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Berthon A, Wernisch L, Stoukidi M, Thornton M, Tessier-Lariviere O, Fortier-Poisson P, Mamen J, Pinkney M, Lee S, Sarkans E, Annecchino L, Appleton B, Garsed P, Patterson B, Gonshaw S, Jakopec M, Shunmugam S, Edwards T, Tukiainen A, Jennings J, Lajoie G, Hewage E, Armitage O. Using neural biomarkers to personalize dosing of vagus nerve stimulation. Bioelectron Med 2024; 10:15. [PMID: 38880906 PMCID: PMC11181600 DOI: 10.1186/s42234-024-00147-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 05/17/2024] [Indexed: 06/18/2024] Open
Abstract
BACKGROUND Vagus nerve stimulation (VNS) is an established therapy for treating a variety of chronic diseases, such as epilepsy, depression, obesity, and for stroke rehabilitation. However, lack of precision and side-effects have hindered its efficacy and extension to new conditions. Achieving a better understanding of the relationship between VNS parameters and neural and physiological responses is therefore necessary to enable the design of personalized dosing procedures and improve precision and efficacy of VNS therapies. METHODS We used biomarkers from recorded evoked fiber activity and short-term physiological responses (throat muscle, cardiac and respiratory activity) to understand the response to a wide range of VNS parameters in anaesthetised pigs. Using signal processing, Gaussian processes (GP) and parametric regression models we analyse the relationship between VNS parameters and neural and physiological responses. RESULTS Firstly, we illustrate how considering multiple stimulation parameters in VNS dosing can improve the efficacy and precision of VNS therapies. Secondly, we describe the relationship between different VNS parameters and the evoked fiber activity and show how spatially selective electrodes can be used to improve fiber recruitment. Thirdly, we provide a detailed exploration of the relationship between the activations of neural fiber types and different physiological effects. Finally, based on these results, we discuss how recordings of evoked fiber activity can help design VNS dosing procedures that optimize short-term physiological effects safely and efficiently. CONCLUSION Understanding of evoked fiber activity during VNS provide powerful biomarkers that could improve the precision, safety and efficacy of VNS therapies.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Guillaume Lajoie
- Université de Montréal and Mila-Quebec AI Institute, Montréal, Canada
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Bidault S, Girard E, Attard M, Garcia G, Guerlain J, Breuskin I, Baudin E, Hadoux J, Garcia C, Lamartina L, Hartl DM. Preoperative ultrasound mapping of the vagus nerve in thyroid surgery. Gland Surg 2022; 11:91-99. [PMID: 35242672 PMCID: PMC8825509 DOI: 10.21037/gs-21-580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 11/05/2021] [Indexed: 08/29/2023]
Abstract
BACKGROUND Intraoperative neuromonitoring (IONM) in thyroid surgery requires electric stimulation of the vagus nerve to verify correct electrode placement. Classically the nerve is found deep to or in-between the common carotid artery and internal jugular vein, but previous studies have shown that the nerve can sometimes be found superficial to the vessels. Our aim was to determine the incidence of a superficial vagus nerve using ultrasound (US) and study possible clinical factors associated with an anteriorly-located vagus nerve. METHODS Retrospective study of patients undergoing thyroid surgery (lobectomy or total thyroidectomy) with intermittent IONM. Substernal goiters, locally invasive tumors or bulky lymph nodes were excluded. The vagus nerve was identified at the level of the mid-thyroid lobe on each side on preoperative US performed by two specialized radiologists, and its location according to 6 possible positions in relationship to the common carotid artery was recorded. The anatomic variability of the vagus nerve was analyzed in relationship to patient demographics and thyroid pathology. RESULTS Five-hundred twenty-seven patients were included. The right vagus nerve (n=522) was in-between, superficial or deep to the vessels in 92.3%, 6.1% and 1.5% and of cases, respectively, and the left vagus (n=517) in 80.2%, 18.6% and 1.2% of cases, respectively, with a statistically significant difference between right and left vagus nerves (P<0.001). The type of pathology, size of the dominant nodule or the volume of the thyroid lobe were not correlated to finding a superficial vagus nerve. CONCLUSIONS The vagus nerve was identified in all cases on US and found to be anterior to common carotid artery at the level of the thyroid lobe in 18.6% of cases on the left and 6.1% of cases on the right. Identifying this anatomic variant preoperatively may facilitate IONM and avoid inadvertent trauma to the vagus nerve during thyroid surgery.
