Parameters for contralateral approach to ophthalmic segment aneurysms of the internal carotid artery

OBJECTIVE: This study was undertaken to define more accurately the feasibility and indications of the contralateral pterional approach to ophthalmic segment aneurysms of the internal carotid artery (ICA). METHODS: Between 1995 and 1999, 46 patients with ophthalmic segment aneurysms of the ICA were surgically treated in our institution. Eleven of the 46 aneurysms were operated using the contralateral pterional approach. All aneurysms were successfully clipped without complications; three patients required bone resection around the aneurysm neck. We studied the 11 patients who were treated with the contralateral approach by defining six parameters to assess the feasibility of the approach and to predict the necessity for bone resection: 1) Parameter A, the distance between the anterior aspect of the optic chiasm and the limbus sphenoidale; 2) Parameter B, the distance between the bilateral optic nerves at the entrance to the optic canal; 3) Parameter C, the interrelation of the optic nerve and the ICA, expressed as a/b in which a is the length from the midline to the optic nerve and b is the length from the midline to the ICA; 4) Parameter D, the size of the aneurysm neck; 5) Parameter E, the direction of the aneurysm from the ICA wall on the anteroposterior angiogram; and 6) Parameter F, the distance from the medial side of the estimated distal dural ring to the proximal aneurysm neck on the lateral angiogram. RESULTS: Parameters A to F were 8.8 mm (range, 5.4-11.1 mm), 14.5 mm (range, 10.4-22.2 mm), 0.9 mm (range, 0.6-1.3 mm), and 3.0 mm (range, 2.3-4.7 mm), 5 to 160 degrees, and 1.3 mm (range, 0.3-2.4 mm), respectively. All patients had excellent operative outcomes without visual dysfunction. Three patients required drilling of the bone around the optic canal on the craniotomy side; bone drilling was not required when Parameter E was between 30 and 160 degrees and Parameter F was more than 1 mm. CONCLUSION: Parameters A to D are important for assessing the feasibility of the contralateral approach to ICA-ophthalmic segment aneurysms, and Parameters E and F are most useful for calculating the difficulty of this approach.     

Radiographic Imaging of the Distal Dural Ring for Determining the Intradural or Extradural Location of Aneurysms

The effectiveness of several anatomical and radiological landmarks proposed to determine whether an aneurysm is located intradurally or extradurally is still debated. In anatomical and radiological studies, we examined the relationships of the distal dural ring (DDR) to the internal carotid artery (ICA) and surrounding bony structures to aid in the localization of aneurysms near the DDR. Anatomical relationships were examined by performing dissections on 10 specimens (5 formalin-fixed cadaveric heads). After the position of the DDR, optic nerve, and tuberculum sellae were marked with surgical steel wire, radiographs were taken in multiple projections. The only bony landmark consistently visible on radiographs was the planum sphenoidale. The superior border of the DDR is located at or below the level of the tuberculum sellae, which laterally becomes the superomedial aspect of the optic strut; thus, the optic strut marks the dorsal limit of the DDR. On 50 dry skulls, we measured the vertical distance between the planum sphenoidale and medial aspect of the optic strut (5.0 +/- 0.4 mm), the interoptic strut distance (14.4 +/- 1.4 mm), and the linear distance between the most posterior aspect of the planum sphenoidale (limbus sphenoidale) and the tuberculum sellae (6.0 +/- 0.5 mm). Using these measurements and the planum sphenoidale, tuberculum sellae, and optic strut as reference landmarks, we determined the location of the aneurysm relative to the DDR on angiographic images. In this way, we were able to identify whether lesions were intra- or extradural.     

向鞍上、鞍旁扩展的经蝶窦手术入路相关结构的显微解剖研究

目的为扩大经蝶窦手术提供蝶窦外侧壁和海绵窦内侧面观、蝶骨平台骨窗腹面观以及蝶窦后方斜坡周围的显微解剖参数。方法20具干颅骨漂白标本(40侧)用于观察入路相关的骨性解剖结构;15具成人头颅灌注标本(30侧)模拟扩大经蝶窦入路,研究垂体周边解剖结构的位置关系,测量相应的距离或手术相关角度。同时,利用血管铸型技术,对鞍周静脉窦及动脉分支进行形态学观察。结果后组筛窦形成蝶旁、蝶上筛房,对扩大经蝶窦入路术中视野显露有直接影响。视神经管颅口内侧缘间距为(15.7±3.2)mm,鞍结节处颈内动脉间距为(13.9±3.8)mm,鞍结节后缘与筛板后缘之间的距离平均为(23.3±3.2)mm,视神经管与矢状面夹角为36.3°±1.6°。提示扩大经蝶窦手术入路相关的骨窗为“”型。结论扩大经蝶窦入路向鞍旁、鞍前、蝶骨平台扩展适合沿中线生长的的中、小型病灶。向鞍旁海绵窦扩展时,垂体与海绵窦段颈内动脉关系密切,增加施行扩大经蝶手术的风险。术中最易损伤的是颈内动脉和外展神经。     

Microanatomy of endoscope-assisted glabellar nasal keyhole approach.

