The Effects of Adolescent Idiopathic Scoliosis on the Factors Affecting the Respiratory System and Its Function: A Systematic Review

Background: Scoliosis is defined as a three-dimensional deformity of the spine associated with lateral deviation from the normal vertical direction, and mostly with rotation of the vertebras. Although some studies have been performed on the effect of scoliosis on the respiratory system, there are still some ambiguities at issue and some results are contradictory. The aim of the present systematic review study was to help clarify the effect of scoliosis on the respiratory system and the factors affecting respiration. Methods: An electronic search was done in databases including PubMed, Web of Science, Ebsco, and Science Direct. The quality of papers was assessed using Black and Down instrument. The following keywords were used in search engines; adolescent idiopathic scoliosis, respiratory function, respiratory problem, respiratory system, ventilatory function, ventilatory problem, ventilatory system, chest wall motion, respiratory muscle, and exercise capacity. Papers in English language, subjects being over the age of 10 and suffering from adolescent idiopathic scoliosis, and no other abnormalities were among the inclusion criteria, while suffering any underlying disease was an exclusion criterion. Results: Based on the keywords used, 76 papers were found; based on the inclusion and exclusion criteria, 7 papers were approved. Five papers had dealt with pulmonary and respiratory factors, two investigating respiratory muscles, 2 examined exercise capacity, and 2 tested the chest wall motions. The score of reporting, external validity, internal validity bias, internal validity - confounding (selection bias), and power varied within 5-7, 0-2, 2-4, 0-3, and 2-5, respectively. Conclusion: Based on studies carried out so far, scoliosis affects respiratory function including respiratory volumes, chest wall motions, strength of respiratory muscles, respiratory patterns, and respiratory function during exercise. Although some studies show contradictory results, relying on the results of the majority of studies, it can be stated that these effects had been mentioned as negative effects on the mentioned factors. The reasons stated for the results include mechanical insufficiency and muscular disorders, which arise from developmental and systemic disorders associated with scoliosis itself. The relationships between respiratory volumes, strength of respiratory muscles, and chest wall motions are still unclear. Since only limited studies have been performed in this regard, these results still warrant further investigation.