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Chen Y, Baraz J, Xuan SY, Yang X, Castoro R, Xuan Y, Roth AR, Dortch RD, Li J. Multiparametric Quantitative MRI of Peripheral Nerves in the Leg: A Reliability Study. J Magn Reson Imaging 2024; 59:563-574. [PMID: 37191075 PMCID: PMC11188919 DOI: 10.1002/jmri.28778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/30/2023] [Accepted: 05/01/2023] [Indexed: 05/17/2023] Open
Abstract
BACKGROUND Patients with polyneuropathies typically have demyelination and/or axonal degeneration in peripheral nerves. Currently, there is a lack of imaging biomarkers to track the changes in these pathologies. PURPOSE To develop and evaluate the reliability of a multiparametric quantitative magnetic resonance imaging (qMRI) method of peripheral nerves in the leg. STUDY TYPE Prospective. SUBJECTS Seventeen healthy volunteers (36.2 ± 13.8 years old, 9 males) with 10 of them scanned twice for test-retest. FIELD STRENGTH/SEQUENCE 3 T, three-dimensional gradient echo and diffusion tensor imaging. ASSESSMENT A qMRI protocol and processing pipeline was established for quantifying the following nerve parameters that are sensitive to myelin and axonal pathologies: magnetization transfer (MT) ratio (MTR), MT saturation index (MTsat), T2 *, T1 , proton density (PD), fractional anisotropy (FA), and mean/axial/radial diffusivities (MD, AD, and RD). The qMRI protocol also measures the volume of nerve fascicles (fVOL) and the fat fraction (FF) of muscles. STATISTICAL TESTS The intersession reproducibility and inter-rater reliability of each qMRI parameter were assessed by Bland-Altman analysis and intraclass correlation coefficient (ICC). Pairwise Pearson correlation analyses were performed to investigate the intrinsic association between qMRI parameters. Distal-to-proximal variations were evaluated by paired t-tests with Bonferroni-Holm multiple comparison corrections. P < 0.05 was considered statistically significant. RESULTS The MTR, MTsat, T2 *, T1 , PD, FA, AD, and fVOL of the sciatic and tibial nerves, and the FF of leg muscles, had an overall good-to-excellent test-retest agreement (ICC varying from 0.78 to 0.99). All the qMRI parameters had good-to-excellent inter-rater reliability (ICC > 0.80). The data demonstrated a pattern of distal-to-proximal changes of an increased nerve MTsat and FA, and a decreased nerve T1 , PD, MD, and RD, as well as a significantly increased muscle FF. DATA CONCLUSION The proposed multiparametric qMRI method of the peripheral nerves is highly reproducible and provided healthy control data which will be used in developing monitoring biomarkers in patients with polyneuropathies. LEVEL OF EVIDENCE 1 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Yongsheng Chen
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jacob Baraz
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Stephanie Yan Xuan
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Xue Yang
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Ryan Castoro
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Yang Xuan
- Department of Radiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Alison R. Roth
- Department of Translational Neuroscience, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Richard D. Dortch
- Department of Translational Neuroscience, Barrow Neurological Institute, Phoenix, AZ, USA
| | - Jun Li
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
- Department of Neurology, Houston Methodist Research Institute, Houston, TX, USA
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Tan RES, Jeyaratnam S, Lim AYT. Updates in peripheral nerve surgery of the upper extremity: diagnosis and treatment options. ANNALS OF TRANSLATIONAL MEDICINE 2023; 11:391. [PMID: 37970602 PMCID: PMC10632574 DOI: 10.21037/atm-23-1500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 08/11/2023] [Indexed: 11/17/2023]
Abstract
The loss of function resulting from peripheral nerve injuries confers a significant burden to the patient and society. The treatment of peripheral nerve injuries requires an accurate diagnosis and formulation of a functional reconstructive plan. Advances in peripheral nerve imaging complement electrodiagnostic studies, and provide us with detailed information regarding the status of nerve injury, repair, and regeneration in order to prognosticate recovery and determine the need for surgical intervention. When direct nerve repair is not possible, the methods for bridging a nerve gap are the nerve autograft, allograft and conduit. While current research supports the use of conduits and nerve allografts for shorter nerve gaps, the nerve autograft still remains the gold standard for bridging a nerve gap. When direct nerve repair or nerve grafting fails, or is anticipated to be insufficient, nerve transfers are an alternative for reconstruction. Knowledge of axonal counts, upper limb innervation patterns, location and clustering of upper limb peripheral nerves allows for the design of new nerve transfers. The options of nerve transfers for radial, ulnar and median nerve injuries are outlined, as well as their outcomes. Nerve transfers are an attractive option for restoring motor and sensory function while minimizing donor site morbidity. However, one must consider their limitations, and preserve donor sites for secondary tendon transfer options. This article presents the latest information regarding the imaging of peripheral nerves, methods to bridge a nerve gap, and nerve transfers to aid the peripheral nerve surgeon in choosing a reconstructive plan.
