Publications by authors named "Mustafa Berker"

25 Publications

  • Page 1 of 1

Role of Hypofractionated Stereotactic Radiosurgery in Recurrent Pineal Parenchymal Tumors of Intermediate Differentiation: A Case Report and Review of the Literature.

Cureus 2020 Aug 13;12(8):e9709. Epub 2020 Aug 13.

Radiation Oncology, Hacettepe University Medical School, Ankara, TUR.

A pineal parenchymal tumor of intermediate differentiation (PPID) is a rare entity, and optimal treatment is still unclear. Combined multimodality treatment should be considered in PPID due to high recurrence rates. Gross total resection is the first choice of treatment, however, it may not be feasible in every case due to location. Stereotactic radiosurgery (SRS) can be considered for the treatment of primary and recurrent disease, as it enables us to deliver a high radiation dose to the target while minimizing radiation exposure to normal tissue. In this report, we present a case treated with hypofractionated SRS for recurrent/metastatic PPID after the primary tumor was controlled with the combination of surgery and conventionally fractionated radiotherapy.
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http://dx.doi.org/10.7759/cureus.9709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7489324PMC
August 2020

The Effect of Training, Used-Hand, and Experience on Endoscopic Surgery Skills in an Educational Computer-Based Simulation Environment (ECE) for Endoneurosurgery Training.

Surg Innov 2019 Dec 2;26(6):725-737. Epub 2019 Aug 2.

Hacettepe University, Ankara, Turkey.

Today, virtual simulation environments create alternative hands-on practice opportunities for surgical training. In order to increase the potential benefits of such environments, it is critical to understand the factors that influence them. This study was conducted to determine the effects of training, used-hand, and experience, as well as the interactions between these variables, on endoscopic surgery skills in an educational computer-based surgical simulation environment. A 2-hour computer-based endoneurosurgery simulation training module was developed for this study. Thirty-one novice- and intermediate-level resident surgeons from the departments of neurosurgery and ear, nose, and throat participated in this experimental study. The results suggest that a 2-hour training during a 2-month period through computer-based simulation environment improves the surgical skills of the residents in both-hand tasks, which is necessary for endoscopic surgical procedures but not in dominant hand tasks. Based on the results of this study, it can be concluded that computer-based simulation environments potentially improve surgical skills; however, the scenarios for such training modules need to consider especially the bimanual coordination of hands and should be regularly adapted to the individual skill levels and progresses.
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http://dx.doi.org/10.1177/1553350619861563DOI Listing
December 2019

Can Convexity Subarachnoid Hemorrhage be Caused by Rupture of a Saccular Aneurysm?

J Vasc Interv Neurol 2018 Nov;10(2):1-3

Department of Neurology and Neurological Intensive Care Unit, Hacettepe University Hospitals, Sihhiye, Ankara, Turkey.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350862PMC
November 2018

A case of idiopathic granulomatous hypophysitis.

Hormones (Athens) 2017 Jul;16(3):331-332

Ege University, Faculty of Medicine, Endocrinology Department, Izmir, Turkey.

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http://dx.doi.org/10.14310/horm.2002.1752DOI Listing
July 2017

Construct and face validity of the educational computer-based environment (ECE) assessment scenarios for basic endoneurosurgery skills.

Surg Endosc 2017 11 7;31(11):4485-4495. Epub 2017 Apr 7.

Department of Neurosurgery, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Background: In neurosurgery education, there is a paradigm shift from time-based training to criterion-based model for which competency and assessment becomes very critical. Even virtual reality simulators provide alternatives to improve education and assessment in neurosurgery programs and allow for several objective assessment measures, there are not many tools for assessing the overall performance of trainees. This study aims to develop and validate a tool for assessing the overall performance of participants in a simulation-based endoneurosurgery training environment.

Methods: A training program was developed in two levels: endoscopy practice and beginning surgical practice based on four scenarios. Then, three experiments were conducted with three corresponding groups of participants (Experiment 1, 45 (32 beginners, 13 experienced), Experiment 2, 53 (40 beginners, 13 experienced), and Experiment 3, 26 (14 novices, 12 intermediate) participants). The results analyzed to understand the common factors among the performance measurements of these experiments. Then, a factor capable of assessing the overall skill levels of surgical residents was extracted. Afterwards, the proposed measure was tested to estimate the experience levels of the participants. Finally, the level of realism of these educational scenarios was assessed.