OBJECTIVE: To make a study of the detailed microanatomy of endoscope-assisted glabellar nasal keyhole approach (GNKA) to be used clinically. METHODS: 10 dry adult Chinese skulls were measured and 10 perfused cadaveric heads were dissected to mimic the GNKA. RESULTS: Average distances between bilateral supraorbital foramen/incisure, supratrochlear incisure, medial orbital wall were 47.71+/-3.61 mm, 33.67+/-3.82 mm and 24.34+/-1.29 mm, respectively, in dry skulls. Average distance from nasion to medial inter-canthus line (ICL) was 10.31+/-1.02 mm in cadaveric heads. The nasion was 3.95+/-0.45 mm above the cribriform plate (CP) and the ICL is 6.25+/-0.71 mm below. With the assistance of endoscopes, GNKA can expose all extradural structures near the midline from the anterior skull base to the ventral brain stem corresponding to the clivus. The exposed clival dura was 19.18+/-1.44 mm in width and 25.44+/-1.25 mm in length. Intradural structures such as frontal base, parasellar area, longitudinal fissure and the third ventricle floor, can also be exposed. CONCLUSION: GNKA is a minimally invasive and effective anterior skull base approach. Determining the inferior margin of incision by ICL instead of nasion is more convenient and can expose the subcranial area better.     

Implications for Nasal Recontouring: Nasion Position Preferences as Determined by a Survey of White North Americans

White North American men (n = 75) and women (n = 75) were surveyed to investigate gender specific preferences of nasion position, which may aid plastic surgeons in nasal shaping during rhinoplasty. The subjects were asked to rank preferences of various nasion positions from life-size, scaled, sketched male and female profiles. Nasion positions with regard to height (anterior projection) and level (vertical position) were altered, whereas all other facial and nasal anthropometric measurements were held constant. The nasion heights were drawn at 7, 10, and 13 mm anteriorly to the corneal plane, and the nasion levels were drawn at the supratarsal fold (ST), upper lid ciliary margin (CM), midpupil (MP), and lower limbus (LL). The rank selections made by the female and male subjects of both gender profiles demonstrated statistical significance, as demonstrated by one-way analysis of variance (ANOVA) of ranks (p < 0.001). Further analysis using a post-Dunn test was completed to delineate significant gender specific preferences for the aesthetic nasion level and height. Female nasion levels were preferred at CM or MP over LL or ST on the basis of female ranks, and at ST, CM, or MP over LL on the basis of male ranks (p < 0.05 for all comparisons). Additionally, female nasion heights were preferred at 10 mm > 13 mm > 7 mm anterior to the corneal plane on the basis of both female and male ranks (p < 0.05 for all comparisons). Male nasion levels were preferred at ST, CM, or MP over LL on the basis of both male and female ranks (p < 0.05 for all comparisons). Male nasion heights were preferred at 10 mm > 13 mm > 7 mm anterior to the corneal plane by both male and female ranks (p < 0.05 for all comparisons). In summary, both the male and female subjects strongly disliked a low nasion height of 7 mm and a low nasion level placed at LL for both gender profiles. Both the male and female subjects were most particular concerning nasion height, preferring a 10-mm projection and strongly disliking a deeper 7-mm height for both male and female profiles. Both the male and female subjects were more tolerant of nasion level alterations. Whereas the male subjects tolerated nasion levels at ST, CM, or MP for either gender profile, the female subjects preferred only nasion levels at CM and MP for the female gender. Overall, these findings may lend support to recent trends in radix augmentation during rhinoplasty, especially among male patients.Accepted to the ASPS-PSEF-ASMS 2002 Annual Meeting     

Linear and angular measurements of computer-generated models: are they accurate, valid, and reliable?

