Does myasthenia gravis affect the brain?

Cooccurrence of Myasthenia Gravis and Epilepsy: A Case Report

Myasthenia gravis (MG) is an autoimmune disease characterized by weakness and rapid fatigue of the voluntary muscles. Epilepsy is a neurological disorder marked by recurrent, unprovoked seizures. We present a case of a 34-year-old woman with idiopathic generalized epilepsy who developed MG at 33. While the relationship between MG and epilepsy remains unclear, it is known that antiepileptic drugs can exacerbate MG. The rarity of this association suggests a need for cautious selection of antiepileptic treatments to avoid worsening either condition.

Tracking Eye Movements for Diagnosis in Myasthenia Gravis: A Comprehensive Review

BACKGROUND

Around 60%--75% of myasthenia gravis (MG) patients initially present with nonspecific ocular symptoms. Failed recognition of these symptoms may delay the diagnosis of MG up to 5 years or more, leading to a reduced likelihood of remission and increased morbidity. Current diagnostic tests are either poorly sensitive for patients presenting with ocular symptoms alone or are time consuming, invasive, require a high level of technical expertise, and generally are universally difficult to obtain. This review will explore quantitative eye and pupil tracking as a potential noninvasive, time-effective, and less technically demanding alternative to current diagnostic tests of MG.

EVIDENCE ACQUISITION

Comprehensive literature review.

RESULTS

Thirty-two publications using oculography for the diagnosis of MG and 6 studies using pupillometry were evaluated. In MG patients, extra ocular muscle fatigue was evident in reports of intersaccadic, intrasaccadic and postsaccadic abnormalities, changes in optokinetic nystagmus, slow eye movements, disconjugate saccades, and pupillary constrictor muscle weakness.

CONCLUSIONS

Our review identified several potentially useful variables that derive from oculography and pupillometry studies that could assist with a timely diagnosis of MG. Limitations of this review include heterogeneity in design, sample size, and quality of the studies evaluated. There is a need for larger, well-designed studies evaluating eye-tracking measures in the diagnosis of MG, especially for patients presenting with purely ocular symptoms.

Myasthenia Gravis-An Analysis of Multimodal Evoked Potentials

INTRODUCTION

The aim of this study is a comprehensive analysis of the parameters of exogenous evoked potentials (visual, brainstem auditory, and somatosensory) in patients with myasthenia gravis (MG), a prototype of both neuromuscular junction disease and autoimmune disease. The study also seeks to isolate electrophysiological changes that may indicate disorders within the central and/or peripheral nervous system.

METHODS

A total of forty-two consecutive patients with myasthenia gravis (24 women, 18 men) were included in the study. All of the patients underwent EP examination. MR images were also analyzed.

RESULTS

In the group of MG patients, the latency of P100 (113.9 ± 13.9; p < 0.0001) VEP, wave III (3.92 ± 0.29; p = 0.015), wave V (5.93 ± 0.32; <0.0001), interlatency III-V (2.00 ± 0.12; p < 0.0001), interlatency I-V (4.20 ± 0.28; p < 0.001) BAEP, and all components of SEP (N9, P10, N13, P16, N20, P22) were significantly longer. Mean wave I and V amplitude BAEP were relatively lower.

CONCLUSIONS

The results of the study suggest the presence of disturbances in the bioelectric activities of the central and peripheral nervous system in MG patients.

Social, professional and neuropsychiatric outcomes in patients with myasthenia gravis

BACKGROUND

Recent medical advances have enabled the control of neurological symptoms and increased survival of patients with myasthenia gravis (MG). However, MG has many veiled consequences that may be underestimated by neurologists. Our aim was to clarify the social, professional, and neuropsychiatric issues of MG patients.

METHODS

We carried out a cross-sectional cohort study with MG patients from a university-affiliated referral hospital. We registered clinical and sociodemographic data, and patients were classified according the MGFA classification. Clinical severity was assessed with Myasthenia Gravis Composite (MGC) scale. Trained and blind investigators analyzed social and professional outcomes. Neuropsychiatric symptoms were evaluated with the Hospital Anxiety and Depression Scale (HADS) and the social support with the Multidimensional Scale of Perceived Social Support (MSPSS).

