Publications by authors named "Necmettin Tanriover"

97 Publications

The benefits of inferolateral transtubercular route on intradural surgical exposure using the endoscopic endonasal transclival approach.

Acta Neurochir (Wien) 2021 Apr 13. Epub 2021 Apr 13.

Department of Neurosurgery, Microsurgical Neuroanatomy Laboratory, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey.

Background: Surgical access to the ventral pontomedullary junction (PMJ) can be achieved through various corridors depending on the location and extension of the lesion. The jugular tubercle (JT), a surgically challenging obstacle to access the PMJ, typically needs to be addressed in transcranial exposures. We describe the endoscopic endonasal transclival approach (EETCA) and its inferolateral transtubercular extension to assess the intradural surgical field gained through JT removal. We also complement the dissections with an illustrative case.

Methods: EETCA was surgically simulated, and the anatomical landmarks were assessed in eight cadaveric heads. Microsurgical dissections were additionally performed along the endoscopic surgical path. Lastly, we present an intraoperative video of the trans-JT approach in a patient with lower clival chordoma.

Results: The EETCA allowed adequate extracranial visualization and removal of the JT. The surgical bony window-obtained along the clivus and centered at the JT via the EETCA-measured 11 × 9 × 7 mm. Removal of the JT provided an improved intradural field within the lower third of the cerebellopontine cistern to expose an area bordered by the cranial nerves VII/VIII and flocculus superior and anterior margin of the lateral recess of the fourth ventricle and cranial nerves IX-XI inferiorly, centered on the foramen of Luschka.

Conclusions: Removal of the JT via EETCA improves exposure along the lower third of the cerebellopontine and upper cerebellomedullary cisterns. The inferolateral transtubercular extension of the EETCA provides access to the lateral recess of the fourth ventricle, in combination with the ventral midline pontomedullary region.
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http://dx.doi.org/10.1007/s00701-021-04835-xDOI Listing
April 2021

Assessing the connectional anatomy of superior and lateral surgical approaches for medial temporal lobe epilepsy.

J Clin Neurosci 2020 Nov 22;81:378-389. Epub 2020 Oct 22.

Istanbul University - Cerrahpasa, Cerrahpasa Medical Faculty, Department of Neurosurgery, Microsurgical Neuroanatomy Laboratory, Istanbul, Turkey; Istanbul University - Cerrahpasa, Cerrahpasa Medical Faculty, Department of Neurosurgery, Istanbul, Turkey. Electronic address:

The most common approaches in the treatment of epilepsy, the trans-sylvian selective amygdalohippocampectomy (SAH) and the anterior temporal lobe resection (ATLR) reach the medial temporal lobe through different surgical routes. Our aim was to delineate the white matter (WM) fiber tracts at risk in relation to trans-sylvian SAH and ATLR by defining each fascicle en route to medial temporal lobe during each approach. ATLR and trans-sylvian SAH were performedand related WM tracts en route to medial temporal region were presented in relation to the relevant approaches and surrounding neurovascular structures. The WM tracts most likely to be disrupted during trans-sylvian SAH along the roof of the temporal horn were the UF - and less commonly IFOF - at the layer of the external capsule, anterior commissure, anterior bend of optic radiations, and sublenticular internal capsule. Amygdaloid projections to the claustrum, putamen and globus pallidus, the tail of caudate and the peduncle of the lentiform nucleus were also in close proximity to the resection cavity. Fiber tracts most likely to be impaired during ATLR included the UF, ILF, IFOF, anterior commissure, optic radiations, and, less likely, the vertical ventral segment of the arcuate fascicle. Both ATLR and trans-sylvian SAH carry the risk of injury to WM pathways, which may result in unpredictable functional loss. A detailed 3-D knowledge of the related connectional anatomy will help subside neurocognitive, neuroophtalmologic, neurolinguistic complications of epilepsy surgery, providing an opportunity to tailor the surgery according to patient's unique connectional and functional anatomy.
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http://dx.doi.org/10.1016/j.jocn.2020.10.016DOI Listing
November 2020

Chondrosarcoma in the body of the C2 vertebral axis.

JAAPA 2020 Nov;33(11):29-31

Baris Ozoner practices in the Department of Neurosurgery at the medical faculty of Bahcesehir University in Istanbul, Turkey. Ahmet Kayhan practices in the Department of Neurosurgery at Istanbul University-Cerrahpasa, Cerrahpasa medical faculty in Istanbul, Turkey. Nil Comunoglu practices in the Department of Pathology at Istanbul University-Cerrahpasa. Seckin Aydin practices in the Department of Neurosurgery at the University of Health Sciences, Okmeydani Training and Research Hospital, in Istanbul, Turkey. Galip Zihni Sanus and Necmettin Tanriover practice in the Department of Neurosurgery at Istanbul University-Cerrahpasa. The authors have disclosed no potential conflicts of interest, financial or otherwise.

Chondrosarcoma, a malignant bone tumor, is rarely encountered in the cervical spine. This article describes a patient whose neck pain and dysphagia were caused by an expansive, destructive lesion with calcification that was located in the body of the axis (C2 vertebra), the first time a chondrosarcoma has been reported in this location.
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http://dx.doi.org/10.1097/01.JAA.0000718280.57597.60DOI Listing
November 2020

G-protein Coupled Estrogen Receptor Expression in Growth Hormone Secreting and Non-Functioning Adenomas.

Exp Clin Endocrinol Diabetes 2020 Oct 22. Epub 2020 Oct 22.

Department of Endocrinology and Metabolism, Cerrahpasa Medical School, Istanbul University-Cerrahpasa, Istanbul.

Purpose: To evaluate the expression of G-protein coupled estrogen receptor (GPER1), aromatase, estrogen receptor α (ERα), estrogen receptor β (ERβ), pituitary tumor transforming gene (PTTG), and fibroblast growth factor 2 (FGF2) in GH-secreting and non-functioning adenomas (NFA).

Methods: Thirty patients with acromegaly and 27 patients with NFA were included. Gene expression was determined via quantitative reverse transcription polymerase chain reaction (QRT-PCR). Protein expression was determined via immunohistochemistry.

Results: There was no difference, in terms of gene expression of and between the two groups (p>0.05 for all). gene expression was higher and GPER1 gene expression was lower in GH-secreting adenomas than NFAs (p<0.05 for all). Aromatase and ERβ protein expression was higher in GH-secreting adenomas than NFAs (p=0.01). None of the tumors expressed expression was detected in 62.2% of the GH-secreting adenomas and 45% of NFAs. There was no difference in terms of GPER1, PTTG, FGF2 H scores between the two groups (p>0.05 for all). gene expression was positively correlated to and gene expression (p<0.05 for all). There was a positive correlation between aromatase and GPER1 protein expression (r=0.31; p=0.04).

Conclusions: is expressed at both gene and protein level in a substantial portion of GH-secreting adenomas and NFAs. The finding of a positive correlation between and and gene expression and aromatase and GPER1 protein expression suggests GPER1 along with aromatase and classical ERs might mediate the effects of estrogen through upregulation of PTTG and FGF2.
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http://dx.doi.org/10.1055/a-1274-1330DOI Listing
October 2020

A follow-up study on outcomes of endoscopic transsphenoidal approach for acromegaly.