INTRODUCTION: Traditional advanced imaging modalities such as CT and MRI are limited in their ability to perform accurate linear distance and angular measurements regardless of anatomical orientation. The construction of 3D models has been used to perform anthropometric analyses as well as in the reconstruction of rapid prototypes. We hypothesized that such measurements would be precise to within 2 mm or 2 degrees of measurements performed with a coordinate measurement machine (CMM). We also hypothesized that there would be a high degree of interobserver reliability with these measurements. MATERIALS AND METHODS: Multiple aluminum screws were implanted in various positions in three foam pelvises which were subsequently scanned by CT and rendered as 3D models using a commercially available software package (Mimics). Linear and angular measurements were performed using a CMM machine, the software package, and a dial caliper or goniometer. The deviation of the measurements from the CMM data was compared using ANOVA. The interobserver reliability of both the manual and computer-generated measurements was calculated. RESULTS: The mean difference between the CMM distances and those measured manually and with the software was 2.12 +/- 1.20 mm and 1.57 +/- 1.05 mm, respectively. The mean difference between the CMM angular measurements and the angular measurements performed manually and with the software was 4.07 +/- 4.70 degrees and 1.62 +/- 1.32 degrees, respectively. In all cases, the manual measurements were significantly less accurate (p < 0.0001) and there was a high degree of interobserver reliability. CONCLUSIONS: Computer-generated measurements taken from three-dimensionally reconstructed models are more accurate than manual measurements and are within 2 mm and 2 degrees of measurements performed with a CMM. These measurements have high interobserver reliability.     

Morphological study of abdominal aortic aneurysm: optimal stent-graft size for Japanese patients.

PURPOSE: We report on the optimal stent-graft (SG) size for Japanese patients with abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: Ninety three Japanese patients undergoing elective AAA repair were selected for this study. The parameters measured were the proximal neck (PN) diameter (D1), the diameter of the right and left common iliac arteries (D2 and D3, respectively), the diameter of the right and left external iliac arteries (D4 and D5, respectively), the distance between the lowest renal artery and the common iliac arterial bifurcation (L1), and the distance between the right and left common iliac arterial bifurcations and the internal iliac arterial bifurcation (L2 and L3, respectively). RESULTS: The following results were obtained: D1: 20.7+/-3.9 mm (14 to 28 mm); D2: 14.0+/-3.0 mm (9.5 to 20 mm); D3: 13.8+/-3.1 mm (9 to 19.5 mm); D4: 7.5+/-1.0 mm (6 to 10 mm); D5: 7.4+/-0.9 mm (6 to 10 mm); L1: 107.7+/-13.4 mm (80 to 130 mm); L2: 40.0+/-10.1 mm (20 to 61 mm); L3: 39.7+/-9.6 mm (20 to 60 mm). CONCLUSION: The results indicate the necessity of exercising adequate care when selecting a device for Japanese patients.     

The tentorial notch: anatomical variation,morphometric analysis,and classification in 100 human autopsy cases

OBJECT: Variations in the structure of the tentorial notch may influence the degree of brainstem distortion in transtentorial herniation, concussion, and acceleration-deceleration injuries. The authors examined the anatomical relationships of the mesencephalon, cerebellum, and oculomotor nerves to the dimensions of the tentorial aperture. On the basis of numerical data collected from this study, the authors have developed the first classification system of the tentorial notch and present new neuroanatomical observations pertaining to the subarachnoid third cranial nerve and the brainstem. METHODS: The mesencephalon was sectioned at the level of the tentorial edge in 100 human autopsy cases (specimens from 23 female and 77 male cadavers with a mean age at time of death of 42.5 years [range 18-80 years]). The following measurements were determined: 1) anterior notch width, the width of the tentorial notch in the axial plane through the posterior aspect of the dorsum sellae; 2) maximum notch width (MNW), the maximum width of the notch in the axial plane; 3) notch length (NL), the length of the tentorial notch from the superoposterior edge of the dorsum sellae to the apex of the notch; 4) posterior tentorial length, the shortest distance between the apex of the notch and the most anterior part of the confluence of the sinuses; 5) interpedunculoclival (IC) distance, the distance from the interpeduncular fossa to the superoposterior edge of the dorsum sellae; 6) apicotectal (AT) distance, the distance from the tectum in the median plane to a perpendicular line dropped from the apex of the tentorial notch to the cerebellum; 7) cisternal third nerve distance, the distance covered by the cisternal portion of the third cranial nerve; and 8) inter-third nerve angle, the angle between the two third cranial nerves. The quartile distribution technique was applied to all measurements. Mean values are presented as the means +/- standard deviations. Quartile groups defined by NL (mean 57.7 +/- 5.6 mm) were labeled long, short, and midrange, and those defined by MNW (mean 29.6 +/- 3 mm) were labeled wide, narrow, and midrange. Combining these groups into a matrix formation resulted in the classification of the tentorial notch into the following eight types: 1) narrow (15% of specimens); 2) wide (12% of specimens); 3) short (8% of specimens); 4) long (15% of specimens); 5) typical (24% of specimens); 6) large (9% of specimens); 7) small (10% of specimens); and 8) mixed (7% of specimens). The IC distance (mean 20.4 +/- 3.2 mm) was used to characterize brainstem position as prefixed (28% of specimens), postfixed (36% of specimens), or midposition (36% of specimens). The IC distance was correlated with the left and right cisternal third nerve distances (means 26.7 +/- 2.9 mm and 26.1 +/- 3.2 mm, respectively) and the inter-third nerve angle (mean 57.3 +/- 7.3 degrees). The exposed cerebellar parenchyma within the notch, the relationship between the brainstem and tentorial edge, and the brainstem position varied considerably among individuals. The cisternal third nerve distance, its trajectory, and its anatomical relation to the skull base also varied widely. Two anatomically distinct segments of the subarachnoid third cranial nerves were characterized with respect to the skull base as suspended and supported segments. CONCLUSIONS: The authors present a new classification system for the tentorial aperture to help explain variations in herniation syndromes in patients with otherwise similar intracranial pathological conditions, and responses to concussive and acceleration-deceleration injuries. The authors present observations not previously described regarding the position of the brainstem within the tentorial aperture and the cisternal portion of the third cranial nerves. A significant statistical correlation was discovered among specific morphometric parameters of the tentorial notch, brainstem, and oculomotor nerves. These findings may have neurosurgical implications in clinical situations that cause brainstem distortion. Additionally, this analysis provides baseline data for interpreting magnetic resonance and computerized tomography images of the tentorial notch and its regional anatomy.     

