Intraspinal neural axis abnormalities in severe spinal deformity: a 10-year MRI review

Abstract

Purpose: Documents indicated that the average prevalence of intraspinal neural axis abnormalities (INAAs) in presumed idiopathic scoliosis (PIS) patients was about 17.7%. However, paucity study focuses on the incidence of INAAs in severe spinal deformity (SSDs). In this study, we investigate the incidence of intraspinal neural axis abnormalities (IINAAs) and the clinical relevance in SSD at a single center. Methods: All the patients with SSDs admitted for spinal surgery were evaluated from 2003 to 2014. Inclusion criteria: patients who present with coronal Cobb over 90° (and/or the sagittal Cobb ≥ 90°); patients with whole spine magnetic resonance imaging (MRI) done preoperatively; and patients with documented clinical findings preoperatively. Exclusion criteria: ankylosing spondylitis, adult onset scoliosis, scoliosis secondary to bone destruction, and spinal dysraphism. Results: 101 patients fulfilled the criteria were included. 43 patients were detected with INAAs (42.6%, 43/101). The most common INAAs was syrinx (S) (16/43, 37.2%). Of which, 43.7% (7/16), 37.5% (6/16), and 18.7% (3/16) were spindle, slit, and swelling types, respectively. Most of them were located in thoracic (6/16, 37.5%) and cervical (5/16, 31.3%) region. MRI revealed Chiari malformation with syringomyelia (C + S) in ten patients (10/43, 23.2%), Chiari malformation (C) in 6 patients (6/43, 13.9%) and others in 11 patients (11/43, 25.6%). As to the etiology, most patients with INAAs were PIS (34/43, 79.1%). On clinical examination, 16 of 101 patients (16/101, 15.8%) had abnormal neurologic signs. 15 of 16 patients (15/16, 93.7%) with abnormal neurologic signs had INAAs on MRI. On the other hand, 28 of 43 patients (28/43, 65.1%) with INAAs on MRI presented neurologically intact. 28 of 85 patients (28/85, 32.9%) with neurologically intact were detected with INAAs on MRI. Conclusion: The incidence of INAAs in SSDs was 42.6%. 65.1% of them present intact neurologic status. The most common neural anomaly was syrinx. Preoperative whole spine MRI must be beneficial for SSDs even in the absence of neurological findings. Graphical abstract: These slides can be retrieved under Electronic Supplementary Material.[Figure not available: see fulltext.].