Location of Needle Tips on Plexus Brachialis in Different Supraclavicular Block Techniques: A Cadaver Study.

OBJECTIVE: The present study was performed on cadavers to evaluate the efficacy of the different supraclavicular block techniques (Vongvises, Dalens, plumb-bob and inter-SCM) by investigating the location of the needle tip on the brachial plexus and to determine the most suitable block techniques according to the site of the surgery. METHODS: The study was performed on one embalmed and nine fresh cadavers. After the dissection, the skin of the cadavers was restored in its original position. Then, they are positioned, and the needle was inserted according to the technique described by the authors in the original articles. The distances between the needle tip and the three trunks were measured, and the location of the needle tip on the brachial plexus was determined. RESULTS: A significant difference in the proximity of the needle tip to the middle of the middle truncus was noted only in the inter-SCM technique compared with the Dalens technique at both sides (p<0.05). CONCLUSION: In our study, the distance between the needle tip and truncus medius was the shortest in the plumb-bob technique at both sides. Both in the plumb-bob and inter-SCM techniques, the distribution of the needle tip over the trunci of the plexus brachialis was homogenous. In Dalens technique, the needle tip reached the truncus superior or between the truncus superior and n. suprascapularis in 95% of the cases. Further, we concluded that moving the insertion point approximately 1 cm caudal and maintaining the anteroposterior needle direction in the Vongvises technique would result in a successful brachial plexus block.

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.

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.

Percutaneous ilioinguinal-iliohypogastric nerve block or step-by-step local infiltration anesthesia for inguinal hernia repair: what cadaveric dissection says?

PURPOSE: The repair of groin hernias with local anesthesia has gained popularity. Two main methods have been described for local anesthesia. This study was aimed at comparing percutaneous truncular ilioinguinal-iliohypogastric block and step-by-step infiltration technique by using cadaver dissections. METHODS: The study was performed on an adult male cadaver by using blue dye injection. A percutaneous nerve block simulation was done on right side and the dye was given in between the internal oblique and transversus muscles. On the left side, a skin incision was deepened and the dye was injected under the external oblique aponeurosis. Following the injections, stained areas were investigated superficially and within the deeper tissues with dissection. RESULTS: There was a complete superficial staining covering the iliohypogastric and ilioinguinal nerves in the inguinal floor at both sides. On the right side, intraabdominal observation showed a wide and intense peritoneal staining, while almost no staining was seen on the left side. Preperitoneal dissection displayed a massive staining including testicular vascular pedicule and vas deferens on the right side. The dye solution also infiltrated the area of the femoral nerve prominently. On the contrary, a very limited staining was seen on the left. CONCLUSION: It may not always be easy to keep the percutaneous block within optimum anatomical limits without causing adverse events. A step-by-step infiltration technique under direct surgical vision seems to be safer than percutaneous inguinal block for patients undergoing inguinal hernia repair.

Robotic arthroscopic surgery: a new challenge in arthroscopic surgery Part-I: Robotic shoulder arthroscopy; a cadaveric feasibility study.

BACKGROUND: Arthroscopy of the shoulder is a well-established diagnostic procedure which has widespread application. Advances in technology and the search for more minimal invasive surgery will always offer new techniques in any surgical field. Robotic technology is such an advance, offering technical advantages over standard laparoscopic approaches. The aim of the present study is to test whether robotic surgery can be used while performing shoulder arthroscopy or not. METHODS: Robotic shoulder arthroscopy was tried on two shoulder joints of a male fresh-frozen human cadaver. The arthroscopic control of the biceps tendon, glenoid labrum, rotator cuff muscles, rotator interval, glenohumeral ligament, and the coracoid process were evaluated in beach chair and lateral decubitus positions. RESULTS: The arthroscopic control of the shoulder joint was possible for both beach chair and lateral decubitus positions. CONCLUSIONS: Robotic shoulder arthroscopy seems feasible in a cadaveric model but has some significant limitations at this time. A clinical application could be performed as diagnostic arthroscopy and as simple arthroscopic surgery until more specific instrumentation is developed. It may also enable the surgeon to perform more complex and precise tasks in restricted spaces.

Anatomic basis of percutaneous Kirschner wire insertion in zygoma fractures.

