鼻内镜鼻窦手术前筛窦颅底高度的CT评估价值

目的 探讨内镜鼻窦手术前应用CT评估筛窦颅底高度的价值。 方法 选取就诊于我院的100例共200侧的鼻窦冠状CT扫描图像,测量筛前动脉水平的筛顶中点至眶水平中线的距离,根据测量数据进行分型,同时进行Keros分型,用皮尔森相关系数来确定两者之间是否存在相关性。 结果 筛前动脉管水平的筛顶中点至眶水平中线的距离作为筛窦颅底高度。根据筛窦颅底的高度进行分型,其中Ⅰ型即筛窦颅底高度>7 mm(高位颅底)占44%(88/200),Ⅱ型即筛窦颅底高度介于4~7 mm(中位颅底)占41%(82/200),Ⅲ型即筛窦颅底高度<4 mm(低位颅底)占15%(30/200)。按Keros方法进行测量并分型,Ⅰ型占37%(74/200),Ⅱ型占52%(104/200),Ⅲ型占11%(22/200);Keros分型与筛窦颅底高度之间的皮尔森相关系数为0.384(P<0.001),Keros分型与筛窦颅底高度呈弱相关性。 结论 筛窦颅底高度存在明显差异,术前进行CT影像评估,可有效识别低颅底变异,有助于避免颅底损伤,进而减少内镜手术并发症。     

眶上筛房在CT和鼻内镜下的临床特征

目的通过分析眶上筛房在CT和鼻内镜下的临床特征，进一步阐明眶上筛房和额窦引流通道的关系。方法通过术前评估冠状位和水平位CT和术中鼻内镜所见，确诊眶上筛房5侧（男4例，女1例，每例1侧）。结果①眶上筛房在冠状位CT上表现为额窦区域最外侧的气房；②眶上筛房在水平位CT上表现为额窦后外方的气房；③鼻内镜下见额窦和眶上筛房均引流至前筛顶部，眶上筛房的引流通道位于额窦引流口的后外方，眶上筛房向外上方气化，从后方进入额窦。结论CT和鼻内镜观察证实眶上筛房是位于筛泡上方的气房向上、向外延展过程中，超过了筛骨眶板和筛顶的范围，导致额骨眶板气化而成。     

Sagittal and coronal dimensions of the ethmoid roof: a radioanatomic study

BACKGROUND: Understanding the anatomy of the ethmoid roof is critical to safe surgical outcomes. Normative data regarding the height and slope of this region have been somewhat limited, derived primarily from cadaveric coronal computed tomography (CT) studies. With triplanar imaging programs, precise multidimensional measurements of the ethmoid roof are now possible. We present a radioanatomic study to characterize normative sagittal and coronal dimensions of the ethmoid roof. METHODS: Bilateral measurements were taken in 100 consecutive sinus CT scans using ThinClient 3D software. In the sagittal plane, the height of the ethmoid roof was measured in quadrants at five equidistant points between the frontal beak and sphenoid face, referencing the nasal floor. In the coronal plane, the ethmoid roof was measured at three points at the level of the anterior ethmoid artery and at two points at the junction of the posterior ethmoid and sphenoid sinuses. RESULTS: When examined sagittally, the right side showed significantly lower skull base heights in the anterior ethmoid compared with the left side (59.0 mm versus 59.8 mm, p = 0.017; 53.7 mm versus 54.5 mm, p = 0.0004). Coronal measurements of the anterior ethmoid roof showed similar significant differences. The anterior ethmoid roof had greater asymmetries of height compared with the posterior ethmoid roof, which was fairly constant. CONCLUSION: This study provides numerical correlates to accepted concepts regarding the shape and slope of the ethmoid roof. Differences in height of the skull base between right and left sides, especially in the anterior ethmoid sinus, may be an important surgical consideration. The posterior ethmoid roof appears to be relatively constant and should serve as a reliable surgical landmark.     

