A practical guide to the recognition and management of myasthenia gravis

Characteristics of myasthenia gravis in elderly patients: a retrospective study

BACKGROUND

The incidence of myasthenia gravis (MG) is increasing, and its characteristics in elderly patients are believed to differ from those in younger patients. However, only a few studies have focused on elderly patients with MG.

OBJECTIVE

To review the characteristics of MG in elderly patients and evaluate whether older age is an independent factor associated with achieving minimal manifestation status (MMS).

METHODS

This retrospective cohort study included 367 patients (319 non-elderly and 48 elderly patients) with MG enrolled at Xiangya Hospital from September 1, 2016, to December 31, 2018. We collected demographic data and information regarding comorbidities, antibody status, Myasthenia Gravis Foundation of America classification, affected muscle groups, thymoma, and treatment. MMS was defined as the primary outcome.

RESULTS

Comorbidities were more common in elderly than in younger patients with MG. Anti-acetylcholine receptor antibody was the dominant subtype, whereas anti-muscle-specific tyrosine kinase antibody was rare and detected only in non-elderly patients. Elderly patients were more likely than younger patients to have generalized MG, but the frequency of thymoma was lower (28.5% vs. 10.4%, p = 0.0078). MMS or better was achieved in 154 (48.3%) and 13 (27.1%) non-elderly and elderly patients, respectively. Older age did not appear to be an independent factor associated with MMS (hazard ratio = 0.625; 95% confidence interval, 0.345-1.131).

CONCLUSIONS

Older age was not an independent factor for a worse prognosis in patients with MG. The treatment of elderly patients with MG should be individually tailored.

Chronic stress, depression and personality type in patients with myasthenia gravis

BACKGROUND AND PURPOSE

Stress is a known risk factor for the onset and modulation of disease activity in autoimmune disorders. The aim of this cross-sectional study was to determine any associations between myasthenia gravis (MG) severity and chronic stress, depression and personality type.

METHODS

In all, 179 consecutive adult patients with confirmed MG attending the Neuromuscular Clinic between March 2017 and December 2017 were included. At baseline, patients were assessed clinically and they completed self-administered scales for disease severity, perceived stress, depression and personality type.

RESULTS

Higher disease severity [Myasthenia Gravis Impairment Index (MGII)] showed a moderate correlation with depression score (Beck's Depression Inventory, Second Edition, r = 0.52, P < 0.001) and a lower correlation with chronic stress (Trier Inventory for Assessment of Chronic Stress, r = 0.28, P = 0.001). Chronic stress scores were different according to personality types (anova, P = 0.02). The linear regression model with MGII score as the dependent variable showed R² = 0.34, likelihood ratio chi-squared 74.55, with P < 0.0001. The only variables that predicted disease severity were depression scores (P < 0.0001) and female sex (P = 0.003).

CONCLUSIONS

A significant association of MG severity with depression and chronic stress was found, as well as with female gender. These findings should raise awareness that the long-term management of MG should address depression and potential stress and consider behavioural management to prevent stress-related immune imbalance.

[A comparative analysis of the informative value of anti-AChR-antibody radioimmunoassay and laser correlation spectroscopy in myasthenia gravis]

AIM

An aim of the study was to compare informative value of traditional approach (anti-AChR antibody radioimmunoassay) and evaluation of metabolic shifts by laser correlation spectroscopy in myasthenia gravis.

MATERIAL AND METHODS

The search for the relationship between the disease severity in 77 patients, 12-80 years and the distribution pattern of subfraction serum components revealed three informative zones: 6-15, 27-67, and 127-223 nm.

RESULTS AND CONCLUSION

In patients without disturbances of vital functions, the contribution of the first zone particles into light scatter increases and that of the third zone particles decreases. Considerable differences attaining the level of statistical significance in zones 6 and 20 nm were revealed in the spectra of serum from patients with myasthenia gravis of the same severity with and without thymoma. This opens prospects for dynamic monitoring of the efficiency of therapy.

Prolonged Dyspnea after Interscalene Block: Attributed to Undiagnosed Addison's Disease and Myasthenia Gravis

This report describes a patient who had a series of daily interscalene nerve blocks to treat pain following a shoulder manipulation for postsurgical stiffness. She experienced acute respiratory compromise that persisted for many weeks. All typical and unusual causes of these symptoms were ruled out. Her treating pulmonologist theorized that the ipsilateral carotid body had been injured. However, it was subsequently determined that the constellation of symptoms and their prolonged duration were best explained by a poor stress response from Addison's disease coupled with exacerbation of early onset myasthenia gravis. This patient's case is not a typical reaction to interscalene nerve blocks, and thus preoperative testing would not be recommended for myasthenia gravis or Addison's disease without underlying suspicion. We describe this report to inform physicians to consider a workup for these diagnoses if a typical workup rules out all usual causes of complications from an interscalene block.

The effectiveness of thymectomy on seronegative generalized myasthenia gravis: comparing with seropositive cases

OBJECTIVES

To investigate the efficacy of thymectomy between patients with seronegative myasthenia gravis (SNMG) and seropositive myasthenia gravis (SPMG).

