Assessment of Diaphragm Thickness by Ultrasonography in Guillain Barre Syndrome and Myasthenia Gravis

after IRB (institutional research board ) approval, of the faculty of medicine, Mansoura University, Egypt, written informed consent from all participants will be taken. participants will be allocated into three groups, acute neuropathy (Guillain Barre Syndrome) group, neuromuscular junction disorder(myasthenia gravis ) group, and control group(people with neurological disorders not affecting the respiratory system. inclusion group: age more than 18, both sexes. exclusion criteria: cardiopulmonary disease, chest trauma, diaphragmatic injury, body mass index more than 30. Any participant who shows respiratory dysfunction on doing arterial blood gases and pulmonary function tests will not be enrolled in the study. methods: Ultrasonography is done on the diaphragm. The index test (ultrasound imaging of the diaphragm) is used. A high-resolution portable ultrasound machine is used, with a 7- to 13-MHz linear array transducer. Patients will be examined in the supine position. diaphragmatic thickness will is measured on both sides during a deep breath in inspiration and during expiration. objectives: primary outcome: to compare diaphragm thickness between the three examined groups. Secondary outcome: correlation between clinical scores and reference US values of diaphragm