Results: The factor formed by time, distance, and accuracy on simulated tasks provided an overall performance indicator. The prediction correctness was very high for the beginners than the one for experienced surgeons in Experiments 1 and 2. When non-dominant hand is used in a surgical procedure-based scenario, skill levels of surgeons can be better predicted. The results indicate that the scenarios in Experiments 1 and 2 can be used as an assessment tool for the beginners, and scenario-2 in Experiment 3 can be used as an assessment tool for intermediate and novice levels. It can be concluded that forming the balance between perceived action capacities and skills is critical for better designing and developing skill assessment surgical simulation tools.
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http://dx.doi.org/10.1007/s00464-017-5502-4DOI Listing
November 2017

Descriptive Analysis of Sphenovomerine Suture and Its Importance in Neurosurgery.

J Craniofac Surg 2016 Oct;27(7):1858-1861

*Department of Anatomy †Department of Radiology, Hacettepe University Faculty of Medicine ‡Department of Anatomy, TOBB University of Economics and Technology Faculty of Medicine §Department of Neurosurgery, Hacettepe University, Faculty of Medicine, Ankara, Turkey.

Purpose: Articulation of rostrum of sphenoid bone with alae of vomer forms a schindylesis type of joint. The circumference of this joint, called sphenovomerine suture (SVS), is very important in establishing a reliable surgical field in the endoscopic transsphenoidal pituitary surgery. Because of its vital role in endoscopic transsphenoidal pituitary surgery, this radio-anatomical study was designed to establish the morphological properties of SVS.

Methods: In this study, the authors examined SVS in 235 patients (121 females and 114 males) on the computed tomography images of the paranasal sinus and made 4 measurements to describe SVS.

Results: The mean distance between superior margin of the upper labial philtrum and top of SVS was 6.66 ± 0.43 cm for females and 7.44 ± 0.54 cm for males. The distance between the top of SVS and dorsum sellae was 3.08 ± 0.33 cm for females and 3.19 ± 0.32 cm for males, the alae of vomer angle in the upper surface was 74.22 ± 20.06° for females and 74.23 ± 19.68° for males. The distance between the most lateral points of 2 alae of vomer was 0.99 ± 0.17 and 1.01 ± 0.19 cm for females and males, respectively.

Conclusions: For an easy and successful operation, removal of the SVS is very important as it will provide a better view of the sellar base and make the management of the surgical instruments easier in the wider safe surgical field thus created.
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http://dx.doi.org/10.1097/SCS.0000000000002945DOI Listing
October 2016

Endoscopic Endonasal Transsphenoidal Surgery, A Reliable Method for Treating Primary and Recurrent/Residual Craniopharyngiomas: Nine Years of Experience.

World Neurosurg 2016 Oct 12;94:375-385. Epub 2016 Jul 12.

Department of Neurosurgery, Hacettepe University School of Medicine, Ankara, Turkey.

Objective: Craniopharyngioma resection is one of the most challenging surgical procedures. Herein, we describe our extended endoscopic endonasal transsphenoidal surgery (EETS) technique, and the results of 9 years of use on primary and recurrent/residual craniopharyngiomas.

Methods: This study reviewed 28 EETSs in 25 patients with craniopharyngiomas between January 2006 and September 2015. The patients were divided into 2 groups, newly diagnosed patients (group A, n = 15), and patients having residual or recurrent tumors (group B, n = 10). There was no significant difference between the groups in terms of the largest tumor diameter (P = 0.495), and all patients underwent EETS. The clinical and ophthalmologic examinations, imaging studies, endocrinologic studies, and operative findings for these cases were reviewed retrospectively.

Results: The number of gross total resections in group A was 13/15, and 7/10 in group B. Three of the patients developed postoperative cerebrospinal fluid leakage (all in group A). There were no neurovascular or ophthalmologic complications, and no meningitis or mortality was observed.

Conclusions: There has been a notable increase in the use of EETS in the treatment of craniopharyngiomas during the last decade. Despite its increased use in the treatment of primary craniopharyngiomas, its implementation for recurrent or residual craniopharyngiomas has been viewed with suspicion. In this study, the results have been presented separately for primary and recurrent/residual craniopharyngiomas, so that the results can be compared. Overall, EETS is a reliable and successful surgical treatment method for primary and recurrent/residual craniopharyngiomas.
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http://dx.doi.org/10.1016/j.wneu.2016.07.004DOI Listing
October 2016

Reasons and results of endoscopic surgery for prolactinomas: 142 surgical cases.