METHODS

We present here the first Taiwanese retrospective paired cohort study comparing the effectiveness of thymectomy among 16 seronegative and 32 seropositive MG patients after matching for age-of-onset and time-to-thymectomy, and following up over a mean of 35 +/- 20 (7-86) months. Clinical characteristics and complete stable remission (CSR) rates were compared and analyzed between the groups.

RESULTS

There were no major clinical differences between the two groups except for our finding of a lower percentage of SNMG receiving preoperative plasmapheresis or human immunoglobulin than SPMG (31% for SNMG vs 72% for SPMG, P = 0.007). CSR rates calculated using the Kaplan-Meier method were similar in the two groups (38% for SNMG vs 50% for SPMG, P = 0.709). The median time for CSR was 47.4 months for SNMG and 48.2 months for SPMG. Thymic hyperplasia were the most common pathology (69% for SNMG vs 88% for SPMG, P = 0.24). During the follow-up period, we found no group difference on prednisolone or pyridostigmine dosages. Significant postoperative dosage reductions on pyridostigmine, but not on prednisolone, were found in both groups.

CONCLUSIONS

Thymectomy has a comparable response among SNMG and SPMG in our study. Thymic hyperplasia is prevalent in our SNMG patients and thymectomy may also be a therapeutic option to increase the probability of remission or improvement in SNMG. More prospective controlled trial will be helpful in the future.

Basic immunosuppressive drugs outside solid organ transplantation

Immunosuppressive drugs are the backbone of solid organ transplantation. The introduction of new immunosuppressive drugs led to improved patient and organ survival rates. Nowadays, acute rejection can be reduced to a minimum. Individualization and avoidance of drug-related adverse effects became a new goal to achieve. The potency of immunosuppressive drugs makes them attractive for use in various autoimmune diseases; therefore, the experience on immunosuppressive drugs outside the field of organ transplantation is analysed in this review.

Non-ptotic ocular myasthenia gravis: a common presentation of an uncommon disease

BACKGROUND

Myasthenia gravis (MG) is an acquired autoimmune disease of the neuromuscular junction which causes rapid muscle fatigue and weakness. Two thirds of all cases of myasthenia gravis (MG) initially manifest ptosis. In the absence of the characteristic variable ptosis, MG can present a challenge to the clinician. This article will review the current diagnostic and management strategies for MG.

CASE REPORTS

Five cases will be presented that did not initially present with ptosis. Each of these cases was previously misdiagnosed as a result of presentation of atypical myasthenia gravis signs and symptoms. The first two cases had signs and symptoms of a typical accommodative/vergence anomaly. The others manifested diplopia not normally associated with MG: one had a noncomitant vertical deviation; another had a stable 6(th) nerve palsy; and the third had a basic esotropia.

CONCLUSION

Although the hallmark findings of MG are ptosis and eye muscle palsy with variability, MG may present without ptosis, affect nonstriated muscles, and/or manifest either as a nonstrabismic vergence anomaly or as comitant nonvariable strabismic deviation.

Molecular mechanisms of neurotransmitter release

The release of neurotransmitter from neurons represents one of the pivotal events in synaptic transmission. Neurotransmitters are released from synaptic vesicles in presynaptic neurons in response to neural activity, diffuse across the synaptic cleft, and bind specific receptors in order to bring about changes in postsynaptic neurons. Some of the molecular processes that govern neurotransmitter release are now becoming better understood. The steps involved can be broken down into two partially overlapping presynaptic cycles, the neurotransmitter cycle and the synaptic vesicle cycle. The neurotransmitter cycle involves transmitter biosynthesis, storage, reuptake, and degradation. The synaptic vesicle cycle involves targeting to the nerve terminal, docking, fusion, endocytosis, and recycling. Biochemical and structural studies have yielded important insight into our understanding of each of these two cycles. Further, both pharmacological and genetic interference with either of these cycles results in profound alterations in synaptic transmission and behavior, demonstrating the crucial role of neurotransmitter release.

Clinical characteristics and prognosis of myasthenia gravis in older people

OBJECTIVES

To investigate the characteristics of myasthenia gravis (MG) in older people and to evaluate the benefits of immunosuppressive treatments at this age.

BACKGROUND

Myasthenia gravis in older adults has not been extensively studied. In patients with disease onset after the age of 60, treatment mainly relies on medical therapy because thymectomy is generally not performed unless a thymoma is present.

METHODS

Of 837 myasthenic patients followed since 1978, we identified 172 cases with onset after age 60. All patients were treated with anticholinesterases. In the decade from 1978 to 1988, immunosuppressive therapy was performed mainly with corticosteroids (prednisone); since 1989, azathioprine alone or, more often, associated with prednisone, has been increasingly used in MG patients. Long-term outcome was evaluated in 149 cases with follow-up longer than 1 year. Remission, pharmacological remission, and marked improvement with reduction in drug dosage were considered good results.

