Clinical application of diffusion tensor tractography to postoperative C5 palsy

Study design: Diagnostic study. Objective: Although C5 palsy is a well-known potential complication after cervical procedure, the exact pathophysiology remains uncertain. Diffusion tensor tractography (DTT) has recently been proposed as a useful tool to examine quantitatively and non-invasively the pathology of spinal cord disorders. The purpose of this study is to determine the clinical interest of DTT in patients with C5 palsy after cervical laminoplasty. Setting: Single university hospital. Methods: Five patients with C5 palsy out of 108 patients after cervical laminoplasty were subjected to DTT using a 1.5 Tesla magnetic resonance imaging in our hospital between 2010 and 2012. For the tractography, two regions of interest (ROI) were placed at the C5 segmental level and the bilateral C4/5 intervertebral foramen level. Results: The postoperative number of tract fibers at the C5 segmental spinal cord level was significantly increased compared to the preoperative number, despite the C5 palsy. Analyses of two ROIs (at the C5 segmental level and the C4/5 intervertebral foramen level) showed that the number of tract fibers at the palsy side was significantly decreased compared to the intact side. Furthermore, in the patient who spontaneously recovered from C5 palsy within postoperative 6 months, a gradual augmentation of tract fibers was identified at the palsy side. Conclusions: Our findings suggest that DTT can document C5 palsy in detail, as the anatomical region between C5 segmental level and C4/5 intervertebral foramen level was potentially damaged in patients with C5 palsy after laminoplasty.