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Affiliation(s)
- Sophie Bidault
- Department of Radiology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Elizabeth Girard
- Department of Radiology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Marie Attard
- Department of Radiology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Gabriel Garcia
- Department of Radiology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Joanne Guerlain
- Department of Surgery, Anesthesia and Interventional Medicine, Thyroid Surgery Unit, Gustave Roussy, Villejuif, France
| | - Ingrid Breuskin
- Department of Surgery, Anesthesia and Interventional Medicine, Thyroid Surgery Unit, Gustave Roussy, Villejuif, France
| | - Eric Baudin
- Department of Nuclear Medicine and Endocrine Oncology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Julien Hadoux
- Department of Nuclear Medicine and Endocrine Oncology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Camilo Garcia
- Department of Nuclear Medicine and Endocrine Oncology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Livia Lamartina
- Department of Nuclear Medicine and Endocrine Oncology, Gustave Roussy Cancer Campus and University Paris-Saclay, Gustave Roussy, Villejuif, France
| | - Dana M. Hartl
- Department of Surgery, Anesthesia and Interventional Medicine, Thyroid Surgery Unit, Gustave Roussy, Villejuif, France
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Settell ML, Skubal AC, Chen RCH, Kasole M, Knudsen BE, Nicolai EN, Huang C, Zhou C, Trevathan JK, Upadhye A, Kolluru C, Shoffstall AJ, Williams JC, Suminski AJ, Grill WM, Pelot NA, Chen S, Ludwig KA. In vivo Visualization of Pig Vagus Nerve "Vagotopy" Using Ultrasound. Front Neurosci 2021; 15:676680. [PMID: 34899151 PMCID: PMC8660563 DOI: 10.3389/fnins.2021.676680] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 11/01/2021] [Indexed: 02/05/2023] Open
Abstract
Background: Placement of the clinical vagus nerve stimulating cuff is a standard surgical procedure based on anatomical landmarks, with limited patient specificity in terms of fascicular organization or vagal anatomy. As such, the therapeutic effects are generally limited by unwanted side effects of neck muscle contractions, demonstrated by previous studies to result from stimulation of (1) motor fibers near the cuff in the superior laryngeal and (2) motor fibers within the cuff projecting to the recurrent laryngeal. Objective: Conventional non-invasive ultrasound, where the transducer is placed on the surface of the skin, has been previously used to visualize the vagus with respect to other landmarks such as the carotid and internal jugular vein. However, it lacks sufficient resolution to provide details about the vagus fascicular organization, or detail about smaller neural structures such as the recurrent and superior laryngeal branch responsible for therapy limiting side effects. Here, we characterize the use of ultrasound with the transducer placed in the surgical pocket to improve resolution without adding significant additional risk to the surgical procedure in the pig model. Methods: Ultrasound images were obtained from a point of known functional organization at the nodose ganglia to the point of placement of stimulating electrodes within the surgical window. Naïve volunteers with minimal training were then asked to use these ultrasound videos to trace afferent groupings of fascicles from the nodose to their location within the surgical window where a stimulating cuff would normally be placed. Volunteers were asked to select a location for epineural electrode placement away from the fascicles containing efferent motor nerves responsible for therapy limiting side effects. 2-D and 3-D reconstructions of the ultrasound were directly compared to post-mortem histology in the same animals. Results: High-resolution ultrasound from the surgical pocket enabled 2-D and 3-D reconstruction of the cervical vagus and surrounding structures that accurately depicted the functional vagotopy of the pig vagus nerve as confirmed via histology. Although resolution was not sufficient to match specific fascicles between ultrasound and histology 1 to 1, it was sufficient to trace fascicle groupings from a point of known functional organization at the nodose ganglia to their locations within the surgical window at stimulating electrode placement. Naïve volunteers were able place an electrode proximal to the sensory afferent grouping of fascicles and away from the motor nerve efferent grouping of fascicles in each subject (n = 3). Conclusion: The surgical pocket itself provides a unique opportunity to obtain higher resolution ultrasound images of neural targets responsible for intended therapeutic effect and limiting off-target effects. We demonstrate the increase in resolution is sufficient to aid patient-specific electrode placement to optimize outcomes. This simple technique could be easily adopted for multiple neuromodulation targets to better understand how patient specific anatomy impacts functional outcomes.
