Medical treatment options for ocular myasthenia gravis

OMGMed: Advanced System for Ocular Myasthenia Gravis Diagnosis via Eye Image Segmentation

This paper presents an eye image segmentation-based computer-aided system for automatic diagnosis of ocular myasthenia gravis (OMG), called OMGMed. It provides great potential to effectively liberate the diagnostic efficiency of expert doctors (the scarce resources) and reduces the cost of healthcare treatment for diagnosed patients, making it possible to disseminate high-quality myasthenia gravis healthcare to under-developed areas. The system is composed of data pre-processing, indicator calculation, and automatic OMG scoring. Building upon this framework, an empirical study on the eye segmentation algorithm is conducted. It further optimizes the algorithm from the perspectives of "network structure" and "loss function", and experimentally verifies the effectiveness of the hybrid loss function. The results show that the combination of "nnUNet" network structure and "Cross-Entropy + Iou + Boundary" hybrid loss function can achieve the best segmentation performance, and its MIOU on the public and private myasthenia gravis datasets reaches 82.1% and 83.7%, respectively. The research has been used in expert centers. The pilot study demonstrates that our research on eye image segmentation for OMG diagnosis is very helpful in improving the healthcare quality of expert doctors. We believe that this work can serve as an important reference for the development of a similar auxiliary diagnosis system and contribute to the healthy development of proactive healthcare services.

Diagnostic accuracy and clinical utility of bed side tests versus laboratory tests in the diagnosis of ocular myasthenia

Purpose

To assess the diagnostic accuracy of forced eyelid closure test (FECT), ice pack test (IPT), repetitive nerve stimulation test (RNS), and acetylcholine receptor (AchR) antibody test in patients with suspected ocular myasthenia. To assess the clinical utility of AchR antibody test in predicting disease progression.

Methods

Retrospective cohort study of patients diagnosed with ocular myasthenia at a South-Indian neuro-ophthalmology tertiary eye clinic. Baseline characteristics; ocular myasthenia symptoms; results of FECT, IPT, RNS, and AchR antibody test; and progression time to generalized myasthenia (GM) over 36 months from the time of diagnosis were recorded and analyzed using receiver operator curve analysis, multiple logistic regression, and Kaplan-Meier survival analysis.

Results

FECT had a sensitivity of 96.7% (95% CI: 88.5-99.6) and a specificity of 75% (95% CI: 34.9-96.8). Combination of FECT and IPT, using the positivity of at least one test, increased the sensitivity to 98.3% (95% CI: 91-100), reducing the specificity to 50% (95% CI: 15.7-84.3), whereas using the positivity of both tests, we obtained a sensitivity of 71.7% (95% CI: 58.6-82.5) and a specificity of 100% (95% CI: 63.1-100). In the subset of patients with double negative RNS and AchR antibodies, the positive predictive value of combined FECT and IPT (double positive) was 100%. Patients who developed GM were more likely to have a positive AchR antibody test result (P = 0.001).

Conclusion

Combined FECT and IPT (double positive) has high diagnostic accuracy even among patients with normal RNS and negative AchR antibodies. Despite low sensitivity, AchR-antibody test has a significant predictive value in disease progression.

Pediatric Ocular Myasthenia Gravis: A Review

Pediatric ocular myasthenia gravis (OMG) is difficult to diagnose and manage, owing to its rarity and low index of suspicion in the early stage of the disease. Also, many other conditions having similar presentation cause a further delay in diagnosis. In this review, we highlighted various pointers in history and described bedside clinical tests that can aid in its timely diagnosis. The antibody spectrum in myasthenia is ever increasing and includes anti-muscle specific kinase and low-density lipoprotein-receptor related protein 4 antibodies in addition to acetylcholine receptor antibodies besides many others. However, pediatric OMG patients often test negative for all three antibodies, making the diagnosis even more difficult in triple seronegative patients. Edrophonium and electrophysiological tests, which help in confirming myasthenia in adults, have a limited utility in diagnosing pediatric ocular myasthenia cases. Various practical difficulties are encountered like nonavailability of edrophonium, risk of bradycardia associated with neostigmine use and its lower sensitivity, noncooperative children, and limited technical expertise in performing electrophysiological tests in children. In this article, we described a pragmatic approach to diagnose pediatric OMG along with the important aspects of its management.

