The relationship between ethmoidal foramina and orbital fat herniation.

BACKGROUND: The aims of this study are to determine the incidence and more frequent localizations of orbital fat tissue herniation accompanying dehiscences in the medial orbital wall and to investigate the relationship between orbital fat tissue herniations and the anterior and posterior ethmoidal foramina. METHODS: One thousand two hundred patients who had undergone computed tomography with a preliminary diagnosis of sinusitis and who had no previous facial, orbital, paranasal sinus surgeries or history of trauma were retrospectively analyzed. The localization of the ethmoidal foramina and orbital fat tissue herniations were marked. In patients with orbital fat tissue herniation, the relationship between the localization of orbital fat tissue herniation and the anterior and posterior ethmoidal foramina was investigated. RESULTS: The incidence of orbital adipose tissue herniation in our study was 7.9%. Of the 98 herniations on the bilateral medial orbital wall, 60 were in zone 3, and the most common herniation site was zone 3. A statistically significant difference was noted between the localization zone of the anterior ethmoidal foramen and the localization zones of orbital fat tissue herniations (Fisher's exact test, p < 0.001). DISCUSSION: Zone 3 is the weakest area of the medial orbital wall, and zone 3 is the most prone to herniation of fat tissue. The association of orbital fat tissue herniations with the anterior ethmoidal foramen is extremely common. Being cognizant of this finding may help a surgeon better estimate the anatomical view to be met before functional endoscopic sinus surgery as well as to minimize the risk of possible orbital complications, especially anterior ethmoidal artery injury.

The relationship between ethmoidal foramina and orbital fat herniation.

Background/aim: The aims of this study are to determine the incidence and more frequent localizations of orbital fat tissue herniation accompanying dehiscences in the medial orbital wall and to investigate the relationship between orbital fat tissue herniations and the anterior and posterior ethmoidal foramina. Material and methods: One thousand two hundred patients who had undergone computed tomography with a preliminary diagnosis of sinusitis and who had no previous facial, orbital, paranasal sinus surgeries or history of trauma were retrospectively analyzed. The localization of the ethmoidal foramina and orbital fat tissue herniations were marked. In patients with orbital fat tissue herniation, the relationship between the localization of orbital fat tissue herniation and the anterior and posterior ethmoidal foramina was investigated. Results: The incidence of orbital adipose tissue herniation in our study was 7.9%. Of the 98 herniations on the bilateral medial orbital wall, 60 were in zone 3, and the most common herniation site was zone 3. A statistically significant difference was noted between the localization zone of the anterior ethmoidal foramen and the localization zones of orbital fat tissue herniations (Fisher's exact test, p < 0.001). Conclusion: Zone 3 is the weakest area of the medial orbital wall, and zone 3 is the most prone to herniation of fat tissue. The association of orbital fat tissue herniations with the anterior ethmoidal foramen is extremely common. Being cognizant of this finding may help a surgeon better estimate the anatomical view to be met before functional endoscopic sinus surgery as well as to minimize the risk of possible orbital complications, especially anterior ethmoidal artery injury.

Measurement of interscalene space volume in diagnosis of thoracic outlet syndrome: a cadaver study

Background/aim: The aim of this study was to measure the volume of interscalene space in thoracic outlet region on cadavers and radiological images and to analyze the potential value of these measurements in diagnosis and treatment of thoracic outlet syndrome (TOS). Materials and methods: The dimensions of the anterior interscalene space in 8 formalin-fixed human cadavers were studied by direct measurement and additionally evaluation of the volume of this space were done by using mold and volume calculation formula of square pyramid, due to resembling a pyramid. In the second phase of this study, interscalene space volume was calculated by formula and compared to calculations from computed tomography (CT) sections in 18 TOS and 16 control patients. Results: There was a strong correlation between the volume calculated by formula (4.79 ± 2.18 cm3) and by mold (4.84 ± 1.58 cm3), (R = 0.934, p = 0.001) in cadavers. The average volume measured in TOS patients (2.05 ± 0.32 cm3) was significantly smaller than control patients (4.30 ± 1.85 cm3, p < 0.0001). There were excellent or good results in 14 patients whereas in 4 patients who had neurogenic TOS achieved fair results after surgery. In these 4 patients the average volumes of abnormal sides were close to the healthy sides. Conclusion: In our study, volume of interscalene space in TOS patients was statistically smaller than control group. Also, the volume was even smaller in patients with excellent or good results after surgery. In this respect, volumetric measurements from CT sections could be used in diagnosis and treatment selection in TOS patients.