RESULTS

We enrolled 49 patients with MG. The mean age was 45.3 ± 18.1 years and 39 (79.6%) were women. There were 19 (38.8%) patients who become unemployed, 23 (46.9%) who had to retire prematurely, 31 (63.3%) that reported a significant reduction in work performance, and 23 (46.9%) who had a reduction in monthly income after the diagnosis of MG. Only 16 (32.6%) received any financial support and 24 (48.9%) patients had the perception of receiving a satisfactory social support. The practice of physical activity is a habit in only 10 patients (20.4%). Neuropsychiatric symptoms were present in 26 (53.1%) patients.

CONCLUSION

Patients with MG are vulnerable to social, professional, and mental disadvantages. Therapeutic success in MG goes beyond symptom relief and inevitably depends on a personalized approach to the patient.

Comorbid Depressive and Anxiety Symptoms in a Patient with Myasthenia Gravis

Introduction

Myasthenia gravis (MG) is a chronic illness most commonly found in women under 40 years. The most common psychiatric comorbidities found in MG include depressive and anxiety disorders.

Clinical Presentation

We describe a case of a 43-year-old African American female with MG who was brought in for shortness of breath. History included MG diagnosed twelve years prior to the current presentation and a history of seven intubations. The patient was admitted to the ICU and intubated. She endorsed poor sleep, easy fatigability, and feeling hopeless in the context of psychosocial stressors—being single, homeless, and unemployed. The patient was started on Zoloft 50 mg per oral daily for depression and Atarax 50 mg per oral three times a day for anxiety. The patient responded well to the treatment and was discharged on day 10 after the resolution of her symptoms with appropriate aftercare in place.

Discussion

Depressive and anxiety symptoms usually develop as comorbidity during MG disease. Depressive and anxiety symptoms, besides motor symptoms, have a negative impact on the quality of life. Mental health must be a clinical focus during the treatment of somatic symptoms during MG.

Risk of Depressive Disorders Following Myasthenia Gravis: A Nationwide Population-Based Retrospective Cohort Study

The chronic autoimmune disease myasthenia gravis (MG) is characterized by fluctuating muscle weakness, which can lead to a large amount of stress in the patient. The current investigation plans to assess the risk of depressive disorders in MG patients. A retrospective cohort study of patients ageing 20 years and older and also newly diagnosed with MG between January 1, 2000, and December 31, 2008, was conducted from the National Health Insurance Research Database (NHIRD) in Taiwan. Observations of all 349 MG patients and 1,396 control individuals were made until a diagnosis of a depressive disorder by a psychiatrist, until death, or until December 31, 2013. A range of comorbidities were found, such as coronary artery disease, hypertension, diabetes mellitus, and dyslipidemia, with cerebrovascular disease being reported more frequently in MG patients in comparison with control subjects. After adjustment of patients' sex, age, urbanization, comorbidities, and monthly income, results indicated that MG individuals are 1.94 times more at risk (95% confidence interval [CI], 1.15-3.27, P = 0.014) of developing depressive disorders than are controls. This showed an increased risk in the development of depressive disorders in people with MG. Thus, depressive symptoms in MG patients should be regularly assessed.

Immunopathogenesis in Myasthenia Gravis and Neuromyelitis Optica

Myasthenia gravis (MG) and neuromyelitis optica (NMO) are autoimmune channelopathies of the peripheral neuromuscular junction (NMJ) and central nervous system (CNS) that are mainly mediated by humoral immunity against the acetylcholine receptor (AChR) and aquaporin-4 (AQP4), respectively. The diseases share some common features, including genetic predispositions, environmental factors, the breakdown of tolerance, the collaboration of T cells and B cells, imbalances in T helper 1 (Th1)/Th2/Th17/regulatory T cells, aberrant cytokine and antibody secretion, and complement system activation. However, some aspects of the immune mechanisms are unique. Both targets (AChR and AQP4) are expressed in the periphery and CNS, but MG mainly affects the NMJ in the periphery outside of CNS, whereas NMO preferentially involves the CNS. Inflammatory cells, including B cells and macrophages, often infiltrate the thymus but not the target—muscle in MG, whereas the infiltration of inflammatory cells, mainly polymorphonuclear leukocytes and macrophages, in NMO, is always observed in the target organ—the spinal cord. A review of the common and discrepant characteristics of these two autoimmune channelopathies may expand our understanding of the pathogenic mechanism of both disorders and assist in the development of proper treatments in the future.