内镜下经筛蝶入路视神经减压术的应用解剖

目的 研究内镜下经筛蝶入路视神经减压术的相关解剖以及在手术中的意义.方法 手术显微镜下解剖福尔马林固定的成人尸头视神经管标本15例(30侧),观察视神经管的解剖特点和毗邻关系,并根据鼻内镜入路测定相关参数.结果 ①视神经颈内动脉三角(optic carotid triangle,OCT)与视神经、眼动脉、海绵窦和颈内动脉关系恒定,OCT出现率为66.7%.②鼻小柱基底前缘到视神经管眶口、管中部和颅口内侧缘的距离分别为(72.79±5.40)mm、(75.85±5.10)mm和(79.34±4.95)mm,仰角分别为(39.45±3.68)°、(37.30±4.24)°和(35.45±4.16)°.③视神经内侧壁眶口、管中部和颅口的鞘膜厚度分别为(0.70±0.18)mm、(0.51±0.15)mm和(0.49±0.22)mm,眶口与管中部、颅口差异有统计学意义(P＜0.01);④视神经管眶口、管中部和颅口内侧缘离颅正中矢状面的旁开距分别为1/2(12.69±2.73)mm、1/2(19.61±3.47)mm和1/2(25.79±3.23)mm.结论 OCT是内镜下经筛蝶入路视神经减压术首选的解剖定位标志,减压关键在视神经眶口,从视神经内侧壁与上壁交界处切开鞘膜安全且容易操作.     

The morphometric and cephalometric study of anterior cranial landmarks for surgery.

OBJECTIVE: The aim of this work was to determine reliable bony landmarks for the anterior skull base and to standardize some specific dimensions among the frontal sinus and neighboring structures for safe anterior cranial surgery. METHODS: The study consisted of a topographical anatomic examination and cephalometric analysis of the skull. Thirty adult skulls (60 sides) were studied regarding the localization and dimensions of the supraorbital foramen (SOF), frontal sinus (FS), frontozygomatic fissure, infraorbital foramen, anterior nasal spine, and nasion. Differences between the measurement of skulls and cephalograms were analyzed by Student's t test. The Pearson correlation test was used for statistical analysis of the cephalogram. RESULTS: Examination of the 60 sides of the bony heads revealed that the shape of the SOF was a foramen in 25 sides (41%), a notch in 29 sides (49%), and a groove in 6 sides (10%). A total of 20 (33%) SOFs were inside the FS and the mean distance was 6.3+1.34 mm from the lateral border of the sinus, 27 (45%) of SOFs were outside of the FS and the mean distance was 8.8+2.01 mm, and 13 (22%) of SOFs were at the border of the FS. According to our measurements the medial border of the craniotomy should be placed approximately 43 mm lateral to the nasion to avoid entering into the frontal sinus. CONCLUSION: To plan and to decide the convenient and safe anterior midline skull base approach and to avoid postoperative complications, bony landmarks and anatomic measurements around the SOF and FS will be helpful for the surgeon to constitute a simplification of topographic anatomy.     