The combination of Gillies elevation with 1-point percutaneous Kirschner wire fixation of isolated simple zygoma fractures was found to be effective in restoring preinjury appearance and function and avoiding soft tissue morbidity. The proximity of the infraorbital nerve, inferior orbital rim, and dental roots warrants care in the placement of the wire. The need for precise anatomic guidelines becomes apparent when considering these relationships. Eighteen adult skulls (36 sides) were examined, and specific points were determined that could be important while inserting Kirschner wire for zygoma fractures, and the distances between those points were measured with a digital caliper. Then, by using these points, the wire was inserted into the zygoma through the medial wall of the maxillary sinus, and the insertion point of the wire on the lateral wall of the maxilla and the angle of the wire were determined. The mean lengths of the wires of the right and left sides of each skull were counted, and for 18 skulls, the mean length of the wire was measured as 45.12 mm. Direction of the insertion during drilling zygoma, conversely to the location of the insertion, nearly determines the course of the wire and the point of insertion on the lateral wall of the maxilla. Obtaining precise information concerning the installation angle and length of the wire before surgery should contribute to safer and smoother surgical procedures.

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.

Lumbosacral intrathecal nerve roots: an anatomical study.

BACKGROUND: The lumbosacral intrathecal anatomy is complex because of the density of nerve roots in the cauda equina. Space-occupying lesions, including disc herniation, trauma and tumor, within the spinal canal may compromise the nerve roots, causing severe clinical syndromes. The goal of this study is to provide spinal surgeons with a detailed anatomical description of the intrathecal nerve roots and to emphasize their clinical importance. METHOD: Ten formalin-fixed male cadavers were studied. They were dissected with the aid of a surgical microscope, and measurements were performed. RESULTS: The number of dorsal and ventral roots ranged from one to three. The average diameter of roots increased from L1 to S1 (0.80 mm for L1 and 4.16 for S1), respectively. Then their diameter decreased from S1 to S5 (4.16 mm for S1, 0.46 mm for S5). The largest diameter was found at S1 and the smallest at S5. The average number of rootlets per nerve root increased from L1 to S1, then decreased (3.25 for L1, 12.6 for S1, and 1.2 for S5), respectively. The greatest rootlet number was seen at S1, and the fewest were observed at S5. The average diameter of the lateral recess gradually decreased from L1 to L4 (9.1 mm for L1; 5.96 mm for L4) and then increased at L5 level (6.06 mm); however, the diameter of the nerve root increased from L1 to L5. The midpoint of distance between the superior and inferior edge of the intradural exit nerve root was 3.47 mm below the inferior edge of the superior articular process at the L1 level, while the origin of the L5 exit root was 5.75 mm above the inferior edge. The root origin gradually ascended from L1 to L5. CONCLUSIONS: The findings of this study may be valuable for understanding lesions compressing intradural nerve roots and may be useful for intradural spinal procedures.

Surgical view of the lumbar arteries and their branches: an anatomical study.

BACKGROUND: Although injury to the lumbar arteries during anterior spinal approaches is often encountered, there are few published articles regarding the relationship between the lumbar arteries and spinal cord ischemia. OBJECTIVE: To examine the morphology of the lumbar arteries and to emphasize their clinical importance. METHODS: With the aid of a surgical microscope, 80 lumbar arteries in 10 formalin-fixed male cadavers were studied. Measurements of these structures were made and relationships observed. RESULTS: The spinal artery was usually the first branch of the lumbar artery. The greatest lumbar artery diameter was at L4 and had a mean diameter of 3.25 mm; the smallest diameter was identified at L2 and had a mean diameter of 2.05 mm. The largest spinal artery diameter was at L3 (mean, 0.56 mm) and the smallest at L1 (mean, 0.42 mm). The largest anastomotic artery diameter was at L4 (mean, 0.42 mm) and the smallest at L1 (mean, 0.32 mm). For the right and left sides, the mean greatest distance between the origin of the lumbar artery and the tendinous arch was at L4 (mean, 40.9 and 31.8 mm, respectively) and the least at L1 (mean, 31.8 and 22.5 mm, respectively). The mean of the greatest distance between the anastomotic branch and the base of the transverse process of the lumbar vertebrae was at L4 (mean, 4.41 and 4.35 mm, respectively) and the smallest at L1 (mean, 4.04 and 4.08 mm, respectively). CONCLUSION: These anatomic findings of the lumbar segmental arteries would be useful for emphasizing their surgical importance.

