Morphometric comparison of computed tomography to magnetic resonance imaging in the evaluation of the lumbar intervertebral foramina

The purpose of this study was to evaluate and compare the ability of computerized tomography (CT) and magnetic resonance imaging (MRI) as techniques to determine linear morphometric measurements of several parameters of the right and left lumbar intervertebral foramina (IVFs). Specifically, the greatest superior-to-inferior diameter and anterior-to-posterior diameter of the lumbar IVFs were measured in a cadaveric imaging phantom. The phantom was first measured directly with vernier calipers and then embedded in gelatin to simulate soft tissue. It was then scanned with two types of protocols each for CT and MRI. The scanned images were transferred directly from the imaging units to optical disks, which were then read using an optical disk drive. The measurements taken directly from the phantom were then taken from the scans using a Macintosh II computer interfaced with the optical disk drive. The results showed that both sagittally reformatted CT images and sagittal MRI images were clinically and statistically reliable and valid methods for linear evaluation of the IVF in the sagittal plane. However, measurements made from the MRI scans were found to be more accurate than those made from the CT scans. The results of this study should help increase understanding of the strengths and weaknesses of both imaging modalities in the sagittal evaluation of the lumbar IVFs. The results may also help with the future evaluation of the IVF in the condition known as nerve root canal stenosis. This study also indicates that a normal morphometric database from the MRI scans of normal human subjects should be developed. © 1994 Wiley-Liss, Inc.     

腰神经根血供的形态学观察

目的：了解腰段神经根的血供。方法：35例新鲜胎尸标本,对其中25例动脉灌注乳胶填充剂,进行显微解剖剥离观察,10例动脉灌注墨汁制成透明标本,用于观察动脉血管走行分布情况。结果：脊支动脉多在椎弓根下方紧贴椎体后外缘或与椎管前支共干或单独一干起于腰动脉,且多在根袖远端1/2区穿入硬脊膜鞘。根动脉伴神经根走行,发出的微动脉主要分布在软脊膜内成为一级动脉,由软脊膜内微动脉再发出细支,斜行或横行进入根束束间,沿根束上下分布排列成为二级动脉。结论：神经根血供主要来源脊支动脉发出的根动脉,神经根内血管系统由根动脉沿神经根发出的微动脉在神经根表面和根束间、根束内的微血管网构成。     

微创脊柱内镜系统辅助下行改良经孔椎体间融合术治疗急慢性腰椎间盘损伤性腰椎疾病的临床疗效观察

目的：探究微创脊柱内镜系统辅助下的改良经孔椎体间融合术(transforaminal lumbar interbody fusion, TLIF)治疗急、慢性腰椎间盘损伤性腰椎疾病的临床治疗效果。方法：本次实验所选取的研究对象为我院从2014年2月至2015年10月接诊的84例腰椎疾病的患者,根据患者的档案纳入顺序和患者的意愿,随机将患者分成观察组和对照组,每组有42例患者。观察组的患者进行微创脊柱内镜系统辅助下的改良TLIF治疗,对照组的患者进行开放脊柱内镜系统辅助下的改良TLIF治疗。对两组患者的手术时间、术中的出血量、术后的引流量、术后的下地时间和术后的并发症的发生率进行统计和比较,同时观察并比较两组患者在手术前后Oswestry功能障碍指数(Oswestry disability index,ODI)、视觉模拟评分法(visual analogue scale,VAS)对患者疼痛的评分和患者椎间植骨的融合情况进行比较。结果：两组患者所需要的手术时间无显著性差异(P>0.05);观察组患者的术中出血量、术后的引流量、术后的下地时间显著低于对照组的患者(P<0.05);两组患者在术后6个月的植骨融合率无明显差异(P>0.05);手术前两组患者的VAS评分和ODI评分无显著性差异(P>0.05);手术1周后,两组患者的VAS和ODI评分显著低于手术前(P<0.05),并且术后1周后观察组患者的VAS和ODI评分显著低于治疗组(P<0.05);两组患者的VAS和ODI评分在术后6个月无明显差异(P>0.05);两组患者均无出现椎间隙感染和神经根损伤等并发症。结论：对于急、慢性腰椎间盘损伤性腰椎疾病的患者,微创脊柱内镜系统辅助下行改良TLIF治疗,患者具有手术创伤小、术中出血少和术后恢复快的临床特点,远期可获得与传统的开放手术相同的临床效果,故微创脊柱内镜系统辅助下的改良TLIF治疗值得临床上推广使用。     