Prognostic factors for conversion to generalization in ocular myasthenia gravis

Patients with ocular myasthenia gravis (OMG) are frequently treated to prevent the development of generalized myasthenia gravis (GMG). This retrospective cohort study aimed to assess prognostic factors associated with conversion to GMG.We analyzed the time from the onset of OMG symptoms to GMG in relation to demographic variables, clinical findings, initial investigation results, and treatment regimens using Kaplan-Meier survival curves and multivariate Cox proportional regression analysis.Of 115 patients diagnosed with OMG (median follow-up time, 2.9 years), 28 (30.4%) developed GMG. The 2-year probability of GMG conversion was 23.7%. Patients with thymic abnormalities and a positive response to repetitive facial nerve stimulation had a significantly higher risk than those with negative results (hazard ratios [HR] 4.28, P < .001 and HR 3.84, P = .04, respectively). Treatment with immunosuppressants was found to be a preventive factor for secondary generalization (HR 0.36, P = .02).Patients with OMG had a low risk of developing GMG. Immunosuppressive treatments may mitigate disease progression. Chest imaging and repetitive nerve stimulation should be routinely performed to assess the risk of generalization.

Clinical features and treatment status of antiacetylcholine receptor antibody-positive ocular myasthenia gravis

PURPOSE

To clarify the factors predictive of progression from ocular myasthenia gravis (OMG) to generalized MG (GMG) among patients with positive antiacetylcholine receptor antibodies (AChRAb) and to evaluate the efficacy of our OMG treatment protocol including tacrolimus (TAC).

STUDY DESIGN

Retrospective study.

METHODS

Fifty-two patients with AChRAb positivity and ptosis and/or eye movement disturbance showing diurnal fluctuation and fatigability were included. First, we compared the clinical characteristics of patients without OMG progression (p-OMG) with those of patients whose OMG transformed to GMG (TMG). Second, we subdivided the p-OMG patients according to the time of approval of TAC into the Before group and the After group. We compared the dosage and period of prednisolone administration (PSL) of the 2 groups. Third, we evaluated the responses to OMG treatment using the Myasthenia Gravis Foundation of America Postintervention Status (MGFA-PS) scale.

RESULTS

Forty-one patients were classified into the p-OMG group, and 11, into the TMG group. The AChRAb level (P = 0.0006) and prevalence of thymoma (P = 0.001) were significantly higher in the TMG group than in the p-OMG group. In the p-OMG group, the MG composite score (P ≤ 0.0001) and AChRAb level (P = 0.005) improved after treatment. The periods of PSL administration at ≥ 20 mg/day (P = 0.009) and at 10 to 19 mg/day (P = 0.002) were significantly shorter in the After group. At the last follow-up, 78.0% of the p-OMG group patients had achieved MGFA-PS minimal manifestations or better status with PSL ≤ 5 mg/day.

CONCLUSIONS

The TMG cases were characterized by higher AChRAb levels and presence of thymoma. The P-OMG patients could be managed with our treatment protocol. Combined use of TAC was efficacious in patients with steroid-dependent p-OMG.

Efficacy and Safety of Low-to-Moderate Dose Oral Corticosteroid Treatment in Ocular Myasthenia Gravis

PURPOSE

To evaluate the response to corticosteroid therapy as a primary treatment for ocular myasthenia gravis.

