Bahadir Murat Demirel

Akdeniz University, Antalya, Antalya, Turkey

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Publications (11)18.31 Total impact

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    ABSTRACT: Facial nerve injury is a common clinical trauma involving long-term functional deficits with facial asymmetry leading to associated psychological issues and social hardship. We have recently shown that repair by hypoglossal-facial or facial-facial nerve surgical end-to-end anastomosis and suture [hypoglossal-facial anastomosis (HFA) or facial-facial anastomosis (FFA)] results in collateral axonal branching, polyinnervation of neuromuscular junctions (NMJs) and poor function. We have also shown that another HFA repair procedure using an isogenic Y-tube (HFA + Y-tube) and involving a 10-mm gap reduces collateral axonal branching, but fails to reduce polyinnervation. Furthermore, we have previously demonstrated that manual stimulation (MS) of facial muscles after FFA or HFA reduces polyinnervation of NMJs and improves functional recovery. Here, we examined whether HFA + Y-tube and MS of the vibrissal muscles reduce polyinnervation and restore function. Isogenic Y-tubes were created using abdominal aortas. The proximal hypoglossal nerve was inserted into the long arm and sutured to its wall. The distal zygomatic and buccal facial nerve branches were inserted into the two short arms and likewise sutured to their walls. Manual stimulation involved gentle stroking of the vibrissal muscles by hand mimicking normal whisker movement. We evaluated vibrissal motor performance using video-based motion analysis, degree of collateral axonal branching using double retrograde labeling and the quality of NMJ reinnervation in target musculature using immunohistochemistry. MS after HFA + Y-tube reduced neither collateral branching, nor NMJ polyinnervation. Accordingly, it did not improve recovery of function. We conclude that application of MS after hypoglossal-facial nerve repair using an isogenic Y-tube is contraindicated: it does not lead to functional recovery but, rather, worsens it.
    Experimental Brain Research 03/2014; · 2.22 Impact Factor
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    ABSTRACT: Despite increased understanding of peripheral nerve regeneration, functional recovery after surgical repair remains disappointing. A major contributing factor is the extensive collateral branching at the lesion site, which leads to inaccurate axonal navigation and aberrant reinnervation of targets. To determine whether the Y tube reconstruction improved axonal regrowth and whether this was associated with improved function. We used a Y-tube conduit with the aim of improving navigation of regenerating axons after facial nerve transection in rats. Retrograde labeling from the zygomatic and buccal branches showed a halving in the number of double-labeled facial motor neurons (15% vs 8%; P < .05) after Y tube reconstruction compared with facial-facial anastomosis coaptation. However, in both surgical groups, the proportion of polyinnervated motor endplates was similar (≈ 30%; P > .05), and video-based motion analysis of whisking revealed similarly poor function. Although Y-tube reconstruction decreases axonal branching at the lesion site and improves axonal navigation compared with facial-facial anastomosis coaptation, it fails to promote monoinnervation of motor endplates and confers no functional benefit.
    Neurosurgery 01/2012; 70(6):1544-56; discussion 1556. · 2.53 Impact Factor
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    ABSTRACT: The outcome of severe peripheral nerve injuries requiring surgical repair (transection and suture) is usually poor. Recent work suggests that direct suture of nerves increases collagen production and provides unfavourable conditions for a proper axonal regrowth. We tested whether entubulation of the hypoglossal nerve into a Y-tube conduit connecting it with the zygomatic and buccal facial nerve branches would improve axonal pathfinding at the lesion site, quality of muscle reinnervation and recovery of vibrissal whisking. For hypoglossal-facial anastomosis (HFA) over a Y-tube (HFA-Y-tube) the proximal stump of the hypoglossal nerve was entubulated and sutured into the long arm of a Y-tube (isogeneic abdominal aorta with its bifurcation). The zygomatic and buccal facial branches were entubulated and sutured to the short arms of the Y-tube. Restoration of vibrissal motor performance, degree of collateral axonal branching at the lesion site and quality of neuro-muscular junction (NMJ) reinnervation were compared to animals receiving HFA-Coaptation (no entubulation) after 4 months. HFA-Y-tube reduced collateral axonal branching. However it failed to reduce the proportion of polyinnervated NMJ and did not improve functional outcome when compared to HFA-Coaptation. Elimination of compression by tightly opposed nerve fragments improved axonal pathfinding. However, biometric analysis of vibrissae movements did not show positive effects suggesting that polyneuronal reinnervation - rather than collateral branching - may be the critical limiting factor. Since polyinnervation of muscle fibers is activity-dependent and can be manipulated, the present findings raise hopes that clinically feasible and effective therapies after HFA could be soon designed and tested.
