Page 2 - Best Deep brain stimulation (DBS) surgery doctors in Turkey: TOP 46 doctors

Dr. Ulvi Samadzade is a neurologist with training from Azerbaijan State Medical University, Gazi University, and Dokuz Eylul University Hospital. He diagnoses and treats neurological disorders such as Alzheimer’s disease, epilepsy, movement disorders, stroke, migraine, and multiple sclerosis.

Dr. Samadzade uses advanced treatments, including botulinum toxin injections, intravenous immunoglobulin (IVIG) therapy, migraine vaccines, and plasmapheresis. He practices at İzmir University of Economics Medical Point Hospital.

He is a member of several professional organizations. These include the Multiple Sclerosis Research Association, Turkish Neurological Society, European Academy of Neurology, and the International Parkinson and Movement Disorder Society (MDS).

EDUCATION:

• Turhan and Mediha Tansel Primary School (1979–1984)
• Kültür College (1984–1988)
• Semiha Şakir High School (1988–1991)
• Marmara University Faculty of Medicine (1991–1997)
• Marmara University Faculty of Medicine, Neurosurgery Department, Specialist Training (1997–2002)
• Title of Associate Professor in Neurosurgery (May 31, 2021)

ADDITIONAL TRAINING:

• "Visiting Physician," University of Southern California, Department of Neurosurgery (1998)
• "Microsurgery Training," GATA (Gülhane Military Medical Academy), Ankara Education and Research Hospital (2003)

PROFESSIONAL EXPERIENCE:

• Gülhane Military Medical Academy Haydarpaşa Training and Research Hospital (2002–2003)
• Dr. Lütfi Kırdar Kartal Training and Research Hospital (2003–2005)
• Private Avicenna Ataşehir Hospital (2005–2012)
• Private 29 Mayıs Hospital (2012–2013)
• Maltepe State Hospital (2013–2018)
• Kartal Dr. Lütfi Kırdar City Hospital (2018–2020)
• Private Academic Hospital (2020–2022)
• Hisar Intercontinental Hospital (2022–2024)
• Private Medipol Acıbadem Regional Hospital (2024–Present)

ADMINISTRATIVE AND ACADEMIC ROLES:

• Board Member, Neurosurgical Society (2006–2009)
• Head of the Emergency Department, Maltepe State Hospital (2014–2016)
• Deputy Chief Physician, Private Academic Hospital (2020–2021)
• Advisory Board Member, Beykent University Faculty of Medicine (2018–2024)
• Faculty Member, Galata University Faculty of Health Sciences (2022–2024)
• Director, Continuous Education Center, Galata University (2022–2024)

Dr. Gulnar Ibrahimova, MD, is a neurologist at Istanbul Medipol University. She specializes in Parkinson’s disease and movement disorders. She graduated from Azerbaijan Medical University in 2008. She completed her neurology training at Istanbul University in 2017.

Dr. Ibrahimova is accredited by the General Medical Council (UK). She is also a member of the Turkish Neurological Association. She has published work in both local and international medical journals. Her research and clinical work focus on advancing the field of neurology.

Education and Expertise

GATA Military Medical Faculty

GATA Haydarpaşa Training Hospital Neurosurgery Clinic (Specialization)

Beykent University Hospital and Health Institutions Management (Master's)

Experience

GATA Military Medical Faculty Trainee Doctor (6 months)

Samsun Sahara Medical School Comm. (3 months)

Naval Command War Squadron TCG Diligence Medical Officer (2 years)

Dz.K.K. Submarine Battery Factory Infirmary Doctor (3 months)

Naval Forces Command Infirmary Doctor (3 months)

GATA Haydarpaşa Training Hospital Chief Assistant (12 years)

Kasımpaşa Marine Hospital Neurosurgery Clinic Chief (5 years)

Bahçelievler Medical Park Hospital Neurosurgery Specialist (11 years)

Altınbaş University Faculty of Medicine Neurosurgery Lecturer. Member (4 years)