胎儿腰椎间孔韧带的观测及意义

目的:观察腰椎间孔韧带的形态,探讨其生理意义。方法:选用足月胎儿尸体标本11具,解剖观察腰椎间孔韧带,用游标卡尺进行相关测量。结果:在22侧腰椎标本中未发现横孔上韧带,L1、L2和L3横孔下韧带的宽度、厚度和长度分别为:L1:(1.4±0.4)mm、(0.4±0.2)mm、(2.8±0.5)mm,L2:(1.3±0.4)mm、(0.4±0.2)mm、(2.8±0.5)mm,L3:(1.6±0.1)mm、(0.4±0.1)mm、(2.8±0.9)mm,L4和L5椎间孔内未发现横孔下韧带;标本中未发现体横上韧带,体横下韧带分布于L3～L5椎间孔的外侧,其宽度、厚度和长度分别为:L3:(2.1±0.4)mm、(0.6±0.1)mm、(4.5±1.2)mm、L4:(2.0±1.2)mm、(0.4±0.2)mm、(5.7±0.8)mm,L5:(2.4±0.8)mm、(0.4±0.2)mm、(5.0±1.0)mm。结论:胎儿腰椎间孔韧带普遍存在,其为腰椎的正常组织结构。     

腰椎后外侧部血供的应用解剖学研究及临床意义

目的：探讨腰椎后外侧入路摘除极外侧椎间盘突出手术中减少血管损伤的方法。方法：对30侧经动脉灌注乳胶的成人尸体标本进行局部解剖研究，解剖观测椎间孔前缘以后的腰动脉各级分支的起源、走行、外径及与出口神经的关系。结果：腰动脉从椎间孔前缘向外后内发出分支。在椎间孔外区，后支主干及其分支与出口腰神经前支的关系密切，血管呈“树叉”状从外侧将神经包绕。结论：紧贴腰椎峡部外缘，将后支血管及其分支推向外侧，是显露腰神经前支与极外侧型突出椎间盘的最安全、快捷的方法。     

选择性关节突周围减压结合改良TLIF治疗退变性腰椎管狭窄症

目的探讨选择性关节突周围减压、结合改良TLIF、椎弓根钉固定治疗退变性腰椎管狭窄症的治疗效果。方法采用选择性关节突周围减压、结合改良TLIF、椎弓根钉固定治疗退变性腰椎管狭窄症患者22例,男14例,女8例,平均年龄63.5岁;融合单节段8例,双节段10例,三节段4例。结果全部患者均安全完成手术,未出现严重并发症。经6个月～2年（平均13月）随访,术前症状及体征均缓解,脊柱融合率达90.9%,未发生植入骨的吸收、移位和沉陷。本组疗效优13例,良6例,可3例,优良率86.3%。结论选择性关节突周围减压、结合改良TLIF、椎弓根钉固定是一种有效治疗退变性腰椎椎管狭窄症的手术方法,并且创伤相对小,恢复快,经济适用,尤其适合于基础医院。     

腰神经后支影像解剖学定位研究及其意义

目的　为诊治腰背部疼痛及麻醉定位提供腰神经后支的影像解剖学资料。 方法　选择符合实验要求成年30例,行螺旋CT薄层扫描（范围T12-S1）,将原始数据导入重建软件进行相关指标测量,并行统计分析。 结果　横突根点旁开距离L1-L5分别为（20.86±6.00）mm,（21.19±4.71）mm,（22.86±4.53）　mm,（24.56±5.10）mm,（26.68±5.98）mm;横突根点深L1-L5分别为（27.55±4.42）mm,（29.02±5.39）mm,（32.64±5.03）mm,（33.92±4.74）mm,（35.65±4.89）mm;横突根点高L1-L5分别为（8.12±5.84）mm,（8.22±　4.87）mm,（8.61±4.60）mm,（8.40±6.13）mm,（8.49±4.67）mm;L1- L5横突、横突根点旁开距离及深度等观测指标均有明显的变化规律。 结论　三维重建,可真实客观地反映各腰椎相关结构指标和变化规律,为腰段麻醉定位、腰背痛疾患诊治提供影像解剖学依据。     