Cognitive fatigue in patients with myasthenia gravis

INTRODUCTION

Cognitive fatigue has frequently been reported in myasthenia gravis (MG). However, objective assessment of cognitive fatigability has never been evaluated.

METHODS

Thirty-three MG patients with stable generalized disease and 17 healthy controls underwent a test battery including repeated testing of attention and concentration (d2-R) and Paced Auditory Serial Addition Test. Fatigability was based on calculation of linear trend (LT) reflecting dynamic performance within subsequent constant time intervals. Additionally, fatigue questionnaires were used.

RESULTS

MG patients showed a negative LT in second d2-R testing, indicating cognitive fatigability. This finding significantly differed from stable cognitive performance in controls (P < 0.05). Results of Paced Auditory Serial Addition Test testing did not differ between groups. Self-assessed fatigue was significantly higher in MG patients compared with controls (P < 0.001), but did not correlate with LT.

CONCLUSIONS

LT quantifies cognitive fatigability as an objective measurement of performance decline in MG patients. Self-assessed cognitive fatigue is not correlated with objective findings. Muscle Nerve 56: 449-457, 2017.

Cognitive impairment as a central cholinergic deficit in patients with Myasthenia Gravis

Background

The purpose of this study was to investigate with neurophysiological and neuropsychological methods such as pupillometry, cognitive test and Hamilton Depression Rating Scale (HAM-D) the hypothesis of Central Nervous System (CNS) cholinergic involvement in patients with Myasthenia Gravis (MG).

Methods

Thirty-two patients (32) with MG and a mean age of 51.1 ± 17.2 volunteered to participate in this investigation, while thirty-three (33) healthy subjects with a mean age of 50.2 ± 14.8 served as controls. All subjects underwent pupillometric measurements and performed the Wechsler Memory Scale (WMS) and HAM-D. The pupillometric indices studied were: 1) latency for the onset of constriction (T1), 2) maximum constriction velocity (VCmax) and 3) maximum constriction acceleration (ACmax).

Results

T1 was found significantly increased by 21.7% (p < 0.05) in MG patients as compared to healthy subjects. Conversely, VCmax and ACmax were significantly decreased in MG patients by 33.3% (p < 0.05) and 43.5% (p < 0.05) respectively, as opposed to healthy subjects. Additionally, MG patients showed significantly decreased score in WMS by 41.6% (p < 0.05) as compared to healthy controls. No significant difference was found for HAM-D between the two groups.

Conclusions

VCmax and ACmax are governed mainly by the action of the Parasympathetic Nervous System, through acetylcholine. The results of this study demonstrate that the CNS may be affected in MG and support the hypothesis that MG has central cholinergic effects manifested by cognitive dysfunction.

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Myasthenia Gravis has central cholinergic deficits manifested by cognitive dysfunction.

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The hypothesis of Central Nervous System cholinergic involvement was examined with pupillometry and cognitive tests.

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Central Cholinergic System and/or the iris sphincter smooth muscle might be affected in Myasthenia Gravis.

Epilepsy in systemic autoimmune disorders

Autoimmunity and inflammation have been implicated as causative factors of seizures and epilepsy. Autoimmune disorders can affect the central nervous system as an isolated syndrome or be part of a systemic disease. Examples of systemic autoimmune disorders include systemic lupus erythematosus, antiphospholipid syndrome, rheumatic arthritis, and Sjögren syndrome. Overall, there is a 5-fold increased risk of seizures and epilepsy in children with systemic autoimmune disorders. Various etiologic factors have been implicated in causing the seizures in these patients, including direct inflammation, effect on blood vessels (vasculitis), and production of autoantibodies. Potential treatments for this autoimmune injury include steroids, immunoglobulins, and other immune-modulatory therapies. A better understanding of the mechanisms of epileptogenesis in patients with systemic autoimmune diseases could lead to targeted treatments and better outcomes.