METHODS

Patients diagnosed as having ocular myasthenia gravis by an acetylcholine receptor binding antibody test between January 2011 and September 2015 were included in the study and started receiving treatment with a corticosteroid. Patients with a blowout fracture, hyperthyroidism, diabetes mellitus, hypertension, cardiovascular disease, or history of strabismus surgery were excluded. Disappearance of diplopia and ptosis were considered a response to treatment.

RESULTS

Methylprednisolone therapy was administered to 29 patients (19 men and 10 women; average age: 49 ± 16.5 years) as an initial treatment. A total of 6 patients were lost to follow-up. Twenty-three of 29 patients (82.6%) were regarded as having presented a response to treatment. The average treatment duration was 3 weeks for patients responding to primary treatment. Eight patients complained of adverse effects from steroid therapy such as heartburn, insomnia, weight gain, and myalgia.

CONCLUSIONS

A corticosteroid could be considered as an initial treatment for patients diagnosed as having ocular myasthenia gravis by an acetylcholine receptor binding antibody test. [J Pediatr Ophthalmol Strabismus. 2018;55(5):339-342.].

Ocular vestibular evoked myogenic potential in patients with myasthenia gravis: A prospective clinical study

OBJECTIVE

Myasthenia gravis (MG) is an archetypic disorder of neuromuscular junctions (NMJs) and autoantibody-mediated disease causing fatigable weakness of skeletal muscles with an ocular onset in up to 85%. The aim of this study was to detect extra ocular muscles (EOMs) abnormalities in MG patients using ocular vestibular evoked myogenic potential (oVEMP) n10 response.

METHODS

The oVEMP was performed on 40 myasthenia gravis patients that were divided into three groups: newly diagnosed (10 patients), uncontrolled on treatment (15 patients) and controlled on treatment (15 patients) groups in addition to a control group of 10 subjects. Also a comparison of oVEMP response was held between patients with generalized and ocular MG.

RESULTS

The oVEMP n10 showed significant difference between the 3 study groups and the control. The n10 showed no significant difference between the newly diagnosed group and the other 2 groups. There was also significant difference between uncontrolled and controlled on treatment group and between generalized and ocular types of myasthenic patients.

CONCLUSION

The oVEMP can be usefully used in diagnosis of new MG patients as regard n10 amplitude, threshold and AR except n10 latency with no therapeutic or monitoring value of oVEMP in MG.

Ocular presentation of myasthenia gravis: A natural history cohort

INTRODUCTION

There are limited data on the natural history of untreated myasthenia gravis (MG) with ocular presentation.

METHODS

We analyzed 93 patients from symptom onset who presented to the Birmingham Midlands Eye Centre (BMEC) between January 2004 and July 2015. We used multiple stepwise logistic regression to identify predictive factors of generalization and Kaplan-Meier analysis on time to generalization.

RESULTS

Forty-six percent of patients developed generalized symptoms during the study period. Median time to generalization was 7 months. Time to generalization was earlier in patients seropositive for acetylcholine receptor (AChR) antibody (median 5 months vs. 21 months, P < 0.0001) and bilateral ptosis at onset (P = 0.015). Multivariate analysis identified AChR seropositivity [hazard ratio (HR) 5.03; 95% confidence interval (CI) 1.48-17.14; P = 0.001] and disease onset < 50 years (HR 3.58; 95% CI 1.18-10.90; P = 0.035) as risk factors for generalization.

DISCUSSION

As patients were steroid-naive before generalization, our cohort approximated the natural history of the condition. Muscle Nerve 57: 622-627, 2018.

Ocular myasthenia gravis: a review

Myasthenia gravis (MG) is a disease that affects the neuro-muscular junction resulting in classical symptoms of variable muscle weakness and fatigability. It is called the great masquerader owing to its varied clinical presentations. Very often, a patient of MG may present to the ophthalmologist given that a large proportion of patients with systemic myasthenia have ocular involvement either at presentation or during the later course of the disease. The treatment of ocular MG involves both the neurologist and ophthalmologist. Thus, the aim of this review was to highlight the current diagnosis, investigations, and treatment of ocular MG.

