The concept of stroke-related sarcopenia has been proposed in recent years. The disease is considered to be different from age-related sarcopenia. Studies have found that muscle structural changes begin to appear within a few hours after stroke, and then muscle mass decreases rapidly . Park et al.  conducted a large-scale survey of 3009 men and 4199 women and found a strong positive correlation between stroke and sarcopenia. This study intends to investigate the incidence of stroke-related sarcopenia in hospitalized stroke patients recovering from stroke.
2. Objects and Methods
2.1. Research Objects
45 stroke male patients hospitalized in Linyi People’s Hospital from June 2018 to June 2019 were set as the observation group, and 50 healthy men with physical examination at the same time period were selected as the control group. This study has been reviewed by the ethics committee of our hospital.
Inclusion criteria: 1) Patients who meet the diagnosis of stroke; 2) Patients who meet the diagnosis of sarcopenia.
Exclusion criteria: 1) Patients with other diseases; 2) Patients with long-term use of hormones and other drugs that cause sarcopenia.
Sarcopenia refers to the 2019 diagnostic criteria of the Asian Sarcopenia Working Group : Dual-energy X-ray examination of male skeletal muscle mass index (SMI) < 7.0 kg/m2, female SMI < 5.4 kg/m2; male grip strength < 28 kg, female Grip strength < 18 kg; calf circumference: male < 34 cm, female < 33 cm.
2.2. Measurement Method
Use the Lunar dual-energy X-ray bone densitometer (DXA) from GE Company to measure the body muscle mass. After removing the metal objects worn by all patients, they lie supine on the measuring bed at room temperature and rest, and measure the muscle mass of the whole body according to the DXA procedure. A grip device (EH101, Xiangshan, China) was used to test the grip strength. The subject was in a standing position and the elbow extension was tested; if the subject could not stand independently, a sitting position was used for the test. Use the dominant hand or both hands to perform the test with the maximum force, at least 2 times, and select the maximum value.
2.3. Statistical Processing
Using SPSS22.0 statistical software, t-test or rank-sum test was used for comparison of measurement data between groups, and chi-square test was used for count data.
A total of sarcopenia and pre-sarcopenia were detected in the observation group, and a total of sarcopenia and pre-sarcopenia were detected in the control group. The incidence of the observation group was significantly higher than that of the control group (see Table 1).
The SMI, grip strength, skeletal muscle mass of the upper and lower limbs, and calf circumference of the observation group of sarcopenia patients were significantly lower than those of non sarcopenia patients (see Table 2).
Table 1. The incidence of sarcopenia in the two groups.
Table 2. Comparison of basic data of the two groups of subjects ( ).
acompared with patients with non-sarcopenia, P < 0.05, bcompared with patients with pre-sarcopenia, P < 0.05.
This study shows that the prevalence of sarcopenia is higher among stroke rehabilitation patients, which is significantly higher than that of the general population. Ryan et al.  studied 190 patients 6 months after the onset of stroke and showed that the prevalence of sarcopenia in stroke patients was between 14% and 18%. Jyunya et al.  conducted a study on 117 chronic stroke survivors 65 years of age or older, and detected a total of 60 sarcopenia patients, and found that sarcopenia patients are mainly knee extension weakness and ankle weakness. The assessment and intervention of skeletal muscle in patients with stroke sarcopenia should focus on the knee and ankle joints. Su et al.  found that the combined prevalence of stroke-related sarcopenia was 42%. In this study, the incidence of sarcopenia was 33.33%, and the incidence of pre-sarcopenia was 24.44%, which was higher than healthy people.
The study found that the number of motor units in patients with cerebral infarction began to decrease 4 hours after cerebral infarction, and the number of motor units in muscle tissue decreased significantly within 30 hours after cerebral infarction. The reason may be due to the synapses of the spinal cord alpha motor neurons that innervate the muscle was suppressed . Deyne et al.  found that in contrast to the transition of the fiber type in elderly patients with sarcopenia from fast muscle contraction fibers to slow muscle contraction fibers, in stroke patients, slow muscle contraction fibers were observed to be fast muscle contraction dominated by anaerobic metabolism. The reverse transition of fiber MHC type II subtype, and the proportion of fast muscle contraction fiber MHC type II is inversely proportional to the severity of gait defect. Matsushita et al.  showed that stroke-related sarcopenia seems to be a predictor of how male patients will engage in activities of daily living after recovery.
In summary, the incidence of stroke-related sarcopenia is relatively high, and it is not significantly affected by age, and has an important impact on the prognosis of patients. Therefore, it is necessary to pay special attention to the screening of sarcopenia for stroke rehabilitation patients in clinic.
 Scherbakov, N., Sandek, A., Doehner, W., et al. (2015) Stroke-Related Sarcopenia: Specific Characteristics. Journal of the American Medical Directors Association, 16, 272-276.
 Park, S., Ham, J.O. and Lee, B.K. (2014) A Positive Association between Stroke Risk and Sarcopenia in Men Aged ≥ 50 Years, But Not Women: Results from the Korean National Health and Nutrition Examination Survey 2008-2010. The Journal of Nutrition, Health & Aging, 18, 806-812. https://doi.org/10.1007/s12603-014-0553-x
 Chen, L.K., Woo, J., Assantachai, P., et al. (2020) Asian Working Group for Sarcopenia: 2019 Consensus Update on Sarcopenia Diagnosis and Treatment. Journal of the American Medical Directors Association, 21, 300-307. https://doi.org/10.1016/j.jamda.2019.12.012
 Ryan, A.S., Ivey, F.M., Serra, M.C., et al. (2017) Sarcopenia and Physical Function in Middle-Aged and Older Stroke Survivors. Archives of Physical Medicine and Rehabilitation, 98, 495-499. https://doi.org/10.1016/j.apmr.2016.07.015
 Su, Y., Yuki, M. and Otsuki, M. (2020) Prevalence of Stroke-Related Sarcopenia: A Systematic Review and Meta-Analysis. Journal of Stroke and Cerebrovascular Diseases, 29, Article ID: 105092. https://doi.org/10.1016/j.jstrokecerebrovasdis.2020.105092
 Arasaki, K., Igarashi, O., Ichikawa, Y., et al. (2006) Reduction in the Motor Unit Number Estimate (MUNE) after Cerebral Infarction. Journal of the Neurological Sciences, 250, 27-32.
 Matsushita, T., Nishioka, S., Taguchi, S., et al. (2019) Sarcopenia as a Predictor of Activities of Daily Living Capability in Stroke Patients Undergoing Rehabilitation. Epidemiology, Clinical Practice and Health, 19, 1124-1128. https://doi.org/10.1111/ggi.13780