Prevalence and clinical specificity of fatigue symptoms in chronic fatigue syndrome, multiple sclerosis, and myasthenia gravis

This article provides a critical review of the psychological and related literature on fatigue resulting in both mental and physical experiences. On one hand, prolonged severe fatigue is a prominent disabling symptom in various diseases of different aetiology – psychiatric (e.g. depression), somatic (e.g. some infections) and neurologic (e.g. multiple sclerosis, myasthenia gravis). For instance, fatigue is a main symptom of myasthenia that leads to pathological skeletal muscle weakness. Furthermore, 40 to 90 per cent of individuals suffering from multiple sclerosis confirm they have experienced fatigue, which impairs their cognitive functioning. In both multiple sclerosis and myasthenia, fatigue has not only a physical but also a psychological dimension. On the other hand, fatigue can be seen as an isolated set of symptoms of unknown origin called the chronic fatigue syndrome (CFS). The development of the concept, diagnostic criteria and some strategies of coping with CFS are presented. Various somatic disorders, as well as subjective cognitive and emotional complaints, are common and well documented in patients with CFS. The most typical include depression, as well as problems with concentration of attention, decision-making and reasoning in complex situations. However, general intellectual abilities and higher order cognitive skills are intact. Directions for future research are outlined.

The decreased expression of thioredoxin-1 in brain of mice with experimental autoimmune myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease caused by circulating antibodies that block acetylcholine receptor (AchR) at the neuromuscular junction. There is the cognitive and memory impairment in patients with MG. However, the molecular mechanisms underlying the alteration of central nervous system in MG remain unknown. In the present study, we found that the level of malondialdehyde (MDA) was increased in the brain of experimental autoimmune myasthenia gravis (EAMG). Furthermore, the expression of thioredoxin-1 (Trx-1) and the activity of cAMP response element-binding protein (CREB) were significantly decreased in frontal lobe and hippocampus of mice with EAMG. We also found that the expression of pro-apoptotic C/EBP homologous protein (CHOP) was increased in the frontal lobe and hippocampus of mice. However, the expressions of glucose regulated protein 78 (GRP78/Bip) was not changed in same areas. Inversely, the expressions of pro-caspase-12, pro-caspase-3 and pro-caspase-9 were decreased. These data indicate that Trx-1 mediated endoplasmic reticulum and mitochondria pathways are involved in brain damage in MG. Trx-1 may be a pivotal target for brain protective treatment in MG.

The Relationship of Symptoms of Anxiety and Depression with Disease Severity and Treatment Modality in Myasthenia Gravis: A Cross-sectional Study

INTRODUCTION

Findings about the relationship between psychopathology and severity of myasthenia gravis (MG) seem scarce and conflicting. The aim of this study was to investigate the relationship of depressive and anxiety symptoms with disease severity and treatment modalities among a cohort of patients with MG.

METHODS

Sixty-seven patients, who presented to the neuromuscular outpatient clinic, at a neuropsychiatry hospital in Istanbul, Turkey in a two-month period, were recruited consecutively. A total of 42 patients with MG were invited to participate in the study. None of the patients refused to participate. Severity of MG was assessed according to the Osserman and Genkins classification. The participants were evaluated by a sociodemographic form, the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Hamilton Depression Rating Scale 17-item version (HAM-D), and the Hamilton Anxiety Rating Scale (HAM-A).

RESULTS

The patients with stage IIB MG had significantly higher scores on the BAI, HAM-D, HAM-A total and somatic anxiety than those with stage I and IIA MG (p<0.05). Likewise, the patients taking a combination of prednisolone+pyridostigmine/azathioprine had significantly higher scores on the BAI, HAM-D, HAM-A total and somatic anxiety than those taking only prednisolone (p<0.05). Linear regression analysis revealed that disease severity and stressful life events were the factors associated with the HAM-D scores. Disease severity, treatment modalities, and gender were the factors associated with the HAM-A scores.

CONCLUSION

The results of the present study may suggest that patients with relatively more severe MG or those taking a combination of immunosupressive and anticholinesterase medications need psychiatric/psychological evaluation.