Acta Neurochir (Wien) 2016 May 12;158(5):933-42. Epub 2016 Mar 12.

Faculty of Medicine, Department of Neurosurgery, Hacettepe University, Ankara, Turkey.

Background: We report herein a retrospective analysis of the results of 142 consecutive prolactinoma cases operated upon using an endoscopic endonasal trans-sphenoidal approach over a period of 6 years.

Methods: Medical records of 142 cases were analysed with respect to indications for surgery, duration of hospital stay, early remission rates, failures and recurrence rates during a median follow-up of 36 months.

Results: On the basis of magnetic resonance imaging (MRI) data, 19 patients (13.4 %) had microadenoma, 113 (79.6 %) had macroadenoma, and the remaining 10 (7.0 %) had giant adenomas. Cavernous sinus invasion was identified in 25 patients by MRI and confirmed during surgery. Atypical adenoma was diagnosed in 16 patients. Sparsely granulated prolactin adenoma was identified in 99 patients (69.7 %). Our results demonstrate that male sex and higher preoperative prolactin levels are independent factors predicting persistent disease. The post-surgical complications are as follows: 2.8 % patients had meningitis, 2.1 % patients had postoperative cerebrospinal fluid leak and 2.1 % patients had panhypopituitarism. At the end of follow-up, 74.6 % patients went into remission. During follow-up period, five patients who had initial remission developed recurrence.

Conclusions: Our series together with literature data suggest that an endoscopic endonasal trans-sphenoidal approach in the treatment of proloctinomas has a favourable rate of remission. According to the findings of this study, endoscopic endonasal trans-sphenoidal surgery might be an appropriate therapy choice for patients with prolactinoma who could not have been managed with recommended therapeutic modalities.
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http://dx.doi.org/10.1007/s00701-016-2762-zDOI Listing
May 2016

Splitting of the Optic Nerve by a Pituitary Macroadenoma.

World Neurosurg 2016 May 22;89:726.e11-4. Epub 2016 Jan 22.

Department of Neurosurgery, Hacettepe University Faculty of Medicine, Ankara, Turkey.

Background: Splitting of the optic nerve by a pituitary adenoma is an extremely unusual condition with only 3 cases reported to date.

Case Description: A 41-year-old woman presented with visual loss as a result of an aggressive pituitary macroadenoma causing the splitting of the right optic nerve. Possible mechanisms of this condition are discussed, and the literature is reviewed.

Conclusions: In aneurysm and tumor cases, awareness of the exact anatomy is particularly important to preserve function. An overlooked duplication or penetration of cranial nerves may result in inadvertent injury to important structures and loss of function.
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http://dx.doi.org/10.1016/j.wneu.2016.01.035DOI Listing
May 2016

Thyrotropinoma and multinodular goiter: A diagnostic challenge for hyperthyroidism.

J Res Med Sci 2013 Nov;18(11):1008-10

Department of Internal Medicine, Section of Endocrinology and Metabolism, Medical School, Hacettepe University, Ankara, Turkey.

Thyroid disorders are frequently encountered. The diagnosis is straightforward unless clinical or laboratory findings are inconclusive and/or perplexing. Hyperthyroidism due to a thyrotropin-secreting pituitary adenoma rarely occurs and symptoms due to thyroid hormone excess are subtle. The presentation of the disease becomes unusual when co-secretion of other hormones with thyrotropin or concomitant thyroid parenchymal pathology exist. We present the case of a 63-year-old female patient with thyrotropinoma co-secreting growth hormone and multinodular goiter. She developed hyperthyroidism first due to thyrotropinoma and later due to a toxic nodule. Herein, we discuss the diagnostic and therapeutic challenges of hyperthyroidism with atypical presentation.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3906776PMC
November 2013

Early promising results for the endoscopic surgical treatment of Cushing's disease.

Neurosurg Rev 2013 Nov 15. Epub 2013 Nov 15.