Clin Neurol Neurosurg 2020 Nov 4;198:106201. Epub 2020 Sep 4.

Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University - Cerrahpasa, Istanbul, Turkey. Electronic address:

Objective: A thorough follow-up study in which the same clinic presents the change in the surgical outcomes of acromegaly over the years, is still lacking in the endoscopic era. In this study, we intended to evaluate the clinical characteristics, radiological features, surgical and late remission rates of newly diagnosed acromegaly patients treated in our clinic between 2014 and 2019 in order to delineate the surgical remission status according to radiological, microscopic, and hormonal features. As a follow-up to our initial report, we also aimed to display the change of surgical remission rates over time in a tertiary center.

Methods: A total of newly diagnosed 106 patients with acromegaly, who underwent endoscopic endonasal trans-sphenoidal approach (EETSA) in the last five years were retrospectively analyzed and presented in this study. Medical records were reviewed in clinical, biochemical, pathological, and radiological aspects to assess the relationship of preoperative patient characteristics with surgical remissions.

Results: The percentages of the giant pituitary adenomas (≥4 cm), adenomas with suprasellar extension and adenomas with surgically proven invasion of the cavernous sinus in the present series were 13%, 34%, and 20%, respectively. Gross total resection was achieved in 80% of the patients. Surgical remission and late remission rates were 66% and 86%, respectively. Nine (9.4%) patients in our current report had postoperative transient diabetes insipidus. The mean follow-up period in this series was 36.1 ± 18.1 (range 12-59) months.

Conclusion: The presented surgical results are considerably better than our published initial series of acromegaly patients operated in the same clinic between 2007 and 2014. The improvement in surgical remission rate support a positive surgical volume - remission rate relationship for acromegaly in the era of endoscopic endonasal skull base approaches. One possible factor for better results may be the increasing surgical experience in EETSA, which follows a trend toward gradual improvement of long-term late remissions via a multidisciplinary approach.
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http://dx.doi.org/10.1016/j.clineuro.2020.106201DOI Listing
November 2020

Evaluation of Ideal Extent of Corpus Callosotomy Based on the Location of Intracallosal Motor Fibers.

World Neurosurg 2020 Dec 8;144:e568-e575. Epub 2020 Sep 8.

Department of Neurosurgery, Faculty of Medicine, Istanbul University - Cerrahpasa, Istanbul, Turkey; Microsurgical Neuroanatomy Laboratory, Department of Neurosurgery, Faculty of Medicine, Istanbul University - Cerrahpasa, Istanbul, Turkey.

Background: The corpus callosotomy (CCT) has been reported as an effective procedure to alleviate drop attacks. However, the extent of CCT remains debatable. Classical studies suggest that motor fibers traverse mainly through the anterior half of the corpus callosum (CC), although recent diffusion tensor imaging studies described that motor fibers crossed the CC in a more posterior location, emphasizing the posterior midbody and the isthmus.

Methods: Cortical and subcortical structures were examined in 30 hemispheres prepared for white matter fiber dissection. Dissections were carried out under surgical magnification to trace fibers originating from the primary motor cortex and their course through the CC. The distance of the most anterior and posterior motor fibers to the tip of the genu were measured, and the extent of CCT enabling disconnection of all motor fibers was calculated.

Results: Motor fibers coursed through the posterior half of the CC in the majority of hemispheres, mainly locating in posterior midbody and the isthmus. Callosal fibers should be interrupted to an average of 61% ± 0.07% point of the CC to reach the anterior limit of motor fibers and to an average of 69% ± 0.07% point to include posterior limit of motor fibers. Motor fibers were extending until the posterior one third of the CC in 22 specimens.

Conclusions: Anterior-half CCT did not include all motor fibers in any specimen. Anterior two thirds CCT disrupted all motor fibers in one fourth of the cases. Our findings suggest that an ideal CCT should extend to the posterior midbody and isthmus of the CC.
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http://dx.doi.org/10.1016/j.wneu.2020.09.006DOI Listing
December 2020

SNPs of miR-23b, miR-107 and HMGA2 and their Relations with the Response to Medical Treatment in Acromegaly Patients.

Exp Clin Endocrinol Diabetes 2020 Aug 24. Epub 2020 Aug 24.

Department of Medical Biology, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey.

Introduction: Acromegaly is a chronic disease of increased growth hormone (GH) secretion and elevated insulin-like growth factor-I (IGF-I) levels induced by a pituitary adenoma. HMGA2 (high mobility group A2) and AIP (aryl hydrocarbon receptor-interacting protein) expression levels are related to GH-secreting adenomas, and also a response to Somatostatin Analogs (SSAs). We studied SNPs in miR-107 and miR-23b that related with AIP and HMGA2 genes respectively and control their expression, and also SNP in the 3'UTR of HMGA2 gene. Our aim was to investigate genotype distributions of the studied SNPs, as well as the possible relationship between disease and/or response to SSAs treatment in patients with acromegaly.

Material And Methods: Genotypes were determined by qRT-PCR method from DNA materials obtained blood samples of acromegaly patients (141) and healthy individuals (99). The genotype distributions of patients and healthy groups, as well as the relationship between the clinical data of the disease and genotypes were statistically compared.

Results: In acromegaly patients with T-allele, p53 expression (p=0.049) was significantly higher. In patients with CT+TT genotype and T-allele who were responder to SSA-treatment Ki-67 index (respectively p=0.019, p=0.020 respectively) was higher. We did not observe the genotypes for miR-23b and miR-107 polymorphisms in the patients and control group of Turkish population.

Conclusion: The genetic variations of the miRNAs genes related with HMGA2 and AIP genes were not seen in our study. Although there is no relationship between HMGA2-rs1351394 polymorphism and acromegaly disease, T allele was associated with some clinical features related to adenoma in patients with acromegaly.
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http://dx.doi.org/10.1055/a-1185-9121DOI Listing
August 2020

Endoscopic endonasal transclival approach to the ventral brainstem: Radiologic, anatomic feasibility and nuances, surgical limitations and future directions.

J Clin Neurosci 2020 Mar 28;73:264-279. Epub 2020 Jan 28.

Department of Neurosurgery, Cerrahpasa Faculty of Medicine, Istanbul University, Istanbul, Turkey.