经Wiltse入路椎间孔椎体间融合术治疗腰椎滑脱合并腰椎管狭窄的疗效

目的探讨经椎旁肌间隙(Wiltse)入路椎间孔椎体间融合术(TLIF)治疗腰椎滑脱合并腰椎管狭窄的效果。方法选取腰椎滑脱合并腰椎管狭窄患者107例,按治疗方案不同分为Wiltse入路组(n=53)和传统入路组(n=54)。Wiltse入路组采取Wiltse入路TLIF,传统入路组采取传统后正中入路TLIF。对比2组患者手术情况,术后1年疗效、椎体融合率,术前及术后1 d、3 d血清促肾上腺皮质激素(ACTH)、肿瘤坏死因子-α(TNF-α)、皮质醇(Cor)水平,术前及术后6个月、1年腰、腿痛视觉模拟量表(VAS)评分、日本骨科协会(JOA)评分、Oswestry功能障碍指数(ODI),术前及术后6个月椎旁肌组织面积。结果Wiltse入路组患者手术时间短于传统入路组(P<0.05),术中出血量、术后引流量低于传统入路组(P<0.05);2组患者术后1年疗效、椎体融合率比较,差异无统计学意义(P>0.05);2组患者术后1 d、3 d血清ACTH、Cor、TNF-α水平较术前升高,但Wiltse入路组低于传统入路组(P<0.05);2组患者术后6个月、1年腰、腿痛VAS评分、ODI较术前降低,JOA评分较术前提高,且Wiltse入路组术后6个月腰、腿痛VAS评分、ODI低于传统入路组,JOA评分高于传统入路组(P<0.05);Wiltse入路组术后6个月左、右侧椎旁肌组织面积大于传统入路组(P<0.05)。结论Wiltse入路TLIF与传统后正中入路TLIF治疗老年腰椎滑脱合并腰椎管狭窄效果相当,但Wiltse入路可减少术中出血,且手术创伤相对更小、术后应激反应水平更低,可在短期内促进腰椎功能改善。     

Comparison of magnetic resonance imaging and computed tomography-myelography for quantitative evaluation of lumbar intracanalar cross-section

Purpose

A comparison of MRI and computed tomography-myelography (CTM) for lumbar intracanalar dimensions. To compare the capability and reproducibility of MRI and CTM in measuring the cross-sectional morphology of intracanalar lesions of the lumbar spine.

Materials and Methods

MRI and CTM of lumbar disc levels from 61 subjects with various lumbar spinal diseases were studied. Dural area, dural anteroposterior (AP) diameter, dural right-left diameter, and thickness of the ligamentum flavum were measured by two orthopedic surgeons. Each section was graded by degree of stenosis. Absolute value and intra- and inter-observer correlation coefficients (ICC) of these measurements and the associations between MRI and CTM values were determined.

Results

Except for MRI determination of ligament flavum thickness, CTM and MRI and intra- and ICC suggested sufficient reproducibility. When measurements of dural area, dural AP diameter, and RL diameter were compared, values in CTM were significantly (p = 0.01-0.004) larger than those in MRI (CTM/MRI ratios, 119%, 111%, and 105%, respectively). As spinal stenosis became more severe, discrepancies between CTM and MRI in measurements of the dural sac became larger.

Conclusion

Both CTM and MRI provided reproducible measurements of lumbar intracanalar dimensions. However, flavum thickness may be more accurately measured by CTM. Because the differences in the measurements between CTM and MRI are very slight and there is very little data to suggest that the precise degree of stenosis is related to symptoms or treatment outcome, the usefulness of the CTM over MRI needs to be confirmed in future studies.     

经皮大通道内镜下与Wilste入路经椎间孔腰椎椎间融合术治疗退变性腰椎椎管狭窄症的疗效比较

目的 比较经皮大通道脊柱内镜下腰椎椎间融合术（percutaneous coaxial large-channel endoscopic lumbar interbodyfusion,PE-LIF）与Wilste入路经椎间孔腰椎椎间融合术（Wiltse-approachtransforaminallumbar interbody fusion, MIS-TLIF）治疗退变性腰椎椎管狭窄症的临床疗效。方法 回顾性分析2021年1月至2021年12月因退变性腰椎椎管狭窄症于成都中医药大学附属医院行腰椎减压融合术的65例患者的临床资料,据手术方式分为PE-LIF组（24例）和MIS-TLIF组（41例）。比较两组患者的手术时间、术中出血量、术后引流量、术后住院天数及并发症情况。比较两组患者术前、术后1 d、术后3 d全血C反应蛋白（CRP）及术前、术后1 d、术后7 d血清磷酸肌酸激酶（CK）含量评估椎旁肌肉损伤情况。比较两组患者术前,术后3 d、1个月、3个月、12个月的腰腿痛视觉模拟评分（visual analogue scale, VAS）,以及术前,术后3个月、12个月的Oswest...     

