Adolescent Idiopathic Scoliosis: Associated Factors, Progression, and a Risk-Benefit Analysis of Treatment Options Davis, Bonnie E. ABSTRACT Objective: The purpose of this paper is to discuss the associated factors of adolescent idiopathic scoliosis (AIS), the progression of AIS, and to compare conservative vs. surgical management of AIS with respect to the benefits, risks, and costs of each. After reviewing the literature, a conclusion will be made as to which type of management has the most reasonable and beneficial approach. Methods: Research literature covering AIS was obtained through colleagues, databases such as PubMed, and relevant websites. Discussion: Associated factors of AIS include female gender and genetic predispositions, respiratory deficiency, melatonin-signaling pathway deficiencies, pes cavus, and high platelet calmodulin levels. Treatment options for AIS patients include conservative care (electric stimulation, manual therapy, bracing, acupuncture), and surgical care, which may also include post-surgical bracing. Conservative care has shown some promising results for both immediate and long-lasting effects on scoliotic curvatures. Side effects are limited due to the non-invasive procedures. Surgical management of AIS can be very effective at immediate curve reduction, however long- term results may not be as promising. It also has many more serious side effects such as implant failure, infections, and decreased spinal range of motion. Conclusion: Due to numerous factors involved in the development of AIS, a holistic approach must be taken when dealing with these patients. Surgical management, due to its cost, its risks, and its limited applications for AIS patients should be considered a last option for most patients with AIS. Key Words: Adolescent Idiopathic Scoliosis, Melatonin, Pes Cavus, Platelet Calmodulin, Kyphosis, Lordosis, Manual Therapy, Chiropractic, Acupuncture, Thoracoplasty, Harrington rod 2 INTRODUCTION The History, Prevalence, and Treatment of Scoliosis Scoliosis has been a recognized deformity of the human body for thousands of years. The deformity was first described by Hippocrates (430-370 B.C.)38, and the term "scoliosis" was first coined by Galen (131-201 A.D.). Just recently, however, did the Scoliosis Research Society (founded in 1965) solidify the term. The agreed upon definition of scoliosis is a deviation of the spine in which there is a curvature of 10 degrees or more, as measured by the Cobb method, and the spinous processes of the vertebrae involved are directed towards the concavity of the curvature. The prevalence of scoliosis is estimated to be between two and four percent, and it effects all countries and all races. Scoliosis is not just a skeletal problem, however. Its consequences reach much further, affecting the gross physiology and psychology of the patient. Therefore, having the tools to effectively treat scoliosis is an asset to any doctor. Scoliosis is rapidly progressive during the periods of growth in adolescence20. However, a less known fact is that most scoliotic curvatures continue to progress after the end of a person’s growth, the average having been found to be 0.4 degrees per year2. Because of this, it is imperative that doctors approach all scoliosis cases, regardless of the age of the patient, with a degree of seriousness. Today, doctors choose to manage scoliosis in a number of different ways. The most common type of scoliosis treated is adolescent idiopathic scoliosis (AIS), which describes one or multiple curvatures found in young adults that has/have developed from unknown reasons. AIS makes up roughly 90% of all cases of scoliosis in North America49. Treatment options for these patients include surgical intervention and conservative treatments (chiropractic adjustments, 3 strengthening and rehabilitative exercises, bracing, and acupuncture, among others). The effectiveness of each of these types of treatment has been evaluated. Topics that will be discussed in this paper include factors known to be associated with AIS such as gender & genetics, respiratory deficiency, melatonin levels, pes cavus, and platelet calmodulin levels. After which, the natural progression of untreated AIS will be discussed. Finally, the treatment options for AIS, the effectiveness, and the estimated costs of these treatment options (surgical vs. conservative) will be compared. METHODS Most of the articles used for this review were graciously donated by a chiropractic colleague of the author. Other sources of information for this review included various internet sites dedicated to scoliosis and research databases such as PubMed. DISCUSSION Associated Factors Gender and Genetics The incidence of mild scoliotic curvatures that are noted during school screenings is relatively equal between girls and boys, with a ratio of 1.2:147. However, the ratio jumps up to 8:1 in favor of girls when moderate to severe forms of scoliosis are compared between genders8. Girls are also more at risk for severe progression of AIS than boys are, with a ratio of 3.6 to 149. The prevalence of scoliosis has been observed