Treatment of ocular motor palsies

OPINION STATEMENT

The management of ocular motor palsies first requires careful determination of the etiology. Possibilities include ischemia, inflammation, infection, trauma, compression, or congenital. Prognosis for recovery varies greatly between etiologies; hence, determination of the underlying process is crucial in the short- and long-term management of these patients. Naturally, our ultimate goal is to improve visual function as much as possible. A guiding principle in the initial management of ocular motor palsies is to improve patient comfort and visual function by eliminating diplopia in primary position while clinically observing the patient for improvement or stability. Offering a definitive treatment which creates the largest possible zone of binocular single vision in primary and reading positions can be undertaken once stability has been demonstrated. In the initial phase after an acute ocular motor palsy has occurred, occlusion of an eye can be used to eliminate diplopia. Options include a patch or applying translucent or satin tape to one of the lenses which prevents diplopia but still lets light through. Alternatively, prismatic correction placed on or ground into spectacles may improve function and restore binocularity in patients with temporary or permanent ocular deviations. This is generally effective for patients with up to 20 to 25 prism diopters (PD) of horizontal misalignment and 10 to 15 PD of vertical. Once a stable misalignment has been demonstrated (several months), a variety of surgical options exist. Use of adjustable sutures, improved suture materials, and surgical techniques has expanded the role and scope of surgery for these patients. Planning the surgical approach is based on residual extraocular muscle function, careful measurements, and assessment of patient expectations.

Protective effect of Sijunzi decoction on neuromuscular junction ultrastructure in autoimmune myasthenia gravis rats

OBJECTIVE

To investigate the protective role of Sijunzi decoction in neuromuscular junction (NMJ) and muscle cell mitochondria ultrastructure; as well as its effects on the amount of adenosine triphosphate (ATP) and the activities of mitochondrial respiratory chain complexes I, II, III, and IV in autoimmune myasthenia gravis rats.

METHODS

An experimental autoimmune myasthenia gravis (EAMG) rat model was established by inoculating rats with acetylcholine receptors extracted from Torpedo. Rats were divided into three groups: model, prednisone, and Sijunzi decoction, and were fed physiological saline, prednisone, or Sijunzi decoction, respectively. NMJ and muscle cell mitochondria ultrastructure were observed by transmission electron microscope. The amount of ATP was assessed by high performance liquid chromatography. The activities of mitochondrial respiratory chain complexes I, II, III, and IV was determined using the Clark oxygen electrode method.

RESULTS

In the model group, there were sparse muscle fibers, with decreased mitochondria, and sparse, diffluent, or absent NMJ folds. After intervention with Sijunzi decoction, the above pathology changes were improved: muscle fiber structure was clear and complete; the mitochondria count was higher; and the NMJ structure was close to normal. Gastrocnemius muscle mitochondria in the model group produced significantly less ATP than those in the prednisone group (P < 0.01). Conversely, the ATP of Sijunzi decoction group was significantly higher than prednisone group (P < 0.01). The activities of gastrocnemius muscle mitochondrial respiratory chain complexes I, II, III, and IV in both the prednisone and Sijunzi decoction groups was dramatically higher compared with the model group (P < 0.05). The activities of complexes I and III in the Sijunzi decoction group were significantly higher than those in the prednisone group (P < 0.05), but there was no obvious difference in complex II or IV activities between the two groups (P > 0.05).

CONCLUSION

Sijunzi decoction improved pathological changes in muscle mitochondria and NMJ, enhanced the amount of ATP in gastrocnemius muscle mitochondria, and improved the activities of respiratory chain complexes I, II, III, and IV (especially I and III) of the EAMG rats.