Anatomic measurements for the endoscopic modified Lothrop procedure

BACKGROUND: The aim of this study was to introduce preoperative radiographic frontal recess and sinus anatomic measurements to assist in the selection of patients considered for the modified Lothrop procedure. METHODS: Data were collected from sagittally reconstructed computed tomography (CT) scans of seven cadaver heads. Four anatomic parameters for measurement were defined as follows: (1) thickness of the nasal beak (desirable < 10 mm); (2) midsagittal distance from nasal beak to skull base (adding 1 and 2 provides the anterior-posterior (AP) space at the cephalad margin of the frontal recess; desirable, > or = 15 mm); (3) accessible dimension (in a parasagittal plane through the frontal ostium; the distance between two lines drawn parallel to the plane of the anterior skull base and perpendicular to the line of the insertion of the nasal endoscope during surgery; the posterior line is drawn at the skull base and the anterior line is drawn at the posterior margin of the nasal beak; the distance between the lines indicates the space available for instrumentation; desirable, > 5 mm); (4) AP dimension of each frontal sinus. RESULTS: The average and the range of each parameter measured were as follows: (1) nasal beak thickness = 8.0 mm (5.0-10.4 mm); (2) nasal beak-skull base = 7.9 mm (2.5-14.1 mm); (3) accessible dimension, 6.1 mm (0.9-9.6 mm); (4) AP diameter of the frontal sinus, 9.7 mm (5.2-14.1 mm). Four specimens were considered candidates for modified Lothrop and three were not. CONCLUSION: Preoperative radiographic frontal recess and sinus anatomic measurements may assist in the selection of patients considered for the endoscopic modified Lothrop procedure.     

Anterior skull base: High risk areas in endoscopic sinus surgery in chronic rhinosinusitis: A computed tomographic analysis

Computed Tomography (CT) scan of nose and paranasal sinuses play a key role in preoperative evaluation of patients undergoing endoscopic sinus surgeries (ESS) for chronic rhinosinusitis. The asymmetry of ethmoid fovea olfactory fossa, anatomical variations of lateral lamella and course of anterior ethmoid artery are critical in ESS as it may predispose to dangerous consequences like hemorrhage. CSF leak and intracranial complications. A prospective study was done on 75 patients of clinically and diagnostically proven chronic rhinosimusits. The coronal CT scan was evaluated with special attention to anatomical variations of anterior skull base including ethmoid fovea, olfactory fossa, lateral lamella and course of anterior ethmoid artery. The endoscopic surgeon's awareness of these variations and its role in preventing complications are highlighted.     

筛泡前气房CT三维重组的影像特征及手术技巧

目的筛泡前气房可严重阻碍额窦引流,但却常被忽视,本文通过CT三维重组技术分析筛泡前气房的影像特点及其同额窦引流通道的关系,探讨手术去除筛泡前气房、开放额窦的技巧。方法对鼻及鼻窦炎患者术前轴位薄层螺旋CT扫描,冠状位、矢状位重组,明确筛泡前气房的存在,在鼻内镜下确认,分析它同额隐窝引流通道的关系。结果筛泡前气房在矢状位和轴位CT均表现为额窦区域后上方的气房,从额隐窝沿着颅底进人额窦：手术中沿着筛泡前气房的前壁可顺利找到额窦口。结论 CT三维重组对明确筛泡前气房和额窦引流通道的关系有重要意义,筛泡前气房是筛泡过度气化形成从颅底越过额窦口延伸至额窦内影响额窦引流,手术中去除筛泡前气房,可明显扩大额窦口,改善额窦引流。     

Anterior skull base trauma during endoscopic sinus surgery for nasal polyposis preferred sites for iatrogenic injuries

