Initial findings in traumatic peripheral nerve injury and repair with diffusion tensor imaging

Abstract

Objective Management of peripheral nerve injuries requires physicians to rely on qualitative measures from patient history, electromyography, and physical exam. Determining a successful nerve repair can take months to years for proximal injuries, and the resulting delays in clinical decision‐making can lead to a negative impact on patient outcomes. Early identification of a failed nerve repair could prevent permanent muscle atrophy and loss of function. This study aims to test the feasibility of performing diffusion tensor imaging (DTI) to evaluate injury and recovery following repair of wrist trauma. We hypothesize that DTI provides a noninvasive and reliable assessment of regeneration, which may improve clinical decision‐making and alter the clinical course of surgical interventions. Methods Clinical and MRI measurements from subjects with traumatic peripheral nerve injury, carpal tunnel syndrome, and healthy control subjects were compared to evaluate the relationship between DTI metrics and injury severity. Results Fractional anisotropy from DTI was sensitive to differences between damaged and healthy nerves, damaged and compressed nerves, and injured and healthy contralateral nerves. Longitudinal measurements in two injury subjects also related to clinical outcomes. Implications of other diffusion measures are also discussed. Interpretation DTI is a sensitive tool for wrist nerve injuries and can be utilized for monitoring nerve recovery. Across three subjects with nerve injuries, this study has shown how DTI can detect abnormalities between injured and healthy nerves, measure recovery, and determine if re‐operation was successful. Additional comparisons to carpal tunnel syndrome and healthy nerves show that DTI is sensitive to the degree of impairment.

Meta-analysis of the normal diffusion tensor imaging values of the median nerve and how they change in carpal tunnel syndrome

“…Ten studies (32%) were performed at a field strength of 1·5 tesla 18 , 30 , 33 , 36 , 39 , 43 , 45 , 49 , 50 , 52 , twenty one (65%) at 3 tesla 9 , 17 , 20 , 27 – 29 , 31 , 32 , 34 , 35 , 37 , 38 , 40 – 42 , 44 , 46 – 48 , 51 , 53 , and one at 7 tesla 19 . The median echo and repetition times were 87 ms (IQR 65–91, range 21–103) and 7000 ms (IQR 3800–7650, range 1470–10,254), respectively.…”

“…The FA of the median nerve in asymptomatic adults was reported in 29 studies 9 , 17 – 20 , 27 – 36 , 38 – 42 , 44 – 51 , 53 . Overall, the normal FA was 0.58 (95% CI 0·56, 0.59; I 2 98%).…”

Technical Update on MR Neurography

“…RD may be decreased when there is a remyelination repair. [32][33][34][35] Finally, DTI studies allow high-resolution 3D neurographic reconstructions that provide additional information on the morphological and functional characteristics of the PNs, as well as their relationship with neighboring structures including PN tumors (►Fig. 10).…”

Diffusion Tensor Imaging of the Median Nerve: A Systematic Review and Meta-Analysis of Normal Values in Asymptomatic Adults and How They Change in Carpal Tunnel Syndrome

“…Ten studies (32%) were performed at a eld strength of 1•5 tesla 17,29,32,35,38,42,44,49,50,52 , twenty one (65%) at 3 tesla 16,19,[26][27][28]30,31,33,34,36,37,[39][40][41]43,[45][46][47][48]51,53 , and one at 7 tesla 18 . The median echo and repetition times were 87ms (IQR 65-91, range 21-103) and 7000ms (IQR 3800-7650, range 1470-10,254), respectively.…”

“…The FA of the median nerve in asymptomatic adults was reported in 29 studies [16][17][18][19][26][27][28][29][30][31][32][33][34][35][37][38][39][40][41][43][44][45][46][47][48][49][50][51]53 .…”