经椎间孔椎间融合固定治疗急慢性腰椎间盘损伤回顾性分析

目的总结经椎间孔椎间融合术(TLIF)治疗腰椎间盘急慢性损伤的疗效。方法 2007年7月-2010年10月应用双侧椎板部分切除减压后行TLIF融合固定,治疗腰椎间盘急慢性损伤10例共12个节段,男6例,女4例,年龄38～72岁,平均年龄51岁。腰椎退行性变伴神经根管狭窄1例,慢性腰椎滑脱3例,急性外伤性腰椎滑脱伴双侧神经根损伤2例,腰椎间盘突出合并腰椎失稳4例。结果全部患者均未出现神经系统并发症,平均随访10(6～48个月)个月,根据Denis疼痛分级、JOA评分法,术后平均改善率90%。结论 TLIF方法可在充分减压的前提下获得脊柱的即刻稳定同时完成植骨,融合率高,并发症少,用于腰椎间盘急、慢性损伤中、短期随访临床效果肯定。     

Projection field of primary afferent fibers innervating the ventral portion of the lumbar intervertebral disc in the spinal cord dorsal horn

In the present study, we investigated the central projection of afferent fibers innervating the lumbar intervertebral disc using the fluorescent neurotracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil). The tracer Dil was applied to the ventrolateral portion of the L5-L6 intervertebral disc in 11 adult rats. Fluorescent sites were observed microscopically on spinal cord transverse sections. Fluorescent spots in laminae I-III were plotted on the central projection map of cutaneous afferents. In six of 11 rats, Dil was restricted to the application site. Of these six rats, three showed no evident fluorescent sites. In the remaining three rats, small fluorescent spots were scattered in the dorsal horn. Fluorescent spots in dorsal horn lamina I were located in the central projection fields of the low back and groin skin. Fluorescent spots were observed, also sporadically, in Clarke's column in T12-L1 segments. The central projection of afferent fibers innervating the rat lumbar intervertebral disc was indistinct with Dil labeling. We presumed this was due to the scarcity of central terminal arbors of disc afferent fibers. Spotty projections in laminae I-IllIIere present near the central projection fields of the loin and groin, indicating that pain would be perceived in the groin.     

Danger of damaging the medial branches of the posterior rami of spinal nerves during a dorsomedian approach to the spine

Postoperative atrophy of the deep back muscles may be caused by denervation during a dorsomedian approach to the thoracolumbar spine; ensuing instability of the spine with poor clinical results, perhaps due to such muscle loss, has been observed in 11.7% of cases (Sihvonen et al., 1993, Spine 18:575--581). More specifically, this complication may be caused by damaging the medial branches of the posterior rami of the spinal nerves during lateral retraction of the muscles. To investigate the anatomic topography of the medial branches of the posterior rami of the spinal nerves, 18 carbol-formol-fixed specimens were dissected using an operation microscope; also, 3 fresh cadavers were cut in horizontal and vertical planes with a rotary cryotome to confirm the anatomic topography observed in the fixed specimens. In the thoracolumbar spine the medial branch of the posterior ramus of the spinal nerve is subject to ligamentous fixation by the strong fibers of the mammillo-accessory ligament, which extends between the mammillary process and accessory process infero lateral to the superior articular process. When the dorsomedian approach to the thoracolumbar spine is enlarged laterally to the articular processes by retracting the paraspinous muscles, the medial branches of the posterior rami of the spinal nerves are endangered. This may cause postoperative pain as well as dynamic instability beyond the corresponding segments. The results of our anatomic study suggest that the posterior surgical midline approach to the thoracolumbar spine should not be enlarged laterally to the articular processes to prevent injury to the medial branches of the posterior rami of the spinal nerves.     

