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.

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.

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.

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.

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.

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.

Numerical study of the aerodynamic effects of septoplasty and partial lateral turbinectomy.

OBJECTIVES: To investigate, first, the effects of septal deviation and concha bullosa on nasal airflow, and second, the aerodynamic changes induced by septoplasty and partial lateral turbinectomy, using computational fluid dynamics (CFD). METHODS: A three-dimensional model of a nasal cavity was generated using paranasal sinus computed tomography images of a cadaver with concha bullosa and septal deviation. Virtual septoplasty and partial lateral turbinectomy were performed on this model to generate a second model representing the postoperative anatomy. Aerodynamics of the nasal cavity in the presence of concha bullosa and septal deviation as well as postoperative changes due to the virtual surgery were analyzed by performing CFD simulations on both models. Inspiratory airflow with a constant flow rate of 500 mL/second was used throughout the analyses. RESULTS: In the preoperative model, the airflow mostly pass through a narrow area close to the base of the nasal cavity. Following the virtual operation, a general drop in the maximum intranasal air speed is observed with a significant increase of the airflow through right middle meatus. While in the preoperative model the greatest reduction in pressure is found to be in the localization of anterior septal deviation on the right side and confined to a very short segment, for the postoperative model, it is observed to be in the nasal valve region in both nasal cavities. Following septoplasty and partial lateral turbinectomy, total nasal resistance is reduced significantly. CONCLUSIONS: CFD simulations promise to make great contributions to understand the airflow characteristics of healthy and pathologic noses. Before surgery, planning for any specific intervention using CFD techniques on the nasal cavity model of the patient may help foreseeing the aerodynamic effects of the operation and might increase the success rate of the surgical treatment.

Posterior osseous bridging of C1.

The sulcus of the vertebral artery is located behind the lateral mass of the atlas and in some cases is converted into a foramen by anomalous ossification known as the posterior ponticulus (osseous bridge). This study involved anatomical observations of 158 isolated anatomical specimens of dry C1 vertebrae. The incidence and types of posterior osseous bridging were identified for the 158 dry samples of atlas vertebrae. In nine (5.6%) dry C1 vertebrae, partial osseous bridging was detected (bilaterally in eight vertebrae and unilaterally on the left in one). Complete osseous bridging (arcuate foramen) was observed in six (3.8%) dry C1 vertebrae (bilaterally in one vertebra, unilaterally on the left in three, and on the right in two). Awareness of the types of posterior osseous bridging of C1 in craniocervical junction surgery is essential, and may be helpful in surgical interventions in this region.

Axial rotation and mediolateral translation of the fibula during passive plantarflexion.

BACKGROUND: Since the fibula is linked to the ankle as well as the knee joint, its importance for knee and ankle disabilities should be investigated. This study evaluates its movement during range of motion of the ankle. MATERIALS AND METHODS: An instrument, together with the experimental protocol, was devised to determine the relative motion of the fibula in reference to the tibia with motion of the ankle joint on 20 paired lower extremity cadaver specimens. RESULTS: It was demonstrated in all specimens that the fibula had a relative rotation around its longitudinal axis and mediolateral translation with reference to the tibia with ankle motion. The distal end of the fibula rotates more compared to the proximal end. The mediolateral translation of the proximal end of the fibula is rather close to that of the distal end. Although there was no consistent pattern for rotation, dorsiflexion caused lateral translation and plantarflexion caused medial displacement for most of the specimens. CONCLUSION: A novel, invasive but relatively simple test setup was devised. Movement of the fibula which is important for the kinematics and kinetics of the knee and ankle joints was evaluated by this new device. CLINICAL RELEVANCE: Evaluation of the fibula movement in normal lower extremities may lead to better understanding of its dynamic function which could have treatment implications for pathological conditions.

The anatomic branch pattern of the axillary nerve.

