Browsing by Author "Tekdemir, I"

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    Anatomic limitations of posterior exposure of the sinus tympani
    Aslan, A; Guclu, G; Tekdemir, I; Elhan, A
    OBJECTIVE. The sinus tympani is a challenging area for the otologic surgeon to access and from which to remove the disease process. Recently, a posterior approach to the sinus tympani through the mastoid was proposed as an alternative technique in cases of deep sinus tympani. STUDY DESIGN AND SETTING: The posterior approach was performed by dissecting the triangular bony area formed by the facial nerve, lateral semicircular canal, and posterior semicircular canal in 8 temporal bone specimens. RESULTS: The edges of the triangle on the facial nerve and lateral semicircular canal were almost constant at 5 mm. The edge on the posterior semicircular canal was about 4 mm. CONCLUSION: It is possible to expose the sinus tympani from the posterior by careful dissection through this triangle, which has almost constant dimensions.
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    Defining the Macroscopic and Microscopic Findings of Experimental Focal Brain Ischemia in Rats From a Forensic Scientist's Point of View
    Tatlisumak, E; Inan, S; Asirdizer, M; Apaydin, N; Hayretdag, C; Kose, C; Tekdemir, I
    Approximately 10% of all deaths in the world occur as a result Of stroke. Determination of the time schedule of the pathologic events in a stroke patient is invaluable for a forensic specialist. The aim of this study was to define the schedule of the macroscopic and microscopic changes that occurred in a rat model of permanent focal ischemia for providing useful clues for the evaluation of stroke patients. Male Wistar rats weighing 250 to 350 g were used in this study. Permanent focal brain ischemia was applied by the suture occlusion method. The animals were divided into 7 experimental groups (n = 6) with time schedules including 1.5, 3, 6, 12, 24, 72 hours, and the sham. Brains were harvested at the end of the determined time schedule. Lesions in the frontoparietal cortex were evaluated macroscopically first and later hematoxylin eosin stained sections from the infarct core were investigated microscopically. Macroscopically, enlargement of the ipsilateral hemisphere was mild at 6 hour, apparent at 12 and 24 hours, and mild again at 72 hours. Microscopically, ischemic changes were apparent even at 1.5 hour. Red neurons and infiltration of the parenchyma with neutrophil leukocytes were observed at 12 hours. Pannecrosis and massive leukocyte infiltration were observed at 72 hours. Macroscopic and microscopic findings obtained from a rat model may provide clues for determination of the time-dependent changes due to brain ischemia in human subjects. Finally, the benefits of determination of time course of pathologic changes in the brain for forensic scientists were discussed.
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    Surgical anatomy of the nasolacrimal duct on the lateral nasal wall as revealed by serial dissections
    Tatlisumak, E; Aslan, A; Cömert, A; Ozlugedik, S; Acar, HI; Tekdemir, I
    The anatomy of the nasolacrimal duct (NLD) in relation with the lateral nasal wall was studied in 15 half-heads of human adult cadavers by serial photographs of the dissection of the lateral nasal wall. The aim of the study was to determine the intranasal anatomical relationships of the NLD with the lateral nasal wall for surgical reference during endoscopic dacryocystorhinostomy. Following removal of the nasal mucosa anterior to the uncinate process, the exposed bone was removed by drilling. The entire NLD was exposed intranasally. The relationships of the NLD with the maxillary sinus ostium and anterior nasal spine were determined, and the length of the NLD was measured. The morphology of the NLD opening was observed, and its distance from several landmarks were measured. There were three types of intranasal orifice: pin-point, triangular and slit-like. The NLD is located, on average, 24.6 +/- A 3.56 mm posterior to the anterior nasal spine. The nearest distances between the opening of the NLD and the nasal floor and between the opening of the NLD and the most anterior attachment of the inferior nasal concha were 13.7 +/- A 3.15 and 14.3 +/- A 2.05 mm, respectively. The length of the NLD was 21.9 +/- A 2.03 mm on average. The nearest distances between the NLD and the maxillary sinus ostium was 3.9 +/- A 0.88 mm. Cadaver dissections and the photographs of the fine dissections provide a more accurate description of the lateral nasal wall anatomy. These data provide valuable anatomical information to the surgeon performing endonasal dacryocystorhinostomy.