OBJECTIVE: To determine typical locations for traumatic lesions of the anterior skull base during endoscopic sinus surgery. STUDY DESIGN: In this retrospective study 12 patients were included who had undergone endoscopic sinus surgery for nasal polyposis and were referred to the author for revision surgery after iatrogenic trauma of the anterior skull base during the procedure. Each patient had been operated by a different surgeon, all of the physicians being in an advanced stage of their surgical career and being board certified otolaryngologists. RESULTS: During endoscopically controlled revision surgery, all lesions could be detected, 10 of them being located in the ethmoid roof, while one injury had occurred in the lateral lamella of the cribriform plate and another one in the olfactory groove between the medial turbinate and the nasal septum. CONCLUSION: In contrast to reports in the literature, the preferred site for anterior skull base injuries during endoscopic sinus surgery in our group was not the lateral lamella of the cribriform plate, but the anterior part of the ethmoid roof, just behind the frontal recess. Apparently the course of the ethmoid roof might be misinterpreted during sinus surgery even by surgeons who are familiar with the operative technique.     

正常额窦引流通道的三维CT研究

目的 研究正常额窦引流通道的三维CT影像解剖学特征.方法 对51例健康成人（102侧）,采用16排螺旋CT扫描,层距0.300 mm,层厚0.625 mm,使用三维重建技术,观察额窦引流通道毗邻气房分布、钩突附着情况、测量额窦引流通道不同径线.结果 1～4型额气房、1型额气房、眶上筛房、泡状中甲的出现率没有显著性差异（P＞0.05）.额窦中隔气房、终末隐窝的出现率有显著性差异（P＜0.05）.双侧额窦引流通道各径线,除额隐窝左-右径有统计学差异外（P＜0.05）,其余各组间差异均没有显著性（P＞0.05）.钩突顶端同时附着于眶纸板和中鼻甲（垂直板）的为82.35%,同时附着于中鼻甲（垂直板）和颅底的为17.65%.钩突的顶端与中鼻甲之间总有骨性连接,钩突与中鼻甲（垂直板）之间有第二骨性连接的达55.88%.钩突的顶端与眶纸板之间骨性连接有0～4个不等,分别占0.98%、7.84%、68.63%、21.57%、1.96%.当钩突的顶端与眶纸板之间骨性连接的个数≤1个的时候,观察不到鼻丘气房的存在.结论 以三维影像解剖为基础,构建额窦引流通道毗邻空间立体构象,正确的认识额窦引流通道,有助于个性化地选择鼻内镜下额窦开放术式,提高手术的成功率.     

The relationship between pneumatized middle turbinate and the anterior ethmoid roof dimensions: a radiologic study

The development of pneumatized middle turbinate may affect anterior ethmoid roof formation. The aim of this study was to investigate the relationship between the pneumatized middle turbinate and the dimensions of the anterior skull base structures using computed tomography scans. The coronal reconstructed images of the computed tomography scans were evaluated retrospectively. The lateral and medial ethmoid roof points, the width of the cribriform plate (CP), and the anterior ethmoid roof were identified at the first coronal cut, which was determined by the infraorbital nerve. The pneumatized middle turbinates were measured on the axial, vertical, and sagittal planes. The images of 101 patients were evaluated. The mean axial diameters of the pneumatized middle turbinate on the right and left sides were between 6.93 and 4.95 mm, respectively. The correlation between the axial diameters of the pneumatized middle turbinate and the width of the anterior ethmoid roof (termed AER width) was significant for both sides and gender (p < 0.05). There was a higher correlation on the right side where the pneumatized middle turbinate was observed more frequently (r = 0.357). The relationship between CP width and the diameters of the pneumatized middle turbinate was not significant (p > 0.05) for both sides. Iatrogenic lesions of the skull base occur predominantly in the lateral lamella of the CP. The risk of this complication may decrease with increasing of the AER width. Pneumatized middle turbinate may cause an increase in the width of the anterior ethmoid roof and provide more reliable endoscopic intervention of the anterior skull base and frontal sinus.     