Department of Neurosurgery, Faculty of Medicine, Hacettepe University, 06100, Sihhiye, Ankara, Turkey,

High levels of endogenous cortisol due to Cushing's disease cause significant mortality and morbidity. Treatment of Cushing's disease is challenging. For many years, transsphenoidal microsurgical resection of the adenoma has been the treatment of choice. However, recently, neuroendoscope has taken its place in the neurosurgeon's armamentarium, and the endoscopic transsphenoidal resection of pituitary tumors has become a familiar approach. Our aim was to present the results of pure endoscopic surgery in the treatment of corticotropinomas for comparison with the results of previous endoscopic and microsurgical series. We present a retrospective analysis of 90 patients with diagnosis of Cushing's disease who were operated between 2006 and 2012. Among 90 patients, a total of 81 (90.0 %) had a remission (28 out of 29 macroadenomas (96.6 %) and 53 out of 61 microadenoma patients (86.9 %)). Of note is that 66 out of 69 (95.7 %) primary patients (i.e., those who were operated in our center) and 15 out of 21 (71.4 %) patients previously operated in other centers reached a hypo/eucortisolemic state. A remission rate comparable with previous endoscopic series was achieved. In nine patients, it was not possible to achieve remission at all. On the other hand, only four of our cases (5.6 %) had a recurrence, and with reoperation, all of these patients entered a re-remission. To our knowledge, our series is the largest series studying endoscopically operated adrenocorticotropic hormone-secreting adenomas. Our results suggest that the endoscopic approach has opened a new avenue in the treatment of Cushing's disease, previously a therapeutic challenge for both the clinician and the neurosurgeon. Endoscopic approach in the treatment of Cushing's disease is clearly better for patients because of its low morbidity rates and short duration of hospital stay. On the other hand, long-term follow-up of our patients will show whether these favorable observations will persist.
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http://dx.doi.org/10.1007/s10143-013-0506-6DOI Listing
November 2013

Treatment of acromegaly by endoscopic transsphenoidal surgery: surgical experience in 214 cases and cure rates according to current consensus criteria.

J Neurosurg 2013 Dec 27;119(6):1467-77. Epub 2013 Sep 27.

Department of Neurosurgery, Muğla Sıtkı Koçman University Faculty of Medicine, Muğla;

Object: Acromegaly is a disease that has significant morbidity and mortality related to high levels of growth hormone (GH) and insulin-like growth factor-I (IGF-I), and is usually caused by pituitary adenomas. The goal in this study was to investigate the role of endoscopic transsphenoidal surgery and surgical experience in the treatment of GH adenoma cases in relation to surgical results and hormonal cure rates, and to perform a review of the literature.

Methods: The authors present a retrospective analysis of 214 GH adenoma cases. Restoration of IGF-I levels to normal for age and sex, suppression of GH levels below 0.4 μg/L on the oral glucose tolerance test, and demonstration of the total removal of the tumor on MRI studies obtained after administration of contrast material at the 3-month postoperative follow-up visit were the criteria for cure.

Results: In total 214 patients with a mean age of 41.9 ± 12 years (range 17-75 years) and a male/female ratio of 106/108 were enrolled in the study. Cure was achieved in 134 (62.6%) of 214 patients. One hundred sixty-nine patients were primary cases, and of these 109 (64.5%) were cured, whereas 61 patients were previously operated cases and of these 25 (41%) were cured. With a 51.1% decrease in the 1st month postoperatively, IGF-I levels were found to be predictive of cure (74.4% sensitivity and 73.7% specificity). Cut-off values for GH levels in predicting cure for the 1st day, 1st week, and 1st month postoperatively were 2.33, 2.05, and 2.25 μg/L, respectively. The cut-off value for surgical experience was 57 for primary surgeries (58.5% cure rate before this cut-off value compared with 72.6% after it; p = 0.025) and 108 for all operations (45.8% vs. 79.4%, p = 0.037). Although 28 patients were found to be in remission according to the criteria in 2000, they were not in remission according to the new consensus criteria. Nine of these cases (32.1%) had random GH levels < 1 μg/L at the 1-year follow-up. The 1-year IGF-I and GH levels in these 28 patients showed no significant difference when compared with the cases defined as cured according to the current criteria.

Conclusions: In acromegaly treatment, transsphenoidal endoscopic surgery performed by an expert senior surgeon and increased surgical experience are important for higher cure rates. Random GH levels < 2.33 μg/L after the 1st day postoperatively and a > 50% decrease in IGF-I levels after the 1st month postoperatively are predictive of cure. Moreover, there is no urgency for additional therapy in patients with GH levels of 0.4-1 μg/L and MRI sequences showing no tumor at the 3-month follow-up, because for these cases remission can be achieved at the 1-year follow-up.
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http://dx.doi.org/10.3171/2013.8.JNS13224DOI Listing
December 2013

Management of cerebrospinal fluid leak during endoscopic pituitary surgery.