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Affiliation(s)
| | | | - Aymeric Y. T. Lim
- Department of Hand and Reconstructive Microsurgery, National University Health System, Singapore, Singapore
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Boonsuth R, Battiston M, Grussu F, Samlidou CM, Calvi A, Samson RS, Gandini Wheeler-Kingshott CAM, Yiannakas MC. Feasibility of in vivo multi-parametric quantitative magnetic resonance imaging of the healthy sciatic nerve with a unified signal readout protocol. Sci Rep 2023; 13:6565. [PMID: 37085693 PMCID: PMC10121559 DOI: 10.1038/s41598-023-33618-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 04/15/2023] [Indexed: 04/23/2023] Open
Abstract
Magnetic resonance neurography (MRN) has been used successfully over the years to investigate the peripheral nervous system (PNS) because it allows early detection and precise localisation of neural tissue damage. However, studies demonstrating the feasibility of combining MRN with multi-parametric quantitative magnetic resonance imaging (qMRI) methods, which provide more specific information related to nerve tissue composition and microstructural organisation, can be invaluable. The translation of emerging qMRI methods previously validated in the central nervous system to the PNS offers real potential to characterise in patients in vivo the underlying pathophysiological mechanisms involved in a plethora of conditions of the PNS. The aim of this study was to assess the feasibility of combining MRN with qMRI to measure diffusion, magnetisation transfer and relaxation properties of the healthy sciatic nerve in vivo using a unified signal readout protocol. The reproducibility of the multi-parametric qMRI protocol as well as normative qMRI measures in the healthy sciatic nerve are reported. The findings presented herein pave the way to the practical implementation of joint MRN-qMRI in future studies of pathological conditions affecting the PNS.
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Affiliation(s)
- Ratthaporn Boonsuth
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK.
- Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.
| | - Marco Battiston
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Francesco Grussu
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Christina Maria Samlidou
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Alberto Calvi
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
- Laboratory of Advanced Imaging in Neuroimmunological Diseases, Center of Neuroimmunology, Hospital Clinic Barcelona, Fundació Clinic Per a La Recerca Biomedica, Barcelona, Spain
| | - Rebecca S Samson
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Claudia A M Gandini Wheeler-Kingshott
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
- Brain Connectivity Research Centre, IRCCS Mondino Foundation, Pavia, Italy
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Marios C Yiannakas
- NMR Research Unit, Department of Neuroinflammation, Faculty of Brain Sciences, Queen Square MS Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
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Pušnik L, Serša I, Umek N, Cvetko E, Snoj Ž. Correlation between diffusion tensor indices and fascicular morphometric parameters of peripheral nerve. Front Physiol 2023; 14:1070227. [PMID: 36909220 PMCID: PMC9995878 DOI: 10.3389/fphys.2023.1070227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 02/03/2023] [Indexed: 02/25/2023] Open
Abstract