Endoscopic anterior ethmoidal artery ligation: a cadaver study

OBJECTIVE: The objective of this study was to investigate the radiologic and endoscopic anatomy of the anterior ethmoidal canal (AEC) and feasibility of endoscopic ligation of the anterior ethmoidal artery (AEA). STUDY DESIGN: The authors conducted a prospective analysis of computed tomography (CT) of the paranasal sinuses and endoscopic cadaver dissection. METHODS: Twenty-two cadaver heads had CT scans of the paranasal sinuses. The height of the lateral lamella of the cribriform plate was calculated and staged according to the Keros staging system. The presence of a bony mesentery, distance from AEC to the skull base, and dehiscence of the AEC were documented. Forty-four dissections were performed, the AECs identified, and AEA ligation attempted. RESULTS: The mean height of the lateral lamella was 5.4 mm on the right and 4.7 mm on the left. In all cadaver heads with asymmetry, the right lateral lamella was longer (P<.005). A Keros type 1 pattern was seen in 23%, type 2 in 50%, and type 3 in 27%. Thirty-six percent of AECs were in a bony mesentery. AEC distance from the skull base was greater on the right (P<.009). A longer lateral lamella was correlated with the artery being in a mesentery. Sixteen percent of the AECs were dehiscent. Sixty-six percent of AEAs were unable to be clipped. Twenty percent were clipped effectively, all in a mesentery. In 14%, the AEA was not effectively clipped. CONCLUSIONS: Endoscopic AEA ligation may be possible in some patients. The AEA should be in a mesentery for an effective clip to be placed and be associated with a dehiscence of the AEC. If the lateral lamella is classified as Keros grade 2 or 3, it is likely the AEC will be found in a mesentery.     

Management of the lateral frontal sinus lesion and the supraorbital cell mucocele

BACKGROUND: Masses that radiographically appear in the lateral aspect of the frontal sinus can be difficult to access and often are approached through external approaches. Supraorbital ethmoid cells pneumatize the orbital plate of the ethmoid bone to lie posterior and lateral to the frontal sinus. Opacification of a supraorbital cell may radiographically give the appearance of a laterally based frontal sinus lesion. Often, these represent mucoceles, in which their drainage can be achieved through endoscopic techniques and without the need for an external approach. METHODS: Retrospective review of patients treated for lateral frontal sinus lesions at a tertiary sinus center was performed. Radiology, endoscopic findings, operative reports, and patient symptoms were reviewed. RESULTS: Ten patients were identified with lateral frontal sinus lesions based on radiography of the paranasal sinuses and nasal endoscopy. All patients were determined to be supraorbital mucoceles. These patients underwent surgical drainage using computer-aided endoscopic techniques. Initially, endoscopic drainage of the mucocele was successful in all patients. One patient was lost to follow-up after 3 months and one patient underwent a revision endoscopic surgery with trephination 5 months after the initial drainage. The remaining eight patients remain free of disease by nasal endoscopy and postoperative computed tomography scans (median follow-up of 25 months; range, 8-38 months). CONCLUSION: Knowledge of the anatomy of the ethmoid complex and presence of various cells within the frontal recess such as supraorbital cells are important in the management of the laterally based frontal sinus lesion. Often, these lesions may represent supraorbital cell mucoceles amenable to endoscopic drainage. Given the nature of mucoceles, long-term follow-up is needed before endoscopic drainage of these lesions can be validated. However, preliminary data suggest that an endoscopic approach provides for adequate drainage and helps avoid external approaches.     

