amyotrophy

Amyotrophy is a term used to describe wasting and progressive loss of muscle bulk, often accompanied by weakness. It is a descriptive finding rather than a single disease, and it can result from a variety of underlying conditions that affect the muscles or their nerve supply. The word itself comes from Greek roots meaning “without muscle nourishment,” reflecting the loss of muscle mass.

Causes and mechanisms

Amyotrophy can arise from neurogenic processes, where motor neurons or the nerves supplying muscles are damaged. This includes neurodegenerative diseases such as amyotrophic lateral sclerosis, peripheral neuropathies, and nerve injuries. It can also result from primary myopathies, in which the muscle fibers themselves are diseased, as seen in muscular dystrophies, inflammatory myopathies, and metabolic or mitochondrial myopathies. Other contributing factors include disuse atrophy from prolonged inactivity, malnutrition, chronic systemic illnesses, endocrine disorders, and aging.

Clinical features and diagnosis

Clinical presentation typically includes progressive muscle wasting with variable weakness. The pattern may be asymmetric in neurogenic cases or more symmetric in primary myopathies. Additional signs such as fasciculations, cramps, and reflex changes help differentiate neurogenic from myopathic processes. Evaluation usually involves electromyography and nerve conduction studies, serum creatine kinase levels (often elevated in myopathies), imaging as indicated, and sometimes muscle biopsy or genetic testing to identify specific etiologies.

Management and prognosis

Treatment focuses on the underlying cause when possible, with supportive measures such as physical therapy to maintain strength and range of motion, nutritional support, and management of complications. The prognosis varies widely depending on the underlying condition; some causes are progressive, while others may stabilize with appropriate therapy.