Endoscopic endonasal skull base surgery: Part 1--The midline anterior fossa skull base.

OBJECTIVE: An endonasal endoscopic surgery to the anterior fossa skull base was developed in cadaver dissection as a minimally invasive surgical technique and, subsequently, used in patient treatment. METHODS: Six cadaver head specimens were used. Ideal head positioning and various surgical routes were studied. To estimate the extent of surgical exposure provided by this technique, the width of the exposed anterior cranial fossa was measured between the medial margin of the orbits, the optic nerves and the carotid arteries. Three demonstrative patient cases are presented. RESULTS: Ideal head positioning was discovered to be at 15-degree extension of the forehead-chin line. Paraseptal, middle meatal and middle turbinectomy approaches were developed. The average width between the medial orbits was measured to be 24 mm (range 22-29 mm) at the crista galli level, 27 mm (range 24-30 mm) at the planum sphenoidale, 18 mm (range 15-22 mm) between the optic nerves, and 17 mm (range 13-21 mm) between the rostral carotid siphons. This technique, when it was applied in patient care, proved to be minimally invasive. CONCLUSIONS: This endoscopic endonasal approach provided a direct "short-cut" access to the midline anterior fossa skull base. This technique can be used for the surgical treatment of cerebrospinal fluid (CSF) leak, meningiomas, craniopharyngiomas, pituitary adenomas, and other midline intracranial anterior skull base lesions. This is the first report in the English literature describing endonasal endoscopy for the surgical treatment of primary intracranial anterior fossa skull base lesions.     

Transethmoidal approach to the optic canal: surgical and radiological microanatomy

BACKGROUND: The purpose of the study is to describe anatomic topographic landmarks for transethmoidal approach to optic canal for optic nerve decompression. The study focuses on microsurgical/radiologic anatomies and their relationships in the region of the optic canal and orbit. METHODS: Human optic canal and related anatomic structures were studied in orbits of 6 formalin preserved adult human cadavers. In addition, anatomic measurements were made with digital vernier caliper on the orbits of 25 adult human skulls. The relation between ethmoidal and sinus was assessed with computed tomography (CT) scan in 25 living human heads needing cranial CT scan for any reason. RESULTS: The suture on the conjunction of frontal, maxilla, and lacrimal bones with a location in medial side of the orbit was accepted as a landmark. When the measurements were taken from this landmark, the distances to supraorbital margin were: right(R): 16.76 +/- 2.62 mm, left (L): 17.10 +/- 1.97 mm, and to infraorbital margin were R: 20.18 +/- 3.24 mm, L: 18.94 +/- 2.19 mm. The distances to the anterior ethmoidal foramen were R: 19.66 +/- 3.96 mm, L: 19.11 +/- 2.84 mm, and to the posterior ethmoidal foramen were R: 32.01 +/- 2.90 mm, L: 32.62 +/- 3.33 mm. Mean distance between the anterior and posterior ethmoidal foramen were R: 12.55 +/- 3.4 mm, L: 13.51 +/- 4.2 mm. The posterior ethmoidal foramen and optic ring were separated only by the mean distances of R: 5.34 +/- 2.81 mm, L: 4.9 +/- 3.35 mm. The distance from the suture to the distal (orbital) opening of the optic canal was R: 37.35 +/- 2.73 mm, L: 37.52 +/- 3.47 mm and to proximal (intracranial) opening of the canal were R: 49.52 +/- 2.62 mm, L: 50.94 +/- 3.35 mm. The average widths of proximal (intracranial) canal measured were R: 7.43 +/- 1.95 mm, L: 7.38 +/- 2.01 mm and those of distal canal (orbital) were R: 5.12 +/- 1.1 mm, L: 4.95 +/- 1.32 mm. The mean lengths of the optic canal were R: 11.19 +/- 2.68 mm, L: 12.42 +/- 3.38 mm. In radiologic examinations, the mean numbers of anterior group ethmoidal cells were R: 7, L: 6 and those of posterior group ethmoidal cells were R: 4, L: 3. The results of CT demonstrated 7 (14%) Onodi or sphenoethmoidal cells in 50 orbits of living humans. CONCLUSION: The examination of radiologic anatomy in addition to microanatomy can significantly contribute to preoperative and postoperative evaluation of the patients.     

