Diaphragmatic Paralysis - Symptoms, Evaluation, Therapy and Outcome

The diaphragm has a major role in inspiration. The muscle separates the mostly negative pressure chest cavity, from the positive pressure abdomen. The displacement of the muscle with inspiration expands the chest, augmenting the negative pleural pressure, thereby forcing air flow into the lung. However paralysis of the muscle, unilaterally or even bilaterally, is compatible with life in most cases due to effective adaptation of the other muscles of respiration. Patients with diaphragmatic paralysis may experience a wide range of symptoms: from being asymptomatic, symptomatic only with exercise, or respiratory insufficiency and death. Symptoms depends on the pre existing cardiorespiratory status, the extent of paralysis, unilateral or bilateral and on the nature of the paralysis, acute or chronic. Some symptoms are distinct and should always raise the diagnosis of diaphragmatic paralysis. The wide range of symptoms will be described, as well as the anatomical and physiological aspects in the normal and in the disease state, etiologies, work up and therapy. Unilateral and bilateral paralysis will be discussed together, despite differences in the prevalence, causes and course.