双通道镜下腰椎间融合术治疗退变性腰椎疾病的手术要点和早期疗效

目的　介绍双通道镜下腰椎间融合术（biportal endoscopic lumbar intervertebral fusion,BELIF）的手术要点,报道短期临床疗效及手术并发症。 方法　54例患者（男性24例,女性30例,年龄38~79岁）接受BELIF术并随访3个月以上的。记录术前术后腰腿痛VAS及ODI评分。统计总手术时间,镜下操作时间,记录围手术期并发症,计算围手术期失血量,测量植骨区域占总椎间盘面积的百分比。 结果　腰疼VAS评分由术前（6.13±0.64）分改善至末次随访时的（2.21±1.04）分（P<0.05）,ODI评分由术前（46.54±13.75）改善至（14.78±9.23）（P<0.05）。平均手术时间164 min,平均镜下时间102 min。平均出血量为（156±31）ml。平均植骨面积（48.5±9.4）%。未出现严重并发症。 结论　BELIF术短期临床疗效好,并发症少,是一种兼顾微创,安全及效率的腰椎融合手术。     

双通道镜下腰椎间融合术治疗退变性腰椎疾病的手术要点和早期疗效

目的　介绍双通道镜下腰椎间融合术（biportal endoscopic lumbar intervertebral fusion,BELIF）的手术要点,报道短期临床疗效及手术并发症。 方法　54例患者（男性24例,女性30例,年龄38~79岁）接受BELIF术并随访3个月以上的。记录术前术后腰腿痛VAS及ODI评分。统计总手术时间,镜下操作时间,记录围手术期并发症,计算围手术期失血量,测量植骨区域占总椎间盘面积的百分比。 结果　腰疼VAS评分由术前（6.13±0.64）分改善至末次随访时的（2.21±1.04）分（P<0.05）,ODI评分由术前（46.54±13.75）改善至（14.78±9.23）（P<0.05）。平均手术时间164 min,平均镜下时间102 min。平均出血量为（156±31）ml。平均植骨面积（48.5±9.4）%。未出现严重并发症。 结论　BELIF术短期临床疗效好,并发症少,是一种兼顾微创,安全及效率的腰椎融合手术。     

C7神经移位椎管内吻合腰神经前根重建截瘫屈髋伸膝功能的应用解剖

目的:为C7神经移位椎管内吻合腰神经前根重建截瘫患者屈髋伸膝功能提供解剖学基础。方法:在20例成人尸体标本上,观测L1阶段椎管内L1～4神经前根排列及纤维数、C7神经转移路径距离及坐骨神经可切取长度及远端纤维数。结果:一侧C7神经经椎体前通路跨越椎体中线的长度为(2.4±0.58)cm,可与对侧C7神经编织成束。在L1节段,L1～4神经前支可辨认并能编织成束供吻合。胫神经和腓总神经可切取长度(52.35±2.60)cm,(48.20±2.37)cm能够满足C7至L1段椎管的距离(48.35±3.36)cm。一侧胫神经和腓总神经远端纤维数(26856±112),(25700±156)大于一侧腰L1～4神经前支纤维数(20766±354)。结论:坐骨神经可选择为颈7神经移位重建截瘫下肢功能的桥接神经,双侧C7神经可经椎体前通路编织成束作为动力神经源,在L1阶段椎管内吻合L1～4腰神经前根的具有可行性。     

Three-dimensional freehand ultrasonography to measure muscle volume of the lumbar multifidus: Reliability of processing technique and validity through comparison to magnetic resonance imaging

