THE NOTOM HYPOTHESIS FOR IDIOPATHIC SCOLIOSIS: IS IT NULLIFIED BY THE DELAYED PUBERTY OF FEMALE RHYTHMIC GYMNASTS AND BALLET DANCERS WITH SCOLIOSIS?

Abstract

Nachemson [2] suggested that there are more girls than boys with progressive AIS for the following reason. The maturation of postural mechanisms in the nervous system is complete about the same time in boys and girls. Girls enter their skeletal adolescent growth spurt with immature postural mechanisms. So, if they have a predisposition to develop a scoliosis curve, the spine deforms. In contrast, boys enter their adolescent growth spurt with mature postural mechanisms so they are protected from developing a scoliosis curve. We termed Nachemson’s concept the neuro-osseous timing of maturation (NOTOM) hypothesis and used it to propose a possible medical treatment for idiopathic scoliosis by delaying puberty through the pituitary using gonadorelin analogues as in idiopathic precocious puberty [3,4].

The prevalence of scoliosis is reported to be increased in rhythmic gymnasts (RGs) in Bulgaria [5] and in ballet dancers (BDs) in the USA [6]. Both groups exhibit delayed puberty, which, at first sight, nullifies the NOTOM hypothesis for idiopathic scoliosis. There are similarities between scoliotic RGs and BDs that include intensive exercise from a young age, dieting, delayed menarche, increased scoliosis prevalence (RGs 12%, BDs 24%), mild scoliosis curves (10–30 degrees), and presumably generalised joint laxity. Other differences in addition to country of origin and exercises, include certain anthropometric features and importantly in RGs, thoracolumbar and lumbar curves and, in BDs, right thoracic curves. While constitutional and environmental factors may determine the scoliosis, the different curve types in RGs and BDs suggest that the exercise pattern over many years determines which type of scoliosis develops, although not the curve severity.

Conclusion: The view that scoliotic RGs should be included in a group of sports-associated scoliosis separate from idiopathic scoliosis [5] is supported. We suggest that most BDs who develop mild-moderate scoliosis do not have idiopathic scoliosis but a scoliosis related to intensive exercises over many years acting on a particular phenotype and genotype, similar to the sports-associated scoliosis. In this context the delayed puberty of RGs and BDs with scoliosis does not nullify the NOTOM hypothesis. There is a need to focus research on such subjects who have defined constitutional and environmental factors related to their scoliosis.