In muscular dystrophy, progressive weakness of respiratory muscles can result in varying degrees of breathing difficulty. One of the most important respiratory muscles is the diaphragm, which sits just below the lungs and helps in the process of inhalation, or breathing in, which supplies oxygen to the lungs. The weakening of the diaphragm in people with muscular dystrophy results in reduced oxygen intake and decreased lung function.
Different muscles help in exhalation, or removal of carbon dioxide. Contraction of muscles in the abdomen during activity supports exhalation, while at rest, lung elasticity aides in the removal of carbon dioxide. In muscular dystrophy patients, the excessive workload on the lungs, due to poor diaphragm function and the weakening of abdominal muscles, hinders the elimination of carbon dioxide.
Weakness in the muscles of the upper respiratory tract, or the nose and throat, causes difficulty breathing during sleep. This makes muscular dystrophy patients, therefore, prone to breathing problems while they are sleeping. Respiratory muscles also support coughing, and their breakdown causes coughing difficulties.
Source: Muscular Dystrophy News
Spinal Muscular Atrophy
Spinal muscular atrophy (SMA) is a disease that robs people of physical strength by affecting the motor nerve cells in the spinal cord, taking away the ability to walk, eat, or breathe. It is the number one genetic cause of death for infants. Individuals with SMA have difficulty performing the basic functions of life, like breathing and swallowing.
Duchenne Muscular Dystrophy
Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration and weakness due to the alterations of a protein called dystrophin that helps keep muscle cells intact.
Muscle weakness is the principal symptom of DMD. It can begin as early as age 2 or 3, first affecting the proximal muscles (those close to the core of the body) and later affecting the distal limb muscles (those close to the extremities). Usually, the lower external muscles are affected before the upper external muscles. The affected child might have difficulty jumping, running, and walking. Other symptoms include enlargement of the calves, a waddling gait, and lumbar lordosis (an inward curve of the spine). Later on, the heart and respiratory muscles are affected as well. Progressive weakness and scoliosis result in impaired pulmonary function, which can eventually cause acute respiratory failure.
Source: Muscular Dystrophy Association