计算机辅助鼻额区域影像解剖学研究

OBJECTIVE: To evaluate the value of Advantage Windows 3.1 (AW 3.1) software for anatomical study of nasofrontal region, and to study the CT characteristics of nasofrontal region which related to the frontal sinus surgery. METHODS: Eighty patients underwent axial consecutive computed tomography scans and these data were studied with AW 3.1 software which provided reconstructional imaging of continuous coronal, sagittal, axial sections. Some related structures of nasofrontal region were studied and measured. RESULTS: AW 3.1 software could identify and measure the following structures accurately: The diameter of frontal sinus was (22.5 +/- 8.6) mm in height, (16.3 +/- 6.8) mm in depth, (23.8 +/- 9.8) mm in breadth. The diameter of frontal sinus ostium: the anterior-posterior diameter was (7.3 +/- 1.7) mm, the transverse diameter was (8.5 +/- 1.9) mm. The width of nasal beak of frontal bone(5.9 +/- 1.4 ) mm. The distance of frontal sinus ostium to the floor of columella nasi and the corresponding angle to the nasal floor were (60.8 +/- 4.2) mm and (70.1 +/- 4.7) degrees. The superior attachment sites of the uncinate process were as follows: lamina papyracea 41%, posteromedial wall of agger nasi cell 11%, middle turbinate 19%, anterior skull base 16%, superior bifurcation 13%. The cells could impinge on the frontal recess to cause obstruction (terminal recess 38.8%, anterior ethmoid cell 27.6%, agger nasi cells 24.5%). The accessory cells could impinge on the frontal sinus (perifrontal cells 32.7%, superaorbital cells 38.8%, intersinus septal cells 32.0%). There was significant difference between two groups of characteristics of nasofrontal region. CONCLUSIONS: AW 3.1 software is a helpful and powerful new tool for anatomical study of nasofrontal region and for preoperative evaluation. The structures of nasofrontal region are complex and various, frontal sinusitis almost always results from the obstruction of frontal sinus outflow tract. These results of anatomical study of nasofrontal region are helpful in directing the functional endoscopic surgery in frontal sinus.     

Preoperative sagittal CT evaluation of the frontal recess

Endoscopic surgical approaches for chronic frontal sinusitis require the reestablishment of adequate frontal sinus ventilation and drainage for relief of symptoms. After the resection of anterior ethmoid mucosal disease and cellular structure, the anterior to posterior depth of the nasofrontal beak to the base of skull at the insertion of the ethmoidal bulla (frontal sinus ostium) often represents a critical margin for functional success. However, little information concerning this dimension is available. Depending on intraoperative surgical judgment of this distance, extended endoscopic surgical procedures involving additional bone resection may be indicated. These approaches may be hazardous due to the proximity of the cranial cavity and orbit. In addition, secondary stenosis can result from the subsequent inflammatory response. Improved CT imaging, high resolution sagittal reformatting, and computer workstations provide the ability to obtain direct preoperative measurements of the frontal recess. We used a paramedian sagittal section and recorded the maximal anterior to posterior depth from the nasofrontal beak to the base of skull at the insertion of the ethmoidal bulla in 20 patients, 31 sides, undergoing primary endoscopic frontoethmoidectomy. In addition, we found a positive correlation between this distance and agger nasi air cell size measured in the same 31 sides.     

侵犯鼻窦的前颅窝底脑膜瘤术中脑脊液漏的预防

目的:介绍侵犯颅底骨质及鼻窦的前颅窝底脑膜瘤的手术方法及颅底重建经验。方法:回顾性分析13例患者的临床资料。大冠状或小冠状皮瓣开颅,骨膜向前完整分离,分块切除肿瘤后,咬除或磨除颅底受侵蚀及增生的骨质,将突入鼻窦内的肿瘤切除。切取患者下腹部合适大小的脂肪组织,修剪后填塞入颅骨缺损处,将额骨骨膜翻下,严密缝合骨膜和颅底缺损处周边正常硬膜,用耳脑胶在缝合处粘合一圈。结果:按照Simpson标准,12例Ⅰ级切除,1例Ⅱ级切除。术后并发症包括无菌性脑膜炎3例,额叶症状包括多语、躁动、欣快及缄默3例,无脑脊液漏及颅内感染,无死亡。病理诊断均为良性脑膜瘤,其中2例为细胞增生活跃。随访9个月～8年,平均3.4年,肿瘤无复发。结论:脂肪填塞颅底缺损处,带蒂骨膜与缺损周边正常硬膜严密缝合,用生物胶加固缝合处能有效防止脑脊液漏。     