Redefining the collateral system between the superior mesenteric artery and inferior mesenteric artery: a novel classification.

AIM: The aim of this study was to evaluate the arterial collateral vasculature between the superior mesenteric artery and the inferior mesenteric artery (IMA) from a surgical perspective. METHOD: A total of 107 fresh adult cadavers (94 male) were studied with emphasis on the vascular anatomy of the left colon. Dissections were carried out mimicking the anterior resection technique. The vasculature of the left mesocolon and the collaterals between the superior mesenteric artery and the IMA with respect to their relationship to the inferior mesenteric vein (IMV) were assessed and classified. Collaterals were classified into three different groups: marginal anastomoses (via the marginal = pericolic artery), intermediate mesocolic anastomoses (parallel to the marginal artery but neither adjacent to the IMV nor close to the duodenum) and central mesocolic anastomoses (next to the IMV at the level of the duodenojejunal junction and the lower border of the pancreas). RESULTS: All patients had a marginal anastomosis. However, the marginal anastomosis, as the only anastomosis between the superior and inferior mesenteric arteries at the splenic flexure, was observed in 41 cases (38%). In addition to the marginal artery, intermediate mesocolic anastomoses were found in 49 (46%) and a central mesocolic anastomosis was observed in 17 (16%) of the 107 cases in the splenic flexure mesocolon. It is in this latter variant that collateral vessels can be compromised during ligation/transection of the IMV. CONCLUSION: This new classification can contribute to a precise mesocolic dissection technique and splenic flexure mobilization and help prevent ischaemic damage to the descending colon.

The importance of costoclavicular space on possible compression of the subclavian artery in the thoracic outlet region: a radio-anatomical study.

OBJECTIVES: The purposes of this study were to identify possible compression points along the transit route of the subclavian artery and to provide a detailed anatomical analysis of areas that are involved in the surgical management of the thoracic outlet syndrome (TOS). The results of the current study are based on measurements from cadavers, computed tomography (CT) scans and dry adult first ribs. METHODS: The width and length of the interscalene space and the width of the costoclavicular passage were measured on 18 cervical dissections in 9 cadavers, on 50 dry first ribs and on CT angiography sections from 15 patients whose conditions were not related to TOS. RESULTS: The average width and length of the interscalene space in cadavers were 15.28 ± 1.94 mm and 15.98 ± 2.13 mm, respectively. The widths of the costoclavicular passage (12.42 ± 1.43 mm) were significantly narrower than the widths and lengths of the interscalene space in cadavers (P < 0.05). The average width and length of the interscalene space (groove for the subclavian artery) in 50 dry ribs were 15.53 ± 2.12 mm and 16.12 ± 1.95 mm, respectively. In CT images, the widths of the costoclavicular passage were also significantly narrower than those of the interscalene space (P < 0.05). The measurements from cadavers, dry first ribs and CT images were not significantly different (P > 0.05). CONCLUSIONS: Our results showed that the costoclavicular width was the narrowest space along the passage route of the subclavian artery. When considering the surgical decompression of the subclavian artery for TOS, this narrowest area should always be kept in mind. Since measurements from CT images and cadavers were significantly similar, CT measurements may be used to evaluate the thoracic outlet region in patients with TOS.

Relationship of dorsal root ganglion to intervertebral foramen in lumbar region: an anatomical study and review of literature.

BACKGROUND: The purpose of this study was to clarify the morphologic features, location and variations of the dorsal root ganglion (DRG). METHODS: Fifteen formalin fixed cadavers for the current study were included. Total of 150 DRGs were examined from L1 to L5. The relationships of the nerve root DRGs to the intervertebral foramen were noted. Position of the DRG was classified by the location of the ganglia in relation to the pedicle. The relationship of the DRG to the intervertebral foramen was evaluated. RESULTS: The distance between the midpoint of the DRG to the cross section of the root with the medial border of the pedicle gradually increased from L1 to L5. The medial border of the foramen distances along the nerve root were L1, 1.77 mm; L2, 2.79 mm; L3, 3.23 mm; L4, 7.28 mm and L5, 8.31 mm. The mean width of the lumbar DRGs were L1, 4.36 mm; L2, 4.56 mm; L3, 4.99 mm; L4, 5.22 mm and L5, 5.82 mm. The mean length of DRGs were as follows: L1, 5.39 mm; L2, 5.83 mm; L3, 7.24 mm; L4, 7.97 mm and L5, 10.83 mm. The mean width and length of DRGs gradually increased from L1 to L5. CONCLUSIONS: The DRG in the lumbar region play a key role in the occurence of low-back pain and sciatica; therefore, it is important to understand the anatomy of DRG. The accurate anatomic information about the position of DRGs would be useful to perform a safe surgical intervention in the lumbar foraminal region.