Sight and sound out of synch: fragmentation and renormalisation of audiovisual integration and subjective timing

The sight and sound of a person speaking or a ball bouncing may seem simultaneous, but their corresponding neural signals are spread out over time as they arrive at different multisensory brain sites. How subjective timing relates to such neural timing remains a fundamental neuroscientific and philosophical puzzle. A dominant assumption is that temporal coherence is achieved by sensory resynchronisation or recalibration across asynchronous brain events. This assumption is easily confirmed by estimating subjective audiovisual timing for groups of subjects, which is on average similar across different measures and stimuli, and approximately veridical. But few studies have examined normal and pathological individual differences in such measures. Case PH, with lesions in pons and basal ganglia, hears people speak before seeing their lips move. Temporal order judgements (TOJs) confirmed this: voices had to lag lip-movements (by ∼200 msec) to seem synchronous to PH. Curiously, voices had to lead lips (also by ∼200 msec) to maximise the McGurk illusion (a measure of audiovisual speech integration). On average across these measures, PH's timing was therefore still veridical. Age-matched control participants showed similar discrepancies. Indeed, normal individual differences in TOJ and McGurk timing correlated negatively: subjects needing an auditory lag for subjective simultaneity needed an auditory lead for maximal McGurk, and vice versa. This generalised to the Stream-Bounce illusion. Such surprising antagonism seems opposed to good sensory resynchronisation, yet average timing across tasks was still near-veridical. Our findings reveal remarkable disunity of audiovisual timing within and between subjects. To explain this we propose that the timing of audiovisual signals within different brain mechanisms is perceived relative to the average timing across mechanisms. Such renormalisation fully explains the curious antagonistic relationship between disparate timing estimates in PH and healthy participants, and how they can still perceive the timing of external events correctly, on average.

Facial Affect Recognition in Myasthenia Gravis

The assessment of facial expression is an important aspect of a clinical neurological examination, both as an indicator of a mood disorder and as a sign of neurological damage. To date, although studies have been conducted on certain psychosocial aspects of myasthenia, such as quality of life and anxiety, and on neuropsychological aspects such as memory, no studies have directly assessed facial emotion recognition accuracy. The aim of this study was to assess the facial emotion recognition accuracy (fear, surprise, sadness, happiness, anger, and disgust), empathy, and reaction time of patients with myasthenia. Thirty-five patients with myasthenia and 36 healthy controls were tested for their ability to differentiate emotional facial expressions. Participants were matched with respect to age, gender, and education level. Their ability to differentiate emotional facial expressions was evaluated using the computer-based program Feel Test. The data showed that myasthenic patients scored significantly lower (p < 0.05) than healthy controls in the total Feel score, fear, surprise, and higher reaction time. The findings suggest that the ability to recognize facial affect may be reduced in individuals with myasthenia.

Fracture rate in patients with myasthenia gravis: the general practice research database

SUMMARY

The aim of this study was to evaluate fracture risk after onset of myasthenia gravis using the UK General Practice Research Database. Overall fracture risk is not statistically increased compared with age- and gender-matched controls irrespective of glucocorticoid use, but was increased in those using antidepressants, anxiolytics or anticonvulsants.

INTRODUCTION

Myasthenia gravis (MG) is a neuromuscular disease which has been associated with an increased falls risk and glucocorticoid-induced osteoporosis, recognized determinants of increased fracture risk. The aim of this study was to evaluate the risk of fracture after onset of MG.

METHODS

We conducted a retrospective cohort study using the UK General Practice Research Database (1987-2009). Each MG patient was matched by age, sex, calendar time and practice to up to six patients without a history of MG and we identified all fractures and those associated with osteoporosis.

RESULTS

Compared to the control cohort, there was no statistically significant increased risk observed in patients with MG for any fracture (adjusted hazard ratio [AHR] 1.11; 95 % confidence interval [CI], 0.84-1.47) or osteoporotic fractures (AHR 0.98 [95 % CI 0.67-1.41]). Further, use of oral glucocorticoids up to a cumulative dose exceeding 5 g prednisolone equivalents did not increase risk of osteoporotic fracture (AHR 0.99 [95 % CI, 0.31-3.14]) compared with MG patients without glucocorticoid exposure. However, fracture risk was higher in patients with MG prescribed antidepressants (AHR 3.27 [95 % CI, 1.63-6.55]), anxiolytics (AHR 2.18 [95 % CI, 1.04-4.57]) and anticonvulsants (AHR 6.88 [95 % CI, 2.91-16.27]).

CONCLUSION

Overall risk of fracture in patients with MG is not statistically increased compared with age- and gender-matched controls irrespective of glucocorticoid use but was increased in those using antidepressants, anxiolytics or anticonvulsants. These findings have implications in strategies preserving bone health in patients with MG.