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Affiliation(s)
- Megan L. Settell
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
| | - Aaron C. Skubal
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
| | - Rex C. H. Chen
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
| | - Maïsha Kasole
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
| | - Bruce E. Knudsen
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
| | - Evan N. Nicolai
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, United States
| | - Chengwu Huang
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
| | - Chenyun Zhou
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
- Department of Ultrasound, West China Hospital of Sichuan University, Chengdu, China
| | - James K. Trevathan
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
| | - Aniruddha Upadhye
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States
| | - Chaitanya Kolluru
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States
| | - Andrew J. Shoffstall
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Louis Stokes Cleveland VA Medical Center, Cleveland, OH, United States
| | - Justin C. Williams
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
- Department of Neurosurgery, University of Wisconsin-Madison, Madison, WI, United States
| | - Aaron J. Suminski
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
- Department of Neurosurgery, University of Wisconsin-Madison, Madison, WI, United States
| | - Warren M. Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, United States
- Department of Neurobiology, Duke University, Durham, NC, United States
- Department of Neurosurgery, Duke University, Durham, NC, United States
| | - Nicole A. Pelot
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Shigao Chen
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
| | - Kip A. Ludwig
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States
- Wisconsin Institute of Neuroengineering (WITNe), University of Wisconsin-Madison, Madison, WI, United States
- Department of Neurosurgery, University of Wisconsin-Madison, Madison, WI, United States
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Papadopoulou M, Papapostolou A, Bakola E, Masdrakis VG, Moschovos C, Chroni E, Tsivgoulis G, Michopoulos I. Neurophysiological and ultrasonographic comparative study of autonomous nervous system in patients suffering from fibromyalgia and generalized anxiety disorder. Neurol Sci 2021; 43:2813-2821. [PMID: 34557968 DOI: 10.1007/s10072-021-05606-3] [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: 06/01/2021] [Accepted: 09/16/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Fibromyalgia (FM) and generalized anxiety disorder (GAD) share common clinical features: they both affect women more than men, their diagnosis is based solely on clinical criteria, and some of the symptoms such as anxiety, aches and muscle tension, sleep disorders, and cognitive dysfunction occur in both diseases. For both conditions, an underlying dysregulation of the autonomic nervous system (ANS) has been proposed. OBJECTIVE The aims of this study were to investigate ANS dysfunction in FM and GAD and compare them with controls. METHODS Sympathetic skin response (SSR) from palm and sole and cross-sectional area (CSA) of bilateral vagus nerves (VN) were measured in 28 healthy controls, 21 FM patients, and 24 GAD patients. RESULTS CSA of VN was significantly smaller in FM patients (right: 1.97 ± 0.74mm2, left: 1.75 ± 0.65 mm2) and GAD patients (right: 2.12 ± 0.97mm2, left: 1.71 ± 0.86 mm2) compared to controls (right: 3.21 ± 0.75 mm2, left: 2.65 ± 1.13 mm2, p < 0.001, but did not differ between the two patient groups. SSR parameters were similar between patients and controls. SSR latency correlated to clinical scales (FM Widespread Pain Index) in the FM group (r = 0.515, p = 0.02 and r = 0.447, p = 0.05) for the upper and lower limbs respectively, but no other correlation between clinical and neurophysiological parameters was identified. CONCLUSION This study confirms similar ANS abnormalities in FM and GAD that fairly distinguish them from controls and support the hypothesis of a common pathophysiological substrate underlying both conditions.