Auris Nasus Larynx 2013 Aug 21;40(4):373-8. Epub 2012 Dec 21.

Department of Neurosurgery, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Objective: Dural opening and closures are major steps in endoscopic pituitary surgery. Restoring the normal anatomy at the end of the procedure creates a natural barrier between the intrasellar compartment and the sinonasal cavity.

Methods: In this study, we present a relatively simple dural opening and closure technique for endoscopic pituitary surgery. This technique provides a better alternative to the use of a more complex nasoseptal flap or the multilevel closure with artificial materials as it restores the normal anatomy after the tumor removal and provides a better physiological barrier between the sinonasal cavity and the intrasellar compartment. Incision is performed in circular or horseshoe fashion leaving a small peduncle, and then the dura is reflected.

Results: Of the 733 endoscopic transsphenoidal procedures in 667 patients conducted between January 2006 and May 2012, we used this described technique in 50 cases (7.4%). In these 50 cases with dural flap, there was no postoperative CSF leakage. Intraoperative CSF leakage was observed in 135 (20.2%) of the 667 patients. In 15 (11.1%) of these 135 patients we used the dural flap technique accompanied with fat and/or fascia lata support. There was no postoperative leakage in these patients. In the remaining 120 (89.9%) patients who had intraoperative CSF leakage, we used fat and/or fascia lata for the reconstruction of the sella floor. But we observed postoperative CSF leakage in 12 (10%) of the 120 patients without the dural flap which were reoperated.

Conclusion: The dural flap technique we employ has several advantages. First of all, it allows optimal physiological reconstruction after the surgery. Secondly, the bridge between the flap and the main dura helps maintain the vascular supply, which in turn can radically shorten the healing time. Thirdly, this technique is obviously a better alternative to the time consuming and expensive multilevel closures with tissue sealants and artificial grafts.
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http://dx.doi.org/10.1016/j.anl.2012.11.006DOI Listing
August 2013

Complications of endoscopic surgery of the pituitary adenomas: analysis of 570 patients and review of the literature.

Pituitary 2012 Sep;15(3):288-300

Department of Neurosurgery, Faculty of Medicine, Hacettepe University, Sıhhiye, 06100, Ankara, Turkey.

Endoscopic transsphenoidal surgery is emerging as a minimally invasive and maximally effective procedure for pituitary adenomas. In this report we analyzed the complications in 624 procedures of endonasal transsphenoidal endoscopic surgery in the treatment of 570 patients with pituitary adenomas. The leading author (MB) operated pituitary adenomas via pure endoscopic endonasal transsphenoidal surgery between January 2006 and August 2011 at the Hacettepe University, Department of Neurosurgery in Ankara. Complications were assessed in 624 surgical procedures under five groups; rhinological, CSF leaks, infection, vascular and endocrinologic complications. We observed a total of 76 complications (12.1%). Rhinological complications occurred in 8 patients (1.3%): 4 epistaxis (0.6%) and 4 hyposmia (0.6%). Postoperative CSF leaks occurred in 8 patients (1.3%), and infectious complications occurred in 8 patients: 3 cases of sphenoidal sinusitis (0.4%), 5 cases of meningitis (0.8%). Only 1 case of internal carotid aneurysm rupture during the opening of sellar floor (0.16%) was observed. Endocrinologic complications occurred in 51 (8.1%) patients: Anterior pituitary deficiency in 12 (1.9%), transient diabetes insipidus (DI) in 29 (4.6%), permanent DI in 3 (0.4%) and inappropriate antidiuretic hormone secretion syndrome occurred in 7 (1.1%). There was no mortality directly related to the surgical procedure. The complication rates observed in our study suggests that the endoscopic pituitary surgery is at least as safe as microscopic transphenoidal surgery. These rates were obtained with due experience and well-coordinated teamwork. To further improve these rates, new technological developments will be helpful.
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http://dx.doi.org/10.1007/s11102-011-0368-2DOI Listing
September 2012

A case of intracranial hypotension complicated with hydrocephalus.

Turk Neurosurg 2010 Oct;20(4):550-6

Hacettepe University, Department of Neurosurgery, Ankara, Turkey.