Introduction: Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that measures the anisotropy of water diffusion. Clinical magnetic resonance imaging scanners enable visualization of the structural integrity of larger axonal bundles in the central nervous system and smaller structures like peripheral nerves; however, their resolution for the depiction of nerve fascicular morphology is limited. Accordingly, high-field strength MRI and strong magnetic field gradients are needed to depict the fascicular pattern. The study aimed to quantify diffusion tensor indices with high-field strength MRI within different anatomical compartments of the median nerve and determine if they correlate with nerve structure at the fascicular level. Methods: Three-dimensional pulsed gradient spin-echo (PGSE) imaging sequence in 19 different gradient directions and b value 1,150 s/mm2 was performed on a 9.4T wide-bore vertical superconducting magnet. Nine-millimeter-long segments of five median nerve samples were obtained from fresh cadavers and acquired in sixteen 0.625 mm thick slices. Each nerve sample had the fascicles, perineurium, and interfascicular epineurium segmented. The diffusion tensor was calculated from the region-average diffusion-weighted signals for all diffusion gradient directions. Subsequently, correlations between diffusion tensor indices of segmentations and nerve structure at the fascicular level (number of fascicles, fascicular ratio, and cross-sectional area of fascicles or nerve) were assessed. The acquired diffusion tensor imaging data was employed for display with trajectories and diffusion ellipsoids. Results: The nerve fascicles proved to be the most anisotropic nerve compartment with fractional anisotropy 0.44 ± 0.05. In the interfascicular epineurium, the diffusion was more prominent in orthogonal directions with fractional anisotropy 0.13 ± 0.02. Diffusion tensor indices within the fascicles and perineurium differed significantly between the subjects (p < 0.0001); however, there were no differences within the interfascicular epineurium (p ≥ 0.37). There were no correlations between diffusion tensor indices and nerve structure at the fascicular level (p ≥ 0.29). Conclusion: High-field strength MRI enabled the depiction of the anisotropic diffusion within the fascicles and perineurium. Diffusion tensor indices of the peripheral nerve did not correlate with nerve structure at the fascicular level. Future studies should investigate the relationship between diffusion tensor indices at the fascicular level and axon- and myelin-related parameters.
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Affiliation(s)
- Luka Pušnik
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Igor Serša
- Jožef Stefan Institute, Ljubljana, Slovenia
| | - Nejc Umek
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Erika Cvetko
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Žiga Snoj
- Department of Radiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Clinical Institute of Radiology, University Medical Centre Ljubljana, Ljubljana, Slovenia
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Yeoh S, Warner WS, Merchant SS, Hsu EW, Agoston DV, Mahan MA. Incorporating Blood Flow in Nerve Injury and Regeneration Assessment. Front Surg 2022; 9:862478. [PMID: 35529911 PMCID: PMC9069240 DOI: 10.3389/fsurg.2022.862478] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/04/2022] [Indexed: 01/22/2023] Open
Abstract
Peripheral nerve injury is a significant public health challenge, with limited treatment options and potential lifelong impact on function. More than just an intrinsic part of nerve anatomy, the vascular network of nerves impact regeneration, including perfusion for metabolic demands, appropriate signaling and growth factors, and structural scaffolding for Schwann cell and axonal migration. However, the established nerve injury classification paradigm proposed by Sydney Sunderland in 1951 is based solely on hierarchical disruption to gross anatomical nerve structures and lacks further information regarding the state of cellular, metabolic, or inflammatory processes that are critical in determining regenerative outcomes. This review covers the anatomical structure of nerve-associated vasculature, and describes the biological processes that makes these vessels critical to successful end-organ reinnervation after severe nerve injuries. We then propose a theoretical framework that incorporates measurements of blood vessel perfusion and inflammation to unify perspectives on all mechanisms of nerve injury.
