Study design: This is a cross-sectional study. Objectives: The goal of this study was to characterize the diffusion properties across segments of the spinal cord and peak cerebrospinal fluid (CSF) velocities in the stenotic spinal canal, and to determine the correlation between these properties and clinical and electrophysiological parameters in patients with cervical spinal cord injury (SCI). Setting: This study was conducted in the University teaching hospital. Methods: The study involved 17 patients with cervical SCI. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the spinal cord and peak systolic and diastolic velocities of CSF were measured at the level of maximum compression (region 1) and at the levels above (region 2) and below (region 3) the level of injury with no signal change in conventional magnetic resonance imaging. Neurological and electrophysiological parameters were measured, including American Spinal Injury Association (ASIA) Impairment Scale (AIS), ASIA motor score, ASIA sensory score, Modified Barthel Index, Spinal Cord Independence Measure III (SCIM III), somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP). Results: The ADC was significantly higher and the FA was significantly lower in regions 1, 2 and 3 of the SCI patients than in the normal controls (Po0.05 each). FA of the level below correlated with AIS, ASIA sensory score and SCIM III score, and FA of the level above correlated with SSEP latencies and MEP amplitudes (Po0.05 each). The reductions in FA correlated with CSF flow, functional measurements and evoked potentials.
INTRODUCTIONOwing to its high soft-tissue resolution, conventional magnetic resonance imaging (MRI) is used routinely in the diagnosis of spinal cord injury (SCI). However, conventional MRI has low sensitivity for diffusion abnormalities in the white matter, limiting the associations between MRI results and clinical status. 1,2 Diffusion tensor imaging (DTI) with fiber tractography provides a threedimensional model of water diffusion for longitudinal evaluations of the central nervous system. 3 Although the application of DTI to the human spinal cord is challenging technically, owing to the small cross-sectional area of the spinal cord, cardiac and respiratory motion, and widely varying magnetic susceptibility, 4 recent developments in magnetic resonance (MR) pulse sequence design have greatly reduced these problems. Moreover, phase-contrast MRI (PC-MRI) is a noninvasive technique that can be used to quantify variations in the flow of the cerebrospinal fluid (CSF) gated with the cardiac cycle. 5 CSF flow can be influenced by stenotic lesions in the brain and spinal cord. 6,7 Initially, SCI results in the physical disruption of structures in the spinal cord (primary insult), and it might also induce secondary events that injure intact, neighboring tissues in the epidural, subdural,