Sarcopenia is a pathological condition associated with age, characterized by a decrease in skeletal muscle mass. Clinically manifested by a decrease in muscle strength and functionality. It can lead to problems with self-care, disability and even death. The diagnosis of sarcopenia is made with the help of studies measuring muscle strength and mass, as well as specially designed tests. As a treatment, regular exercise, nutrition correction (an increase in the diet of protein products), vitamin D are prescribed. In severe cases, anabolic steroids, growth hormone are used.
ICD 10
M62.5 Muscle wasting and atrophy, not classified elsewhere
Meaning
Sarcopenia (from the Greek “sarx” — body, flesh + “penia” — reduction) is a degenerative process in which there is a gradual loss of functional muscle fibers. The use of this term was first proposed by the American doctor I. Rosenberg in 1989. Age-related atrophic changes in muscles have been known for a very long time. However, sarcopenia was separated into an independent nosological unit only in 2016 and included in the international classification of diseases. In 2009, the European Working Group on Sarcopenia in Old People (EWGSOP) was established. The prevalence of pathology is 30% among 60-year-olds and about 50% among the population over 80 years old. The ratio of men and women is 1:1.
Causes
This condition is considered to be a consequence of involutive and neurodegenerative phenomena that occur during aging both in the whole body as a whole and in skeletal muscles. These include a decrease in the ability to regenerate myosatellite cells, deterioration of the functioning of neuromuscular synapses, etc. An important role is played by age-related insufficiency of hormones that activate anabolic processes in muscles – testosterone, somatotropin, insulin-like growth factor-1.
Predisposing factors that aggravate muscular dystrophy include low physical activity, vitamin D deficiency. An unfavorable effect is also provided by insufficient protein intake from food, which can be caused by both incorrect composition of one’s diet and pathologies of the gastrointestinal tract that prevent the normal assimilation of amino acids (chronic pancreatitis, Crohn’s disease, celiac disease). Sarcopenia is also caused by chronic diseases – rheumatoid arthritis, chronic obstructive pulmonary disease, severe liver disease.
Pathogenesis
The mechanism of changes in muscle tissue in sarcopenia is complex. On the one hand, there is a physiological effect of apoptosis (programmed cell death) directly related to aging, on the other ‒ the influence of numerous factors that accelerate apoptosis. The deficiency of anabolic hormones, vitamin D, amino acids shifts the balance between the synthesis and breakdown of proteins in the muscles towards the latter. Insufficient physical activity impairs muscle circulation, which disrupts the biogenesis of mitochondria in muscle cells and triggers oxidative stress, which damages cell membranes.
The mediators and cytokines produced (interleukin-6, C-reactive protein, adiponectin) in chronic inflammatory diseases also contribute to dysmetabolism in myocytes. Recently, the leading pathogenetic value has been assigned to the protein myostatin, which inhibits the regeneration of muscle fibers. The outcome of these processes is a decrease in the number and volume of myofibrils, their replacement with adipose and connective tissue.
Classification
Traditionally, sarcopenia is considered a disease of the elderly and in the vast majority of cases occurs in people over 60 years of age. It is often combined with senile asthenia, cachexia. At the same time, there is a primary sarcopenia that accompanies aging, and a secondary one that develops in some chronic diseases (liver failure, rheumatoid arthritis). There are also the following phenotypic forms:
- Isolated. There is only a decrease in muscle mass and strength.
- Sarcoosteoporosis, or osteosarcopenia. Sarcopenia is combined with a decrease in bone mineral density.
- Sarcopenic obesity. A combination of sarcopenia and increased fat mass.
- Osteosarcopenic obesity. The most unfavorable type. It is characterized by a severe course and a large number of complications.
The presented phenotypes are characteristic of both the primary and secondary forms. Depending on the severity of the patient ‘s condition and the number of available diagnostic criteria , there are:
- Presarcopenia (mild degree). Only muscle mass is reduced.
- Sarcopenia (moderate degree). Reduced muscle mass, strength or function.
- Severe sarcopenia. All 3 parameters (mass, function and muscle strength) are reduced.