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Affiliation(s)
- Stewart Yeoh
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah, United States
| | - Wesley S. Warner
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah, United States
| | - Samer S. Merchant
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States
| | - Edward W. Hsu
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States
| | - Denes v. Agoston
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States
| | - Mark A. Mahan
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah, United States
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Manzanera Esteve IV, Farinas AF, Pollins AC, Nussenbaum ME, Cardwell NL, Kahn H, Does MD, Dortch RD, Thayer WP. Noninvasive diffusion MRI to determine the severity of peripheral nerve injury. Magn Reson Imaging 2021; 83:96-106. [PMID: 34403759 DOI: 10.1016/j.mri.2021.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 07/07/2021] [Accepted: 08/12/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Primary repair of peripheral nerves is recommended following transection; however, patient management following repair is challenged by a lack of biomarkers to nerve regeneration. Previous studies have demonstrated that diffusion magnetic resonance imaging (MRI) may provide viable biomarkers of nerve regeneration in injury models; though, these methods have not been systematically evaluated in graded partial transections and repairs. METHODS Ex vivo diffusion MRI was performed in fixed rat sciatic nerve samples 4 or 12 weeks following partial nerve transection and repair (25% cut = 12, 50% cut = 12 and 75% cut = 11), crush injuries (n = 12), and sham surgeries (n = 9). Behavioral testing and histologic evaluation were performed in the same animals and nerve samples for comparison. RESULTS Diffusion tractography provided visual characterizations of nerve damage and recovery consistent with the expected degree of injury within each cohort. In addition, quantitative indices from diffusion MRI correlated with both histological and behavioral evaluations, the latter of indicated full recovery for sham and crush nerves and limited recovery in all partially transected/repaired nerves. Nerve recovery between 4 and 12 weeks was statistically significant in partial transections 50% and 75% depth cuts (p = 0.043 and p = 0.022) but not for 25% transections. INTERPRETATION Our findings suggest that DTI can i) distinguish different degrees of partial nerve transection following surgical repair and ii) map spatially heterogeneous nerve recovery (e.g., due to collateral sprouting) from 4 to 12 weeks in partially transected nerves.
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Affiliation(s)
- Isaac V Manzanera Esteve
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America.
| | - Angel F Farinas
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, United States of America
| | - Alonda C Pollins
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, United States of America
| | - Marlieke E Nussenbaum
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, United States of America
| | - Nancy L Cardwell
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, United States of America
| | - Hakmook Kahn
- Vanderbilt University Medical Center, Department of Biostatistics, Nashville, TN, USA
| | - Mark D Does
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America; Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, United States of America
| | - Richard D Dortch
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America; Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, United States of America; Barrow Neurological Institute, Division of Neuroimaging Research, Phoenix, AZ, United States of America
| | - Wesley P Thayer
- Vanderbilt University Medical Center, Department of Plastic Surgery, Nashville, TN, United States of America; Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, United States of America
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Wan Q, Yu Y, Bao Y, Hu J, Wang P, Peng Y, Xia X, Liao Y, Liu J, Xie X, Li X. Evaluation of peripheral nerve acute crush injury in rabbits: comparison among diffusion kurtosis imaging, diffusion tensor imaging and electromyography. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2021; 35:291-299. [PMID: 34374905 DOI: 10.1007/s10334-021-00952-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 05/01/2021] [Accepted: 08/05/2021] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Diffusion kurtosis imaging (DKI) has been proven to provide additional value for assessing many central nervous system diseases compared with conventional diffusion tensor imaging (DTI); however, whether it has the same value in peripheral nerve injury is unclear. This study aimed to investigate the performance of DKI, DTI, and electromyography (EMG) in evaluating peripheral nerve crush injury (PNCI) in rabbits. MATERIALS AND METHODS A total of 27 New Zealand white rabbits were selected to establish a PNCI model. Longitudinal DTI, DKI, and EMG were evaluated before surgery and 1 day, 3 days, 1 week, 2 weeks, 4 weeks, 6 weeks, and 8 weeks after surgery. At each time point, two rabbits were randomly selected for pathological examination. RESULTS The results showed that fractional anisotropy (FA) derived from both DKI and DTI demonstrated a significant difference between injured and control nerves at all time points (all P < 0.005) mean kurtosis of the injured nerve was lower than that on the control side after 2-8 weeks (all P < 0.05). No statistically significant difference was found in radial kurtosis, axial kurtosis, and apparent diffusion coefficient at almost every time point. The difference in compound muscle action potential (CMAP) of the bilateral gastrocnemius at each time point was statistically significant (all P < 0.001). CONCLUSIONS CMAP was a sensitive and reliable method to assess acute PNCI without being affected by perineural edema. DKI may not be superior to DTI in evaluating peripheral nerves, DTI with a shorter scanning time was preferred as an effective choice for evaluating acute peripheral nerve traumatic injury.
