A 54-year-old man is admitted to the hospital following a high-speed motor vehicle accident. He is found to have right leg long bone fractures requiring open reduction/internal fixation. After the patient is stabilized, he is transferred to a skilled nursing facility for an extended rehabilitation period. During his stay at the facility, his right leg is immobilized for several weeks. The patient's management is complicated by decreased nutritional intake due to side effects from opioid pain medications. Measurement of his thigh following removal of casting materials finds a 2-centimeter decrease in diameter during the time of immobilization. This change in body measurement is due to a pathologic process similar to that seen in which of the following?

Question

A 54-year-old man is admitted to the hospital following a high-speed motor vehicle accident.  He is found to have right leg long bone fractures requiring open reduction/internal fixation.  After the patient is stabilized, he is transferred to a skilled nursing facility for an extended rehabilitation period.  During his stay at the facility, his right leg is immobilized for several weeks.  The patient's management is complicated by decreased nutritional intake due to side effects from opioid pain medications.  Measurement of his thigh following removal of casting materials finds a 2-centimeter decrease in diameter during the time of immobilization.  This change in body measurement is due to a pathologic process similar to that seen in which of the following?

Quizplus · Accepted Answer

This patient experienced decreased physical workload when his leg was immobilized. As a result, the skeletal muscle fibers in his leg decreased in size, leading to disuse atrophy. Atrophy is tissue loss due to cellular death or reduced cell size. It may be physiologic (eg, atrophy of Wolffian ducts in the female fetus, atrophy of maternal uterus following childbirth) or pathologic. Pathologic atrophy can be due to lack of use, loss of hormonal or neurologic stimulation (denervation atrophy), impaired circulation, mechanical compression, aging, or nutritional insufficiency. Pathologic atrophy may be local or generalized. On a cellular level, atrophy is seen as a reduction in mitochondria and rough endoplasmic reticulum. Muscular atrophy is characterized by decreased protein synthesis and loss of myofibrils. In prolonged atrophic states, apoptosis can lead to reduced cellular numbers. Pathologic atrophy is also seen in the adrenal cortex during prolonged glucocorticoid use due to suppression of ACTH release. This can lead to acute adrenal insufficiency if the exogenous glucocorticoid therapy is abruptly discontinued. (Choice B) After menopause, falling estrogen levels can lead to atrophy of the breasts, endometrium, and vaginal mucosa. Conversely, estrogen replacement in these patients can cause endometrial hyperplasia unless combined with progesterone therapy. (Choice C) In chronic gastroesophageal reflux, esophageal mucosa subjected to repeated acid exposure may undergo metaplasia. Squamous epithelium is replaced by columnar epithelium in a condition known as Barrett esophagus. (Choice D) Heart muscle subjected to long-standing hypertension is prone to developing hypertrophy, not atrophy. (Choice E) Prolonged exposure to tobacco smoke can induce metaplasia in the epithelium of the lung. Columnar epithelium may be replaced by squamous epithelium (squamous metaplasia) with an associated risk of squamous cell carcinoma. Educational objective: Pathologic atrophy can be caused by decreased physical workload, loss of innervation, decreased blood supply, inadequate nutrition, absent endocrine stimulation, aging, or mechanical pressure. __________ References: Disuse-induced muscle wasting. (http://www.ncbi.nlm.nih.gov/pubmed/23800384)

A 54-Year-Old Man Is Admitted to the Hospital Following a High-Speed