Regional Differences in Outcomes of Surgical Treatment for Cervical Spondylotic Myelopathy Outcomes of the AOSpine Multicenter Prospective CSM-I Study
Authors: Fehlings Michael , Kopjar Branko , Kale Shashank , Defino Helton , Barbagallo Giuseppe , Ibrahim Ahmed , Tetreault Lindsay , Massicotte Eric , Bartels Ronald , Zhou Qiang , Arnold Paul , Zileili Mehmet , Tan Gamiel , Moraes Osmar , Yukawa Yasutsugu , Alvarado Manuel , Scerrati Massimo , Toyone Tomoaki , Tanaka Masato , Bolger Ciaran 
Published: May 2015

Introduction Cervical spondylotic myelopathy (CSM) is a condition that is commonly seen in those over the age of 50 to 60 years. A progressive increase in the number of patients who present with CSM is expected in the coming decades as the proportion of those over 60 years is anticipated to double by 2050 according to the World Health Organization (WHO). Regional variations in the pattern of presentations, etiology, and surgical management of CSM are likely to be important determinants of outcome of treatment. Here, we report the current presentation and management of CSM in a large prospective international multicenter study (AOSpine CSM-International). Materials and Methods Between 2007 and 2011, all adult patients with imaging-confirmed CSM were enrolled at 16 international high-volume centers. Detailed data on presentation, treatment, and functional outcomes were collected prospectively. The decision on surgical approach, levels decompressed, and use of instrumentation was left to the attending surgeons. Patients with inflammatory, infective, or neoplastic myelopathic etiologies were excluded. Patients were followed-up for up to 24 months. Results Participating centers were based in Asia (AP, n = 150), Europe (E, n = 126), Latin (LA, n = 80), and North America (NA, n = 123). The mean age of the cohort was 56.4 years (range, 22–87 years) and majority of them were males. Patients from AP and LA were significantly younger (53.9 and 54.2 years, respectively) than those from NA and E ( p < 0.0003). The presenting underlying CSM pathology varied between regions ( p < 0.001). Posterior ligamentum flavum hypertrophy was most frequently seen in LA, and OPLL was prevalent in patients in AP (35%) and E (32%). Despite etiological variations, there were no differences in baseline mJOA, Nurick, and NDI scores ( p < 0.1). However, patients in AP scored the highest and those in LA scored the lowest on SF36 PCS, and LA patients had highest SF36 MCS scores ( p < 0.008). Anterior surgical decompression was performed in a majority in Europe (71.43%), AP (61.07%), and NA (56%) but not in LA (33%). Circumferential decompression surgery was rarely performed in NA (4.88%) and E (3.17%). At 24 months, there was significant improvement in overall outcome measures ( p < 0.001) in all regions. Patients in Asia demonstrated the greatest improvement in NDI and SF-36 PCS/MCS and patients in Europe the least. Patients from Europe had lower SF-36 QOL scores and showed less functional improvement in mJOA. NDI score was highest in the AP region. Conclusion There were significant regional variations in etiology of CSM but not at presenting functional status. Anterior cervical approach for CSM was the most common surgical approach worldwide. Surgical decompression achieved statistically significant improvements in mJOA, NDI, Nurick score, and SF36v2 across centers. However, there were variations in the degree of functional improvements gained across the regions.