Altınbaş University Faculty of Medicine Head of Neurosurgery Department. (3 years)

Basic and Advanced Cardiac life support courses (BASIC)

Basic and Advanced Cardiac life support courses (ADVANCED)

GATA Military Medical Faculty. Microsurgery Training Course

Istanbul Vatan Hospital Hand surgery microsurgery course

Neuroanatomy course

Spine Surgery course

Professional Memberships

Turkish Neurosurgery Association

Spine Society of Europe

Turkish Spinal and Peripheral Nerve Surgery Group

Prof. Dr. Ilhan Elmaci is a leading neurosurgeon. He is known for his skill in brain and spinal surgeries, neurooncology, and skull base surgery. He has worked at top institutions such as Johns Hopkins University. Dr. Elmaci has introduced new techniques in microsurgery and endoscopic skull base surgery.

He is the founding chairman of the Skull Base Society in Turkey. He is also an active member of the European Skull Base Society. Dr. Elmaci has helped advance neurosurgery through teamwork across specialties. He led Turkey’s first EANS-accredited neurosurgery clinic. He also holds accreditations from the European Association of Neurosurgical Societies.

Dr. Elmaci has published over 110 scientific papers and given more than 250 presentations at congresses. His work continues to influence neurosurgical practice and patient care around the world.

Prof. Dr. Salih Murat İmer is a neurosurgeon with over 30 years of experience. He founded and led the Neurosurgery Department at Okan University Hospital. He has written 68 scientific articles and contributed to 9 book chapters. Dr. İmer has also presented at 33 international congresses, showing his influence in neurosurgery worldwide.

Dr. İmer holds advanced certifications in functional and stereotactic neurosurgery, Leksell Gamma Knife radiosurgery, and endoscopic spine surgery. He received specialized training in several European countries. He has worked with leading experts such as Prof. Matti Vapalahti and Prof. Juha Hernesniemi. Through these collaborations, he has helped improve neurosurgical practice and education around the world.

Dr. Mehmet Tonge is a neurosurgeon with expertise in Stereotactic and Functional Neurosurgery. He specializes in MR Guided Focused Ultrasound, deep brain stimulation, Gamma Knife Radiosurgery, and surgery for movement disorders, pain, and spasticity.

Dr. Tonge has published 32 articles in international and national journals and written 12 book chapters. He has presented 92 oral and poster presentations and delivered 41 invited lectures. He completed a Deep Brain Stimulation Fellowship at Maastricht University and finished the 4-year EANS training cycle. Dr. Tonge is known for his research and clinical work in functional neurosurgery.

2015 - 2015

Medipol Üniversitesi Parkinson Hastalığı ve Hareket Bozuklukları Merkezi

2009 - 2009

Medicalpark Bahçelievler Hastanesi

1999 - 2004

Medicalpark Bahçelievler Hastanesi

1997 - 2009

Amerikan Hastanesi

1997 - 1997

VKV Amerikan Hastanesi

1995 - 1995

Division of Neurosurgery, Toronto Western Hospital Research Fellow

1995 - 1995

Department of Neurosurgery, The Johns Hopkins Hospital

1995 - 1997

Toronto Western Hospital,

1994 - 1994

Division of Neurosurgery, Toronto Western Hospital

1992 - 1992

Department of Neurosurgery, University of Virginia

1992 - 1992

Department of Neurosurgery, University of Washington

1992 - 1992

İsrail Kudüs, The European Association of Neurosurgical Societies European

1991 - 1991

İspanya Zaragoz- The European Association of Neurosurgical Societies European

1990 - 1990

Glasgow, Scotland, İngiltere

1990 - 1990

Glasgow ve Edinburg, The British Council

1990 - 1990

Glasgow ve Edinburg, The British Council1994

Marmara University Institute of Health Sciences, Neurophysiology

1993

Marmara University Faculty of Medicine, Neurosurgery and Neurosurgery

1989

Marmara University Faculty of Medicine, Neurosurgery and Neurosurgery

1983

Hacettepe University, Faculty of Medicine

1983

Hacettepe University, Faculty of Medicine

Education

University of Wisconsin Clinic of Neurosurgery (2017, Madison/USA)
Bakırköy Psychiatric Hospital (2014, Istanbul/Turkey)
Mersin University Faculty of Medicine (2007, Mersin/Turkey)