Aim: Intracranial hypotension may have variable clinical presentation. The imaging characteristics of intracranial hypotension are especially well depicted on magnetic resonance imaging studies. Although the clinical and radiological manifestations of spontaneous intracranial hypotension are increasingly recognized in many reports, many other abnormalities in this disorder and complicating cases still exist.

Material And Methods: A 16-year-old patient suffering from nausea vomiting and blurred consciousness was admitted to the hospital. MRI showed diffuse pachymeningeal thickening resembling intracranial hypotension and ventricular enlargement like compensated hydrocephalus. The patient was investigated and treated using endoscopic third ventriculostomy.

Conclusion: The authors presented a case of intracranial hypotension complicated with hydrocephalus. Specific causes for intracranial hypotension as well as additional new treatment options will also be discussed.
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http://dx.doi.org/10.5137/1019-5149.JTN.2005-09.1DOI Listing
October 2010

Effects of pravastatin on cellular ultrastructure and hemorheology in rats after traumatic head injury.

Clin Hemorheol Microcirc 2010 ;46(1):1-11

Department of Neurosurgery, Cankiri State Hospital, Cankiri, Turkey.

Pravastatin has neuroprotective effects against aging but its role in brain injury remains unclear. This study evaluated the effects of pravastatin on the ultrastructural changes and hemorheological parameters in rats after traumatic brain injury (TBI) of right parietal cortical contusion by a controlled weight-dropping method. There were three groups: (I) Sham operated group; (II) TBI + vehicle (saline) group; and (III) TBI + pravastatin group. Right parietal craniectomy was performed in all groups. In TBI + pravastatin group, pravastatin was administered orally at a dose of 1 mg/kg every day for 7 days starting at 24 hours after the injury. Plasma viscosity, erythrocyte deformability and erythrocyte aggregation were measured from blood samples of all rats on 2nd, 7th and 15th days. At the same time electron microscopic study was done on designated days for groups II and III. Treatment with pravastatin markedly increased aggregation amplitude and γIsc max values and significantly decreased erythrocyte deformability but did not change plasma viscosity in 2 weeks time. Ultrastructural parameters such as perinuclear edema, mitochondrial swelling and intraneuronal vacuoles were detected in lower degree in the statin group when compared to the saline group, especially decreased demyelinization and endothelial detachment was prominent. As a result, the hyperviscosity state with increased erythrocyte aggregation and decreased erythrocyte deformability induced by pravastatin in this study was accompanied by an improvement of the ultrastructural findings in TBI. This hyperviscosity state may be a compensatory mechanism to increase the oxygenation of the injured tissue by inducing the release of antiaggregant and vasodilatory substances by increasing shear stress. Therefore, we suggest that prolonged pravastatin usage may exert affirmative effects on traumatic brain injury conditions by increasing blood viscosity.
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http://dx.doi.org/10.3233/CH-2010-1328DOI Listing
January 2011

Somatotroph adenoma cells may populate paranasal sinus mucosa.

Acta Neurochir (Wien) 2010 Sep 6;152(9):1629-30; discussion 1630. Epub 2010 May 6.

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http://dx.doi.org/10.1007/s00701-010-0677-7DOI Listing
September 2010

Microscopic and electrophysiological changes on regenerating sciatic nerves of rats treated with simvastatin.

Folia Neuropathol 2010 ;48(1):49-56

Department of Neurosurgery, Ankara Numune Education and Research Hospital, Kuzgun Sok. 15/14, Ayranci, 06540, Ankara, Turkey.

Unlabelled: Simvastatin is a hypocholesterolemic agent presumed to cause peripheral neuropathy. We arranged an experimental design which focuses on the effect of simvastatin on peripheral nerves and neural regeneration. Sciatic nerve injury was performed at midthigh region of male wistar rats either by clamp compression or fine cut. Electrophysiological and electron microscopical studies were carried out to assess the effect of simvastatin on peripheral nerve and nerve regeneration. There was no difference between the groups that were given simvastatin and standard regimen in the sciatic nerve when electrophysiological measurements were concerned. However, some of the rats that were given simvastatin show reduction in axoplasm density (intensity) of myelinated nerve fibers and prominent vacuolization of myelin sheath according to light and electron microscopic studies. Sciatic nerve compound muscle activation potential measurements of the animals given simvastatin showed that this drug doesn't have a delaying effect on the peripheral nerve recovery time. Electrophysiological measurements showed that simvastatin did not influence nerve regeneration however it was found to induce severe vacuolization of myelin sheath of the sciatic nerve. It was apparent that the drug induces some form of structural dysfunction as myelin changes supported by electron microscopical studies.