Neurovascular structures adjacent to the lumbar intervertebral discs: an anatomical study of their morphometry and relationships.

OBJECT: Although infrequent, injury to adjacent neurovascular structures during posterior approaches to lumbar intervertebral discs can occur. A detailed anatomical knowledge of relationships may decrease surgical complications. METHODS: Ten formalin-fixed male cadavers were used for this study. Posterior exposure of the lumbar thecal sac, nerve roots, pedicles, and intervertebral discs was performed. To identify retroperitoneal structures at risk during posterior lumbar discectomy, a transabdominal retroperitoneal approach was performed, and observations were made. The distances between the posterior and anterior edges of the lumbar intervertebral discs were measured, and the relationships between the disc space, pedicle, and nerve root were evaluated. RESULTS: For right and left sides, the mean distance from the inferior pedicle to the disc gradually increased from L1-2 to L4-5 (range 2.7-3.8 mm and 2.9-4.5 mm for right and left side, respectively) and slightly decreased at L5-S1. For right and left sides, the mean distance from the superior pedicle to the disc was more or less the same for all disc spaces (range 9.3-11.6 mm and 8.2-10.5 mm for right and left, respectively). The right and left mean disc-to-root distance for the L3-4 to L5-S1 levels ranged from 8.3 to 22.1 mm and 7.2 to 20.6 mm, respectively. The root origin gradually increased from L-1 to L-5. The right and left nerve root-to-disc angle gradually decreased from L-3 to S-1 (range 105°-110.6° and 99°-108°). Disc heights gradually increased from L1-2 to L5-S1 (range 11.3-17.4 mm). The mean distance between the anterior and posterior borders of the intervertebral discs ranged from 39 to 46 mm for all levels. CONCLUSIONS: To avoid neighboring neurovascular structures, instrumentation should not be inserted into the lumbar disc spaces more than 3 cm from their posterior edge. Accurate anatomical knowledge of the relationships of intervertebral discs to nerve roots is needed for spine surgeons.

Botulinum toxin injection of the subscapularis muscle.

Patients with hemiplegia frequently suffer from pain and have a limited range of motion (ROM) of the shoulder. The common pattern of shoulder movement in a patient with spastic hemiplegia is primarily adduction and internal rotation. Spasticity of the subscapularis muscle limits the abduction, external rotation and flexion of the shoulder. Injection of botulinum toxin or application of phenol can reduce the spasticity of the subscapularis muscle and various techniques to inject this muscle have been reported. We injected five patients with hemiplegia with botulinum toxin using our previously reported inferior approach, which is easy, safe and effective. We observed a reduction in pain and spasticity and improvement in the ROM of the shoulder for all patients.

Temporal branch of the facial nerve and its relationship to fascial layers.

OBJECTIVES: To eliminate the inconsistency in the nomenclature, to anatomically and definitively describe the topographic relationship of the temporal branch of the facial nerve to the fascial layers and the fat pads, and to create an effective algorithm to define the safest approaches and planes for surgical procedures in this area. METHODS: The study was performed using 18 hemifacial cadaveric specimens. In 12 hemifacial specimens, the facial halves were coronally sectioned and dissected. In 6 hemifacial specimens, planar dissection was performed layer by layer. RESULTS: The temporal branch of the facial nerve that traversed inside the deep layers of the temporoparietal fascia and the superficial musculoaponeurotic system coursed along the zygomatic arch as 1 (14.3%), 2 (57.1%), 3 (14.3%), and 4 (14.3%) twigs in the specimens. The temporoparietal fascia had no attachment to the zygomatic arch and continued caudally as the superficial musculoaponeurotic system. Adhesions were between the temporoparietal fascia and the superficial layer of the deep temporal fascia around the zygomatic arch. In most specimens, the superficial layer of the deep temporal fascia continued as the parotideomasseterica fascia, and a deep layer abutted the posterosuperior edge of the zygomatic arch. CONCLUSION: An easy and safe surgical approach in this area is to elevate the superficial layer deep to the intermediate fat pad directly on the deep layer of the deep temporal fascia descending to the periosteum along the zygomatic arch.

Hidden unilateral agenesis of the frontal sinus: human cadaver study of a potential surgical pitfall.