Symptoms
Clinical symptoms develop slowly. With minimal atrophic changes in the muscles, a person begins to poorly tolerate the usual physical activity for him (fatigue quickly sets in, more time is required for rest). With the progression of pathological processes, it becomes difficult for the patient to climb the stairs, carry even a small load (2-3 kg), comb the hair on his head.
Due to the pronounced weakness of the muscles, the patient’s legs give way when walking on a straight surface, balance is disturbed, frequent falls occur. The defeat of the diaphragm and intercostal muscles is accompanied by mixed shortness of breath. When the predominant amount of muscle fibers is replaced by connective and adipose tissue, the patient cannot serve himself, he needs help to get out of bed.
Complications
Sarcopenia is a serious disease that leads to temporary or permanent disability and disability due to critical muscle weakness. The most life-threatening conditions arise due to the functional inferiority of the respiratory muscles – these are aspiration pneumonia and respiratory failure. The most frequent complications (fractures of long tubular bones) are caused by constant falls. In secondary sarcopenia, adverse effects are associated with the underlying disease (for example, bleeding with liver failure). Also, sarcopenia due to increased insulin resistance can worsen the course of type 2 diabetes mellitus. Sarcopenic obesity exacerbates coronary heart disease and chronic heart failure.
Diagnostics
Geriatric doctors are responsible for the curation of patients with sarcopenia. To identify clinical signs of pathology, use the SARC-F questionnaire. In the questionnaire, you need to answer questions such as “how difficult is it for you to walk around the house?”, “do you have difficulty climbing stairs?”, “how often have you fallen over the past year?”. The European Working Group has developed a special diagnostic algorithm to determine muscle strength, mass and function. If a person, answering SARC-F questions, scores a large number of points, it is advisable to conduct the following studies:
- Measurement of muscle function and strength. The most informative are the test with a 6-minute walk and dynamometry of the hands. Muscle strength is considered reduced if the patient walks at a speed of less than 0.8 m /s and squeezes the dynamometer with a force of less than 30 kg (for men) and less than 20 kg (for women). An SPPB test is conducted, which examines the time spent getting up from a chair five times and the ability to keep balance for 10 seconds.
- Measurement of muscle and fat mass. Computer and magnetic resonance imaging are considered the gold standard, but due to their high cost, they are rarely used. In clinical practice, bioimpedance measurement and dual-energy X-ray absorptiometry are more preferable. A decrease in the lean mass index by 2 standard deviations is pathological.
Sarcopenia must be differentiated from muscular dystrophy, dermato– and polymyositis, neurological diseases (myasthenia gravis, Guillain-Barre syndrome). Severe forms require mandatory exclusion of malignant neoplasms and HIV infection. Neurologists and oncologists take part in the differential diagnosis.
Treatment
The most important role in the treatment is given to regular physical exercise. Preference should be given to anaerobic endurance training, as they restore muscle strength better. However, if a person has obesity, then training should be combined with aerobic exercise (running, swimming, cycling). It is also necessary to include in the diet foods rich in high-grade protein (containing essential amino acids) – meat, fish, eggs.
From medicines, native vitamin D preparations are used; in the presence of osteoporosis, active forms of vitamin are prescribed. With pronounced signs of muscular atrophy, anabolic steroids (nandrolone decanoate) are used. If they are ineffective, they resort to growth hormone analogues (somatotropin). Currently, clinical studies of new promising drugs are underway – myostatin inhibitors, ghrelin agonists and selective androgen receptor modulators. Secondary form therapy additionally includes treatment of the underlying disease.
Prevention and prognosis
Sarcopenia is a severe pathology that reduces performance, leading patients to disability, depriving them of the ability to self-care. The risk of death is about 5-10%. The main causes of death are respiratory failure, cardiovascular pathology, cachexia. Sarcopenia reduces life expectancy in patients with cirrhosis of the liver and other concomitant diseases. Prevention consists in regular exercise, proper nutrition (normal protein intake), taking preventive doses of vitamin D.