-controlled studies are needed to definitively delineate how HIV-AN affects gastrointestinal motility, SIBO, and systemic inflammation in HIV, and whether treatment improves clinical outcomes.

Subcutaneous neostigmine appears safe and effective for acute colonic pseudo-obstruction (Ogilvie's syndrome)

BACKGROUND

Intravenous neostigmine is a well-established treatment for acute colonic pseudo-obstruction (ACPO). Its use is hampered by the perceived requirement for continuous cardiac monitoring, and patients are often transferred to high-dependency units for close observation during treatment. Subcutaneous neostigmine has the potential to minimize adverse cardiovascular effects while maintaining efficacy. This study aims to assess the safety of subcutaneous neostigmine on ward inpatients with ACPO monitored with standard nursing care.

METHODS

This is a retrospective case series of 30 patients with ACPO who were treated with subcutaneous neostigmine between August 2008 and October 2012. Data were collected prospectively. All patients were diagnosed using clinical examination and radiology and were assessed for contraindications to neostigmine. Patients were treated on regular wards and monitored with standard nursing observations. The main outcomes were time to flatus and bowels working and complications.

RESULTS

No serious complications such as clinically evident bradycardia were encountered. Ninety-three percent of patients had clinically successful resolution of ACPO. Two patients (7%) developed caecal tenderness and proceeded to colonoscopic decompression, which was successful in both instances.

CONCLUSIONS

Subcutaneous neostigmine appears to be safe for the treatment of ACPO. No clinically evident serious adverse events occurred, meaning continuous cardiac monitoring as a routine may not be necessary. In our cohort, we achieved similar success rates compared with reported rates using intravenous neostigmine.

Interaction of neurotransmitters and neurochemicals with lymphocytes

Neurotransmitters and neurochemicals can act on lymphocytes by binding to receptors expressed by lymphocytes. This review describes lymphocyte expression of receptors for a selection of neurotransmitters and neurochemicals, the anatomical locations where lymphocytes can interact with neurotransmitters, and the effects of the neurotransmitters on lymphocyte function. Implications for health and disease are also discussed.

A Neurologist's Perspective on Understanding Myasthenia Gravis: Clinical Perspectives of Etiologic Factors, Diagnosis, and Preoperative Treatment

Myasthenia gravis (MG) is a disease of neuromuscular transmission caused by antibodies directed toward proteins concentrated at the neuromuscular junction. Mild to life-threatening weakness varies in severity over time and with level of activity. Therefore, clinical diagnosis is often challenging. MG may be categorized by autoantibody type, thymic pathologic condition, and age of onset. Treatments are tailored for each group. A key management concern is severe exacerbation of weakness resulting from infections or exposure to certain medications, including antibiotics, which may be severe enough to produce respiratory decompensation. The article reviews key diagnostic issues and treatment options.

Pharmacological Modulation of Vagal Nerve Activity in Cardiovascular Diseases

Cardiovascular diseases are life-threatening illnesses with high morbidity and mortality. Suppressed vagal (parasympathetic) activity and increased sympathetic activity are involved in these diseases. Currently, pharmacological interventions primarily aim to inhibit over-excitation of sympathetic nerves, while vagal modulation has been largely neglected. Many studies have demonstrated that increased vagal activity reduces cardiovascular risk factors in both animal models and human patients. Therefore, the improvement of vagal activity may be an alternate approach for the treatment of cardiovascular diseases. However, drugs used for vagus nerve activation in cardiovascular diseases are limited in the clinic. In this review, we provide an overview of the potential drug targets for modulating vagal nerve activation, including muscarinic, and β-adrenergic receptors. In addition, vagomimetic drugs (such as choline, acetylcholine, and pyridostigmine) and the mechanism underlying their cardiovascular protective effects are also discussed.

Effects of Heart Rate Reduction With Either Pyridostigmine or Ivabradine in Patients With Heart Failure: A Randomized, Double-Blind Study

Background:

Heart rate (HR) reduction with ivabradine has been proved to reduce hospitalization and death from heart failure (HF). We sought to investigate whether pyridostigmine would effectively reduce HR in patients with chronic HF as compared with ivabradine.

Methods:

Twenty-one patients with HF who were in sinus rhythm with a resting HR over 70 bpm, despite optimal medical treatment, were included in a randomized, double-blind study comparing pyridostigmine versus ivabradine. The initial dose of ivabradine was 5 mg twice daily to reach a target HR between 50 and 60 bpm and could be titrated to a maximum of 7.5 mg twice daily. Pyridostigmine was used in a fixed dose of 30 mg 3 times daily.

