Ibrahim Tekdemir

Thoracic pedicle: surgical anatomic evaluation and relations.

This anatomic study investigated the thoracic pedicle and its relations. The objective was to emphasize the importance of the thoracic pedicle for transpedicular screw fixation to avoid complications during surgery. Twenty cadavers were used to observe the cervical pedicle and its relations. The isthmus of the pedicle was exposed after removal of whole-posterior bony elements, including spinous processes, laminas, lateral masses, and the inferior and superior facets. The pedicle width and height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, root exit angle, and nerve root diameter were measured. There was no distance between the pedicle and dural sac in eight specimens. There was, however, a short distance in 12 remaining specimens in the upper and lower thoracic regions. The distances between the thoracic pedicle and the adjacent nerve roots ranged from 1.5 to 6.7 mm and 0.8 to 6.0 mm superiorly and inferiorly at all levels. The mean pedicle height and width at T1-T12 ranged from 2.9 to 11.4 mm and 6.2 to 21.3 mm, respectively. The interpedicular distance decreased gradually from T1 to T5 and then increased gradually to T12. The mean root exit angle decreased consistently from 104 degrees to 60 degrees. The nerve root diameter was between 2.3 and 2.5 mm at the T1-T5 level and then increased consistently from 2.5 to 3.7 mm. All significant differences were noted at p < 0.05 and p < 0.01. The following suggestions are made based on these results. 1) More care should be taken when a transpedicular screw is placed in the horizontal plane. 2) Improper medial placement of the pedicle screw, especially in the middle thoracic spine, should be avoided, and the anatomic variations between individuals should be considered. 3) Because of substantial variations in the size of thoracic pedicles, utmost attention should be given to the findings of a computed tomographic evaluation before thoracic transpedicular fixation is begun.

Temporoparietal fascia : An anatomic and histologic reinvestigation with new potential clinical applications

Temporoparietal fascia constitutes a very important structural unit from both an aesthetic and a reconstructive surgical point of view. A histologically supported anatomic study was conducted for the reappraisal of the anatomic relationships and clinical application potentials of the data obtained. Anatomy of the temporoparietal fascia was investigated on 20 sides from 10 cadavers. After dissections, necropsies were obtained to demonstrate histologic features of the temporoparietal fascia. The outer part of the temporoparietal fascia is continuous with the superficial musculoaponeurotic system (SMAS) in the inferior border and with orbicularis oculi and frontalis muscles in the anterior border. Therefore, plication of the temporoparietal fascia can increase tightness of the SMAS, orbicularis oculi, and frontalis muscle in rhytidectomy. The frontal branches of facial nerve were noted to course parallel to the frontal branch of the superficial temporal artery, lying deeper to the temporoparietal fascia within the innominate fascia. In the view of these findings, conventional subfascial dissection, which is performed to protect frontal branches of the facial nerve, is not reasonable during the temporal part of rhytidectomy. Careful subcutaneous dissection just under the hair follicles is more appropriate to avoid nerve injury and also provides excellent exposure of the temporoparietal fascia for plication in rhytidectomy with protection of the auriculotemporal nerve and the superficial temporal vessels. Furthermore, two layered structures of the temporoparietal fascia are very suitable to insert a framework into the temporoparietal fascia for ear reconstruction to eliminate some of the shortcomings of Brents technique. A thin muscle layer was also noted within the outer part of the temporoparietal fascia below the temporal line; the term “temporoparietal myofascial flap” would, therefore, be more accurate than “temporoparietal fascial flap.” Finally, the innominate fascia and the deep temporal fascia can be elevated with the two layers of the temporoparietal myofascial flap to obtain a well‐vascularized, four‐layered myofascial flap based on the superficial temporal vessels. This multilayered flap can be used to reconstruct all defects when fine, pliable, thin, multilayered flaps are required. (Plast. Reconstr. Surg. 105: 40, 2000.)

A clinico-anatomic study of the auricular branch of the vagus nerve and arnold's ear-cough reflex