Conclusion: simvastatin was shown to delay regeneration as shown in microscopic studies but still there was no influence on nerve regeneration.
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July 2010

Parenchymal lymphoma of the brain on initial MR imaging: a comparative study between primary and secondary brain lymphoma.

Eur J Radiol 2011 Aug 3;79(2):288-94. Epub 2010 Mar 3.

Hacettepe University, Faculty of Medicine, Department of Radiology, 06100 Sihhiye-Ankara, Turkey.

Background And Purpose: Parenchymal lymphomatous brain masses have not been investigated considering if they are primary or as a part of systemic lymphoma (secondary) on imaging studies previously. We aimed to determine characteristics of the secondary parenchymal lymphomatous involvement of the brain and to find if there is any radiologic feature to help discrimination of untreated primary and secondary central nervous system lymphoma on patients' initial magnetic resonance imaging.

Materials And Methods: We evaluated MR images of 18 patients with the diagnosis of primary (n=12) and secondary central nervous system lymphoma (n=6). We considered the number, localization, enhancement pattern, signal characteristics, diffusion properties, presence of hemorrhage and presence of butterfly pattern on MR imaging at initial presentation.

Results: Secondary central nervous system lymphomas predominantly presented as multiple (n=4, 66.7%) lesions. Homogenous nodular enhancement and supratentorial white matter involvement were present in all patients with butterfly pattern and infiltrative/perivenular enhancement in half (n=3) of the patients. Deep gray matter (n=1, 16.7%) and infratentorial involvement (n=1, 16.7%) were scarce and no ring enhancement was observed. There was no statistically significant difference in any of the investigated MR features between the two groups.

Conclusion: Statistical analyses revealed no significant distinctive radiologic characteristics between primary and secondary lymphoma of the brain parenchyma.
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http://dx.doi.org/10.1016/j.ejrad.2010.01.017DOI Listing
August 2011

Overview of vascular complications of pituitary surgery with special emphasis on unexpected abnormality.

Pituitary 2010 Jun;13(2):160-7

Department of Neurosurgery, Hacettepe School of Medicine, Ankara, Turkey.

Arterial bleeding during transsphenoidal surgery for pituitary adenoma is known complication. This usually happens due to rupture of intracavernous carotid or delayed hemorrhage due to the carotico-cavernous fistula and/or pseudoaneurysm. There is also evidence that cavernous carotid aneurysms may occur with pituitary tumors, yet largest series failed to demonstrate any link between aneurysm formation and pituitary tumors. Usually such an aneurysm rupture results in formation of carotico-cavernous fistula. However, pituitary apoplexy and even epistaxis have been reported. In this paper we present a patient with recurrent pituitary adenoma and cavernous carotid artery aneurysm, which caused significant hemorrhage during the surgery. Although retrospective analysis of MRI disclosed that the patient had the aneurysm before the first surgery, it remained silent until the second operation. Therefore neurosurgeons should be very susceptive to any signal changes on preoperative MR images, especially in recurrent cases, where normal anatomical relations are disturbed by fibrotic tissue. Also, we reviewed the vascular complication of pituitary surgery based on the literature.
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http://dx.doi.org/10.1007/s11102-009-0198-7DOI Listing
June 2010

A case of acromegaly in pregnancy: concomitant transsphenoidal adenomectomy and cesarean section.

J Matern Fetal Neonatal Med 2006 Jan;19(1):69-71

Department of Obstetrics and Gynecology, Hacettepe University Faculty of Medicine, Ankara, Turkey.

The case of a 32-year-old woman at 29 weeks gestational age with acromegaly initially diagnosed in pregnancy is presented. During follow-up at 34 weeks of gestation, concomitant emergency cesarean section and transsphenoidal surgery were performed because of advancing vision loss. In tertiary centers, success in pregnancy can be made possible for a patient with acromegaly under the constant supervision of an obstetrician and neurosurgeon.
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http://dx.doi.org/10.1080/14767050500434021DOI Listing
January 2006

A giant intramedullary spinal epidermoid cyst of the cervicothoracic region.

Pediatr Neurosurg 2004 May-Jun;40(3):120-3

Department of Neurosurgery, Hacettepe University Medical School, Ankara, Turkey.