PURPOSE: The aim of the study was to attract attention to the surgical significance of unilateral agenesis of the frontal sinus hidden by the overlapping expansion of the contralateral sinus toward the agenetic side. MATERIALS AND METHODS: Retrospective review of endoscopic transnasal sinus dissections of 55 human cadavers (42, formalin fixated; 13, fresh frozen) was done in a tertiary care academic medical center. Surgical and radiologic findings were noted. RESULTS: Absence of right frontal sinus ostium in the presence of a connection between the right and left frontal sinuses was demonstrated in 2 (3.6%) cadavers. An absent and an incomplete septum between the frontal sinuses were also noted in these cadavers. No accompanying abnormality of other sinuses was found, and no evidence of previous sinus surgery was noted in these 2 cadavers. CONCLUSIONS: If one of the frontal sinus ostia cannot be found during sinus surgery, although this sinus and its recess can be seen on the thick-sliced coronal computed tomographic (CT) scans, keep in mind that it may be (3.6%) an agenetic frontal sinus hidden by the extensive pneumatization of the contralateral sinus that is crossing the midline. It may not be possible to foresee this variant preoperatively by endoscopic examinations or thick-sliced CT scans. If there is suspicion, thin-sliced CT scans with reconstruction will be ideal to confirm the agenesis of the frontal sinus and to avoid complications. In the presence of such variant of frontal sinus, 1-sided successful frontal sinusotomy is adequate because this sinus or cell will already be drained through the treated frontal recess.

Safe zone for C1 lateral mass screws: anatomic and radiological study.

OBJECTIVE: To evaluate the possible complications of overpenetrated C1 lateral mass screws and to identify and define a "safe zone" area anterior to the C1 vertebra. METHODS: The study was performed on 10 cadavers and 50 random patients who had undergone computed tomographic scanning with contrast medium of the neck for other purposes. Atlas lateral mass screw trajectories were plotted, and the safe zone for screw placement anterior to the atlas vertebra was determined for each trajectory. RESULTS: The trajectory of the internal carotid artery was measured from its medial wall. The trajectory of the internal carotid artery according to the ideal entrance point of the screw was 11.55 +/- 4.55 degrees (range, 2-22 degrees) in the cadavers and 9.78 +/- 4.55 degrees (range, -5 to 22 degrees) bilaterally in the patients. At 15 degrees (ideal screw trajectory), the thickness of the rectus capitis anterior muscle and longus capitis muscle was 6.69 +/- 0.83 mm (range, 5.32-7.92 mm) in the cadavers and 7.29 +/- 1.90 mm (range, 0.50-13.63 mm) bilaterally in the patients. The smallest distance from the internal carotid artery to the anterior cortex of the C1 vertebra was calculated as 4.33 +/- 2.03 mm (range, 1.15-8.40 mm) bilaterally in the cadavers and 5.07 +/- 1.72 mm (range, 2.15-8.91 mm) bilaterally in radiological specimens. CONCLUSION: The internal carotid artery trajectory is lateral to the ideal entrance point of C1 lateral mass screws. The medial angulation of a screw placed in the lateral mass of C1 seemed to increase the margin of safety for the internal carotid artery. The rectus capitis anterior and longus capitis muscles may be thought of as a safe zone area for C1 lateral mass screws. At more than 25 degrees of medial angulation, the risk of perforation of the oropharyngeal wall increases.

Ideal screw entry point and projection angles for posterior lateral mass fixation of the atlas: an anatomical study.

Although various posterior insertion angles for screw insertion have been proposed for C1 lateral mass, substantial conclusions have not been reached regarding ideal angles and average length of the screw yet. We aimed to re-consider the morphometry and the ideal trajections of the C1 screw. Morphometric analysis was performed on 40 Turkish dried atlas vertebrae obtained from the Department of Anatomy at the Medical School of Ankara University. The quantitative anatomy of the screw entry zone, trajectories, and the ideal lengths of the screws were calculated to evaluate the feasibility of posterior screw fixation of the lateral mass of the atlas. The entry point into the lateral mass of the atlas is the intersection of the posterior arch and the C1 lateral mass. The optimum medial angle is 13.5 +/- 1.9 degrees and maximal angle of medialization is 29.4 +/- 3.0 degrees . The ideal cephalic angle is 15.2 +/- 2.6 degrees , and the maximum cephalic angle is 29.6 +/- 2.6 degrees . The optimum screw length was found to be 19.59 +/- 2.20 mm. With more than 30 degrees of medial trajections and cephalic trajections the screw penetrates into the spinal canal and atlantooccipital joint, respectively. Strikingly, in 52% of our specimens, the height of the inferior articular process was under 3.5 mm, and in 70% was under 4 mm, which increases the importance of the preparation of the screw entry site. For accommodation of screws of 3.5-mm in diameter, the starting point should be taken as the insertion of the posterior arch at the superior end of the inferior articular process with a cephalic trajection. This study may aid many surgeons in their attempts to place C1 lateral mass screws.