There is a growing interest in muscle characteristics of the lumbar multifidus related to low back pain, but findings between studies are inconsistent. One of the issues explaining these conflicting findings might be the use of two-dimensional measures of cross-sectional area and thickness of the lumbar multifidus in most studies, which might be a suboptimal representation of the entire muscle volume. A three-dimensional volumetric assessment, combined with standardized imaging and processing measurement protocols, is highly recommended to quantify spinal muscle morphology. Three-dimensional freehand ultrasonography is a technique with large potential for daily clinical practice. It is achieved by combining conventional two-dimensional ultrasound with a motion-tracking system, recording the position and orientation of the ultrasound transducer during acquisition, resulting in a three-dimensional reconstruction. This study investigates intra- and interprocessor reliability for the quantification of muscle volume of the lumbar multifidus based on three-dimensional freehand ultrasound and its validity, in 31 patients with low back pain and 20 healthy subjects. Two processors manually segmented the lumbar multifidus on three-dimensional freehand ultrasound images using Stradwin software following a well-defined method. We assessed the concurrent validity of the measurement of multifidus muscle volume using three-dimensional freehand ultrasound compared with magnetic resonance imaging in 10 patients with low back pain. Processing reliability and agreement were determined using intraclass correlation coefficients, Bland–Altman plots, and calculation of the standard error of measurement and minimal detectable change, while validity was defined based on correlation analysis. The processing of three-dimensional freehand ultrasound images to measure lumbar multifidus volume was reliable. Good to excellent intraclass correlation coefficients were found for intraprocessor reliability. For interprocessor reliability, the intraclass correlation coefficients were moderate to good, emphasizing the importance of processing guidelines and training. A single processor analysis is preferred in clinical studies or when small differences in muscle volume are expected. The correlation between magnetic resonance imaging and three-dimensional freehand ultrasound measurements of lumbar multifidus volume was moderate to good but with a systematically smaller multifidus volume measured on three-dimensional freehand ultrasound. These results provide opportunities for both researchers and clinicians to reliably assess muscle structure using three-dimensional freehand ultrasound in patients with low back pain and to monitor changes related to pathology or interventions. To allow implementation in both research and clinical settings, guidelines on three-dimensional freehand ultrasound processing and training were provided.     

Magnetic resonance imaging of the lumbar spine and blood volume in professional cyclists

Stimulated hematopoiesis is observed in the bone marrow of endurance-trained athletes by magnetic resonance imaging (MRI) independent of the hemoglobin concentration (hematocrit or erythrocyte count) or circulating reticulocytes, but may be related to blood volume (BV). This study determined whether hyperplasia of hematopoietic bone marrow of professional cyclists correlates with their red cell volume (RCV). Twelve male professional cyclists (mean ± SD; 20.2 ± 1.4 years, 69.0 ± 4.5 kg, VO2max 64.4 ± 4.6 ml/min/kg, BV 7257 ± 884 ml, RCV 2990 ± 299 g) completed an MRI of the lumbar spine, a total BV determination using a CO-rebreathing method and a graded exercise testing within two consecutive days. Significant correlations were found between performance and BV data. A significant correlation existed also between the signal intensity of the Turbo inversion-recovery sequence with short inversion time (Turbo-STIR) and BV (r ² = 0.47, P < 0.05), RCV (r ² = 0.56, P < 0.05) and plasma volume (r ² = 0.39, P < 0.05) per kilogram body mass. The present study provides evidence of stimulated erythropoiesis with hyperplasia of the hematopoietic bone marrow of endurance athletes explaining their large RCV.     

Magnetic resonance imaging of the upper airway in patients with quadriplegia and obstructive sleep apnea

The aim of this study was to investigate upper airway anatomy in quadriplegics with obstructive sleep apnea. Fifty subjects were recruited from three hospitals in Australia: people with quadriplegia due to spinal cord injury and obstructive sleep apnea (n = 11), able‐bodied people with obstructive sleep apnea (n = 18), and healthy, able‐bodied controls (n = 19). All underwent 3‐Tesla magnetic resonance imaging of their upper airway. A subgroup (n = 34) received a topical vasoconstrictor, phenylephrine and post‐phenylephrine magnetic resonance imaging. Mixed‐model analysis indicated no significant differences in total airway lumen volume between the three groups (P = 0.086). Spinal cord injury–obstructive sleep apnea subjects had a significantly larger volume of soft palate (P = 0.020) and retroglossal lateral pharyngeal walls (P = 0.043) than able‐bodied controls. Able‐bodied–obstructive sleep apnea subjects had a smaller mandible volume than spinal cord injury–obstructive sleep apnea subjects and able‐bodied control subjects (P = 0.036). No differences were seen in airway length between groups when controlling for height (P = 0.055). There was a marginal increase in velopharyngeal volume across groups post‐phenylephrine (P = 0.050), and post hoc testing indicated the difference was confined to the able‐bodied–obstructive sleep apnea group (P < 0.001). No other upper airway structures showed significant changes with phenylephrine administration. In conclusion, people with obstructive sleep apnea and quadriplegia do not have a structurally smaller airway than able‐bodied subjects. They did, however, have greater volumes of soft palate and lateral pharyngeal walls, possibly due to greater neck fat deposition. The acute response to upper airway topical vasoconstriction was not enhanced in those with obstructive sleep apnea and quadriplegia. Changes in upper airway anatomy likely contribute to the high incidence in obstructive sleep apnea in quadriplegic subjects.