Intranasal Extramucosal Access: A New Access for Lateral Osteotomy in Open Rhinoplasty.

BACKGROUND AND OBJECTIVE: Different accesses have been used to perform lateral osteotomies in rhinoplasty. All of them have some disadvantages. The aim of this paper was to report a new access to overcome drawbacks of the other techniques in lateral osteotomy during open rhinoplasty. METHODS: An anatomical study was designed to search possibility of intranasal extramucosal access (open sky access) for the lateral osteotomy in open rhinoplasty. It was performed directly on the lateral wall of piriform aperture, and then possible advantages of this technique were investigated. Five fixed cadavers were used for this purpose. No drawbacks were observed during procedure in cadavers. Then the same procedure was performed in 23 consecutive rhinoplasty patients. Nineteen operations were primary and 4 operations were secondary. Median oblique osteotomies were added to the procedure in all patients. The mean follow-up was 17 months. RESULTS: Intranasal extramucosal access during lateral osteotomy was easily performed in all patients. Hemorrhage due to angular vessel injury was not occurred during intraoperative period. Edema and ecchymosis was minimal. Intranasal examination did not show any sign for nasal mucosal tearing in all patients. Residual bone spurs or bone irregularities were not observed in any patients. CONCLUSION: Intranasal extramucosal access that produces precise, predictable, and reproducible aesthetic and functional results could also provide better exposure during lateral osteotomy. Additionally, open sky access minimizes scars because it does not need additional incisions on the skin and mucosa. Protection of the internal periosteum of the nasal bones may be the main advantages of this technique.

Polidocanol injection for chemical delay and its effect on the survival of rat dorsal skin flaps.

BACKGROUND AND AIM: Surgical delay is an invasive method requiring a two-stage surgical procedure. Hence, methods that may serve as an alternative to surgical delay have become the focus of interest of research studies. From a conceptual view, any technique that interrupts the blood flow along the edges of a proposed flap will render the flap ischemic and induce a delay phenomenon. Polidocanol (Aethoxysklerol(®)-Kreussler) was initially used as a local anesthetic. Nowadays, it has been used as a sclerosing agent to treat telangiectasias and varicose veins. The aim of this experimental study was to investigate the effects of polidocanol injected around the periphery of a random flap as a sclerosing agent on flap delay and survival in a random flap model. METHODS: A preliminary histopathologic study was performed on two rats to evaluate the sclerosing effect and distribution of polidocanol injection. After the preliminary study, the main study was carried out with three groups: group 1: dorsal flap (n = 10); group 2: dorsal flap + surgical delay (n = 10), group 3: dorsal flap + chemical delay (n = 10). RESULTS: Tissue samples obtained from the flap and injection area revealed destruction of intradermal vessels. The area affected with sclerosis was limited to 0.1 cm beyond the injection site. Mean viable flap areas were 52.1 ± 4.38% (44.0-58.2) in group 1, 64.8 ± 8.92% (57.2-89.2) in group 2, and 71.8 ± 5.18% (64.0-84.0) in group 3. A statistically highly significant difference was found between the surgical delay and chemical delay groups versus the group without delay (p < 0.001 and p < 0.001, respectively). The difference between the mean viable flap areas was not statistically significant in the surgical and chemical delay groups (p = 0.056). CONCLUSION: In conclusion, this study has shown that polidocanol injection around the dorsal flap in the rat is a safe and easy method for nonsurgical delay. The results have shown a flap survival benefit that is superior to controls and equivalent to surgical delay. The clinical application of polidocanol, already in clinical practice for occlusal of telangiectasias, for surgical delay appears feasible.

