Effect of Postural Changes on Leg Muscle Tone and Arterial Blood Pressure in Able‑Bodied People and People after Chronic Spinal Cord Injury

Abstract

Research background and hypothesis. Following spinal cord injury part of sympathetic nervous system is disrupted from the brain stem control, which results in cardiovascular system regulation disorders. Impaired cardiovascular regulation may cause orthostatic hypotension or other negative impacts on persons’ health. However, there are adaptive mechanisms which may change cardiovascular regulation and compensate these cardiovascular disorders. One of the mechanisms that may affect the occurrence of orthostatic hypotension may be changes in muscle tone after spinal cord injury.The aim of research was to ascertain the effect of muscle tone changes on blood pressure in persons with spinal cord injury through ortho-clinostatic test.Research methods. During passive ortho-clinostatic test, non-invasive blood pressure was continuously measured using the vital signs tracking monitor and leg muscle tone measurement was performed using myotonometer.Research results. In control group muscle tone is characterized as constant wave – it decreases in orthostasis and increases in clinostasis. In paraplegic group muscle tone changes are as similar to those in controls, except that dynamics is not so constant and numeric values are lower. In tetraplegics we can see that muscle tone changes rapidly and tone in thigh muscles has a tendency to decrease through all the test. Discusion and conclusions: 1. Leg muscle tone changes are important for blood pressure compensating mechanisms when the body position changes: it increases during orthostasis and decreases during clinostasis.2. Blood pressure varies differently among able-bodied persons and persons with spinal cord injury. The degree of the breach has a significant impact on the occurrence of compensatory peripheral regulation mechanisms. Characteristics of blood pressure fluctuations during body position changes in paraplegics are similar to those of reactions as in the able-bodied controls, while in tetraplegia case, possibilities of homeostatic blood pressure compensation during body posture changes are significantly reduced.Keywords: blood pressure, muscle tone, paraplegia, tetraplegia.