    Restorative neurology and neuroscience 04/2011; 29(4):227-42. · 2.93 Impact Factor
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    ABSTRACT: Nerve repair after facial nerve injury provides neural input to the distal facial nerve and facial musculature via a variety of motor nerves such as hypoglossal, spinal accessory, masseteric branch of the trigeminal nerve and motor branches of the cervical plexus. The most commonly used procedure is the hypoglossal-facial nerve transfer. This cross-nerve paradigm is a unique nerve repair method as one motor nerve takes over the function of another motor nerve. The hypoglossal-facial nerve repair was reviewed by means of history, terminology, technical variations, and its capacity for recovery of function.
    Annals of anatomy = Anatomischer Anzeiger: official organ of the Anatomische Gesellschaft 03/2011; 193(4):304-13. · 1.96 Impact Factor
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    ABSTRACT: FK506 (also known Tacrolimus, Prograf) is an immunosuppressant drug which is used to prevent rejection after organ transplantation. Although there are several studies on neuroprotective effect of FK506 on brain ischemia, few reports on effects of FK506 after peripheral nerve ischemia have been reported. In the present study, we examined the size of watershed area after stripping of the epineurial vessels and studied the effect of FK506 on reduction of the size of watershed area. Forty-eight adult female rats were used and randomly divided into four groups as control, sham, FK506-treated and vehicle-treated. In FK506-treated and vehicle-treated groups epineurial vessels around the sciatic nerve (vasa nervorum) were stripped. Additionally, FK506-treated group were received subcutaneous injection of 5 mg/kg FK506. Percent of watershed area (100 × total watershed areas / total nerve area) after stripping and FK506 treatment was calculated. We found no significant difference in comparison of the total size of watershed areas in FK506 and vehicle-treated groups or even the percent of the watershed area in both groups. We think that this study will be helpful to understand neuroprotective effect of FK506 and will give an insight into sparing of the nerve fibers from vascular injuries of the peripheral nerve.
    Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie 01/2011; 52(3 Suppl):1077-80. · 0.62 Impact Factor
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    ABSTRACT: Several kinds of injury models, such as crush, transection and graft repair have been well studied in terms of neuroprotective effect of FK506. However, definitive experimental studies are lacking on focal degeneration or ischemia. In the present study, our goal was to investigate the effect of FK506 on functional recovery of the sciatic nerve after focal ischemia, produced by stripping of the epineurial vessels. A total number of 48 Wistar rats were used for this purpose and divided into four groups (control, sham-operated, FK506-treated, and Vehicle-treated). Sciatic nerves were approached by femoral and gluteal muscle splitting. Then, epineurial vessels around the sciatic nerve were stripped in the FK506-treated and Vehicle-treated groups. After operation, 5mg/kg/day FK506 administration was initiated by subcutaneous injection until animal sacrifice. The same volume of saline was administrated to the vehicle-treated group. The functional and sensory recoveries were tested by walking pattern analysis and pinch test in every postoperative week. The animals were sacrificed in the end of the fourth postoperative week and sciatic nerve samples were harvested and processed for electron microscopic evaluation. Our data revealed that FK506 administration showed beneficial effect on subperineurial degeneration/demyelinization from functional, sensorial, and ultrastructural points of view. The sciatic nerve samples in the FK506-treated group had several remyelinated fibers compared to the vehicle-treated group. Our literature searches revealed that FK506 administration has not, to our knowledge, been studied in focal ischemic degeneration produced by stripping of the epineurial vessels.