RESULTS

Patients older than age 60 at onset of the disease were 20.5% of our series, male/female ratio was 1.9, age at onset ranged from 61 to 86 years, 87.2% patients had generalized disease, thymoma was detected in 37 patients (21.5%). Of 149 cases with sufficient follow-up data, 9 were in remission, 111 achieved good results, 3 died of MG, and 120 required immunosuppressive therapy at some time. Sixty-seven patients had been treated with prednisone for 0.5-16 years (mean, 5 years); good results were recorded in 51 patients (76.1%) and severe side effects in 12 (17.9%). Forty-six patients had received combined therapy with prednisone and azathioprine for 1 to 12 years (mean, 3.9 years); good results were recorded in 41 patients (89.1%) and severe side effects in six (19.5%). Seven patients had been treated with azathioprine alone for 1 to 4 years (mean, 2.3 years) with good results in five and with no side effects.

CONCLUSIONS

The prognosis of MG in older people seems to be favorable, although full remission is rare and MG weakness, treatment side effects, and associated thymoma can contribute to mortality rate. In our experience, the combined therapy with prednisone and azathioprine was more effective than prednisone alone, and steroid-related side effects were more frequent than those related to azathioprine.

SFEMG in ocular myasthenia gravis diagnosis

BACKGROUND AND OBJECTIVE

In typical cases, the patient's history and clinical examination make it possible to diagnose ocular myasthenia gravis (OMG). But, in many cases a clear clinical picture is not present and OMG diagnosis is very difficult because gold diagnostic standard tests are not available. The diagnostic tests for OMG are usually unable to display a good sensitivity and specificity simultaneously. In this paper, we studied 86 cases submitted for suspected OMG.

METHODS

The patients were studied clinically and with various other tests used in OMG diagnosis (SFEMG, repetitive nerve stimulation, Ab anti AChR titration, tensilon test).

RESULTS AND CONCLUSION

SFEMG showed the highest sensitivity (100%) while Ab anti AChR showed the highest specificity (100%). To our knowledge this is the largest population of suspected OMG studied using most of the diagnostic parameters, reported in the literature.

Synaptogenesis and myopathy under acetylcholinesterase overexpression

Environmental, congenital, and acquired immunological insults perturbing neuromuscular junction (NMJ) activity may induce a variety of debilitating neuromuscular pathologies. However, the molecular elements linking NMJ dysfunction to long-term myopathies are unknown. Here, we report dramatically elevated levels of mRNA encoding c-Fos and the "readthrough" (R) variant of acetylcholinesterase (AChE) in muscles of transgenic mice overexpressing synaptic (S) AChE in motoneurons and in control mice treated with the irreversible cholinesterase inhibitor diisopropylfluorophosphonate (DFP). Tongue muscles from DFP-treated and AChE-S transgenic mice displayed exaggerated neurite branching and disorganized, wasting fibers. Moreover, diaphragm muscles from both transgenic and DFP-treated mice exhibited NMJ proliferation. 2'-O-methyl-protected antisense oligonucleotides targeted to AChE mRNA suppressed feedback upregulation of AChE and ameliorated DFP-induced NMJ proliferation. Our findings demonstrate common transcriptional responses to cholinergic NMJ stress of diverse origin, and implicate deregulated AChE expression in excessive neurite outgrowth, uncontrolled synaptogenesis, and myopathology.

An ice test for the diagnosis of myasthenia gravis

OBJECTIVE

To determine whether ice application to a ptotic eyelid can differentiate myasthenic from nonmyasthenic ptosis.

DESIGN

Prospective, multicenter, nonrandomized, comparative trial.

PARTICIPANTS

Twenty patients with myasthenia gravis (MG) and ptosis were evaluated in the neuro-ophthalmology service. CONTROL SUBJECTS: Twenty patients with nonmyasthenic ptosis evaluated in the same locale.

METHODS

Palpebral fissures were measured before and immediately after a 2-minute application of ice to the ptotic eyelid.

MAIN OUTCOME MEASURES

The difference in palpebral fissures in millimeters before and after ice application. Two or more millimeters of improvement after ice application was considered a positive ice test result.

RESULTS

A positive ice test result was noted in 16 of the 20 (80%) patients with MG and in none of the 20 patients without MG (P < 0.001). Of the 4 patients with MG and complete ptosis, 3 had a negative ice test result.

CONCLUSIONS

The ice test is a simple, short, specific, and relatively sensitive test for the diagnosis of myasthenic ptosis. The sensitivity of the ice test in patients with complete ptosis decreases considerably.

Neuromuscular disorders

Neuromuscular diseases form an heterogeneous group of illnesses. These diseases are rare and studies concerning their anaesthetic management are difficult. Patients with neuromuscular disease represent a challenge for the anaesthesiologist because of the frequent perioperative complications. Cardiac and respiratory functions are often involved, and the severity of the lesions are difficult to estimate. The possible interactions of different drugs necessitates a good knowledge of the drugs' actions and pathophysiological mechanisms.