Treatment of ocular myasthenia gravis

OPINION STATEMENT

Myasthenia gravis (MG) is an autoimmune disorder that is characterized by variable weakness and fatigability. Often, MG presents with only ocular symptoms such as ptosis and diplopia. Treatment of ocular MG is aimed at relieving the symptoms of ptosis and diplopia, as well as preventing the development of generalized MG symptoms. Immune suppression with steroids is often the main therapy. Steroid doses must be increased slowly because of a risk of precipitating myasthenic crisis. After achieving the highest target dose, steroids are then slowly tapered down to the lowest effective dose. Often, acetylcholinesterase inhibitors such as pyridostigmine and neostigmine are also employed to help control symptoms. When steroids are contraindicated, acetylcholinesterase inhibitors can be tried as the primary therapy. Steroid-sparing agents such as azathioprine and mycophenolate may also have a role in treating ocular MG. Other treatments for MG include plasmapheresis, intravenous immunoglobulin, and other immunosuppressive agents, but these are rarely required for ocular MG. Patients should also be evaluated for thymoma. Thymoma should be resected surgically. Ocular MG without thymoma is not usually treated with thymectomy. Topical agents may be useful as additional therapy for mild or moderate ptosis. Nonpharmacologic treatments include occlusive devices, prisms, eyelid supports, contact lenses, and (in long-standing, stable cases) strabismus surgery or eyelid elevation surgery.

Comparison of clinical manifestations between patients with ocular myasthenia gravis and generalized myasthenia gravis

Purpose

To compare the clinical manifestations between patients with ocular myasthenia gravis and those with generalized myasthenia gravis (MG).

Methods

The medical records of 71 patients diagnosed with MG between January 1995 and December 2007 were reviewed. Demographics, sensitivities of diagnostic methods, the presence of systemic autoimmune diseases, ophthalmic complications caused by MG, and treatments were evaluated and compared.

Results

Fourteen patients (20%) were diagnosed with ocular MG and 57 patients (80%) with generalized MG. Sensitivities of anti-acetylcholine receptor antibody and repetitive nerve stimulation tests were significantly higher in the generalized MG group (84%, 89%) compared to those in the ocular MG group (50%, 54%) (p = 0.011, p = 0.008). The sensitivity of the neostigmine test was the highest in both groups (98% of generalized MG, 79% of ocular MG), and the difference between the two groups was borderline significant (p = 0.058). The most common symptoms were ptosis and diplopia, and both groups presented with pain, blurred vision, and tearing. Systemic autoimmune disease was more prominent in the generalized MG group (21%) than in the ocular MG group (14%), and steroid therapy was used more frequently in the generalized MG group (82%) than in the ocular MG group (57%). Ophthalmic complications associated with long-term steroid treatment were more profound in the generalized MG (30%) compared to those of the ocular MG (21%).

Conclusions

The generalized MG group was associated with higher sensitivities to diagnostic tests, more systemic steroid use, higher ophthalmic complications caused by systemic autoimmune disease, and long-term steroid treatment compared to those of the ocular MG group.

Infranuclear ocular motor disorders

This chapter covers the very large number of possible disorders that can affect the three ocular motor nerves, the neuromuscular junction, or the extraocular muscles. Conditions affecting the nerves are discussed under two major headings: those in which the site of damage can be anatomically localized (e.g., fascicular lesions and lesions occurring in the subarachnoid space, the cavernous sinus, the superior orbital fissure, or the orbit) and those in which the site of the lesion is either nonspecific or variable (e.g., vascular lesions, tumors, "ophthalmoplegic migraine," and congenital disorders). Specific comments on the diagnosis and management of disorders of each of the three nerves follow. Ocular motor synkineses (including Duane's retraction syndrome and aberrant regeneration) and disorders resulting in paroxysms of excess activity (e.g., neuromyotonia) are then covered, followed by myasthenia gravis and other disorders that affect the neuromuscular junction. A final section discusses disorders of the extraocular muscles themselves, including thyroid disease, orbital myositis, mitochondrial disease, and the muscular dystrophies.