    Current neurovascular research 10/2009; 6(4):252-8. · 3.23 Impact Factor
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    L Sarikcioglu, B M Demirel, A Utuk
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    ABSTRACT: Walking track analysis was first described by de Medinaceli et al. This technique has been significantly modified to provide methods of indexing nerve function that are more valid. Moreover, it has been questioned by several authors. The aim of the present review is to offer a combined knowledge about walking track analysis for scientists who deal with neuroscience.
    Folia morphologica 03/2009; 68(1):1-7. · 0.47 Impact Factor
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    ABSTRACT: Treatment of the craniofacial malformations is a primary goal of cranio-maxillo-facial surgeons. Surgical treatment of these malformations requires accurate data. Accuracy of measurement should be a priority of scientists to prevent statistical errors and therefore to promote the comparison of the results obtained from various research groups. In the present study, we aimed to compare three different measurement techniques, which were used frequently in craniofacial measurements. A total number of 35 female and 35 male volunteer adults were included to the study. Two-dimensional (2D) photogrammetry, three-dimensional (3D) digitization and manual anthropometry methods were used for the present study. Measurements were obtained from the ear, eye, nose and face. By comparing three methods, our findings revealed that 3D digitization method is an easy, robust, and sensitive method to obtain the data. We think that 3D digitization method is accurate, and it can be applied to both clinical practice and research. Advantages and disadvantages of three methods are discussed with the relevant literature.
    Journal of cranio-maxillo-facial surgery: official publication of the European Association for Cranio-Maxillo-Facial Surgery 02/2009; 37(5):285-90. · 1.25 Impact Factor
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    ABSTRACT: Peripheral nerve trunks are well-vascularized structures where a well-developed collateral system may compensate for local vascular damage. Vasculitis in nerve has a predilection for epineurial vessels and causes to the peripheral neuropathy, which is a major clinical feature of primary and secondary systemic vasculitides. In the present study, the goal was to simulate the vasculitic neuropathy in rat sciatic nerve and to investigate the watershed zones after stripping of the epineural vessels of the sciatic nerve. Sciatic function index values, light and electron microscopic evaluations of the experimental sciatic nerve suggested that the sciatic nerve was normal except for some watershed zones located in the peripheral part of the nerve. Although there is abundant collateral circulation in the peripheral nerve, distribution of the vessels of the watershed zones as observed in the present study should be elucidated by further studies.
    The International journal of neuroscience 09/2008; 118(8):1145-55. · 0.86 Impact Factor
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    ABSTRACT: During dissection of the retropubic region of a 55-year-old female cadaver, we encountered an angiolipoma located inside the obturator canal which was connected to the wall of the urinary bladder by a fibrous cord. The angiolipoma was supplied by a branch originating from the umbilical artery. Microscopically the benign soft tissue tumor was characterized by lobules of mature adipocytes and densely distributed networks of small and larger blood vessels, thus resembling typical histological features of an angiolipoma. Both the uncommon location of the angiolipoma and the abnormal branch of the umbilical artery entering the obturator canal should be taken into account during surgical procedures in this region, such as for orthopedic pelvic procedures, hernia repair or bladder/urethra-related interventions (e.g. transobturator tape, tension-free vaginal tape, colposuspension).
    Annals of Anatomy - Anatomischer Anzeiger 02/2007; 189(1):75-8. · 1.96 Impact Factor
  • Levent Sarikcioglu, Bahadir Murat Demirel
    Journal of the History of the Neurosciences 07/2006; 15(2):99-101. · 0.28 Impact Factor