Intramedullary epidermoid cysts of the spinal cord are rare lesions. The authors report a case of giant intramedullary epidermoid cyst at the cervicothoracic region. A 6-year-old boy presented with motor and sensory loss related to a spinal intramedullary epidermoid cyst. Almost all cyst content was liquid and it was surgically removed totally in two successive operations. To the author's knowledge, this is the largest intramedullary epidermoid cyst published in the literature and no other case of intramedullary epidermoid cyst with a complete liquid content has been reported before. The authors discuss the clinical features, MR imaging characteristics and surgical findings of this rare tumor and review the associated literature.
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http://dx.doi.org/10.1159/000079853DOI Listing
December 2004

Hemorheology, melatonin and pinealectomy. What's the relationship? An experimental study.

Clin Hemorheol Microcirc 2004 ;30(1):47-52

Department of Neurosurgery, Hacettepe University School of Medicine, Ankara, Turkey.

The circadian rhythm of stroke and myocardial infarction (MI) may be related to the circadian rhythm of melatonin, and erythrocyte deformability may be the key mechanism in this relationship. Therefore, this study has been performed to determine if there is a relationship between the pineal gland and melatonin and red cell deformability. Twenty-eight rats underwent pinealectomy, pinealectomy plus melatonin administration (200 mg/kg), or no treatment (n=7 in each group). Erythrocyte deformability was determined using the filtration technique. The results are reported in mean (+/-SD) seconds: control: 1.45+/-0.44; pinealectomy (A): 1.55+/-0.16; pinealectomy (B): 1.34+/-0.26 and pinealectomy and melatonin: 2.56+/-0.69. Pinealectomy by itself did not cause any statistically significant change in erythrocyte deformability but the addition of melatonin significantly decreased it. These results suggest a relationship between melatonin and erythrocyte deformability. Further investigations may uncover the causes of the circadian rhythm of stroke and MI, which may help improve chronobiological therapies.
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September 2004

Acute parotitis following sitting position neurosurgical procedures: review of five cases.

J Neurosurg Anesthesiol 2004 Jan;16(1):29-31

Department of Neurosurgery, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Acute bacterial parotitis subsequent to major abdominal surgery is well documented, reportedly occurring in as many as 0.1% of patients. Postoperative parotitis has been reported between 1 to 15 weeks after surgery, commonly appearing within 2 weeks of the procedure. However, postoperative parotitis has not been reported previously after neurosurgical procedures. The authors report five cases of postoperative parotitis after neurosurgical operations in the sitting position with mild flexion and rotation of the head. This group of patients accounted for 0.16% of all craniotomy and 1.9% of all sitting position neurosurgical procedures performed in the authors' institution from 1996 through 2001. Neck flexion and head tilt in the sitting position might have an influence on acute parotitis. The authors found that the side of the parotitis was on the opposite side of the head rotation. Dehydration therapy may also be a contributing factor. The objective of this paper is to state that parotitis is a possible complication in neurosurgical patients operated on in sitting position and to discuss its pathophysiology and treatment options.
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http://dx.doi.org/10.1097/00008506-200401000-00007DOI Listing
January 2004

Neuronal nuclear antigen (NeuN): a new tool in the diagnosis of central neurocytoma.

Pathol Res Pract 2003 ;199(7):463-8

Department of Pathology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

The use of neuronal nuclear antigen (NeuN) as a reliable neuronal marker in the differential diagnosis of clear cell neoplasms of the central nervous system was determined in a biopsy series of 23 cases. Immunohistochemical analyses were carried out by antisera against neuronal nuclear antigen, synaptophysin, neuron-specific enolase, microtubule-associated protein 2, and glial fibrillary acidic protein. All eight central neurocytomas were characteristically immunolabeled by NeuN. NeuN immunoreactivity was uniformly strong and basically located in the nuclei of neurocytes. Despite this uniform staining pattern of central neurocytomas, 12 cases of oligodendrogliomas and three cases of ependymoma were negative for NeuN. As the diagnostic criteria for central neurocytoma include immunohistochemical and/or ultrastructural evidence for neuronal differentiation, NeuN as a sensitive and specific neuronal marker in formalin-fixed, paraffin-embedded tissues may greatly facilitate the differential diagnosis of central neurocytomas.
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http://dx.doi.org/10.1078/0344-0338-00446DOI Listing
April 2004