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Affiliation(s)
- Marianna Papadopoulou
- Second Department of Neurology, Medical School, National and Kapodistrian University of Athens Attikon University General Hospital, Athens, Greece. .,Department of Physiotherapy, Laboratory of Neuromuscular and Cardiovascular Study of Motion, University of West Attica, 28 Ag. Spyridonos, 12243, Athens, Greece.
| | | | - Eleni Bakola
- Second Department of Neurology, Medical School, National and Kapodistrian University of Athens Attikon University General Hospital, Athens, Greece
| | - Vasilios G Masdrakis
- First Department of Psychiatry, Medical School, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
| | - Christos Moschovos
- Second Department of Neurology, Medical School, National and Kapodistrian University of Athens Attikon University General Hospital, Athens, Greece
| | - Elisabeth Chroni
- Department of Neurology, School of Medicine, University of Patras, Rio-Patras, Greece
| | - Georgios Tsivgoulis
- Second Department of Neurology, Medical School, National and Kapodistrian University of Athens Attikon University General Hospital, Athens, Greece
| | - Ioannis Michopoulos
- Second Department of Psychiatry, Medical School, National and Kapodistrian University of Athens, Attikon University General Hospital, Athens, Greece
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Laucius O, Gabrinovičienė R, Jucevičiūtė N, Vaitkus A, Balnytė R, Petrikonis K, Rastenytė D. Effect of aging on vagus somatosensory evoked potentials and ultrasonographic parameters of the vagus nerve. J Clin Neurosci 2021; 90:359-362. [PMID: 34275575 DOI: 10.1016/j.jocn.2021.03.048] [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: 01/09/2021] [Revised: 02/18/2021] [Accepted: 03/30/2021] [Indexed: 10/21/2022]
Abstract
Vagus somatosensory evoked potentials (VSEP) and ultrasonography can be used to detect functional and structural changes of the vagus nerve (VN) that are hypothesized to be associated with neurodegenerative diseases. However, it has not yet been established whether age-related changes in the VN occur in the healthy population. In this pilot study we included healthy volunteers in the 26-30 and 51-55 age range who comprised the younger (n = 20) and older (n = 20) groups, respectively. VSEP were recorded separately for stimulation of the auricular branch of the left and right VN. The VN CSA was measured in the transverse plane proximal to the carotid bifurcation, at the level of the distal end of the common carotid artery. No differences were found between the younger and older groups when comparing the average VN CSA (2.01 ± 0.20 vs 2.05 ± 0.20, mm2; p = 0.570) or the CSA of the right (2.08 ± 0.19 vs 2.17 ± 0.24, mm2; p = 0.233) or left VN (1.94 ± 0.26 vs 1.93 ± 0.24, mm2; p = 0.911). The right VN was larger than the left in 95% (n = 19) of older participants and in 65% (n = 13) of younger participants (p = 0.055). In comparison with the younger group, older participants showed significantly longer VSEP latencies of all wave components for electrodes C4-F4 and Fz-F3, of P1 for electrodes C3-F3 and of N1 and P2 for electrodes Fz-F4. The results of this study indicate that older age is associated with longer VSEP latencies but not with changes in VN CSA.
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Affiliation(s)
- Ovidijus Laucius
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania.
| | - Radvilė Gabrinovičienė
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania
| | - Neringa Jucevičiūtė
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania
| | - Antanas Vaitkus
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania
| | - Renata Balnytė
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania
| | - Kęstutis Petrikonis
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania
| | - Daiva Rastenytė
- Department of Neurology, Lithuanian University of Health Sciences, Eiveniu street 2, Kaunas LT-50009, Lithuania
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Ahn D, Lee GJ, Sohn JH, Kim JK. Prevalence and characteristics of vagus nerve variations on neck ultrasonography. Ultrasonography 2021; 41:124-130. [PMID: 34261211 PMCID: PMC8696142 DOI: 10.14366/usg.21045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 04/26/2021] [Indexed: 11/15/2022] Open
Abstract
Purpose We aimed to evaluate the true prevalence and characteristics of vagus nerve (VN) variations using the carotid artery (CA) and the internal jugular vein (C-I axis). Methods We examined patients who underwent neck ultrasonography (US) conducted by a single operator. A VN variation was defined as a VN located anterior or medial to the C-I axis. The subtypes of VN variation were classified as anterolateral, anteromiddle, anteromedial, and medial based on the relative location of the VN to the CA. The primary outcome parameters were the prevalence of VN variations and differences according to side, age, and sex. Results Out of 536 patients, right and left VN variations were identified in 20 (3.7%) and 186 (34.7%), respectively (P<0.001). The anteromiddle type was the commonest type observed on both sides. Eight right (1.5%) and 50 left VNs (9.3%) were located <2 mm from the lateral border of the ipsilateral thyroid gland (P<0.001). The prevalence of VN variations in male and female patients was 42.1% and 32.7%, respectively (P=0.029), and that in patients aged <20, 20-39, 40-59, and ≥60 years was 23.8%, 22.5%, 34.4%, and 47.4%, respectively (P<0.001). Conclusion Variations in the VN position were relatively common on US. The variations primarily involved the left VN in the lower cervical region, and an increasing prevalence with age was observed.