Laser scanning tomography measurement of the extent of papilledema in the follow-up examination of patients with idiopathic intracranial hypertension

OBJECT: The authors evaluated the characteristics of patients with idiopathic intracranial hypertension (IIH), and compared laser scanning tomography (LST) measurements of papilledema with the clinical parameters and cerebrospinal fluid (CSF) opening pressures obtained. METHODS: Twenty-four patients were included in this study; these individuals included 21 women and three men with a mean age of 35.5 +/- 9.7 years and a mean body mass index (BMI) of 35.4 +/- 8.3 kg/m2. The authors conducted a prospective follow-up study over a period of 12 months through a series of four consultations with each patient. These patients had a mean time to treatment of 6.2 +/- 7.9 months and, at the time of diagnosis, suffered a mean of 2.8 +/- 1.3 symptoms each. Laser scanning tomography of the optic disc revealed a mean global rim volume of 1.693 +/- 1.662 mm3 and a mean height of 0.604 +/- 0.306 mm. The mean CSF opening pressure was 31.3 +/- 6.3 cm H2O. RESULTS: During the follow-up period, all patients improved significantly with regard to clinical parameters (p < 0.001), BMI reduction (p < 0.001), and reduction of visual field deficits (p = 0.007); visual acuity remained unchanged. In all patients at each successive consultation, the CSF opening pressure was lower than it had been at the previous consultation (p = 0.001). Laser scanning tomography measurements demonstrated a statistically significant reduction in both optic disc parameters over the follow-up period (global rim volume, p = 0.044; mean height, p = 0.019). The CSF opening pressure and the LST measurements correlated significantly with the number of symptoms (CSF opening pressure, p < 0.001; global rim volume, p = 0.001; mean height, p < 0.001). The mean area under the receiver operating characteristic curve in detecting the presence of clinical symptoms was 0.87 for CSF opening pressure, 0.7 for rim volume, and 0.81 for mean optic disc height. CONCLUSIONS: Laser scanning tomography measurements are useful for evaluating the degree of papilledema in patients with IIH and correspond well with clinical data and measurements of CSF opening pressure. If a diagnosis of IIH is established, LST measurements may replace repeated CSF opening pressure measurements in follow-up monitoring.     

Accurate course and relationships of the intraorbital part of the ophthalmic artery in the sagittal plane.

INTRODUCTION: Knowledge of variations in the course and distribution of the intraorbital part of ophthalmic artery (OA) is necessary for the diagnosis and treatment of anterior cranial and orbital disorders. MATERIAL: 38 human cadaver dissections to demonstrate the microsurgical anatomy of the intraorbital part of the OA were studied in three stages, considering its neighbourhood with the optic nerve in the sagittal plane. RESULTS: The first part of the OA was located on the inferolateral aspect of the optic nerve in 89.47%. The diameter and the length of the first part of the OA were 1.69+/-0.34 mm and 7.58+/-0.89 mm. 73.68% of the cases crossed the optic nerve superiorly, and 26.31% inferiorly. The diameter and length of the second part of the OA were as 1.52+/-0.29 mm and 4.12+/-0.85 mm. The diameter and length of the third part of the OA were 1.07+/-0.18 mm and 4.12+/-0.85 mm. The first branch of the intraorbital part of the OA was the central retinal artery in 26.31% of the specimens. CONCLUSION: A better understanding of the vascular anatomy of the orbit should allow for the modification of surgical techniques to reduce bleeding during biopsy or excision of orbital structures.     

Sex-specific differences of subacromial space width during abduction, with and without muscular activity, and correlation with anthropometric variables

The objectives of this study were to determine sex-specific differences of the subacromial space width during active and passive arm abduction and to analyze the correlation of this space with general and regional anthropometric variables. Fourteen healthy subjects (7 men, 7 women) were examined with an open magnetic resonance system at 30 degrees and 90 degrees of abduction (with and without muscle activity). After 3-dimensional reconstruction, the minimal acromiohumeral distance, the glenoid size, and the humeral head radius were determined. At 30 degrees of abduction, a significant difference of the acromiohumeral distance was observed between men (8.18 +/- 1.0 mm) and women (6.98 +/- 0.75 mm) (P < .05), but not at 90 degrees (6.7 +/- 2.0 mm versus 5.9 +/- 1.0 mm) or under muscle activity (4.9 +/- 2.4 mm versus 3.5 +/- 2.1 mm). Significant correlations between the acromiohumeral distance and anthropometric variables were found at 30 degrees of abduction (r = 0.48 to 0.72), but not at 90 degrees, with or without muscle activity (r = 0.21 to 0.55). The results demonstrate that at physical rest, the subacromial space width is dependent on sex, but the interindividual variability increases substantially during abduction and under muscle activity.     