Profound olfactory dysfunction in myasthenia gravis

In this study we demonstrate that myasthenia gravis, an autoimmune disease strongly identified with deficient acetylcholine receptor transmission at the post-synaptic neuromuscular junction, is accompanied by a profound loss of olfactory function. Twenty-seven MG patients, 27 matched healthy controls, and 11 patients with polymiositis, a disease with peripheral neuromuscular symptoms analogous to myasthenia gravis with no known central nervous system involvement, were tested. All were administered the University of Pennsylvania Smell Identification Test (UPSIT) and the Picture Identification Test (PIT), a test analogous in content and form to the UPSIT designed to control for non-olfactory cognitive confounds. The UPSIT scores of the myasthenia gravis patients were markedly lower than those of the age- and sex-matched normal controls [respective means (SDs) = 20.15 (6.40) & 35.67 (4.95); p<0.0001], as well as those of the polymiositis patients who scored slightly below the normal range [33.30 (1.42); p<0.0001]. The latter finding, along with direct monitoring of the inhalation of the patients during testing, implies that the MG-related olfactory deficit is unlikely due to difficulties sniffing, per se. All PIT scores were within or near the normal range, although subtle deficits were apparent in both the MG and PM patients, conceivably reflecting influences of mild cognitive impairment. No relationships between performance on the UPSIT and thymectomy, time since diagnosis, type of treatment regimen, or the presence or absence of serum anti-nicotinic or muscarinic antibodies were apparent. Our findings suggest that MG influences olfactory function to the same degree as observed in a number of neurodegenerative diseases in which central nervous system cholinergic dysfunction has been documented.

Psychiatric disorders in myasthenia gravis

OBJECTIVE: To investigate the prevalence of psychiatric disorders in patients with myasthenia gravis (MG). METHOD: Forty-one patients with MG answered to a structured psychiatric interview (MINI-Plus). RESULTS: Eleven (26.1%) patients were diagnosed with a depressive disorder and 19 (46.3%) were diagnosed with an anxiety disorder. Patients with dysthymia were older (p=0.029) and had longer disease duration (p=0.006). Patients with social phobia also had longer disease duration (p=0.039). CONCLUSION: Psychiatric disorders in MG are common, especially depressive and anxiety disorders.

Factors associated with depressive state in patients with myasthenia gravis: a multicentre cross-sectional study

Objectives The objective of this study was to examine clinical factors associated with depressive state in patients with myasthenia gravis (MG). Design Cross-sectional study. Setting and participants We evaluated 287 consecutive cases of MG seen at six neurological centres located in Eastern Japan. Outcome measures All MG patients completed the Japanese version of the Beck Depression Inventory-Second Edition (BDI-II). Disease severity was determined according to the MG Foundation of America (MGFA) quantitative MG score, MG activities of daily living scale and MG composite scale (MG composite). Clinical state following treatment was categorised according to MGFA postintervention status. Associations between detailed clinical parameters of MG and BDI-II score were then examined statistically. Results Mean BDI-II score for patients with MG (11.0±8.1) did not differ substantially from and overlapped with that reported as the Japanese standard (8.7±6.4). The mean +2 SDs for the Japanese standard is 21.5, approximately equal to the cut-off level indicative of moderate or worse depression (>20 points) in the original English version. We thus defined BDI-II >21.5 as depressive state, with a frequency of 13.6% in patients with MG. Multivariate logistic regression analysis revealed current dose of oral prednisolone (OR 1.09, 95% CI 1.02 to 1.17; p=0.01), unchanged MGFA postintervention status (OR 3.55, 95% CI 1.18 to 10.71; p=0.02), time since onset (OR 0.93, 95% CI 0.87 to 0.99; p=0.03) and MG composite (OR 1.16, 95% CI 1.00 to 1.34; p=0.046) as factors independently associated with depressive state in MG. Conclusions Dose of oral corticosteroids appears to represent the major factor associated with depressive state in MG. Unchanged status despite treatment and early disease stage are also significant background factors for depressive state, along with disease severity.

Demyelinating disease in patients with myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disease characterized by fluctuating muscle weakness, caused by impaired neuromuscular transmission. Patients with MG can present other autoimmune diseases in association, commonly hypo or hyperthyroidism. The association of MG to demyelinating disease is rare and has been described before. We report on three Brazilian patients with MG that presented distinct demyelinating diseases, two monophasic and one recurrent neuromyelitis optica, several years after the diagnosis of MG, and discuss their clinical courses.