Surgical Anatomy of the Infralabyrinthine Approach.

OBJECTIVE: The objective of this study is to demonstrate the surgical anatomy of the infralabyrinthine approach (ILA) and ways to prevent complications based on the complex anatomy. STUDY DESIGN: Cadaveric study. SETTING: Ankara University Faculty of Medicine, Department of Anatomy. SUBJECTS AND METHODS: Temporal bones were selected from 30 sides of 20 fixed human cadaver heads. Computed tomography (CT) scans of the heads were performed and, afterward, the cadavers were dissected using a surgical microscope and electric drill. RESULTS: An appropriate tract could be achieved in 73.3% of the dissections by applying slight pressure to the jugular bulb (JB). The narrowest portion of the ILA was defined as the inner window, which was located superior-inferiorly between the inferior border of the cochlea and the inferior wall of the petrous apex and anterior-posteriorly between the posterior wall of the carotid canal and the cochlear opening of the cochlear aqueduct. The ILA could not be performed when the distances between the facial nerve-JB and JB-cochlea were less than 2.9 mm and 2.6 mm, respectively, on CT scan. CONCLUSION: Close attention should be paid to the access and inner window during preoperative temporal bone imaging to assess for ILA. The detailed anatomy of the route, measurements of the topography of the cochlea from the mastoid view, and angles of the route are defined to prevent complications.

Surgical anatomy of facial nerve for revision transmastoid surgery.

We analyze the relationships of the 3 segments of the facial nerve with respect to constant anatomic structures that can be identified during revision surgery via translabyrinthine approach. This study was conducted on 15 formalin-fixed cadavers whose facial nerves were dissected bilaterally under operative microscope via translabyrinthine approach. The distances between the round window niche and the midpoint of the tympanic segment and the beginning of the mastoid segment were 6.64 ± 1.79 mm and 3.99 ± 0.79 mm, respectively. The distances between the tympanic ostium of the eustachian tube and the first and the second genu were 7.02 ± 0.62 mm and 12.25 ± 1.24 mm, respectively. We used the superior semicircular canal, the tympanic ostium of the eustachian tube, and the round window niche as landmarks to identify the facial nerve during revision surgery. Our study also showed that the auricular branch may also be originated from the posterior surface of the facial nerve.

Anatomy of Meckel's cave and the trigeminal ganglion: anatomical landmarks for a safer approach to them.

AIM: Surgical approaches to Meckel's cave (MC) are often technically difficult and sometimes associated with postoperative morbidity. The relationship of surgical landmarks to relevant anatomy is important. Therefore, we attempted to delineate quantitatively their anatomy and the relationships between MC and surrounding structures. MATERIAL AND METHODS: With the aid of a surgical microscope, MC and its contents were studied in 15 formalin-fixed cadaver head specimens. Measurements were made and their relationships were observed. RESULTS: The distance from the zygomatic arch and the lateral end of the petrous ridge to MC was 26.5 and 34.4 mm, respectively. The distance from the arcuate eminence, the facial nerve hiatus, and the foramen spinosum to MC was 16.6, 12.8 and 7.46 mm respectively. The TG lay 5.81 mm posterior to the foramen ovale. The distance from the abducens, trochlear and oculomotor nerves to the trigeminal ganglion was 1.87, 5.53 and 6.57 mm respectively. The distance from the posterior and the anterior walls of the sigmoid sinus to the trigeminal porus was 43.6 and 33.1 mm respectively. The trigeminal porus was on average 7.19 mm from the anterior wall of the internal acoustic meatus. CONCLUSION: The anatomical landmarks as presented herein regarding MC may be used for a safer skull base approach to the region.

Measurements for the direct approach to the oval foramen to apply mandibular nerve blockade.