The endoscopic endonasal transclival approach (EETA) is less invasive than traditional open approaches; however, there is currently limited data on the pre-operative features that may predict success of the EETA. Surgical landmarks and exposure of the EETA and expanded EETA are assessed. We retrospectively measured multiple anatomic features in 154 adult dry skulls, 22 C1 and C2 dry bone vertebrae, and 500 paranasal sinus computed tomography (CT) scans. We also dissected 13 formalin-fixed, silicone-injected adult cadaveric heads. Relevant qualitative and quantitative data were obtained with CT (n = 10) and cadaveric dissection (n = 13). They are expressed as mean (SD), as appropriate and compared with unpaired t tests. Categorical variables were compared with χ tests. We determined the prevalence of clival and sphenoid sinus anatomic variations and assessed potential exposure of the craniovertebral region, based on the relative position of the nasal bone tip, posterior point of the hard palate, and their relation to the position of C1 and C2. Depending on anatomic features, EETA should allow visualization of the ventral brainstem. The mean (SD) dimensions of the surgical window for EETA were 43.2 (5.1) × 18.3 (1.1) mm, in the craniocaudad and horizontal dimensions, respectively. The craniocaudad dimension enlarged to 60.2 (4.7) mm with expanded EETA. The EETA allowed satisfactory exposure for odontoid and C1 anterior arch resection (expanded EETA) in all specimens, regardless of the orientation of the palate. The combination of preoperative radiographic assessment and intraoperative considerations allows safe and effective application and facilitate selection of the most appropriate approach.
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http://dx.doi.org/10.1016/j.jocn.2020.01.012DOI Listing
March 2020

Vascularization of the Subthalamic Nucleus: Highlighting the Significance of the Premamillary Artery.

World Neurosurg 2020 Mar 19;135:e562-e566. Epub 2019 Dec 19.

Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey. Electronic address:

Background: The need for a better understanding of the subthalamic nucleus (STN)'s vascular anatomy is still evident because revealing its vascular supply may increase insight in the pathogenesis of related disorders, such as STN ischemia. The mechanisms under motor, behavioral, and cognitive changes following deep brain stimulation treatment may also be explained by its pattern of vascularization. The primary goal of this study was to delineate the vascularization of the STN and highlight the predominant perforating arteries supplying its territory.

Methods: Fiber dissections were performed with the modified Klingler technique under 6-40× magnification by preserving all vascular structures.

Results: The thalamic and subthalamic regions were dissected from medial to lateral in silicone-injected cadavers. The STN was revealed as a biconvex-shaped structure surrounded by dense inferolateral bundles of myelinated fibers, the zona incerta, bordering the superolateral portion of the red nucleus. The ventral limit of the STN was the substantia nigra, and the internal capsule traversed from its inferior to anterolateral side. The premamillary artery, a large perforator arising from the posterior communicating artery, constantly supplied the STN and was followed proximally along the anterior third ventricular floor toward its origin. The premamillary artery was found to be one of the posterior perforators of the posterior communicating artery in all hemispheres.

Conclusions: The 3-dimensional microsurgical anatomy of the deep-seated STN region is complex, and the additional knowledge on its vascularization should improve our understanding of its surgical anatomy.
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http://dx.doi.org/10.1016/j.wneu.2019.12.062DOI Listing
March 2020

A Novel Expression Profile of Cell Cycle and DNA Repair Proteins in Nonfunctioning Pituitary Adenomas.

Endocr Pathol 2020 Mar;31(1):2-13

Department of Medical Biology, Cerrahpasa Medical School, Istanbul University-Cerrahpasa, Istanbul, Turkey.

The molecular mechanisms underlying the formation of nonfunctioning pituitary adenomas (NFAs) are largely unknown. In this study, we aimed to understand the relationship between NFAs and functional pituitary adenomas and the possible role of proteins involved in cell cycle, senescence, and DNA damage control mechanisms in the etiology of NFA. We analyzed pATM-S1981, pRb-S608, Rb, pE2F1-S364, p16, E2F1, p73, cyclin D1, and CHEK2 protein expression (in a group of 20 patients with acromegaly, 18 patients with Cushing's disease (CD), and 29 NFA patients) by immunohistochemistry and their relevant mRNA expression by qRT-PCR (in a group of 7 patients with acromegaly, 7 patients with CD, and 7 NFA patients). The clinical and histopathological results on the patients were statistically evaluated. pE2F1-S364 protein expression in the CD group was significantly lower than that in the NFA and acromegaly groups (p = 0.025, p = 0.034, respectively). However, the expression of the p16 protein was lower than in the NFA group than in the CD and acromegaly groups (p = 0.030, p = 0.033, respectively), and E2F1 protein expression was significantly higher in the NFA group than in the CD group (p = 0.025). p73 protein expression in patients with acromegaly was significantly higher (p = 0.031) than that in the CD group. CHEK2 mRNA expression in the CD group was significantly higher than that in the acromegaly group (p = 0.012). The selective and tumor-specific associations between E2F1, pE2F1-S364, CHEK2, and p73 mRNA and protein levels indicate their involvement in pituitary adenoma formation in NFA, CD, and acromegaly patients.
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http://dx.doi.org/10.1007/s12022-019-09598-xDOI Listing
March 2020

Microneuroanatomy of the Anterior Frontal Laser Trajectory to the Insula.

World Neurosurg 2019 Dec 24;132:e909-e921. Epub 2019 Jul 24.

Department of Neurosurgery, Rutgers-RWJ Medical School, New Brunswick, New Jersey, USA.

Background: Magnetic resonance imaging-guided laser interstitial thermal therapy (LITT) is an emerging minimally invasive procedure for the treatment of deep intracranial lesions. Insular lesions are challenging to treat because of the risk of damaging important surrounding structures. The precise knowledge of the neural structures that are at risk along the trajectory and during the ablation is essential to reduce associated complications. This study aims to describe the relevant anatomy of the anterior frontal LITT trajectory to the insular region by using sectional anatomy and fiber dissection technique.

Methods: Three silicone-injected cadaveric heads were used to implant laser catheters bilaterally to the insular region by using a frameless stereotactic technique from a frontal approach. Sections were cut in both the oblique axial plane parallel to the trajectory and in the coronal plane. White matter fiber dissections were used to establish the tracts related to the laser trajectory from lateral to medial and medial to lateral.

Results: Supraorbital regions were selected as entry points. After crossing the frontal bone, the track intersected the inferior frontal lobe. The catheter was illustrated reaching the insular region medial to the inferior fronto-occipital fasciculus and insular cortex, and superior to the uncinate fasciculus. The uncinate fasciculus, extreme capsule, claustrum, external capsule, and putamen were traversed, preserving the major vascular structures.

Conclusions: Independent of the insular area treated, an understanding of the neuroanatomy related to the anterior frontal laser trajectory is essential to improve the ability to perform LITT of this challenging region.
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http://dx.doi.org/10.1016/j.wneu.2019.07.130DOI Listing
December 2019

Clinicopathologic Characteristics and Surgical Treatment of Plurihormonal Pituitary Adenomas.

World Neurosurg 2019 Oct 8;130:e765-e774. Epub 2019 Jul 8.

Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey. Electronic address:

Objective: Plurihormonal pituitary adenomas (PPAs) have recently been divided into 2 subtypes: pituitary specific transcription factor 1-positive plurihormonal pituitary adenomas (PIT-1+ PPAs) and plurihormonal adenomas with unusual immunohistochemical combinations (PAwUIC). The purpose of this study was to review patients with PPAs, elucidate their clinicopathologic characteristics, and present the surgical results.

Methods: Records were analyzed for 665 patients who underwent endoscopic endonasal transsphenoidal surgery for pituitary adenomas between 2007 and 2018. Data were reviewed for 27 patients who met the definition of PPAs and delineated regarding clinical, radiologic, pathologic features, and surgical outcomes.