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    The location of the obturator nerve: a three-dimensional description of the obturator canal
    Kendir, S; Akkaya, T; Comert, A; Sayin, M; Tatlisumak, E; Elhan, A; Tekdemir, I
    Satisfactory analgesia cannot be achieved in every obturator nerve block. To attempt to improve the success rate of obturator nerve block, this study describes the detailed anatomy of the obturator region and canal. Eleven (5 female and 6 male) cadavers, totally 22 sides were dissected. Anatomical positions of the structures entering and leaving the canal were defined. The position of the obturator nerve and its branches and their relation with the obturator artery, vein, and with the internal iliac and femoral veins were investigated. A mould of the canal and a model were created. Detailed measurements were performed on the cadavers and models. The obturator canal was in the shape of a funnel compressed from superior to inferior, with anterior and posterior openings. At the entrance of the canal, the nerve lay superiorly; the artery was in the middle, and the vein lay inferiorly. The obturator nerve ran close to the lateral wall of the obturator canal. The distance of lateral wall of obturator canal to the median plane was 41.4 +/- 1.1 mm After leaving the canal, the nerve lay laterally while the anterior branch of the artery was medial. A venous plexus lay between the two structures. The presence of the branches of the obturator artery and vein alongside the obturator nerve may increase the risk of injury to these structures during anaesthetic procedures. The anterior division of the obturator nerve has a close relationship with these vessels. To provide complete analgesia, the obturator nerve should be blocked in the obturator canal or at its external orifice.
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    Comprehensive microsurgical anatomy of the jugular foramen and review of terminology
    Tekdemir, I; Tuccar, E; Aslan, A; Elhan, A; Ersoy, M; Deda, H
    The microsurgical anatomy of the jugular foramen was studied in 12 formalin preserved cadavers (24 foramina) and 40 dry-skulls (80 foramina). The jugular foramen was exposed by microsurgical dissection with drilling from a superior to inferior direction. Observations regarding dural architecture of the jugular foramen and relationships between neurovascular structures passing through the foramen were noted in cadavers. Normal bony construction of the foramen and its variational anatomy were examined in dry-skull specimens. Using photographs and drawings, the anatomy of the jugular foramen is presented and related terminology is discussed in the light of a literature review. (C) 2001 Harcourt Publishers Ltd.
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    A radiologico-anatomical comparative study of the cochlear aqueduct
    Tekdemir, I; Aslan, A; Ersoy, M; Karahan, ST; Tellioglu, Ç
    AIM: A comparative radiologico-anatomical study of the cochlear aqueduct (CA) was performed. MATERIALS AND METHODS: Eight cadavers and 23 dry temporal bones were studied. High-resolution computed tomography (HRCT) was carried out on each cadaver before microdissection. Microdissection was carried out in a plane parallel to the HRCT sections. RESULTS: The CA was found to be located an average of 7 mm inferior to the internal acoustic meatus and at the superior edge of the jugular foramen. The external aperture of the CA was triangular in shape in 18 bones (78.3%). The petrosal fossa was located just inferior to the external aperture and housed the glossopharyngeal nerve, which had an incomplete bony canal in four bones (17.4%) and a complete bony canal in three bones (13%). It was possible to demonstrate the petrosal portion of the CA on both coronal and axial HRCT. The otic capsule segment of the CA was impossible to demonstrate on coronal sections. CONCLUSION: The CA cannot be visualized in only one section of the plane in HRCT. Both the otic capsule and petrosal segments can be demonstrated on axial HRCT. (C) 2000 The Royal College of Radiologists.