Analysis of clinical manifestations and diagnosis of late-onset myasthenia gravis

Introduction. Myasthenia gravis is one of the most common autoimmune neuromuscular diseases, the peak incidence is in the age of 20–40 years. However, studies show that throughout the world in recent decades there has been an increase in the prevalence and incidence of myasthenia gravis among older people.

Purpose of the study – to evaluate the clinical manifestations and diagnostic features of myasthenia gravis in patients with an onset of diseases in the elderly.

Materials and methods. The retrospective, non-interventional study included 315 patients over 18 years old with a reliable (3 out of 4 criteria) and an undoubted (4 out of 4 criteria) diagnosis of myasthenia gravis, the duration of the disease for up to 5 years, undergoing inpatient treatment from 2001 to 2017 years. The severity of the clinical manifestations of myasthenia gravis was assessed using the Myasthenia Gravis Foundation of America scale. We were taken into account the information about the first symptoms, duration of the period from the onset of the disease to the verification of the diagnosis, results of the examinations, the presence of concomitant diseases and treatment methods.

Results. The most common symptom of myasthenia gravis in the group of patients with debut disease aged 60 years and older was ptosis (p <0.001). The crises and pathology of the thymus were less common in elderly patients (p <0.0001). The concentration of antibodies to acetylcholine receptors was the same (p = 0.05) among all patients. The level of antibodies to titin was increased in patients with lateonset (p = 0.0014). The presence of bronchopulmonary pathology made worse the course of myasthenia gravis in elderly people (p = 0.01), while cardiovascular and cerebrovascular diseases, as well as diabetes mellitus, did not occur (p >0.005). At the first examination in the group of elderly patients among the incorrectly diagnoses prevailed: stroke or decompensation of chronic cerebral ischemia (p = 0.0002). With a comparable duration and severity of myasthenia gravis in different age groups, the combination of anticholinesterase drugs, glucocorticosteroids and azathioprine (p = 0.01) at a lower daily dose (100 mg) was more often used for the treatment of elderly patients compared with young and middle-aged groups (150 mg) (p = 0.03).

Conclusion. Diagnosis of myasthenia gravis in elderly patients presents the greatest difficulties, and symptoms of manifestation during initial treatment are often regarded as a manifestation of vascular pathology. Despite the presence of concomitant diseases characteristic of this age group, myasthenia gravis does not differ in the severity of the course. To achieve remission and compensation of symptoms, elderly patients do not need large doses of symptomatic and pathogenetic drugs.

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