Results:

The baseline HR for ivabradine and pyridostigmine groups was 89.1 (13.5) and 80.1 (7.2) bpm, respectively ( P = .083). After 6 months of treatment, HR was significantly reduced to 64.8 (8.3) bpm in the ivabradine group ( P = .0014) and 63.6 (5.9) bpm in the pyridostigmine group ( P = .0001). The N-terminal pro-B-type natriuretic peptide was reduced in the ivabradine group (median: 1308.4 [interquartile range: 731-1896] vs 755.8 [134.5-1014] pg/mL; P = .027) and in the pyridostigmine group (132.8 [89.9-829] vs 100.7 [38-360] pg/mL; P = .002). Inflammatory markers interleukin-1, interleukin-6, and tumor necrosis factor were reduced in both groups. Exercise capacity was improved in both groups, with increments in volume of oxygen utilization ([Formula: see text]O2; ivabradine: 13.1 vs 15.6, P = .048; pyridostigmine: 13.3 vs 16.7, P = .032). Heart rate recovery in the first minute postexercise was improved with pyridostigmine (11.8 [3.9] vs 18 [6.5]; P = .046), but not with ivabradine (13.3 [6.9] vs 14.1 [8.2]; P = .70). No differences in either group were observed in the myocardial scintigraphy with 123-iodine-metaiodobenzylguanidine.

Conclusion:

Both drugs significantly reduced HR, with improvements in exercise capacity and in neurohormonal and inflammatory profiles.

Treatment of Myasthenia Gravis With High-Dose Cholinesterase Inhibitors and Calcineurin Inhibitors Caused Spontaneous Muscle Cramps in Patients

OBJECTIVES

The objective of this study was to investigate the influence of treatment with cholinesterase inhibitors (ChEIs) and calcineurin inhibitors (CNIs) on the occurrence of cramps in myasthenia gravis (MG) patients.

METHODS

The frequency and duration of cramp and serum electrolytes were evaluated in 81 patients with MG. The patients were classified using Myasthenia Gravis Foundation of America postintervention status scores based on the treatment and the responsiveness to the treatment. Quantitative MG score, MG activities of daily living score, MG composite score, or MG quality of life 15 score was used to assess the health-related quality of life (QOL).

RESULTS

Muscle cramps developed in 44 (54.3%) of 81 MG patients. The scores of MG activities of daily living, MG composite, or MG-QOL 15-item questionnaire in patients with cramp were significantly higher than those in patients without cramps (P = 0.002, P = 0.01, or P = 0.0022, respectively). The serum magnesium concentrations were lower in patients treated with CNI (n = 16) than in those not treated with CNI (n = 65) (P = 0.002). The probability of cramps was significantly higher in patients treated with ChEIs (≥180 mg/d) in addition to CNI than in patients who were treated with a low dose of ChEIs (≤60 mg/d) without concomitant CNI treatment (P = 0.017).

CONCLUSIONS

Our data suggested that treatment with a high dose of ChEI and CNI accelerated the probability of cramps and reduced the QOL in MG patients.

Advances in autoimmune myasthenia gravis management

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with no cure and conventional treatments limited by significant adverse effects and variable benefit. In the last decade, therapeutic development has expanded based on improved understanding of autoimmunity and financial incentives for drug development in rare disease. Clinical subtypes exist based on age, gender, thymic pathology, autoantibody profile, and other poorly defined factors, such as genetics, complicate development of specific therapies. Areas covered: Clinical presentation and pathology vary considerably among patients with some having weakness limited to the ocular muscles and others having profound generalized weakness leading to respiratory insufficiency. MG is an antibody-mediated disorder dependent on autoreactive B cells which require T-cell support. Treatments focus on elimination of circulating autoantibodies or inhibition of effector mechanisms by a broad spectrum of approaches from plasmapheresis to B-cell elimination to complement inhibition. Expert commentary: Standard therapies and those under development are disease modifying and not curative. As a rare disease, clinical trials are challenged in patient recruitment. The great interest in development of treatments specific for MG is welcome, but decisions will need to be made to focus on those that offer significant benefits to patients.

Open source modular ptosis crutch for the treatment of myasthenia gravis

INTRODUCTION

Pharmacologic treatment of Myasthenia Gravis presents challenges due to poor tolerability in some patients. Conventional ptosis crutches have limitations such as interference with blinking which causes ocular surface drying, and frequent irritation of the eyes. To address this problem, a modular and adjustable ptosis crutch for elevating the upper eyelid in Myasthenia Gravis patients has been proposed as a non-surgical and low-cost solution.

AREAS COVERED

This paper reviews the literature on the challenges in the treatment of Myasthenia Gravis globally and focuses on a modular and adjustable ptosis crutch that has been developed by the Medical Device Laboratory at the University of Cape Town.

EXPERT COMMENTARY

The new medical device has potential as a simple, effective and unobtrusive solution to elevate the drooping upper eyelid(s) above the visual axis without the need for medication and surgery. Access to the technology is provided through an open source platform which makes it available globally. Open access provides opportunities for further open innovation to address the current limitations of the device, ultimately for the benefit not only of people suffering from Myasthenia Gravis but also of those with ptosis from other aetiologies.

