Relationships between the integrity and function of lumbar nerve roots as assessed by diffusion tensor imaging and neurophysiology.
PURPOSE
Diffusion tensor imaging (DTI) has shown promise in the measurement of peripheral nerve integrity, although the optimal way to apply the technique for the study of lumbar spinal nerves is unclear. The aims of this study are to use an improved DTI acquisition to investigate lumbar nerve root integrity and correlate this with functional measures using neurophysiology.


METHODS
Twenty healthy volunteers underwent 3 T DTI of the L5/S1 area. Regions of interest were applied to L5 and S1 nerve roots, and DTI metrics (fractional anisotropy, mean, axial and radial diffusivity) were derived. Neurophysiological measures were obtained from muscles innervated by L5/S1 nerves; these included the slope of motor-evoked potential input-output curves, F-wave latency, maximal motor response, and central and peripheral motor conduction times.


RESULTS
DTI metrics were similar between the left and right sides and between vertebral levels. Conversely, significant differences in DTI measures were seen along the course of the nerves. Regression analyses revealed that DTI metrics of the L5 nerve correlated with neurophysiological measures from the muscle innervated by it.


CONCLUSION
The current findings suggest that DTI has the potential to be used for assessing lumbar spinal nerve integrity and that parameters derived from DTI provide quantitative information which reflects their function.
['Chiou|S Y|SY|', 'Hellyer|P J|PJ|', 'Sharp|D J|DJ|', 'Newbould|R D|RD|', 'Patel|M C|MC|', 'Strutton|P H|PH|']
D000328:Adult D016880:Anisotropy D056324:Diffusion Tensor Imaging D004576:Electromyography D019054:Evoked Potentials, Motor D005260:Female D064368:Healthy Volunteers D006801:Humans D007090:Image Interpretation, Computer-Assisted D008161:Lumbosacral Region D008297:Male D009431:Neural Conduction D013126:Spinal Nerve Roots D050781:Transcranial Magnetic Stimulation
Diffusion tensor imaging Neurophysiology Nerve integrity Electrical stimulation Spinal nerve roots Transcranial magnetic stimulation