Mood and anxiety disorders in patients with myasthenia gravis: aetiology, diagnosis and treatment

Myasthenia gravis (MG) is a chronic, autoimmune disease involving neuromuscular junctions. It is frequently associated with symptoms such as loss of muscle strength, difficulty in respiration and swallowing, diplopia and ptosis. All chronic diseases, including MG, may have psychiatric consequences in terms of coping and adaptation. Psychiatric morbidity usually appears as anxiety disorders, such as panic disorder and generalised anxiety disorder, and as depressive disorders. However, there are very few data on the prevalence and aetiology of such psychiatric symptoms in patients with MG, and those available in the literature are generally from old studies with poor methodology. The interaction between MG and psychiatric disorders needs to be appreciated, especially in the primary care setting, since the symptoms may overlap. MG may be under-recognised initially because the psychiatric symptoms may coincide with those of the actual disease, such as fatigue, lack of energy and shortness of breath. On the other hand, co-morbid psychiatric symptoms that appear during the course of the illness may be misdiagnosed as true myasthenic symptoms; thus, leading to unnecessary drug treatment. Differentiation of the aetiology of these symptoms might alter the treatment choice and, therefore, affect the treatment success rate and patients' well-being. Psychiatric treatments must be carefully planned because of the risk of aggravating the underlying neurological disease. Even though there appears to be an intricate relationship between MG and psychiatric symptoms, there is very limited information on this subject. As such, prospective, randomised, controlled pharmaco/psychotherapy studies are needed to better direct the management of patients and, thus, improve quality of life during the course of the illness.

Current management options in myasthenia gravis

Myasthenia gravis has changed from being a frequently fatal condition with a reputation little better than motor neuron disease to a generally treatable condition over the previous century. However, the chronic, largely immunosuppressive treatment comes with the major problems of very slow response and of treatment-induced morbidity and mortality. -Myasthenia gravis is a model autoimmune disease of a model physiologic structure, so is well placed for trials of novel treatments with ramifications for autoimmunity generally. There are also good animal models, so specific approaches to reinduction of tolerance can be tested. Hope of future revolutions in treatment should not hinder efforts to better understand currently available therapies and a concerted approach to ameliorate the side effects of treatment.

Neuronal acetylcholine receptor alpha9-subunit: a possible central nervous system autoantigen

Nicotinic acetylcholine receptor (AChR) is a membrane glycoprotein composed of five subunits. Muscle AChR is consist of two alpha1 and one each beta, delta, and epsilon subunits, whereas the neuronal AChR molecules are made up of various combinations of alpha (alpha2-alpha10) and beta (beta1-beta4) subunits. Myasthenia gravis (MG) develops as a result of an autoimmune attack against muscular AChR. While the prevailing symptom is muscle weakness, very rarely MG patients may develop additional central nervous system (CNS) symptoms. The majority of the anti-AChR antibodies responsible from disease induction is directed against alpha1 subunit of AChR. There is considerable identity between muscular alpha1 and neuronal alpha9 subunits. Preliminary studies showed antibodies reactive with the CNS antigens in the serum samples of mice with experimental autoimmune myasthenia gravis (EAMG). Also, alpha9 was present in the CNS in widespread locations and the binding pattern of anti-alpha9 antibody was reminiscent of that of serum samples of some of the mice with EAMG. Serum anti-AChR antibodies of myasthenic patients might be cross-reacting with CNS AChR subunits and thus inducing CNS symptoms. Neuronal AChR alpha9-subunit might be a major target antigen in this process.

Sleep and Neuromuscular Disorders

Nocturnal sleep-related ventilatory alterations may occur in dis-proportion to the severity of the neuromuscular disorder. Diaphragm paralysis occurring with a neuromuscular disorder is an overlooked complication. Failure to thrive, daytime tiredness, and incapacitating fatigue may be the result of a correctable sleep-related abnormality, not the result of relentless progression of a neuromuscular condition. Polysomnographic evaluation is recommended for patients who have neuromuscular disorder who develop symptoms and signs of sleep-wake abnormality or nocturnal respiratory failure. Application of noninvasive positive airway ventilation and, in some cases, administration of supple-mental oxygen may improve quality of life and prolong survival of patients who have neuromuscular disorder.

