MYASTENİA GRAVİS’Lİ BİREYLERDE KORTİKAL EKSİTABİLİTENİN DEĞERLENDİRİLMESİ, YORGUNLUK, FİZİKSEL PERFORMANS VE YAŞAM KALİTESİ PARAMETRELERİYLE İLİŞKİSİ

Abstract

This study was planned to assess cortical excitability in individuals with Myasthenia Gravis (MG), compare it with healthy controls, and demonstrate the relationship of the results with fatigue, physical performance, and quality of life. The study included 26 individuals with MG with an average age of 45.73±11.48 years and 24 healthy individuals with an average age of 40.30±12.14 years. After recording the demographic data of the participants, Transcranial Magnetic Stimulation was used to evaluate cortical excitability in both groups. TMS measures included Intracortical Facilitation (ICF), Short-Interval Intracortical Inhibition (SICI), Short-Latency Afferent Inhibition (SAI), and Cortical Silent Period (CSP). The disease classification of the study group was determined using the Myasthenia Gravis Foundation of America Clinical Classification. Disease severity was measured using the Quantitative Myasthenia Gravis Score. Functional capacities were evaluated with the 6-minute walk test and arm movement test, respiratory capacities with respiratory function tests, subjective fatigue with the Checklist Individual Strength Scale, performance-based fatigue with the linear trend (LT), quality of life with the Myasthenia Gravis Quality of Life Scale (MGQoL15), daily living activities with the Myasthenia Gravis Activities of Daily Living Scale (MG-ADL), and sleep disorders with the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale. The study found that SAI, which indicates the activation of cholinergic pathways, was lower in the study group compared to the control group (p=0.009), and CSP latency, which indicates intracortical inhibition, was prolonged (p=0.018). Additionally, a relationship was found between ICF and the MG-ADL parameter, SAI and MGQoL15, FEV1, and FEF25-75 parameters, and CSP and KHT, MGQoL15, and LT6DYT parameters (p<0.05). In conclusion, the changes in cortical excitability observed in individuals with MG may be due to the adverse effects of the disease on central cholinergic pathways involving nicotinic acetylcholine receptors and the potential cortical changes caused by the chronic nature of the disease. It is crucial to assess patients for possible central neurological deficits. Considering the potential impact on the central nervous system, the effects of neuromuscular reeducation programs that promote brain plasticity and motor learning should be investigated.