Effect of pyridostigmine on in vivo and in vitro respiratory muscle of mdx mice

The current work was conducted to verify the contribution of neuromuscular transmission defects at the neuromuscular junction to Duchenne Muscular Dystrophy disease progression and respiratory dysfunction. We tested pyridostigmine and pyridostigmine encapsulated in liposomes (liposomal PYR), an acetylcholinesterase inhibitor to improve muscular contraction on respiratory muscle function in mdx mice at different ages. We evaluated in vivo with the whole-body plethysmography, the ventilatory response to hypercapnia, and measured in vitro diaphragm strength in each group. Compared to C57BL10 mice, only 17 and 22 month-old mdx presented blunted ventilatory response, under normocapnia and hypercapnia. Free pyridostigmine (1mg/kg) was toxic to mdx mice, unlike liposomal PYR, which did not show any side effect, confirming that the encapsulation in liposomes is effective in reducing the toxic effects of this drug. Treatment with liposomal PYR, either acute or chronic, did not show any beneficial effect on respiratory function of this DMD experimental model. The encapsulation in liposomes is effective to abolish toxic effects of drugs.

Neuromuscular Disease in the Neurointensive Care Unit

Neuromuscular diseases are syndromic disorders that affect nerve, muscle, and/or neuromuscular junction. Knowledge about the management of these diseases is required for anesthesiologists, because these may frequently be encountered in the intensive care unit, operating room, and other settings. The challenges and advances in management for some of the neuromuscular diseases most commonly encountered in the operating room and neurointensive care unit are reviewed.

Reversing neuromuscular blockade: inhibitors of the acetylcholinesterase versus the encapsulating agents sugammadex and calabadion

INTRODUCTION

Acetylcholinesterase inhibitors (neostigmine, edrophonium) and encapsulating agents (sugammadex and calabadion) can be used to reverse residual neuromuscular blockade (NMB).

AREAS COVERED

This review provides information about efficacy, effectiveness, and side effects of drugs (acetylcholinesterase inhibitors and encapsulating agents) used to reverse neuromuscular blocking agents (NMBAs).

EXPERT OPINION

The therapeutic range of acetylcholinesterase-inhibitors is narrow and effectiveness studies demonstrate clinicians don't use these unspecific reversal agents effectively to increase postoperative respiratory safety. The encapsulating drugs sugammadex and calabadion reverse all levels of NMB, and complete recovery of muscle strength can be achieved almost immediately after administration. For this reason encapsulating agents can be used as a solution for "cannot intubate cannot ventilate"- situations. Poor binding selectivity of encapsulating agents carries the risk of displacement of the NMBA by a competitively binding drug, which may lead to recurarization. In order to avoid side-effects, related to unspecific binding of endogenous proteins and drugs administered perioperatively it is prudent to titrate the dose of reversal agents to the minimal effective dose, depending on the depth of neuromuscular transmission block identified by neuromuscular transmission monitoring. Calabadions provide a diversified (increased binding selectivity) and expanded (reversal of benzylisoquinolines) spectrum of possible indications.

Clinical Significance of Repetitive Compound Muscle Action Potentials in Patients with Myasthenia Gravis: A Predictor for Cholinergic Side Effects of Acetylcholinesterase Inhibitors

Background and Purpose

Acetylcholinesterase inhibitors (AChEIs) are widely used to treat myasthenia gravis (MG). Although AChEIs are usually tolerated well, some MG patients suffer from side effects. Furthermore, a small proportion of MG patients show cholinergic hypersensitivity and cannot tolerate AChEIs. Because repetitive compound muscle action potentials (R-CMAPs) are an electrophysiologic feature of cholinergic neuromuscular hyperactivity, we investigated the clinical characteristics of MG patients with R-CMAPs to identify their clinical usefulness in therapeutic decision-making.

Methods

We retrospectively reviewed the clinical records and electrodiagnostic findings of MG patients who underwent electrodiagnostic studies and diagnostic neostigmine testing (NT).

Results

Among 71 MG patients, 9 could not tolerate oral pyridostigmine bromide (PB) and 17 experienced side effects of PB. R-CMAPs developed in 24 patients after NT. The highest daily dose of PB was lower in the patients with R-CMAPs (240 mg/day vs. 480 mg/day, p<0.001). The frequencies of PB intolerance and side effects were higher in the patients with R-CMAPs than in those without R-CMAPs [37.5% vs. 0% (p<0.001) and 45.8% vs. 12.8% (p=0.002), respectively]. The MG Foundation of America postintervention status did not differ significantly between MG patients with and without R-CMAPs, and the response to immunotherapy was also good in both groups.

Conclusions

Side effects of and intolerance to AChEIs are more common in MG patients with R-CMAPs than in those without R-CMAPs. AChEIs should be used carefully in MG patients with R-CMAPs. The presence of R-CMAPs after NT may be a good indicator of the risks of PB side effects and intolerance.