The analysis of anterior skull base from two different perspectives: coronal and reconstructed sagittal computed tomography

The aim of the study was to determine the heights of the anterior skull base and the distances between the anterior nasal spine and the skull base at three levels by means of coronal and reformatted sagittal images of computed tomography. The present study was performed on coronal and reformatted sagittal CT scans of 30 patients with sinonasal complaints. On the coronal view, the heights of the cribriform plate, the roof of ethmoid, and lateral lamella and the medial take-off angle between the ethmoid roof and cribriform plate were measured at different levels. On the reformatted sagittal images the distances from the nasal spine to the anterior cranial base at three different levels were measured. Then, the side-to-side variability of these measurements was statistically compared. The variations with normal distribution and abnormal distribution were analysed by paired t test and Wilcoxon paired-signed rank test, respectively. A statistically significant difference was detected only between the right and left sides in the height of the lateral lamella at the crista galli level (p < 0.05). The lateral lamella at the crista galli level on the left side was higher than on the right side. No statistically significant differences between the left and the right sides were noted in the heights and the distances of other data (p > 0.05). The normal anatomy of the anterior skull base has been described in detail on coronal and reconstructed sagittal computed tomography. These measurements may be helpful in the presurgical evaluation of patients undergoing endoscopic sinus surgery to optimize surgical safety.     

鼻鼻窦解剖变异与慢性鼻窦炎的关系

量化研究鼻鼻窦解剖变异与慢性鼻炎的发病的关系。用自行开发计算机图像分析系统定量分析９１例慢性鼻窦炎患者的冠状位鼻窦ＣＴ，观测指标包括：骨性解剖结构变异，筛漏钹突角度，筛泡等，测量相应结构的冠状位截面积，角度，长度。     

嗅相关神经的临床解剖学观测

目的:了解嗅神经的正常走行及其与视神经、鼻窦之间的关系,为临床开展相关手术提供解剖学资 料,并为预防鼻窦手术中嗅神经损伤提供解剖学依据。方法:在16例32侧成人尸头上对嗅神经、嗅束、嗅球进行 解剖测量,并观察其与视神经、鼻窦之间的关系。结果:嗅束的长度为(29.32±2.11)mm,中点处宽度为(3.36± 0.83)mm,嗅束中点内侧距前颅底中线垂直距离为(5.48±1.02)mm,嗅束与矢状线之间夹角为(21.32±3.28)°, 嗅球长度为(10.43±2.35)mm,宽度为(5.12±0.62)mm;84.4%(27/32)的嗅束后端与蝶窦、前中部与筛窦顶相 邻,9.4%(3/32)嗅束仅与筛窦顶相邻,6.3%(2/32)嗅束与额窦顶相邻,所有嗅束都在视神经管内口处与视神经 交叉向前内行走,嗅球前缘与筛泡前缘基本在同一水平。结论:嗅束基本都在眶内侧颅底行走,鼻内手术时应注 意不要损伤鼻窦顶部,术中可以筛泡来定位嗅球位置,结合嗅束与矢状线之间夹角可以大致给嗅束定位,对于防 止手术损伤嗅神经具有一定意义。行前颅底手术上抬大脑额叶时应注意防止拉断嗅丝。     

