Respiratory Function at Maturity in Infantile-Onset, Non-Congenital, Non-Syndromic Scoliosis

Background Data: The natural history of infantile onset scoliosis varies from complete resolution to severe and relentless progression throughout the growth period. Historical studies of untreated cases have shown an increased morbidity and mortality from respiratory compromise in those with severe deformity. Treatment aims to reverse the deforming process and prevent these sequelae. Because the condition is uncommon and results cannot be finally assessed until the end of growth, outcome tends to become lost in the discussion of newer methods.

Study Design: Prospective review of respiratory function in patients with non-congenital, non-syndromic, scoliosis of infantile onset (before age 4 years) who were at least 15 years old at the time of study. Method: After ethical approval and informed consent, patients with infantile onset scoliosis (N=23, 11 male and 12 female) were recalled for full pulmonary function testing (spirometry, lung volumes, gas diffusion) and surface topography. Results were correlated with radiographic and surface topographic parameters and with treatment history.

Results: Those whose scoliosis resolved or stabilised at an acceptable stage, (N=6, 1 male, 5 female) with (N=3) or without (N=3) serial casting, had normal cosmesis and pulmonary function at a mean age of 21.1 years (mean FVC=98.83%, FEV1 = 98.7%) Those who were managed by casting or bracing and had avoided surgery until after age 10 (N=6, 3 male, 3 female, mean age at surgery 12.9) had variable cosmesis and good pulmonary function (mean FVC=68.33%, FEV1= 71.5% at a mean age of 20.3 years). Those who received surgery before age 10 (N=11, 7 male, 4 female, mean age at surgery 4.1 years, and at testing 20.5 years) had significant recurrence of deformity and respiratory restriction (mean FVC=41%, range 12-67%, FEV1=41%, range 14 - 72%). In all cases, measures of respiratory function correlated positively with age at surgery and negatively with the most recent Cobb angle and surface topography parameters. DISCUSSION: The aim of early surgery was the preservation of respiratory function, and the control of deformity. It was recommended only for those who were failing to respond to or inappropriate for serial casting, i.e. the malignantly progressive. Those who had the worst prognosis in infancy, now have the worst outcome. While there is variation, there is also a clear pattern of continued progression of deformity after early surgery and a concomitant decline in pulmonary function, such as would be anticipated in an untreated case.

Conclusion: In this type of scoliosis, numbers will always be small and natural history plays out over a long time, making meaningful assessment difficult. It is not possible to form an opinion on the efficacy of non-operative management, but the evidence suggests that early corrective spinal surgery has not prevented deformity or preserved respiratory function.