Diaphragm Thickness by Ultrasonography in Neurological Disorders

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.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