Management of multiple spontaneous nasal meningoencephaloceles

OBJECTIVES/HYPOTHESIS: Multiple spontaneous nasal meningoencephaloceles in the same patient are rare lesions. Although many skull base defects occur after prior trauma or surgery, otolaryngologists must be aware of the potential for spontaneous encephaloceles. We present our experience with this unusual condition and discuss its pathophysiology and unique management issues. STUDY DESIGN: Retrospective. METHODS: Review of medical records, radiographic images, and cerebrospinal fluid pressures. RESULTS: We identified 5 patients with multiple, simultaneous, spontaneous encephaloceles: 4 patients with 2 encephaloceles and 1 patient with 3 encephaloceles (11 in all). Locations of the 11 encephaloceles were sphenoid lateral recess (6), frontal sinus with supraorbital ethmoid extension (2), ethmoid roof (1), frontal sinus (1), and central sphenoid (1). Three patients had bilateral sphenoid lateral recess encephaloceles, accounting for all six in that location. All four patients with available radiographic studies demonstrated empty sella turcica. Surgical approaches included endoscopic transpterygoid approach to the lateral sphenoid recess (3), endoscopic approach to ethmoid and central sphenoid (3), and osteoplastic flap with frontal sinus obliteration (2). We had 100% success at latest endoscopic follow-up (mean period, 17 mo). Three patients had postoperative lumbar punctures with mean cerebrospinal fluid pressure of 28.3 cm water (range, 19-34 cm; normal range, 0-15 cm). Conclusions: Multiple spontaneous encephaloceles can be managed safely and successfully using endoscopic and extracranial approaches. A high index of suspicion for this diagnosis must be maintained, especially in patients with radiographic evidence of laterally pneumatized sphenoid sinuses or empty sella. Spontaneous encephaloceles and cerebrospinal fluid leaks represent a form of intracranial hypertension.     

Computed tomographic and anatomical analysis of the basal lamellas in the ethmoid sinus

OBJECTIVES: To investigate the exact anatomical structure of the lamellas in the ethmoid sinus by computed tomography (CT) and anatomical analysis. STUDY DESIGN: Cadaver dissections and CT scans were used to compare lamellar structures and their radiological images. METHODS: Anatomical microdissection of 100 midsagittal sections from adult cadaver head specimens were examined and compared with those of sagittal CT scans at 1-mm intervals. RESULTS: The posteroinferior end of the uncinate process attaching to the inferior turbinate divided the fontanelle into the anterior and posterior portions in the majority of cases. The basal lamellas of the bulla ethmoidalis were subdivided into three major types. The posteroinferior portion of its basal lamella was connected to the lower horizontal portion of the third basal lamella in all cases. The anterior indentation of the third lamella was identified in nine cases, but there was no indentation in the posterior direction. The basal lamella of the superior turbinate was attached to the skull base superiorly either separately or fused to the third lamella, and its posteroinferior portion was attached to the lowest portion of the anterior wall of the sphenoid sinus. The supreme turbinate existed in 50 cases; however, its basal lamella was identified in only 15 cases. CONCLUSIONS: Our results indicate that the lamellas of the ethmoid sinus have relatively uniform patterns, although there is variability in shape. It is hoped that this study will provide surgeons with a more detailed structure of the basal lamellas for better surgical results and lower complication rates.     

Preoperative CT scanning for endoscopic sinus surgery: a rational approach.

Recent research on inflammatory sinus disease has implicated a central role for the ethmoid labyrinth, which may influence changes in the maxillary and frontal sinuses. CT can provide excellent definition of the paranasal sinuses and particularly the ethmoids, which is a prerequisite for endoscopic surgery. We describe a prospective series of 110 coronal CT scans performed on patients with a clinical diagnosis of sinusitis who had undergone diagnostic nasal endoscopies and medical treatment prior to surgery. 86% of the scans showed abnormal mucosal thickening. The ethmoids were affected in 73% and the maxillary sinus in 64%. Pneumatization of the middle turbinate was a common variant and when present was associated with anterior ethmoid disease in 60% of patients. Anterior ethmoid inflammatory changes were demonstrable in 95% of patients with maxillary sinus disease. Direct coronal CT can readily demonstrate disease in the infundibulum, frontal recess and posterior ethmoids in the same orientation confronting the endoscopist, and helps in the planning of ethmoidal surgery. Following surgery the sinuses can be directly inspected in outpatients which reduces the need for any further plain radiographs. It is important that the diagnosis of sinusitis is not based on CT findings alone as isolated areas of mucosal thickening are common in the normal population.