PURPOSE: The lack of certain quotable landmarks and not taking the morphometric variations into consideration for mandibular nerve blockade can cause some complications. The aim of this study was to ensure there are data for more feasible and successful lateral extraoral approach to block the mandibular nerve by proposing reliable and quotable landmarks. METHODS: The current study was carried out on 55 skulls at the anatomy departments of the Universities of Mersin and Ankara. The length of the zygomatic arch, measurements indicating the puncture point (PP), injection depth, and injection angle were revealed. The differences between sides and the relationships between the parameters were evaluated by using paired t-test and Pearson correlation test, respectively. RESULTS: Of all skulls, it is observed that the injection line passed anterior to the articular surface of the temporomandibular joint. The distance between external acoustic opening and PP showed positive correlation with the distance between oval foramen and the midpoint of the zygomatic arch on the left side (r = 0.364, P = 0.001). On the right, the correlation was close to the statistically significant level (r = 0.280, P = 0.072). The distance between external acoustic opening and PP that can be adapted to the living subjects was found as 26.31 ± 1.95 mm. Injection angle to the coronal plane was measured to be 16.39 ± 2.96 degrees. The difference between sides for this parameter was not statistically significant. CONCLUSIONS: The determined parameters are suggested to be convenient and quotable to help in successful direct application under three-dimensional computed tomography or computed tomography-fluoroscopy for blocking the mandibular nerve.

Treatment of hyperdynamic nasal tip ptosis in open rhinoplasty: using the anatomic relationship between the depressor septi nasi muscle and the dermocartilaginous ligament.

BACKGROUND: Smiling causes a deformity in some rhinoplasty patients that includes drooping of the nasal tip, elevation and shortening of the upper lip, and increased maxillary gingival show. The depressor septi muscle leads this deformity. The dermocartilaginous ligament originates from the fascia of the upper third of the nose and extends down to the medial crus, merging into the depressor septi muscle. METHODS: In this study, 100 primary rhinoplasty patients were studied for hyperdynamic nasal tip ptosis. Of these patients, 36 had hyperdynamic nasal tip ptosis due to hyperactive depressor septi nasi muscle. The dermocartilaginous ligament was used as a guide to reach the depressor septi muscle in open rhinoplasty. Muscle excision was performed just below the footplates of the medial crura. A strong columellar strut graft was placed between the medial crura to avoid narrowing of the columellar width resulting from tissue excision and to withstand activation of depressor septi muscle remnants. RESULTS: No complications such as infection or hematoma occurred in the early postoperative period. The technique corrected the hyperdynamic nasal tip ptosis, increased upper lip length, and decreased gingival show when patients smiled. There was no narrowing of the columellar width. No depression in the columellar-labial junction due to distal resection of the depressor septi muscle was observed. CONCLUSION: The dermocartilaginous ligament can be used as a reliable guide to reach the depressor septi muscle in open rhinoplasty. Therefore, the hyperactive depressor septi muscle can be definitively identified and treated without an intraoral approach. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at www.springer.com/00266.

Anatomic relationship between the anterior sylvian point and the pars triangularis.

The aim of this study was to show morphological sulcal variations of the pars triangularis of the inferior frontal gyrus and to provide a clearer description of the anterior sylvian point. Thirty-six hemispheres of 18 adult cadavers were studied. The hemispheres were harvested by the classical autopsy method and fixed in 10% formalin solution for three weeks. In six hemispheres, the arteries and veins were filled with colored silicone. The proximal and distal segments of the sylvian fissure, the perpendicular distance of both the anterior sylvian point and inferior rolandic point to the insular cortex and the distances between the anterior ascending ramus and the precentral, central, and postcentral sulcus were measured. The anterior horizontal and ascending rami were exposed. The sulcus located on the pars triangularis was appraised. The relationship between the anterior sylvian point and the vascular structure around the sylvian fissure was examined. The rising of the anterior horizontal and ascending ramus from the sylvian fissure defines the shape of the pars triangularis. The pars triangularis has three shapes: V, U, and Y. In V- and Y-shaped pars triangularis both rami merge but in U-shaped pars triangularis the rami do not merge. The pars triangularis was Y-shaped in 30.76% (4/13) of the right hemispheres and in 50% (7/14) of the left hemispheres; U-shaped in 20.3% (3/13) of the right hemispheres and in 35.71% (5/14) of the left hemispheres; V-shaped in 40.61% (6/13) of the right hemispheres and in 14.29% (2/14) of the left hemispheres. Minimally invasive procedures use basic anatomic landmarks intracranially to reach the targeted area; therefore, exact and detailed knowledge of the anatomy of the sylvian fissure and pars triangularis is of great importance.

The branching pattern of the middle cerebral artery: is the intermediate trunk real or not? An anatomical study correlating with simple angiography.