The purpose of this study is to determine the surgical anatomy and innervation pattern of the branches of the axillary nerve and discuss the clinical importance of the presented findings. We dissected 30 shoulders in 15 fixed adult cadavers under a microscope through anterior and posterior approaches. The axillary nerve was examined in 2 segments in relation to the underlying subscapularis muscle. The axillary nerve gave off no branches in the first segment in 85% of cases. When the posterior approach was used, the axillary nerve and its branches were observed to be in a triangular-shaped area. The mean distance from the posterolateral corner of the acromion to the axillary nerve and its branches was 7.8 cm. In all cases, the posterior branch of the axillary nerve gave off its first muscular branch to innervate the teres minor. The joint branch of the axillary nerve was observed to branch out in 3 different patterns. The acromial and clavicular parts of the deltoid muscle were observed to be innervated from the anterior branch of the axillary nerve in all cases. The posterior part of the deltoid muscle was observed to be innervated in 3 different patterns. The posterior part of the deltoid was innervated from the branch or branches coming only from the posterior branch in 70% of cases, from the anterior and posterior branches in 26.7% of cases, and from the anterior branch in 3.3% of cases. The findings of this study are useful for identifying each of the branches of the axillary nerve and have implications for surgeries related with selective innervation.

A neurosurgical view of anatomical variations of the distal anterior cerebral artery: an anatomical study.

OBJECT: The vascularization pattern of the anatomy of the distal anterior cerebral artery (ACA) remains a subject of debate. The authors provide detailed information about the distal ACA and shed light on issues concerning it that have not previously been adequately discussed. METHODS: Fifty adult human brains (100 hemispheres) were obtained during routine autopsies. Cerebral arteries were separately cannulated and injected with latex. The vascularization patterns of the cortical branches and the variations of the arteries were investigated. The authors found that the distal ACA supplied all the inner surfaces of the frontal and parietal lobes and a median of one third of the outer surfaces. The origin of the arteries from the main trunk and their exit angles affected the vascularization patterns of the hemispheres. The authors redefine controversial terminology regarding the callosomarginal artery. CONCLUSIONS: In each hemisphere, the vascularization pattern of the distal ACA is different to a greater or lesser extent. An awareness of this fact will contribute significantly to surgical interventions.

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.

The annular ligament: an anatomical study.

BACKGROUND: Despite documentations of ligamentous structures of the elbow, the anatomy and clinical and functional importance of the annular ligament has not been comprehensively defined in the orthopaedic literature. HYPOTHESIS: The annular ligament is an important component of both the proximal radioulnar and humeroradial joints, as well as an important component of the neighboring muscles and ligaments. STUDY DESIGN: Descriptive laboratory study. MATERIALS AND METHODS: To investigate the annular ligament and its relationship with neighboring structures, macroscopic and microscopic dissections were performed on both upper extremities of 30 cadavers (12 female and 18 male) fixed in 10% formaldehyde and on 1 upper extremity of a fresh cadaver (male). RESULTS: The distal ulnar insertion of discrete fibers on the supinator crest was defined as the inferior oblique band of the annular ligament, and the proximal insertion of the annular ligament was defined as the superior oblique band of the annular ligament. These patterns were noted in all specimens. It was difficult to distinguish the fibers of the supinator muscle in every specimen because they were intimately fused with the fibers of the annular ligament. CONCLUSIONS: The superior and inferior oblique bands of the annular ligament attached proximally and distally onto the ulna, thus helping to secure the annular ligament in place.

Arterial vascularization of primary motor cortex (precentral gyrus).