Results: Of the 27 patients, 18 had PAwUIC, and 9 patients were diagnosed with PIT-1+ PPAs. Twenty-four patients (88.8%) had macroadenomas, including 6 giant adenomas (≥4 cm) (22.2%). Cavernous sinus invasion was found in 12 patients (44.4%). Pathologic examinations showed high aggressivity in nearly half of the patients. Most patients with PAwUIC (77.8%) had features of nonfunctioning pituitary adenomas, and only 4 had features of hormone-secreting pituitary adenomas. Gross total resection rates were 57.1% for PAwUIC and 77.8% for PIT-1+ PPAs. The remission rate for hormone-secreting pituitary adenomas was 100% in this case series. Mean follow-up was 74.4 ± 33 months (range, 6-121 months) for overall groups.

Conclusions: To our knowledge, this is the first study to describe the clinicopathologic features of newly classified PPAs, which are characterized by aggressive behavior with higher values of percentage of cavernous sinus invasion. Relevant pathologic diagnosis of PPAs is crucial for appropriate management and follow-up.
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http://dx.doi.org/10.1016/j.wneu.2019.06.217DOI Listing
October 2019

Surgical Approaches to the Thalamus in Relation to the White Matter Tracts of the Cerebrum.

World Neurosurg 2019 Aug 17;128:e1048-e1086. Epub 2019 May 17.

Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey. Electronic address:

Background: Approaching the thalamus from any angle remains a challenge because of its deep-seated location and intimate relations with adjacent important neurovascular structures and functions such as relaying sensory and motor signals and cognition. Our aim was to explore the relationship of the white matter tracts of the cerebrum to the thalamus using a fiber dissection technique, to delineate anatomic principles of approaches to the thalamus, and to discuss the tracts at risk in relation to each approach.

Methods: The thalamus was subdivided into 6 different regions and 13 approaches were examined in an attempt to describe a surgical road map.

Results: To reach the anteroinferior, medial, and lateral parts of the thalamus, the anterior and middle group approaches were used, and to reach the posterosuperior and posteroinferior thalamus, posterior and middle group approaches were used. The anteroinferior zone was the most difficult site to be accessed and the posterosuperior thalamus had the maximum number of alternative approaches. The distal transsylvian approach to the posterosuperior thalamus and the supracarotid infrafrontal approach to the anteroinferior thalamus had the highest number of neural structures severed within the surgical corridor. The infratentorial approaches and the suboccipital transtentorial approach preserve most of the white matter tracts en route to the posterosuperior and medial posteroinferior parts of the thalamus.

Conclusions: When the surgical approaches for thalamic lesions are defined, white matter tracts along the surgical route should be taken into consideration.
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http://dx.doi.org/10.1016/j.wneu.2019.05.068DOI Listing
August 2019

The effects of pre-operative somatostatin analogue therapy on treatment cost and remission in acromegaly.

Pituitary 2019 Aug;22(4):387-396

Division of Endocrinology, Metabolism and Diabetes, Department of Internal Medicine, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Kocamustafapasa Street No:53, Fatih, 34098, Istanbul, Turkey.

Purpose: To investigate the effects of preoperative somatostatin analogue (SSA) treatment on the annual cost of all acromegaly treatment modalities and on remission rates.

Methods: The medical records of 135 patients with acromegaly who were followed at endocrinology clinic of Cerrahpasa Medical Faculty for at least 2 years after surgery between 2009 and 2016 were reviewed.

Results: The mean follow-up time was 50.9 ± 25.7 months. Early remission was defined according to 3rd month values in patients who didn't achieve remission, and 6th month values in patients who achieved remission at the 3rd month after surgery. The early and late remission rates of the entire study population were 40% and 80.7%, respectively. The early remission of the preoperative SSA-treated group (61.5%) was significantly higher than SSA-untreated group (31.2%) (p = 0.002). The early remission of the preoperative SSA-treated patients with macroadenomas (52.2%) was also significantly higher than the SSA-untreated group (23.5%) (p = 0.02). In the subgroup analysis; this difference was much more pronounced in invasive macroadenomas (p = 0.002). There were no differences between the groups in terms of late remission.The median annual cost of all acromegaly treatment modalities in study population was €3788.4; the cost for macroadenomas was significantly higher than for microadenomas (€4125.0 vs. €3226.5, respectively; p = 0.03). Preoperative SSA use in both microadenomas and macroadenomas didn't alter the cost of treatment. The increase in the duration of preoperative medical treatment had no effect on early or late remissions (p = 0.09; p = 0.8).

Conclusions: Preoperative medical treatment had no effect on the costs of acromegaly treatment. There was a benefical effect of pre-operative SSA use on early remission in patients with macroadenomas; however, this effect didn't persist long term.
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http://dx.doi.org/10.1007/s11102-019-00968-6DOI Listing
August 2019

Transsphenoidal surgery for pituitary adenomas in pediatric patients: a multicentric retrospective study.

Childs Nerv Syst 2019 11 11;35(11):2119-2126. Epub 2019 May 11.

Department of Neurosurgery, Demiroğlu Bilim University, Istanbul, Turkey.

Introduction: Pediatric pituitary adenomas are rare lesions. Incidence is reported between 1 and 10% of all childhood brain tumors and between 3 and 6% of all surgically treated adenomas. Although pituitary adenomas present with symptoms of hormone hypersecretion or neurological disruptions secondary to mass effect, they are almost constantly benign. Characteristics of patients may vary in different studies according to age, gender, size of adenoma, hormonal activity, and recurrence rates.

Methods: Data on consecutive pediatric patients who were operated for pituitary adenoma with endoscopic endonasal transsphenoidal surgery (EETS) and transsphenoidal microsurgery (TMS) in the Department of Neurosurgery, Istanbul University Cerrahpasa Medical Faculty, Istanbul, Turkey, in the Neurosurgical Unit of the San Matteo Hospital, Pavia, Italy, and in the Division of Neurological Surgery Department of Biotechnology and Life Sciences, University of Insubria-Varese, ASST Sette Laghi, Ospedale di Circolo e Fondazione Macchi, Varese, Italy, between July 1997 and May 2018, were analyzed. Twenty-seven patients (11 males and 16 females), who were 18 years old or younger at the time of surgery, were included in the study. Medical records, images, and operative notes of patients were retrospectively reviewed.

Results: There were 16 females (59.3%) and 11 males (40.7%). Mean age was 15.3 ± 3.3 (4-18). Thirty-two surgical procedures were performed for 27 patients (6 children required second operation). Thirteen patients (48.14%) had Cushing's disease (CD), 5 patients (18.5%) had growth hormone (GH)-secreting adenoma, 5 patients (18.5%) had prolactinoma, and 4 patients (14.8%) had non-functional adenoma. Twenty-two patients (81.4%) met remission criteria, and 5 patients (18.5%) did not meet remission criteria. Four patients met remission criteria after the second operation.