The results of a clinico-anatomic study of the auricular branch of the vagus nerve (ABVN) and Arnold’s ear-cough reflex are presented. The frequency of the ear-cough reflex was found to be 2.3% (12 out of 514 patients). It was bilateral in 3 cases (0.6%). The reflex was elicited by palpation of the postero-inferior wall of the external acoustic meatus (EAM) in 11 patients, and by palpation of the antero-inferior wall in one patient (0.2%). The reflex was frequently noticed to occur after a short latent period. The course of the ABVN inside the jugular foramen (JF), and distribution of the terminal branches of the ABVN in the external acoustic meatus were determined in 8 male cadavers (16 sides). In addition, the length of the mastoid canaliculus (MC) and the relationships of the ABVN with the facial nerve and stylomastoid foramen (SMF) were studied in both cadavers and 25 dry skulls (50 sides). High-resolution computed tomography (HRCT) scanning was also performed in all cadavers prior to microdissections. The ABVN emerged from the superior ganglion of the vagus nerve in all the cadavers. It ran between the internal jugular vein (IJV) and the bony wall of the jugular foramen. The ABVN was encased in a partial bony canal during its course from the jugular foramen to mastoid canaliculus in 18% of all specimens. The average length of the mastoid canaliculus was 5.6 mm (4.2–6.5), and it ran transversely towards the tympanomastoid suture 4.5 mm (4–5.1) above the stylomastoid foramen. The mastoid canaliculus was well demonstrated in all the HRCT scans.

Certain Anatomical Relations and the Precise Morphometry of the Infraorbital Foramen–Canal and Groove: An Anatomical and Cephalometric Study

Objectives To determine and to standardize the certain anatomical relations, and the precise size, course, and location of the infraorbital foramen, canal, and groove for facilitating surgical and invasive procedures.

Is there a safe area for the axillary nerve in the deltoid muscle? A cadaveric study.

BACKGROUND Several authors have defined a variety of so-called safe zones for deltoid-splitting incisions. The first aim of the present study was to investigate the distance of the axillary nerve from the acromion and its relation to arm length. The second aim was to identify a safe area for the axillary nerve during surgical dissection of the deltoid muscle. METHODS Twenty-four shoulders of embalmed adult cadavers were included in the study. The distance from the anterior edge of the acromion to the course of the axillary nerve was measured and was recorded as the anterior distance. The same measurement from the posterior edge of the acromion to the course of the axillary nerve was made and was recorded as the posterior distance for each limb. Correlation analysis was performed between the arm length and the anterior distance and the posterior distance for each limb. The ratios between arm length and the anterior and posterior distances were calculated for each case and were recorded as an anterior index and a posterior index. RESULTS The average arm length was 30.40 cm. The average anterior distance was 6.08 cm, and the average posterior distance was 4.87 cm. There was a significant correlation between arm length and both anterior distance (r = 0.79, p < 0.001) and posterior distance (r = 0.61, p = 0.001). The axillary nerve was not found to lie at a constant distance from the acromion at every point along its course. The average anterior index was 0.20, and the average posterior index was 0.16. CONCLUSIONS The present study describes a safe area above the axillary nerve that is quadrangular in shape, with the length of the lateral edges being dependent on the individuals arm length. Using this safe area should provide a safe exposure for the axillary nerve during shoulder operations.

Reliability of the safe area for the superior gluteal nerve.

The authors investigated the reliability of the safe area, which previously was defined to prevent injury to the superior gluteal nerve during the lateral approach to the hip, and its relation to body height. The distance between the point of entry of the superior gluteal nerve into the gluteus medius muscle and the greater trochanter, in the regions which were defined as the anterior and posterior halves of the muscle, were measured in 23 cadaveric hips. There was a significant correlation between the height of the cadavers and the distance in the anterior and posterior regions. In all of the anterior regions and 78% of the posterior regions of the hips, the superior gluteal nerve as found to be in the safe area. The current study showed that the average distance between the innervation point of the gluteus medius muscle and the greater trochanter might change as a function of body height. The risk of damage to the superior gluteal nerve may be higher if the direct lateral approach to the hip is used. These data show that it is possible that the safe area is not always safe.

Surgical Anatomic Evaluation of the Cervical Pedicle and Adjacent Neural Structures

OBJECTIVEAlthough several clinical applications of transpedicular screw fixation in the cervical spine have been documented recently, few anatomic studies concerning the cervical pedicle are available. This study was designed to evaluate the anatomy and adjacent neural relationships of the middle and lower cervical pedicle (C3–C7). The main objective is to provide accurate information for transpedicular screw fixation in the cervical region and to minimize complications by providing a three-dimensional orientation. METHODSTwenty cadavers were used to observe the cervical pedicle and its relationships. After removal of the posterior bony elements, including spinous processes, laminae, lateral masses, and inferior and superior facets, the isthmus of the pedicle was exposed. Pedicle width, pedicle height, interpedicular distance, pedicle-inferior nerve root distance, pedicle-superior nerve root distance, pedicle-dural sac distance, medial pedicle-dural sac distance, mean angle of the pedicle, root exit angle, and nerve root diameter were measured. RESULTSThe results indicate that there was no distance between the pedicle and the superior nerve root and between the pedicle and the dural sac in 16 specimens, whereas there was a slight distance in the lower cervical region in the 4 other specimens. The mean distance between the pedicle and the inferior nerve root for all specimens ranged from 1.0 to 2.5 mm. The mean distance between the medial pedicle and the dural sac increased consistently from 2.4 to 3.1 mm. At C3–C7, the mean pedicle height ranged from 5.2 to 8.5 mm, and the mean pedicle width ranged from 3.7 to 6.5 mm. Interpedicular distance ranged from 21.2 to 23.2 mm. The mean root exit angle ranged from 69 to 104 degrees, with the largest angle at C3 and the smallest at C6. The mean angle of the pedicle ranged from 38 to 48 degrees. The nerve root diameter increased consistently from 2.7 mm at C3 to 3.8 mm at C6 and then decreased to 3.7 mm at the C7 level. Differences in measurements were considered statistically significant at levels ranging from P < 0.05 to P < 0.01. CONCLUSIONThis study indicates that improper placement of the pedicle screw medially and superiorly in the middle and lower cervical spine should be avoided and that the anatomic variations between individuals should be established by measurement.