OBJECT: The branching structure of the middle cerebral artery (MCA) remains a debated issue. In this study the authors aimed to describe this branching structure in detail. METHODS: Twenty-seven fresh, human brains (54 hemispheres) obtained from routine autopsies were used. The cerebral arteries were first filled with colored latex and contrast agent, followed by fixation with formaldehyde. All dissections were done under a microscope. During examination, the trunk structures of the MCA and their relations with cortical branches were demonstrated. Lateral radiographs of the same hemispheres were then obtained and comparisons were made. Angles between the MCA trunks were measured on 3D CT cerebral angiography images in 25 patients (50 hemispheres), and their correlations with the angles obtained in the cadaver brains were evaluated. RESULTS: A new classification was made in relation to the terminology of the intermediate trunk, which is still a subject of debate. The intermediate trunk was present in 61% of cadavers and originated from a superior trunk in 55% and from an inferior trunk in 45%. Cortical branches supplying the motor cortex (precentral, central, and postcentral arteries) significantly originated from the intermediate trunk, and the diameter of the intermediate trunk significantly increased when it originated from the superior trunk. In measurements of the angles between the superior and intermediate trunks, it was found that the intermediate trunk had significant dominance in supplying the motor cortex as the angle increased. The intermediate trunk was classified into 3 types based on the angle values and the distance to the bifurcation point as Group A (pseudotrifurcation type), Group B (proximal type), and Group C (distal type). Group A trunks were seemingly closer to the trifurcation structure that has been reported on in the literature and was seen in 15%. Group B trunks were the most common type (55%), and Group C trunks were characterized as the farthest from the bifurcation point. Group C trunks also had the smallest diameter and fewest cortical branches. Similarities were found between the angles in cadaver specimens and on 3D CT cerebral angiography images. Beyond the separation point of the MCA, trunk structures always included the superior trunk and inferior trunk, and sometimes the intermediate trunk. CONCLUSIONS: Interrelations of these vascular structures and their influences on the cortical branches originating from them are clinically important. The information presented in this study will ensure reliable diagnostic approaches and safer surgical interventions, particularly with MCA selective angiography.

Motor nerve lengths of twenty-seven muscles in upper extremity.

The purpose of this study is to determine the lengths of motor nerves in the upper extremity. Motor nerves of 27 muscles in 10 cadavers (16 extremities) were dissected from their roots at the level of intervertebral foramen to the entry point of the nerves to the corresponding muscles. Distance between acromion and the lateral epicondyle of the humerus was also measured in all cadavers. Nerve length of the coracobrachialis muscle was the shortest (18.26 ± 1.64 cm), while the longest was the nerve of the extensor indicis (59.51 ± 4.80 cm). The biceps brachii, the extensor digitorum communis, and the brachialis muscles showed highest coefficient of variation that makes these nerve lengths of muscles inconsistent about their lengths. This study also offers quotients using division of the lengths of each nerve to acromion-the lateral epicondyle distance. Knowledge of the nerve lengths in the upper extremity may provide a better understanding the reinnervation sequence and the recovery time in the multilevel injuries such as brachial plexus lesions. Quotients may be used to estimate average lengths of nerves of upper extremity in infants and children. Moreover, reliability of the biceps brachii as a determinant factor for surgery in obstetrical brachial plexus lesions should be reconsidered due to its highest variation coefficient.

Nerve root to lumbar disc relationships at the intervertebral foramen from a surgical viewpoint: An anatomical study.

The objective of this study was to analyze relationship of the intervertebral disc to the nerve root in the intervertebral foramen. Fourteen formalin-fixed cadavers were studied and measurements were performed. At the medial line of the neural foramen, the disc-root distance gradually increased from L1-L2 to L5-S1. The shortest distance between the disc to nerve root was L1-L2 (mean, 8.2 mm) and the greatest distance was found at L3-L4 (mean, 10.5 mm). In the mid-foramen, the disc-root distance decreased from L1-2 to L5-S1. The shortest distance from the disc to nerve root was found at L5-S1 (mean, 0.4 mm); and the greatest distance, at L1-L2 (mean, 3.8 mm). For the lateral line, the distance between an intersection point between the medial edge of the nerve root and the superior edge of the disc and lateral line of the foramen consistently increased from L1-L2 to L5-S1. The shortest distance from nerve root to the lateral border of the foramen, at the point where the nerve root crosses disc was at level L1-L2 (mean, 2.6 mm), the greatest distance, L5-S1 (mean, 8.8 mm). The width of the foramina progressively increased in a craniocaudal direction (mean, 8.3-17.8 mm from L1-2 to L5-S1, respectively). The mean height of the foramina was more or less the same for disc levels (range, 19.3-21.5). The results showed that nerve roots at lower levels traveled closer to the midline of the foramen. This morphometric information may be helpful in minimizing the incidence of injury to the lumbar nerve root during foraminal and extraforaminal approaches.