Conclusion: Transsphenoidal approach affords effective release of mass effect and not only restoration but also perpetuation of normal endocrine functions in the majority of pediatric pituitary adenoma patients. Satisfactory results are reported with both EETS and TMS in the literature. Despite the technical difficulties in pediatric age, transsphenoidal resection of adenoma is still the mainstay treatment that provides cure in pediatric patients.
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http://dx.doi.org/10.1007/s00381-019-04179-zDOI Listing
November 2019

Predictive Factors for Rathke's Cleft Cyst Consistency.

World Neurosurg 2019 Aug 30;128:e522-e530. Epub 2019 Apr 30.

Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University -Cerrahpasa, Istanbul, Turkey. Electronic address:

Objective: Rathke's cleft cysts (RCCs) may have various anatomic, clinical, and radiologic characteristics, which may be related to their differences in texture or consistency. The purpose of the study was to investigate RCCs based on consistency.

Methods: We retrospectively reviewed 25 cases of patients with RCCs who underwent endoscopic endonasal transsphenoidal surgery between 2008 and 2018. Cases were divided into 3 types based on cyst consistency: fluid (serous) or type A (n = 4); semi-fluid (mucoid) or type B (n = 17); and non-fluid (caseous) or type C (n = 4). Demographic, clinical, radiologic, and surgical characteristics for each group were analyzed.

Results: All type A RCCs (100%) had visual impairment. The mean age (42.8 ± 13 years) and cyst volume (2442.5 ± 533.6 mm) were higher in these patients. T1-weighted images were hypointense and T2-weighted images were hyperintense on magnetic resonance imaging. Type B RCCs were more frequently encountered (68%). Although headache was the most common (82.3%) symptom, endocrine disorders were also prevalent (52.9%). T1-weighted images were typically isointense or hyperintense on magnetic resonance imaging. Type C RCCs had the youngest patient population (30.3 ± 10.2 years) and T2-weighted images were predominantly hypointense in this group.

Conclusions: The proposed novel consistency classification of RCCs will provide a practical tool for more accurately estimating the nature of the pathology, because each type has its own specific characteristics. Furthermore, the new classification of RCCs may aid in planning a consistency-specific surgery.
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http://dx.doi.org/10.1016/j.wneu.2019.04.188DOI Listing
August 2019

Preoperative evaluation of tumour consistency in pituitary macroadenomas: a machine learning-based histogram analysis on conventional T2-weighted MRI.

Neuroradiology 2019 Jul 22;61(7):767-774. Epub 2019 Apr 22.

Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey.

Purpose: To evaluate the potential value of machine learning (ML)-based histogram analysis (or first-order texture analysis) on T2-weighted magnetic resonance imaging (MRI) for predicting consistency of pituitary macroadenomas (PMA) and to compare it with that of signal intensity ratio (SIR) evaluation.

Methods: Fifty-five patients with 13 hard and 42 soft PMAs were included in this retrospective study. Histogram features were extracted from coronal T2-weighted original, filtered and transformed MRI images by manual segmentation. To achieve balanced classes (38 hard vs 42 soft), multiple samples were obtained from different slices of the PMAs with hard consistency. Dimension reduction was done with reproducibility analysis, collinearity analysis and feature selection. ML classifier was artificial neural network (ANN). Reference standard for the classifications was based on surgical and histopathological findings. Predictive performance of histogram analysis was compared with that of SIR evaluation. The main metric for comparisons was the area under the receiver operating characteristic curve (AUC).

Results: Only 137 of 162 features had excellent reproducibility. Collinearity analysis yielded 20 features. Feature selection algorithm provided six texture features. For histogram analysis, the ANN correctly classified 72.5% of the PMAs regarding consistency with an AUC value of 0.710. For SIR evaluation, accuracy and AUC values were 74.5% and 0.551, respectively. Considering AUC values, ML-based histogram analysis performed better than SIR evaluation (z = 2.312, p = 0.021).

Conclusion: ML-based T2-weighted MRI histogram analysis might be a useful technique in predicting the consistency of PMAs, with a better predictive performance than that of SIR evaluation.
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http://dx.doi.org/10.1007/s00234-019-02211-2DOI Listing
July 2019

Surgical technique for the protection of the cervical sympathetic trunk in anterolateral oblique corpectomy: A new cadaveric demonstration.

J Clin Neurosci 2019 May 1;63:267-271. Epub 2019 Feb 1.

Department of Neurosurgery, Istanbul University-Cerrahpasa, Cerrahpasa Medical Faculty, Istanbul, Turkey.

The cervical oblique corpectomy (OC) approach has the advantages of no grafting or instrumentation necessities and theoretically maintains natural neck motions. However, the risk of cervical sympathetic trunk (CST) injury and Horner's syndrome is one of the main difficulties of this demanding surgical approach. The upper necks of 3 adult human cadavers (6 sides) were dissected under a Zeiss surgical microscope. OC was performed in a stepwise manner to simulate the surgical procedure. We specifically studied the technique of the protection of the CST during the cervical OC approach. The superior ganglion of the cervical sympathetic chain is located under the prevertebral fascia over the longus capitis muscle at the level of C3 transverse process, while the CST is situated under the prevertebral fascia over the longus colli muscle. The CST courses obliquely from superolateral to inferomedial. The ganglia and CST are carefully dissected; the fascia of the longus colli muscle is cut medially, preferably in the midline over the vertebrae, and the fascia lifted up. Then, the aponeurotic flap is gently retracted laterally to cover the sympathetic chain safely and secured with a 3/0 suture laterally. Preservation of the CST while performing cervical OC is essential to avoid postoperative Horner's syndrome. The placement of self-retaining retractors, particularly inferiorly, where the sympathetic chain is located more medially, is probably the main cause of its injury. Further studies are needed documenting the incidence of Horner's syndrome in the application of this technique to live patients.
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http://dx.doi.org/10.1016/j.jocn.2019.01.019DOI Listing
May 2019

Predicting response to somatostatin analogues in acromegaly: machine learning-based high-dimensional quantitative texture analysis on T2-weighted MRI.

Eur Radiol 2019 Jun 30;29(6):2731-2739. Epub 2018 Nov 30.

Department of Radiology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey.

Objective: To investigate the value of machine learning (ML)-based high-dimensional quantitative texture analysis (qTA) on T2-weighted magnetic resonance imaging (MRI) in predicting response to somatostatin analogues (SA) in acromegaly patients with growth hormone (GH)-secreting pituitary macroadenoma, and to compare the qTA with quantitative and qualitative T2-weighted relative signal intensity (rSI) and immunohistochemical evaluation.

Methods: Forty-seven patients (24 responsive; 23 resistant patients to SA) were eligible for this retrospective study. Coronal T2-weighted images were used for qTA and rSI evaluation. The immunohistochemical evaluation was based on the granulation pattern of the adenomas. Dimension reduction was carried out by reproducibility analysis and wrapper-based algorithm. ML classifiers were k-nearest neighbours (k-NN) and C4.5 algorithm. The reference standard was the biochemical response status. Predictive performance of qTA was compared with those of the quantitative and qualitative rSI and immunohistochemical evaluation.

