Longitudinal DTI analysis of microstructural changes in lumbar nerve roots following Interspinous process device...

Area of Science:

• Neuroimaging
• Spinal Surgery
• Biomedical Engineering

Background:

• Diffusion tensor imaging (DTI) parameters like fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) are vital for assessing peripheral nerve integrity.
• Nerve conduction studies are standard, but DTI offers complementary microstructural insights into nerve health.
• Interspinous process devices (IPDs) are used for lumbar spinal stenosis, but their biomechanical effects on nerve roots require further elucidation.

Purpose of the Study:

• To compare DTI values of lumbar spinal nerve roots before and after treatment with an interspinous process device (IPD).
• To investigate the microstructural impact of IPD placement on both treated and adjacent untreated nerve roots.

Main Methods:

• A pilot study involving seven patients with neurogenic claudication and lumbar stenosis.
• Assessment of DTI parameters (FA, MD, AD, RD) and clinical outcomes (Visual Analog Scale for pain, Oswestry Disability Index) before (T0) and after (T1) IPD treatment.
• Comparison of DTI changes in treated nerve roots versus adjacent untreated nerve roots.

Main Results:

• In treated roots, MD, RD, and AD significantly altered, while FA showed no significant difference overall. However, FA increased in the intraforaminal segment, and MD, AD, and RD decreased in the pre-foraminal segment.
• Untreated nerve roots exhibited highly significant differences in all DTI parameters between T0 and T1. FA increased, while MD, AD, and RD decreased across all segments.
• Patient-reported pain (VAS) significantly decreased post-treatment (p < 0.0001).

Conclusions:

• IPD treatment leads to significant microstructural changes in lumbar nerve roots, with adjacent untreated roots showing more pronounced DTI alterations.
• DTI can detect biomechanical changes in nerve roots following IPD placement, offering insights into the device's effects.
• Further research is needed to understand the short- to medium-term changes in DTI values and compare outcomes between treated and untreated nerve roots.