Fatigue and Asthenia

The word fatigue implies a sense of exhaustion, lassitude, or inability to generate drive or energy. In taking a medical history of a patient with fatigue, the examiner should pursue questions of timing and circumstance. A medical or psychiatric diagnosis can be established in two thirds of patients who complain of fatigue, and in many cases, they are remediable. This chapter reviews the history of fatigue, including outbreaks. The clinical picture, diagnostic criteria, special considerations in diagnosis, general medical disorders, prescription drugs, postural orthostatic tachycardia syndrome, neutrally mediated hypotension, Chiari malformation, neurologic causes of fatigue, psychiatric investigation, laboratory investigations, magnetic resonance imaging (MRI) studies, pathophysiology, prognosis, and treatment are detailed. Asthenia is discussed in relation to clinical data, the central nervous system, muscle, and electromyography (EMG). Tables include terms and phrases used for indicating fatigue; definitions, features, and medical causes of chronic fatigue syndrome (CFS); blood tests to evaluate chronic fatigue; symptoms of CFS determined from laboratory studies; MRI studies for