Results: Five hundred thirty-five out of 828 texture features had excellent reproducibility. For the qTA, k-NN correctly classified 85.1% of the macroadenomas regarding response to SAs with an area under the receiver operating characteristic curve (AUC-ROC) of 0.847. The accuracy and AUC-ROC ranges of the other methods were 57.4-70.2% and 0.575-0.704, respectively. Differences in predictive performance between qTA-based classification and the other methods were significant (p < 0.05).

Conclusions: The ML-based qTA of T2-weighted MRI is a potential non-invasive tool in predicting response to SAs in patients with acromegaly and GH-secreting pituitary macroadenoma. The method performed better than the qualitative and quantitative rSI and immunohistochemical evaluation.

Key Points: • Machine learning-based texture analysis of T2-weighted MRI can correctly classify response to somatostatin analogues in more than four fifths of the patients. • Machine learning-based texture analysis performs better than qualitative and quantitative evaluation of relative T2 signal intensity and immunohistochemical evaluation. • About one third of the texture features may not be excellently reproducible, indicating that a reliability analysis is necessary before model development.
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http://dx.doi.org/10.1007/s00330-018-5876-2DOI Listing
June 2019

Neurosurgical treatment of Cushing disease in pediatric patients: case series and review of literature.

Childs Nerv Syst 2019 11 28;35(11):2127-2132. Epub 2018 Nov 28.

Pediatric Endocrinology and Adolescent Divisions, Department of Pediatrics, Istanbul University Cerrahpasa Medical Faculty, Istanbul, Turkey.

Aim: Pituitary adenomas are rare in childhood in contrast with adults. Adrenocorticotropic hormone (ACTH)-secreting adenomas account for Cushing's disease (CD) which is the most common form of ACTH-dependent Cushing's syndrome (CS). Treatment strategies are generally based on data of adult CD patients, although some difficulties and differences exist in pediatric patients. The aim of this study is to share our experience of 10 children and adolescents with CD.

Patients And Method: Medical records, images, and operative notes of 10 consecutive children and adolescents who underwent transsphenoidal surgery for CD between 1999 and 2014 in Cerrahpasa Faculty of Medicine were retrospectively reviewed. Mean age at operation was 14.8 ± 4.2 years (range 5-18). The mean length of symptoms was 24.2 months. The mean follow-up period was 11 years (range 4 to 19 years).

Results: Mean preoperative cortisol level was 23.435 μg/dl (range 8.81-59.8 μg/dl). Mean preoperative ACTH level was 57.358 μg/dl (range 28.9-139.9 μg/dl). MR images localized microadenoma in three patients (30%), macroadenoma in four patients (40%) in our series. Transsphenoidal microsurgery and endoscopic transsphenoidal surgery were performed in 8 and 2 patients respectively. Remission was provided in 8 patients (80%). Five patients (50%) met remission criteria after initial operations. Three patients (30%) underwent additional operations to meet remission criteria.

Conclusion: Transsphenoidal surgery remains the mainstay therapy for CD in pediatric patients as well as adults. It is an effective treatment option with low rate of complications. Both endoscopic and microscopic approaches provide safe access to sella and satisfactory surgical results.
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http://dx.doi.org/10.1007/s00381-018-4013-5DOI Listing
November 2019

Surgical Pitfalls in Carotid Endarterectomy: A New Step-By-Step Approach.

J Craniofac Surg 2018 Nov;29(8):2337-2343

Department of Neurosurgery, Istanbul University, Cerrahpasa Faculty of Medicine, Istanbul, Turkey.

Carotid endarterectomy (CEA) is a surgical intervention that may prevent stroke in asymptomatic and symptomatic patients. Our aim was to examine the microsurgical anatomy of carotid artery and other related neurovascular structures to summarize the CEA that is currently applied in ideal conditions. The upper necks of 2 adult cadavers (4 sides) were dissected using ×3 to ×40 magnification. The common carotid artery, external carotid artery (ECA), and internal carotid artery were exposed and examined. The surgical steps of CEA were described using 3-D cadaveric photos and computed tomography angiographic pictures obtained with help of OsiriX imaging software program. Segregating certain neurovascular and muscular structures in the course of CEA significantly increased the exposure. The division of facial vein allowed for internal jugular vein to be mobilized more laterally and dividing the posterior belly of digastric muscle resulted in an additional dorsal exposure of almost 2 cm. Isolating the ansa cervicalis that pulls hypoglossal nerve inferiorly allowed hypoglossal nerve to be released safely medially. The locations of the ECA branches alter depending on their anatomical variations. The hypoglossal nerve, glossopharyngeal nerve, and accessory nerve pierce the fascia of the upper part of the carotid sheath and they are vulnerable to injury because of their distinct courses along the surgical route. Surgical exposure in CEA requires meticulous dissection and detailed knowledge of microsurgical anatomy of the neck region to avoid neurovascular injuries and to determine the necessary surgical maneuvers in cases with neurovascular variations.
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http://dx.doi.org/10.1097/SCS.0000000000004749DOI Listing
November 2018

Surgical Management of Sphenoid Sinus Lateral Recess Cerebrospinal Fluid Leaks: A Single Neurosurgical Center Analysis of Endoscopic Endonasal Minimal Transpterygoid Approach.

World Neurosurg 2018 Oct 6;118:e473-e482. Epub 2018 Jul 6.

Department of Neurosurgery, Istanbul University Cerrahpasa Medical Faculty, Istanbul, Turkey. Electronic address:

Objective: To review the results of sphenoid sinus lateral recess (SSLR) cerebrospinal fluid (CSF) leaks treated with the endoscopic endonasal minimal transpterygoid approach (EEMTPA) and to discuss the surgical technique and outcomes.

Methods: We performed a retrospective analysis of 13 cases who underwent SSLR CSF leak repair through the EEMTPA in our clinic between September 2008 and December 2017. Demographic and etiological features with reconstruction and surgical outcomes were examined. Mean follow-up time was 6.1 years.

Results: In regard to etiology, the SSLR CSF leaks included 9 patients with spontaneous, 2 patients with traumatic, and 2 with iatrogenic causes. CSF leak was at the left lateral recess in 8 cases and at right lateral recess in 5 cases. Nine patients had empty sella syndrome, and 11 patients had meningoencephaloceles in addition to SSLR CSF leaks. All patients underwent surgery through the EEMTPA, and a multilayer closure with tissue overlay grafts were used for reconstruction. A pedicled nasoseptal flap and/or pedicled middle turbinate flap were applied to the area of the leak in all cases. One patient had a persistent CSF leak and another had recurrence, both of which required revision surgery. Our overall success rate was 100%.

Conclusions: EEMTPA is a safe and effective method that can be used to treat challenging pathologies at the SSLR, including CSF leaks accompanying meningoencephaloceles. Furthermore, the success rate of EEMTPA for SSLR CSF leaks can be increased by applying endoscopic skull base reconstruction techniques such as the pedicled nasoseptal flap and pedicled middle turbinate flap.
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http://dx.doi.org/10.1016/j.wneu.2018.06.219DOI Listing
October 2018

Microsurgical anatomy of the subthalamic nucleus: correlating fiber dissection results with 3-T magnetic resonance imaging using neuronavigation.

