Significance of CSF area measurements in cervical spondylitic myelopathy

Mild clinical myelopathy can occur without cord compression, and asymptomat ic cord compression seen on MRI is common. The aim of this study was to asc ertain the MRI features which best correlate with early clinical myelopathy . The study was conducted on three groups: group A, 20 patients with clinic al myelopathy and MRI evidence of cervical spondylosis; group B, 20 patient s without myelopathy, but with other clinical and MRI evidence of cervical spondylosis; and group C, 10 normal volunteers with no MRI evidence of spon dylosis. The cross-sectional area (CSA) of the spinal cord (SP-CSA), spinal canal (SC-CSA) and CSF space (CSF-CSA) were measured on T1-weighted axial images at the level of the most severe spinal canal stenosis. The severity of myelopathy was assessed using a simple scoring system giving a score fro m 0 (normal) to 11 (severe). Subjective demonstration of cord compression o n sagittal images was an insensitive indicator of clinical myelopathy. All three measures of cross-sectional area were significantly smaller in Group A than in B (p<0.01). The reduction in SP-CSA was the only independent prog nosticator for severity of myelopathy (p<0.005) accounting for 63% of the v ariation in myelopathy score. All three variables showed a significant corr elation with the presence of myelopathy (p<0.01); however, logistic regress ion analysis showed a decrease in CSF-CSA to be the only independent signif icant prognosticator of the presence of clinical myelopathy (p<0.02). Reduc tion of the CSF space to less than 0.7 cm(2) was associated with a 90% chan ce of clinical myelopathy (specificity 83%).