Atrophy

Atrophy is a lifetime reduction in the size of cells, tissues or organs, which is accompanied by a decrease or failure of their function. This is an acquired process, in contrast to congenital underdevelopment — hypoplasia or aplasia.

The essence of atrophy lies in the adaptation of cells to changed conditions, such as reduced load, blood supply or hormonal stimulation. At the cellular level, this is achieved by reducing protein synthesis and increasing its breakdown, often through autophagy (self-digestion of cellular components).

Aetiology and pathophysiology

Atrophy is a universal pathological process and is classified depending on its cause.

• Dysfunctional atrophy. It develops as a result of decreased organ function. A classic example is skeletal muscle atrophy due to prolonged immobilisation of a limb.
• Denervation atrophy. It occurs when the innervation of a tissue or organ is disrupted, for example, muscle atrophy after damage to a peripheral nerve.
• Ischemic atrophy. It is a consequence of long-term, chronic lack of blood supply, which leads to hypoxia and nutrient deficiency.
• Endocrine (dyshormonal) atrophy. It is caused by the cessation or reduction of hormonal stimulation (for example, atrophy of the endometrium and mammary glands in postmenopause).
• Senile atrophy. A general aging process that affects many organs and tissues, including skin, bones and brain.

Clinical Significance

Atrophy is an important clinical sign of many diseases. For example, muscle atrophy may indicate neurological pathology (amyotrophic lateral sclerosis, polyneuropathy), and atrophy of the cerebral cortex, detected by MRI, may indicate neurodegenerative diseases such as Alzheimer’s disease.

Diagnosis is based on visual examination, palpation (decrease in organ size, change in its consistency) and instrumental examination data (ultrasound, CT, MRI), which allow an objective assessment of the degree of organ reduction. Treatment of atrophy is aimed primarily at eliminating its underlying cause. In some cases, the process is reversible when normal functional load and blood supply are restored.