[Intelligence, attention, and memory in patients with myasthenia gravis]

BACKGROUND

In patients with myasthenia gravis (MG), poor performance on cognitive tests has been found. Performance on memory tasks has been reported to correlate with disease activity, but memory in MG patients was also recently found to be unimpaired.

PATIENTS AND METHODS

Cognitive functioning was examined in 23 patients with MG and 23 healthy controls. The patients were assessed for IQ, memory, attention, and motor performance. Immunoglobulin G antiacetylcholine receptor autoantibody titers were determined. Event-related potentials were generated for patients and controls.

RESULTS

Mean IQs of patients were at average. Memory and attention were not more impaired in patients than controls. Event-related potentials were not delayed in either group. Patients with elevated autoantibody concentrations similarly showed unimpaired neurocognitive and motor functioning.

CONCLUSION

In this study, no evidence of neuropsychological impairment was found in MG, arguing against the involvement of higher cortical functions. Sleep abnormalities rather than central mechanisms may explain the memory impairments reported by some studies.

Neuromuscular disorders and sleep

Neuromuscular disorders are caused by the primary involvement of the motor unit. In these patients, sleep-disordered breathing (SDB) due to respiratory muscle weakness is often encountered during sleep. Because there is a tendency to overlook this disorder, all patients with neuromuscular disorders should be questioned about SDB. Overnight polysomnography is the best investigation for SDB and nocturnal desaturations. In the management of these patients, noninvasive intermittent positive pressure ventilation results in improvement of SDB and breathing.

[Epilepsy and myasthenia: a case report]

Epilepsy is 5 to 7 times more frequent among patients with myasthenia than in the general population. Myasthenia gravis is often associated with other affectsion, most of immunological origin. However, hypotheses explaining the association are still uncertain. We report a case of association in a woman who had epilepsy since the age of 9 years and developed myasthenia at the age of 23 years after having discontinued here anti-epileptic treatment for two years.

Clinical evaluation and management of myasthenia gravis

Myasthenia gravis (MG) is a syndrome of fluctuating skeletal muscle weakness that worsens with use and improves with rest. Eye, facial, oropharyngeal, axial, and limb muscles may be involved in varying combinations and degrees of severity. Its etiology is heterogeneous, divided initially between those rare congenital myasthenic syndromes, which are genetic, and the bulk of MG, which is acquired and autoimmune. The autoimmune conditions are divided in turn between those that possess measurable serum acetylcholine receptor (AChR) antibodies and a smaller group that does not. The latter group includes those MG patients who have serum antibodies to muscle-specific tyrosine kinase (MuSK). Therapeutic considerations differ for early-onset MG, late-onset MG, and MG associated with the presence of a thymoma. Most MG patients can be treated effectively, but there is still a need for more specific immunological approaches.

What have we learned about cognition in myasthenia gravis?: a review of methods and results

Most individuals with myasthenia gravis (MG) complain of cognitive impairment, but empirical studies of cognition in MG have produced mixed results. In the present review, we critically examined the methodology and results of previous studies that investigated cognition in MG. Results from our review revealed that none of the studies met at least 50% of criteria under review. The most common shortcomings of previous studies included small sample size, no exclusion for visual difficulties in patients, inadequate assessment of mood, and poor control for prednisone use. Despite these methodological difficulties, mild impairments on measures of learning have been identified. These findings need to be replicated with adequate control of potential confounds before any conclusions can be made regarding cognition in this disease. Suggestions for design of future studies are provided.

Cognitive dysfunction in individuals with myasthenia gravis

In the present study we administered a battery of cognitive measures that examined attention, response fluency, information processing, and verbal and visual learning and retention to 28 individuals with generalized myasthenia gravis (MG) and 18 demographically similar control subjects. Results revealed that MG patients performed significantly more poorly than control subjects on the measures of response fluency, information processing and most measures of verbal and visual learning. Significant group differences were not evident on the measure of attention span or on the indices of retention of information. Cognitive performances of the MG group were not related to mood disturbance, disease duration, or daily dose of prednisone. While these results suggest central involvement in MG, previous studies have not provided evidence that MG antibodies bind to central nicotinic receptors. Possible alternative mechanisms underlying cognitive dysfunction in MG are discussed.