to be higher among relatives than it is within the general population18. With mothers who had a scoliotic curvature of more than 15 4 degrees, one researcher found that their daughters showed a 27 percent prevalence of the disorder26. In addition, monozygous twins have shown a 73 percent concordance rate, while dizygous twins have shown a concordance rate of 36 percent22. Ogilvie et al concluded that “Nearly all (97%) AIS patients have familial origins”46. With these observations, the role of genetic factors for scoliosis has received much support. Several studies have been done to look at the type of inheritance pattern of scoliosis (dominant, recessive, or multifactorial)59, and whether or not scoliosis is an X-linked trait15,43. In the end, studies have supported both dominant, recessive, and multifactorial patterns of inheritance59, and have also found that X-linkage has been supported in some, but not all populations43. With this information, it can be concluded that hereditary and genetic factors for scoliosis are definitely present, however the complexity of transmission from one family member to another may be much more complex than simple Mendelian genetics. Respiratory Deficiency The relationship between scoliosis and respiratory deficiency has long been established, and was attributed by Hippocrates to the restriction of chest movement due to the size and shape of the deformed thorax50. However, respiratory deficiency has only been correlated with a severe thoracic curvature, and has been found in both humans and animals. In a study done by Smith et al., the researchers induced spinal deformity in a group of rabbits to study the effect of scoliosis on respiratory function. They found that there was, in fact, a relationship between thoracic scoliosis and respiratory deficiency, but only in rabbits with severe, rapidly progressing curvatures50. 5 Melatonin The idea of decreased melatonin levels playing a pivotal role in the development of AIS has been present since 1983, when Dobousset et al. discovered that chickens who had had their pineal glands removed often developed scoliosis21. Following this study, several researchers measured the levels of melatonin in humans with AIS, only to find that there was no consistent correlations between AIS and decreased melatonin levels44. In response to this, Moreau et al performed a study in 2004, looking instead at the melatonin-signaling pathway in AIS patients. After obtaining osteoblastic cultures from several AIS patients during surgery and comparing their melatonin pathway efficiencies, they found that there was a significant relationship between AIS and a dysfunction with the melatonin-signaling pathway in all 41 patients studied. These findings suggest that there may be distinct mutations in AIS patients that interfere with melatonin signal transduction44, and that this dysfunction could play a significant role in the development of AIS. Pes Cavus Pes cavus, high plantar arches, has been found to be correlated with AIS. In a study done in 1994 by Carpintero et al, researchers compared the incidence of pes cavus and scoliosis between 3 groups: a group with established idiopathic scoliosis (Group A), a group with established idiopathic pes cavus (Group C), and a control group with neither (Group B). Carpintero et al found that 65% of the subjects in Group A had abnormally high plantar arches, compared to only 9.5% of the subjects in the control group. From these results, the researchers concluded that “both deformities may share a common origin in muscle imbalance, either 6 through primary involvement of the muscle or as a result of changes in the central nervous system or the organs of balance”10. Platelet Calmodulin Platelet calmodulin is a receptor protein that helps to regulate the contractile protein systems in skeletal muscle and platelets. In a study done in 1994, Kindsfater et al measured the levels of platelet calmodulin in AIS patients with both progressive (over 10 degrees of progression in 12 months) and stable (less than 5 degrees of progression in 12 months) curves. They found that AIS patients with progressive curves had significantly higher platelet calmodulin levels than those with stable curves, or with no curve at all. They made no hypothesis as to why the levels were higher in AIS patients, but concluded that platelet calmodulin levels may now serve as a useful predictor of the progression of AIS33. This could lead to a more accurate prediction as to whether or not extreme measures such as surgery are needed for a particular patient. The Natural History of Untreated AIS To Progress or Not to Progress The natural history of untreated AIS has long been a controversial topic, and there still appears to be no agreed-upon conclusions between researchers regarding the incidence of progression. Some of the controversy could be resolved if all researchers used the same definitions of “scoliosis” and “progression”. Many researchers, when defining scoliosis, have used participants 7 with less than a 10 degree curvature of the spine, who don’t meet the current criteria for scoliosis.