Preoperative determination of tibial nail length: An anthropometric study

Objective: To assess the correlation between five anthropometric parameters and the distance from tibial tuberosity to medial malleolus in 100 volunteers. Methods: Six anthropometric parameters were measured in 50 male and 50 female medical students using a metallic scale: medial knee joint line to ankle joint line (K-A), medial knee joint line to medial malleolus (K-MM), tibial tuberosity to ankle joint (TT-A), tibial tuberosity to medial malleolus (TT- MM), olecranon to 5th metacarpal head (O-MH) and body height (BH). Nail size predicted based upon TT-MM measurement was chosen as ideal nail size. A constant was derived for each of the six anthropometric parameters which was either added or subtracted to each measurement to derive nail size. A regression equation was applied to BH measurements. Nail sizes calculated were compared with that obtained from TT-MM measurement and accuracy was evaluated. Accuracy of O-MH and BH regression equations recommended by other authors were calculated in our data. Results: Adding 11 mm to TT-A distance had highest accuracy (81%) and correlation (0.966) in predicting nails correctly. Subtracting 33 mm from K-MM measurement and 25 mm from K-A distance derived accurate sizes in 69% and 76% respectively. Adding 6 mm to O-MH distance had a poor accuracy of 51%. Nail size prediction based upon body height regression equation derived correct nail sizes in only 34% of the cases. Regression equation analysis by other authors based on O-MH and BH distances yielded correct sizes in 11% and 5% of the cases respectively. Conclusion: TT-A, K-A and K-MM measurements can be used simultaneously to increase accuracy of nail size prediction. This method would be helpful in determining nail size preoperatively especially when one anatomic landmark is difficult to palpate.     

Distance between mitral anulus and papillary muscles: anatomic study in normal human hearts.

BACKGROUND: Preservation of the annulo-papillary muscle continuity in mitral valve replacement is important. Even in patients who require excision of the mitral apparatus, the continuity can be restored. However, there is no guide to the proper length for the resuspension. METHODS: In 57 normal cadaveric hearts, the distance from the tip of the papillary muscle to its corresponding mitral anulus was directly measured. RESULTS: The distance from the tip of the anterolateral papillary muscle to the left trigone (10-o'clock position: D10) and to the point between the anterior and the middle scallops of the mural leaflet (8-o'clock position: D8) was 23.5 +/- 3.7 mm and 23.2 +/- 3.6 mm, respectively. The distance from the tip of the posteromedial papillary muscle to the right trigone (2-o'clock position: D2) and to the point between the middle and the posterior scallops of the mural leaflet (4-o'clock position: D4) was 23.5 +/- 4.0 mm and 23.5 +/- 3.9 mm, respectively. There was no statistically significant difference among the 4 distances (P =.96). Each distance was significantly longer than the corresponding chordae tendineae (D10 vs the anterior main chorda: 17.2 +/- 3.9 mm, D8 vs the anterior cleft chorda: 14.5 +/- 3.2 mm, D2 vs the posterior main chorda: 17.9 +/- 4.3 mm, and D4 vs the posterior cleft chorda: 14.9 +/- 3.2 mm, respectively; P =.0001). The mean distance had a significant correlation with the mitral annular diameter (r = 0.31, P =.019). CONCLUSIONS: In normal hearts, the annulo-papillary muscle distances of the mitral apparatus are similar in 2-, 4-, 8-, and 10-o'clock positions and correlate with the mitral annular diameter.     

Microsurgical anatomic features of the lamina terminalis

OBJECTIVE: The lamina terminalis (LT) is a structure of considerable interest for microneurosurgery, and precise knowledge regarding its normal anatomic features and the variations thereof is required. The purpose of this study, which was based on microanatomic dissection of human cadaveric specimens, was to review the microsurgical anatomic features of the LT and its neurovascular relationships. The surgical implications of the morphometric data are discussed. METHODS: The region of the LT was examined in 10 human cadaveric heads, obtained from 8 fresh adult cadavers and 2 formalin-fixed adult cadavers, and in 10 formalin-fixed, isolated, adult brains. An operating microscope was used for all dissections and measurements. RESULTS: Assuming the LT to be a triangular structure, we performed measurements of the distance between the midportion of the upper edge of the chiasm and the lower edge of the anterior commissure (height), which averaged 8.25 mm. The distance between the medial edges of the optic tracts (base) averaged 12.81 mm. The area averaged 52.84 mm(2). A minimal amount of retraction was needed to fully expose the LT, and generally there was no need to mobilize the anterior cerebral artery-anterior communicating artery complex. Perforating branches to the hypothalamus and optic apparatus are laterally located and do not interfere with LT incision and/or fenestration. CONCLUSION: The LT constitutes a clearly identifiable microsurgical target. The allowable extent of LT opening is sufficient to provide wide access into and free cerebrospinal fluid flow from the third ventricle. Fenestration of the LT is a safe procedure, provided that the relevant anatomic landmarks are identified and respected.     