Ultrastructural evaluation of pulsed radiofrequency and conventional radiofrequency lesions in rat sciatic nerve

BACKGROUND PRF treatment has recently been described as minimally neurodestructive alternative to radiofrequency heat lesions. Patients with some pain syndromes in whom the pain could not be controlled by alternative techniques may be treated using PRF. In the present study, our main goal was to evaluate and compare the ultrastructure of peripheral nerve tissue that was heated by PRF, CRF with 42 degrees C, and CRF with 70 degrees C. METHODS Forty-five male rats were divided into 5 groups. In PRF group and CRF with 42 degrees C group, the sciatic nerve was heated at a temperature of 42 degrees C for 120 seconds. As a positive control, some rat sciatic nerves were treated with CRF lesions at 70 degrees C. The rats were kept alive for 21 days and then killed. Tissue was evaluated with transmission electron microscope, and grading was done to the groups. RESULTS The unmyelinated nerve fibers were ultrastructurally normal in all groups. The results of myelinated axons indicated that PRF group had better grades, and CRF with 70 degrees C group had the worst grade. Especially, comparison of the group of PRF and CRF with 42 degrees C revealed significant difference. In PRF group, none of the myelinated axons showed severe degeneration findings, and most of the damaged myelinated axons showed only separation in myelin configuration. CONCLUSIONS PRF treatment may cause separation in myelinated axons. However, it seems that all changes were reversible. The present study supports the hypothesis that pulsed RF treatment does not rely on thermal injury of neurologic tissue to achieve its effect.

Should we reevaluate the variables for predicting the difficult airway in anesthesiology

Anesthesiologists have often been confronted with the difficult question of determining which patient will present an increased difficulty for endotracheal intubation. The limits of the previously reported morphometric airway measurements for predicting difficult intubation have inadequately addressed the normal patient population variables. We designed this prospective study to investigate the age and sex-related changes in the morphometric measurements of the airway in a large group of patients without anatomic abnormality and a group of cadavers. Hyomental, thyromental, sternomental distances, neck extension, and Mallampati scores were evaluated in 12 cadavers and in 334 patients. Patients were allocated to three groups based on age: Group 1 (20–30 yr), Group 2 (31–49 yr), and Group 3 (50–70 yr). Male and female sex differences were also evaluated. Hyomental distance was the only variable not affected by age. In addition, the mean population values were less than the threshold values suggested as criteria for difficult endotracheal intubation. All the other criteria were age-dependent and inversely affected by the increase in age. Male sex was also a distinction for increased measurements of all the morphometric distances. The mean degree of neck extension was similar in both sex groups. This study provides a more comprehensible approach to the morphometric measurements of the human airway. Adequate data of normal values may help the clinician to identify patients that are outside the range and therefore may be challenging.

Review of complications due to foramen ovale puncture

We aim to evaluate the mechanisms responsible for complications during trigeminal rhizotomy via foramen ovale puncture. Ten dry skulls and 10 skull-base specimens were investigated in the present study. In cadaveric skull-base specimens, the anatomical relationships between the foramen ovale, mandibular nerve and Gasserian ganglion and the surrounding neurovascular structures were investigated intradurally. The distance between the foramen ovale and Gasserian ganglion was measured as 6 mm. The abducent nerve, adjacent to the anterior tail of the petrolingual ligament, was observed passing along the lateral wall of the cavernous sinus. Advancement of the catheter more than 10 mm from the foramen ovale is likely to damage the internal carotid artery and the abducent nerve at the medial side of the petrolingual ligament. Thermocoagulation of the lateral wall of the cavernous sinus may damage the cranial nerves by heat, giving rise to pareses.