Posterior spinal cord indentation: imaging findings and clinical outcome

Abstract

To identify the imaging findings associated with worse clinical outcome in posterior spinal cord indentation. A retrospective search for cases of dorsal cord indentation on magnetic resonance imaging (MRI) from April 2009 to March 2016 was undertaken. Imaging follow-up and clinical data were recorded. Two neuroradiologists blinded to the clinical data assessed the imaging findings. Differences and association of imaging and clinical findings were assessed via t-test and Fisher's exact and chi-squared tests for continuous and categorical data. Inter-rater agreement was calculated. Seventy-three patients were included, 65 were clinically stable, or the finding was incidental and eight had clinical worsening or required surgery. There was a significant difference in the percentage of cord diameter decrease between the two clinical groups (p=0.013, reader 1; p=0.027 reader 2). The clinical course was significantly associated with subjective cord indentation depth assessment (p=0.03 reader 1) and presence of syrinx (p=0.017 reader 2) on original MRI and worsening on imaging follow-up (p=0.03). The interrater agreement was moderate for syrinx identification (k=0.58). There was only fair agreement for the scalpel sign classification and in the final diagnosis (k=0.35 and 0.28). The degree of cord indentation, the presence of syrinx, and worsening of imaging findings on follow-up are associated with worse clinical course and can be useful in guiding management and directing subspecialty referrals.