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Affiliation(s)
- Qi Wan
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Yudong Yu
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China.,Department of Radiology, Huizhou Central People's Hospital, Huizhou, China
| | - Yingying Bao
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Jianfeng Hu
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Peng Wang
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Yu Peng
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Xiaoying Xia
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | | | - Jieqiong Liu
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Xiaobin Xie
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China
| | - Xinchun Li
- Department of Radiology, The First Affiliated Hospital of Guangzhou Medical University, Yanjiangxilu No. 151, Guangzhou, 510120, China.
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Pridmore MD, Glassman GE, Pollins AC, Manzanera Esteve IV, Drolet BC, Weikert DR, Does MD, Perdikis G, Thayer WP, Dortch RD. Initial findings in traumatic peripheral nerve injury and repair with diffusion tensor imaging. Ann Clin Transl Neurol 2021; 8:332-347. [PMID: 33403827 PMCID: PMC7886047 DOI: 10.1002/acn3.51270] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022] Open
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.
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Affiliation(s)
- Michael D. Pridmore
- Vanderbilt Institute for Imaging ScienceVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Gabriella E. Glassman
- Department of Plastic SurgeryVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Alonda C. Pollins
- Department of Plastic SurgeryVanderbilt University Medical CenterNashvilleTennesseeUSA
| | | | - Brian C. Drolet
- Department of Plastic SurgeryVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Douglas R. Weikert
- Department of Orthopaedic SurgeryVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Mark D. Does
- Department of Biomedical EngineeringVanderbilt UniversityNashvilleTennesseeUSA
| | - Galen Perdikis
- Department of Plastic SurgeryVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Wesley P. Thayer
- Department of Plastic SurgeryVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Richard D. Dortch
- Vanderbilt Institute for Imaging ScienceVanderbilt University Medical CenterNashvilleTennesseeUSA
- Department of Biomedical EngineeringVanderbilt UniversityNashvilleTennesseeUSA
- Department of Neuroimaging ResearchBarrow Neurological InstitutePhoenixArizonaUSA
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Taminato M, Tomita K, Yano K, Otani N, Kuroda K, Kubo T. Targeted sensory reinnervation by direct neurotization of skin: An experimental study in rats. J Plast Reconstr Aesthet Surg 2021; 74:2379-2386. [PMID: 33583760 DOI: 10.1016/j.bjps.2020.12.101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/15/2020] [Accepted: 12/26/2020] [Indexed: 12/01/2022]
Abstract
BACKGROUND No effective methods currently exist for breast neurotization in implant-based breast reconstruction. Here, we focused on direct neurotization (DN), in which axons regenerating from nerve stumps are directed to the mastectomy flap and aimed to assess whether DN can generate a new mechano-nociceptive field using a rat model of back skin sensory denervation. METHODS Dorsal cutaneous nerves (DCNs) of rats were exposed and transected, leaving only the left medial branch of the DCN of thoracic segment 13 (mDCN-T13) intact. This procedure resulted in an isolated innervated field surrounded by a denervated field. The mDCN-T13 was transected, and the proximal nerve stump was sutured to the subdermis (DN subdermal group, n = 6) or dermis (DN dermal group, n = 5) of a different region of the denervated field. In the Crush group (n = 5), the intact mDCN-T13 was only crushed. We evaluated the generation of a new mechano-nociceptive field over time using the cutaneous trunci muscle (CTM) reflex test and histomorphometrically evaluated regenerating nerves in the reinnervated region. RESULTS In the DN groups, the CTM reflex appeared in the DN area after postoperative week 4. The new mechano-nociceptive field gradually expanded afterwards, and by postoperative week 12, the area was substantially larger than the original region innervated by the mDCN-T13 in the DN dermal group, although not as large as that in the Crush group. In histomorphometric evaluations, many S100-positive myelinated fibers were observed in the dermis of the reinnervated area for all groups. CONCLUSION In targeted sensory reinnervation, DN of the skin is revolutionary in that it allows a new innervated area to be generated at a desired location regardless of whether a distal nerve stump is available. DN may present an effective approach for breast neurotization in breast reconstruction after mastectomy, particularly for procedures that cannot use sensate flaps such as implant-based breast reconstruction.
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Affiliation(s)
- Mifue Taminato
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Koichi Tomita
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | | | - Naoya Otani
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kazuya Kuroda
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Tateki Kubo
- Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
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