Comparison of two techniques in achieving planned correction angles in femoral subtrochanteric derotation osteotomy.

Increased femoral anteversion in cerebral palsy alters biomechanics of gait. Femoral subtrochanteric derotational osteotomies are increasingly performed to improve gait in cerebral palsy. The amount of angular correction can be determined and planned preoperatively but, accuracy in achieving planned angular correction has not been tested experimentally before. The aim of this study was to evaluate the accuracy of the two techniques in achieving planned angular correction. Sixteen dry femora were used in this study. Specimens in both groups were derotated to achieve a desired amount of correction with two different techniques, consecutively. In technique one, the cross section of the femur was assumed to be circular and the desired amount of angular correction was calculated and expressed in terms of surface distance by a geometric formula (surface distance=2×π×radius of femur). In both groups, derotations were made based on this surface distance calculation. Consecutively the same specimens were derotated by pins and guide technique. Femoral anteversion of specimens were measured before and after derotation by computerized tomography. There was a statistically significant differance in planned and achieved correction angles (P=0.038) in both subgroups derotated by the surface distance technique. When the two techniques were compared, there was significant difference (P=0.050) between high magnitude correction subgroups (subgroups 2 vs. 4). In conclusion, the results of this study highlighted the difficulty in achieving accurate derotation angles. Derotations based on guide-pins technique yielded more accurate results than derotations based on surface distance technique. In addition, surface diameter technique was not suitable when higher degrees of derotations are needed. In achieving a planned derotation angle two techniques are described for accuracy. Both the techniques have potential pitfalls resulting in malrotations. Surgeons must be aware of these obstacles and try to avoid them.

Subarachnoid, subdural and interdural spaces at the clival region: an anatomical study.

AIM: We aimed to show the significance of the anterior pontine membrane as a determining structure between the subdural and subarachnoid space in the clival region. MATERIAL AND METHODS: Five adult cadaver heads and five cerebral hemispheres were used. The skull vault and hemipheres were removed by sectioning through the pontomesencephalic junction. Five other heads hemispheres were removed but the arachnoid membrane was protected and the cerebral side of the clival dura mater was dissected. In another specimen, the dural porus of the abducens nerve was sectioned for histological evaluation. Three cases of hematoma at the clivus were presented to support our findings. RESULTS: The anterior pontine membrane is the arachnoid membrane forming the anterior wall of the prepontine cistern with its lateral extension at the skull base. This membrane forms the subdural and subarachnoid spaces by forming a barrier between the clival dura mater and neurovascular structures of the brainstem. There were rigid fibrous trabeculations between both cerebral and periosteal dural layers forming the basilar plexus as the interdural space in the clivus. CONCLUSION: The anterior pontine membrane separates the subdural and subarachnoid spaces at the clival region. The hematomas of the clival region require to be evaluated with consideration given to the existance of the subdural space.

Microsurgical anatomy for intraoperative preservation of the olfactory bulb and tract.

Damage to the olfactory bulb and tract is a frequently described complication of brain surgery in the frontal region, and it seems to be influenced by the surgical approaches. Eighty cerebral hemispheres and 5 formalin-fixed cadavers filled with colored latex were used. Parameters were directly measured, and after olfactory bulb and tract were mobilized with careful dissections, retraction of the frontal lobe was noted. The anterior border of the olfactory bulb is 22.21 (SD, 5.45) mm posterior to the frontomarginal sulcus, and arachnoidal dissection should be performed parallel to olfactory structures using sharp instruments to allow early visualization. Overall mobilization of the olfactory bulb and tract as 29.3 (SD, 6.4) mm in length is possible without disrupting the structures and enables a greater degree of the frontal-lobe elevation window up to 13.1 (SD, 3.2) mm. Using the morphometric data and anatomic knowledge may prevent unwanted anosmia complication during surgical approaches.