BACKGROUND: The precentral gyrus (PG) is the primary motor area and is one of the most eloquent brain regions of neurosurgical interest. Although the arterial supply to the PG is generally known, contributions from different arterial branches such as the anterior cerebral artery (ACA), posterior cerebral artery (PCA), and middle cerebral artery (MCA) have not been comprehensively studied. The aim of the present study was to provide detailed information about the arteries of the PG. METHODS: Twenty adult human brains (40 hemispheres) were obtained, and ACA, MCA, and PCA were separately cannulated and injected with latex. The PG was identified. RESULTS: The ACA supplied the medial one third and the MCA supplied the lateral two thirds of the PG. The PCA did not reach the PG in any of the hemispheres. In 16 hemispheres (40%), the callosomarginal artery and, in 13 hemispheres (32.5%), the pericallosal artery were dominant for the medial one third of the PG. In 11 hemispheres (27.5%), equal dominance was observed. MCA branches at the lateral tip of the PG were classified into precentral, central, and postcentral groups. In 29 hemispheres (72.5%), the central group, and in 4 hemispheres (10%), the precentral group were dominant for the lateral two thirds of the PG. In 7 hemispheres (17.5%), the precentral and central groups were equally dominant. No dominance was identified for the postcentral group. CONCLUSION: In each hemisphere, the PG was supplied by different vascularization patterns of ACA and MCA. The present study is the first to describe and discuss these details. Therefore, awareness of this pattern will provide a great contribution to surgical interventions.

Retropharyngeal space and lymph nodes: an anatomical guide for surgical dissection.

Identification of the alar fascia is the key part of surgical dissection of the retropharyngeal lymph nodes (RPLNs). In cases where mandibulotomy is not performed for the removal of the primary tumor and/or the posterior pharyngeal wall is not incised, the medial or lateral approaches described in this paper can be performed. Surgical dissection of the RPLNs may improve prognosis and locoregional control in oropharyngeal, hypopharyngeal and cervical esophageal carcinomas. There have been no previous anatomical studies concerning landmarks and approaches for the surgical dissection of the RPLNs. This study was designed to illustrate the fascial anatomy of the retropharyngeal region (RPR), provide anatomical guidelines for RPLN dissection and describe and compare approaches for surgical removal of the RPLNs. Twelve fixed cadavers were used. Slices were obtained from the necks of the first three cadavers and the RPRs of the slices were dissected under an operating microscope. The other nine cadavers were dissected in a surgical position to expose the RPLNs and the fasciae of the RPR. In the coronal plane, the alar fascia divides the space between the buccopharyngeal and prevertebral fasciae into two compartments and constitutes the posterior border of the retropharyngeal space, which contains the RPLNs. The alar fascia, an important landmark for reaching the RPLNs, can be identified by the cervical sympathetic trunk, superior sympathetic ganglion and superior laryngeal nerve. Two approaches can be performed to remove the RPLNs, namely medial or lateral to the internal and external carotid arteries, internal jugular vein and vagus nerve.

Unanticipated complication of percutaneous radiofrequency trigeminal rhizotomy: rhinorrhea: report of three cases and a cadaver study.

OBJECTIVE AND IMPORTANCE: Several neurosurgical procedures have been developed for the treatment of idiopathic trigeminal neuralgia: vascular decompression of the trigeminal root in the brainstem, percutaneous trigeminal ganglion procedures, and external beam radiosurgery. Percutaneous radiofrequency electrodes target the trigeminal fibers in the gasserian ganglion through the foramen ovale. Several complications of radiofrequency trigeminal rhizotomy (RF-TR) have been described, including puncture of the carotid artery, the cavernous sinus, and the cranial nerves. This study presents a very rare complication of percutaneous RF-TR, rhinorrhea, and attempts to define its mechanism. CLINICAL PRESENTATION: Of 2375 patients with idiopathic trigeminal neuralgia who underwent 2958 percutaneous RF-TR procedures, 3 developed subsequent rhinorrhea, which resolved spontaneously in 2 to 3 days. TECHNIQUE: Two formalin-fixed cadavers were dissected to demonstrate the relationship between the foramen ovale and the tuba auditiva and the mechanism of rhinorrhea. CONCLUSION: This article presents a very rare complication of RF-TR. Rhinorrhea and/or cerebrospinal fluid fistulae in the nasopharyngeal cavity are benign complications of RF-TR that result from puncturing both the membranous portion of the tuba auditiva (eustachian tube) and Meckel's cave with the rhizotomy needle.