Window anatomy for neurosurgical approaches. Laboratory investigation.

OBJECT: Knowledge of the cranium projections of the gyral structures is essential to reduce the surgical complications and to perform minimally invasive interventions in daily neurosurgical practice. Thus, in this study the authors aimed to provide detailed information on cranial projections of the eloquent cortical areas. METHODS: Ten formalin-fixed adult human skulls were obtained. Using sutures and craniometrical points, the crania were divided into 8 windows: superior frontal, inferior frontal, superior parietal, inferior parietal, sphenoidal, temporal, superior occipital, and inferior occipital. The projections of the precentral gyrus, postcentral gyrus, inferior frontal gyrus, superior temporal gyrus, transverse temporal gyri, Heschl gyrus, genu and splenium of the corpus callosum, supramarginal gyrus, angular gyrus, calcarine sulcus, and sylvian fissure to cranial vault were evaluated. RESULTS: Three-fourths of the precentral gyrus and postcentral gyrus were in the superior parietal window. The inferior frontal gyrus extended to the inferior parietal window in 80%. The 3 important parts of this gyrus were located below the superior temporal line in all hemispheres. The orbital and triangular parts were in the inferior frontal window, and the opercular part was in the inferior parietal window. The superior temporal gyrus was usually located in the inferior parietal and temporal windows, whereas the supramarginal gyrus and angular gyrus were usually located in the superior and inferior parietal windows. The farthest anterior point of the Heschl gyrus was usually located in the inferior parietal window. The mean positions of arachnoid granulations were measured as 3.9 +/- 0.39 cm anterior and 7.3 +/- 0.51 cm posterior to the bregma. CONCLUSIONS: Given that recognition of the gyral patterns underlying the craniotomies is not always easy, awareness of the coordinates and projections of certain gyri according to the craniometric points may considerably contribute to surgical interventions.

Ultrasound-guided obturator nerve block: a sonoanatomic study of a new methodologic approach.

BACKGROUND: Obturator nerve block is one of the most technically challenging regional anesthesia techniques. Recently, the characteristics of the nerve have been described using ultrasound. However, clinical application of proximal ultrasound-guided obturator nerve block on patients has not been reported. In this study, we used ultrasound to describe the anatomical localization of the obturator nerve and its two branches in cadavers, volunteers, and also patients. METHODS: A hyperechoic triangular shape formed by the superior pubic ramus, posterior margin of the pectineus muscle and anterior aspect of the external obturator muscle containing the obturator vessels and nerve was defined by ultrasound imaging in cadavers. In eight volunteers, bilateral obturator nerve images were obtained and the distances to specific landmarks (femoral artery, femoral vein, and pubic tubercle) were recorded. Ultrasound-guided obturator nerve block was further performed in 15 patients by using the previously defined approach. The final distance of the needle tip to the femoral artery, distances between the needle insertion point to the pubic tubercle and the depth of needle insertion were recorded. RESULTS: The rates of common obturator nerve, anterior and branching obturator nerve pattern visibility with ultrasound were determined in 12/16, 13/16, and 7/16 sites in volunteers, respectively. Mean (SD) values of critical landmarks obtained from volunteers were obturator nerve-femoral vein 12.9 +/- 2.9 mm and obturator nerve-pubic tubercle 19.9 +/- 2.6 mm. Mean measurements obtained from patients were: femoral artery- needle tip 18.5 +/- 2.4 mm, needle depth 48.3 +/- 10.4 mm, pubic tubercle- needle insertion point (horizontal) 18.8 +/- 2.0 mm, and pubic tubercle- needle insertion point (vertical) 21.1 +/- 2.9 mm. Visual analog scale scores obtained from patients at 1 and 24 h were lower compared to baseline values (P < 0.001). Ninety-three percent (14 of 15) of the patients reported satisfaction from the block. CONCLUSIONS: Landmarks defined in this clinical trial can be used in patients for obturator nerve block with ultrasound guidance.