J Neurosurg 2018 05;130(3):716-732

6Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.

Objective: Despite the extensive use of the subthalamic nucleus (STN) as a deep brain stimulation (DBS) target, unveiling the extensive functional connectivity of the nucleus, relating its structural connectivity to the stimulation-induced adverse effects, and thus optimizing the STN targeting still remain challenging. Mastering the 3D anatomy of the STN region should be the fundamental goal to achieve ideal surgical results, due to the deep-seated and obscure position of the nucleus, variable shape and relatively small size, oblique orientation, and extensive structural connectivity. In the present study, the authors aimed to delineate the 3D anatomy of the STN and unveil the complex relationship between the anatomical structures within the STN region using fiber dissection technique, 3D reconstructions of high-resolution MRI, and fiber tracking using diffusion tractography utilizing a generalized q-sampling imaging (GQI) model.

Methods: Fiber dissection was performed in 20 hemispheres and 3 cadaveric heads using the Klingler method. Fiber dissections of the brain were performed from all orientations in a stepwise manner to reveal the 3D anatomy of the STN. In addition, 3 brains were cut into 5-mm coronal, axial, and sagittal slices to show the sectional anatomy. GQI data were also used to elucidate the connections among hubs within the STN region.

Results: The study correlated the results of STN fiber dissection with those of 3D MRI reconstruction and tractography using neuronavigation. A 3D terrain model of the subthalamic area encircling the STN was built to clarify its anatomical relations with the putamen, globus pallidus internus, globus pallidus externus, internal capsule, caudate nucleus laterally, substantia nigra inferiorly, zona incerta superiorly, and red nucleus medially. The authors also describe the relationship of the medial lemniscus, oculomotor nerve fibers, and the medial forebrain bundle with the STN using tractography with a 3D STN model.

Conclusions: This study examines the complex 3D anatomy of the STN and peri-subthalamic area. In comparison with previous clinical data on STN targeting, the results of this study promise further understanding of the structural connections of the STN, the exact location of the fiber compositions within the region, and clinical applications such as stimulation-induced adverse effects during DBS targeting.
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http://dx.doi.org/10.3171/2017.10.JNS171513DOI Listing
May 2018

An Alternative Endoscopic Anterolateral Route to Meckel's Cave: An Anatomic Feasibility Study Using a Sublabial Transmaxillary Approach.

World Neurosurg 2018 Jun 3;114:134-141. Epub 2018 Mar 3.

Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA. Electronic address:

Objective: To describe an endoscopic anterolateral surgical route to the lateral portion of Meckel's cave.

Methods: A sublabial transmaxillary transpterygoid approach was performed in 6 cadaveric heads (12 sides). A craniectomy was drilled between the foramen rotundum (FR) and foramen ovale (FO) with defined borders. Extradural dissection was performed up to the V2-V3 junction of the trigeminal ganglion. The working space was analyzed using anatomic measurements.

Results: The approach allowed for extradural dissection to the lateral aspect of Meckel's cave and provided excellent exposure of V2, V3, and the V2-V3 junction at the gasserian ganglion. The mean distance between the FR and FO along the pterygoid process of the sphenoid bone was 21.3 ± 2.8 mm (range, 18-24.4 mm). The mean distance of V2 and V3 segments from their foramina to the gasserian ganglion junction was 12.0 ± 2.3 mm (range, 9.2-14.6 mm) and 15.2 ± 2.7 mm (range, 12.3-18.5 mm), respectively (6 sides). A potential working area (mean area, 89 mm) is described. Its superior edge is from the FR to the V2-V3 junction at the gasserian ganglion, its inferior edge is from the FO to the V2-V3 junction at the gasserian ganglion, and its base is from the FO to the FR. The surgical anatomy of the infratemporal fossa, pterygopalatine fossa, and lateral Meckel's cave is highlighted.

Conclusions: An endoscopic anterolateral sublabial transmaxillary transpterygoid approach between the FR and FO avoids crossing critical neurovascular structures within the cavernous sinus and pterygopalatine fossa and can provide a safe surgical corridor for laterally based lesions in Meckel's cave.
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http://dx.doi.org/10.1016/j.wneu.2018.02.128DOI Listing
June 2018

Germline mutations of aryl hydrocarbon receptor-interacting protein (AIP) gene and somatostatin receptor 1-5 and AIP immunostaining in patients with sporadic acromegaly with poor versus good response to somatostatin analogues.

Pituitary 2018 Aug;21(4):335-346

Department of Endocrinology and Metabolism, Cerrahpasa Medical School, Istanbul University, Cerrahpasa, 34303, Istanbul, Turkey.

Objective: To determine aryl hydrocarbon interacting protein (AIP) gene variations and AIP and somatostatin receptor (SSTR) 1-5 immunostaining in patients with apparently sporadic acromegaly with poor versus good response to somatostatin analogues (SRLs).

Methods: A total of 94 patients (66 with poor and 28 with good response to SRLs) were screened for the AIP gene variations using Sanger sequencing. Immunostaining was performed in 60 tumors.

Results: Several variations, albeit some with undetermined significance, were detected, especially in poor responder patients. The prevalence of AIP mutation was 2.1% in the whole group and 1.5% in patients with poor response to SRLs. AIP, SSTR2A, and SSTR2B immunostainings were decreased in patients with poor response (p < 0.05 for all), and other SSTRs did not differ between the groups (p > 0.05 for all). Patients with low AIP had decreased levels of SSTR2A and SSTR3 (p < 0.05 for all). AIP and SSTR2A immunostainings were positively correlated to the treatment response and age at diagnosis was negatively correlated (p < 0.05 for all). In poor responder patients with high SSTR2A immunostaining, SSTR2B immunostaining and preoperative tumor size were positively and negatively correlated, respectively, to SRL response (p < 0.05 for all).

Conclusions: Lack of response to SRLs does not necessarily increase the risk of harboring AIP mutations. The finding of decreased AIP, SSTR2A, and SSTR2B immunostaining in patients with poor response to SRLs and decreased SSTR2A and SSTR3 level in those with low AIP immunostaining suggests a possible interaction between AIP and some SSTR subtypes that might alter SRL sensitivity.
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http://dx.doi.org/10.1007/s11102-018-0876-4DOI Listing
August 2018

Mammillothalamic and Mammillotegmental Tracts as New Targets for Dementia and Epilepsy Treatment.

World Neurosurg 2018 02 10;110:133-144. Epub 2017 Nov 10.

Department of Neurosurgery, Istanbul University, Cerrahpasa Faculty of Medicine, Istanbul, Turkey.

Background: Recently, neuromodulation through deep brain stimulation (DBS) has appeared as a new surgical procedure in the treatment of some types of dementia and epilepsy. The mammillothalamic and mammillotegmental tracts are involved among the new targets. To our knowledge, a review article focused specifically on these mammillary body efferents is lacking in the medical literature. Their contribution to memory is, regrettably, often overlooked.

Methods: A review of the relevant literature was conducted.