Microanatomy of the anterior cerebral artery

The microanatomic features of the anterior cerebral artery were studied in 30 unfixed human brains which were injected with tinted polyester resin via cannulation of the internal carotid arteries under microscopic dissection. The outer diameter, length, and number of perforating branches were measured for each of the following vessels: anterior cerebral artery (proximal A1 segment, distal A2 segment), anterior communicating artery, and recurrent artery of Heubner. The perforating branches of the proximal segment of the anterior cerebral artery penetrated the brain at the anterior perforated substance, lateral chiasm, and optic tracts. The perforating branches of the anterior communicating artery penetrated the brain at the lamina terminalis, anterior perforated substance, and medial chiasm. The first 5 mm of the distal anterior cerebral artery (A2) had perforating branches penetrating the brain at the gyrus rectus and olfactory sulcus. The recurrent artery of Heubner originated from the A2 segment of the anterior cerebral artery in 57% of the cases, from the anterior cerebral artery-anterior communicating artery junction in 35%, and from the A1 segment in 8%. The depth of the interhemispheric fissure at the genu was 36.0 +/- 0.5 mm and at the midbody of the corpus callosum, 35.0 +/- 0.5 mm. Extension of the dissection to approach the anterior communicating artery from the genu of the corpus callosum using the anterior interhemispheric route was an additional 31.7 +/- 0.7 mm. The callosal arterial supply from the anterior cerebral artery showed short callosal branches in all brain specimens and long callosal vessels in 10% of the specimens.     

镍钛记忆合金腕舟骨内固定器的研制及生物力学测试

目的 设计一种新的用于舟骨腰部骨折的内固定器械--镍钛记忆合金舟骨弧形钉 (Ni-Ti shapememory alloy scaphoid arc nail,NT-SAN),并对其进行生物力学测试,为临床应用提供依据.方法 根据舟骨的测量数据及解剖特点研制 NT-SAN.生物力学强度实验:取 32 只成人离体舟骨标本,模拟舟骨腰部骨折,随机分为4组(n=8):分别采用克氏针髓内固定(A 组)、克氏针骑缝钉固定(B组)、螺钉固定(C组)及NT-SAN固定(D组),体外模拟舟骨腰部骨折复位内固定术,测试其固定强度.疲劳实验:24只成人上肢标本(肘关节以下),制备舟骨腰部骨折模型,随机分为3组(n=8);分别用克氏针骑缝钉固定(E组)、螺钉固定(F组)及NT-SAN固定(G组),在腕关节上垂直施加98 N的纵向压缩负荷,并模拟腕关节掌屈和背伸运动,运动范围为掌屈 5°～背伸 30°,运动 100、500、1500 及 2000 次时测量分离及侧方移位距离.并采用NT-SAN临床治疗 1 例左侧腕部舟骨腰部骨折患者,根据Herbert分型为Ⅱ b型. 结果 强度实验:NT-SAN 固定臂产生的回复力可将舟骨腰部骨折聚合于一体,体部可遮挡舟骨腰部骨折向其背侧滑脱.A、B、C、D 组标本骨折间隙分离 1 mm 及 2 mm 时所需牵引力分别为(15.18±3.55)、(36.04±4.30)、(64.88±11.62)、(65.84±12.22)N及(20.28±12.09)、(75.95±47.64)、(120.91±26.68)、(130.21±31.55) N,D组与A、B组比较,各指标差异均有统计学意义(P<0.05),D组与C组间差异无统计学意义(P>0.05).疲劳实验:G 组骨折端分离移位的距离与E、F组比较,各指标差异均有统计学意义(P<0.05).腕关节循环运动500次后,G组舟骨骨折端出现"台阶"移位例数与E组比较,差异均有统计学意义(P<0.05);腕关节循环运动1 500次后,G组与F组比较,差异均有统计学意义(P<0.05).临床应用患者术后切口Ⅰ期愈合,3个月随访X线片示NT-SAN内固定良好. 结论 NT-SAN 的设计符合腕舟骨解剖特点,其固定强度可满足舟骨骨折术后生物力学要求,疲劳强度可满足舟骨骨折术后达骨性愈合的需要.