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Affiliation(s)
- Dongbin Ahn
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, Daegu, Korea
| | - Gil Joon Lee
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, Daegu, Korea
| | - Jin Ho Sohn
- Department of Otolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, Daegu, Korea
| | - Jeong Kyu Kim
- Department of Otolaryngology-Head and Neck Surgery, Catholic University of Daegu School of Medicine, Daegu, Korea
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Rusu GM, Curcean AD, Dudea SM. Ultrasound and magnetic resonance imaging evaluation of the femoral and sciatic nerves. A study of healthy volunteers. Med Pharm Rep 2020; 93:357-364. [PMID: 33225261 PMCID: PMC7664720 DOI: 10.15386/mpr-1629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/05/2020] [Accepted: 05/31/2020] [Indexed: 11/23/2022] Open
Abstract
Background and aims The study describes the femoral (FN) and sciatic nerves (SN), explored using ultrasound (US) and magnetic resonance imaging (MRI). The aims of the study are: to establish US/MRI correlations and define reference values: for the anteroposterior (AP) and mediolateral (ML) diameters and cross-sectional area (CSA) of the two nerves respectively, in well-defined anatomical measuring sites; to analyze the intraobserver variation; to define the value with least variability; to determine differences between the right-left and male-female reference values. Methods A prospective study was carried out on 24 healthy volunteers (11 men and 13 women). MRI scans were performed using a 1.5T system. To visualize both nerves (FN and SN), a single 3D T2 weighted acquisition was performed, in the coronal plane, with a wide FOV. For ultrasonographic examinations, a Hitachi EUB-8500 ultrasound machine, equipped with a 13 MHz linear transducer was used. The measurements were performed at well-defined anatomical locations. The mean reference values of the AP, ML diameters and CSA were calculated for femoral and sciatic nerves, both on MRI and US. The correlations between the values determined by the two techniques were analyzed. The intra-observer variation was calculated by measuring the nerves at the same anatomical location at two separate time points. Results Wilcoxon matched-pairs signed rank test indicated a non-significant difference (p> 0.05) for the femoral and sciatic nerves, on both sides, except the femoral nerve ML diameter on MRI (p=0.014). The mean MRI and US reference values for the femoral nerve were calculated between the psoas and iliac muscles: FNAPMRI 4.533 ± 0.486, FNAPUS 4.800 ± 1.237, FNMLMRI 6.172 ± 1.203, FNMLUS 7.685 ± 3.338, FNCSAMRI 24.811 ± 3.394, FNCSAUS 26.285 ± 17.608. The mean MRI and US measurements for the sciatic nerve were determined under the buttock, at the level of the ischial tuberosity: SNAPMRI 5.500 ± 1.201, SNAPUS 5.975 ± 1.312, SNMLMRI 10.375 ± 2.272, SNMLUS 13.500 ± 1.661, SNCSAMRI 50.625 ± 15.373, SNCSAUS 53.631 ± 15.847. The MRI and US differences between right and left sides, both for the femoral and sciatic nerves were insignificant. In selected cases, Wilcoxon paired test indicated differences between subjects, according to their gender, both on MRI and US. Conclusion Reference values for the femoral and sciatic nerves at specific anatomical sites were identified. Side to side variation and gender related differences add to current knowledge on nerve size in young Caucasian population.
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Affiliation(s)
| | - Andra Diana Curcean
- Radiology Department, Academic Emergency County Hospital, Cluj-Napoca, Romania
| | - Sorin Marian Dudea
- Radiology Department, Academic Emergency County Hospital, Cluj-Napoca, Romania.,Radiology Department, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
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