Results: There is evidence that mammillary bodies can contribute to memory independently from hippocampal formation, but the mechanism is not yet known. Recent studies in animals have provided evidence for the specific roles of these mammillary body efferents in regulating memory independently. In animal studies, it has been shown that the disruption of the mammillothalamic tract inhibits seizures and that electrical stimulation of the mammillary body or mammillothalamic tract raises the seizure threshold. In humans, DBS targeting the mammillary body through the mammillothalamic tract or the stimulation of the anterior thalamic nucleus, especially in the areas closely related to the mammillothalamic tract, has been found effective in patients with medically refractory epilepsy. Nonetheless, little knowledge exists on the functional anatomy of the mammillary body efferents, and their role in the exact mechanism of epileptogenic activity and in the memory function of the human brain.

Conclusions: A comprehensive knowledge of the white matter anatomy of the mammillothalamic and mammillotegmental tracts is crucial since they have emerged as new DBS targets in the treatment of various disorders including dementia and epilepsy.
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http://dx.doi.org/10.1016/j.wneu.2017.10.168DOI Listing
February 2018

Guidewire Breakage During Cavernous Sinus Sampling: A Rare Complication and Its Treatment.

World Neurosurg 2017 Nov 24;107:1052.e1-1052.e6. Epub 2017 Aug 24.

Department of Neurosurgery, Cerrahpasa Faculty of Medicine, Istanbul University, Istanbul, Turkey.

Background: Venous sampling methods are valuable tools for the diagnosis of pituitary adenomas. However, these interventions also have complications, which may complicate the treatment process.

Case Description: A 49-year-old female pituitary adenoma patient with preliminary diagnosis of Cushing disease underwent cavernous sinus sampling (CSS) to delineate the adenoma. The microguidewire broke during the procedure, and the distal part of the microguidewire had to be left within the right cavernous sinus. Eventually, the broken part of the guidewire was removed after the removal of the tumor through an endoscopic endonasal approach.

Conclusions: Current surgical experience on endoscopic skull base surgery allows management of diagnostic complications related to the cavernous sinus, such as safe access to materials which were inadvertently left during CSS, without the necessity for further interventions.
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http://dx.doi.org/10.1016/j.wneu.2017.08.102DOI Listing
November 2017

Outcomes of Primary Transsphenoidal Surgery in Cushing Disease: Experience of a Tertiary Center.

World Neurosurg 2017 Oct 13;106:374-381. Epub 2017 Jul 13.

Department of Neurosurgery, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey; Pituitary Center, Istanbul University, Istanbul, Turkey. Electronic address:

Background: To report the initial and long-term remission rates and related factors, secondary treatments, and outcomes of a series of patients with Cushing disease (CD).

Methods: We included 147 consecutive adult patients with CD who underwent primary transsphenoidal surgery (TSS) between 1998 and 2014 in this study. Eighty-two were followed up in the Cerrahpasa Medical Faculty Endocrinology and Metabolism outpatient clinic. Patients were requested to attend a long-term remission assessment; 55 could be contacted, and data for the remaining 27 patients' last visit to the outpatient clinics were reviewed for early and late remission. Six patients were excluded from the study. Magnetic resonance imaging (MRI) findings and pathologic results including mitosis, Ki-67 levels, and P53 in immunostaining of all patients were evaluated.

Results: Data of 82 patients with CD with an average age of 36 years [interquartile range: 29-47] were analyzed with a mean follow-up of 7.5 years [interquartile range: 5-10]. Overall initial remission rates were 72.3% after TSS. Among the 82 patients, 16 patients had Gamma Knife radiosurgery and 7 patients underwent adrenalectomy. After these additional treatments, the long-term remission rate was found as 69.7%. The highest remission rates were with microadenomas. Recurrence was most frequently seen in patients without tumor evidence on MRI. Patients with high Ki-67 levels had higher recurrence rates in long-term follow-up (P = 0.02).

Conclusion: Life-long follow-up for patients with CD seems essential. Undetectable tumors on MRI before TSS and high Ki-67 immunopositivity were found as risk factors for tumor recurrence.
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http://dx.doi.org/10.1016/j.wneu.2017.07.014DOI Listing
October 2017

Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation.

J Vis Exp 2017 05 23(123). Epub 2017 May 23.

Department of Neurosurgery, University of Minnesota.

The purpose of this study is to show the methodology for the examination of the white matter connections of the supplementary motor area (SMA) complex (pre-SMA and SMA proper) using a combination of fiber dissection techniques on cadaveric specimens and magnetic resonance (MR) tractography. The protocol will also describe the procedure for a white matter dissection of a human brain, diffusion tensor tractography imaging, and three-dimensional documentation. The fiber dissections on human brains and the 3D documentation were performed at the University of Minnesota, Microsurgery and Neuroanatomy Laboratory, Department of Neurosurgery. Five postmortem human brain specimens and two whole heads were prepared in accordance with Klingler's method. Brain hemispheres were dissected step by step from lateral to medial and medial to lateral under an operating microscope, and 3D images were captured at every stage. All dissection results were supported by diffusion tensor imaging. Investigations on the connections in line with Meynert's fiber tract classification, including association fibers (short, superior longitudinal fasciculus I and frontal aslant tracts), projection fibers (corticospinal, claustrocortical, cingulum, and frontostriatal tracts), and commissural fibers (callosal fibers) were also conducted.
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http://dx.doi.org/10.3791/55681DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608134PMC
May 2017

Endoscopic Endonasal Cerebrospinal Fluid Leak Repair on the Ventral Midline Skull Base: A Single Neurosurgical Center Experience.

Turk Neurosurg 2018 ;28(2):193-203

Istanbul University, Cerrahpasa Medical Faculty, Department of Neurosurgery, Istanbul, Turkey.

Aim: To present the results of endoscopic endonasal repair of ventral midline skull base cerebrospinal fluid (CSF) leak (VMSBL) at our institution and to discuss the technique and results from a neurosurgical perspective.

Material And Methods: A retrospective analysis of all VMSBL cases that underwent endoscopic endonasal skull base approach (EESBA) for CSF leak repair at a single tertiary neurosurgical center was performed. Twenty six patients with an average age of 44.4 (range: 17-63) years were included in the study.

Results: The etiology of VMSBL was spontaneous in 16 patients, traumatic in 7, and iatrogenic in 3. The leakage site was the cribriform plate in 13 patients, ethmoidal cells in 7, and sphenoid sinus in 3. There were multiple leaks in 3 patients. This approach for VMSBL repair was performed 28 times on 26 patients. The success rate was 88.5% (23/26 patients) after primary endoscopic repair and 96% after the second attempt. The location of the leakage site relative to the upper attachment of the middle turbinate played a crucial role in the anteriorly located VMSBL, which made an impact on the surgical repair plan. All the 16 cases with accompanying meningoencephaloceles were treated successfully by EESBA. Use of vascularized pedicled flaps to support the repair site resulted in 100% success after primary repair.

Conclusion: EESBA is safe and highly effective and can be a first-line surgical treatment option for VMSBL. In addition, it enables adequate reconstruction of ventral midline skull base meningoencephaloceles regardless of size and location.
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http://dx.doi.org/10.5137/1019-5149.JTN.20009-17.1DOI Listing
July 2018