Experience

Istanbul Kanuni Sultan Süleyman Training and Research Hospital (2014-2021, Istanbul/Turkey)
Istanbul Bakırköy Mental and Neurological Diseases Hospital (2008-2014, Istanbul/Turkey)
Çorlu State Hospital (2007-2008, Çorlu/Turkey)

• In 2014, I completed my specialty training in the Department of Neurosurgery at Istanbul Bakırköy Prof. Dr. Mazhar Osman Mental Health and Neurological Diseases Training and Research Hospital and started to work as a specialist in Neurosurgery at Istanbul Health Sciences University Kanuni Sultan Süleyman Training and Research Hospital,
• In 2017, I was a visiting scholar at the University of Wisconsin Department of Neurosurgery/ Madison USA.
• In 2021, I received the title of associate professor.
• In December 2021, I left Kanuni Sultan Süleyman Training and Research Hospital, where I worked for 7.5 years, and started working at Biruni University Hospital.
•  

Scientific Memeberships

Turkish Neurosurgical Society
Turkish Spine Society
EUROSPINE
Turkish Medical Association

Education

GATA Faculty of Medicine, Doctor of Medicine Education, 1984, Ankara/Istanbul
GATA Faculty of Medicine, Neurology Residency, 1992, Ankara/Istanbul

Experience

GATA Neurology Department Specialization Student (1987-1992, Ankara/Turkey)
GATA Neurology Department Assistant Professor (1992-1995, Ankara/Turkey)
KüTahya Air Hospital Neurology Specialist and Chief Physician (1995-2003, Kütahya/Turkey)
Şişli Memorial Hospital Neurology Specialist (2004-2021, Istanbul/Turkey)

I completed my primary, secondary and high school education in Konya, my hometown, and my medical school and medical specialty education in Ankara GATA. I received flight medicine training and worked as a flight physician in the military and civilian sectors. I received beginner and advanced photography training and opened 4 photography exhibitions. I have made photography studies in 56 countries in Turkey and in 56 countries that I had the opportunity to visit.

Scientific Memberships

Turkish Medical Association
DGCA Health Board Membership

General Information and Presentation

He completed his primary education at Şenlikköy Primary School and his secondary education at the Istek Foundation Florya Bilge Kagan High School. He graduated from Istanbul University Cerrahpaşa Faculty of Medicine in 2001. He completed his specialist education in Istanbul Medical Faculty Neurology Department in 2006. In 2006 he worked at the Neurology Clinic and the PharmaZentrum Research Center of the Faculty of Medicine of the University of Basel, Switzerland. Between 2007 and 2011, Bakırköy Prof. Dr. He worked at Mazhar Osman Mental Health and Neurological Diseases Training and Research Hospital in the 3rd Neurology Clinic and in the Dementia and Movement Disorders policlinics. Since October 2011, he has been working at Istanbul University of Science, Faculty of Medicine, Neurology, USA.

Experience

İstanbul Bilim University Faculty of Medicine Neurology, 

Şişli Florence Nightingale Hospital 

Kadıköy Florence Nightingale Hospital Neurology Clinics, 

Gayrettepe Metropolitan Florence Nightingale Hospital PET department.

Dr. Mustafa Kilic is a skilled neurosurgeon with expertise in neuromodulation. He performs Deep Brain Stimulation, Spinal Cord Stimulation, and Sacral Nerve Stimulation. Dr. Kilic manages all stages of patient care, from preoperative evaluation to postoperative follow-up. He focuses on achieving the best possible outcomes for his patients.

Dr. Kilic is an Associate Professor at Istinye University. He is active in neurosurgery research and education. As a member of the Turkish Neurosurgical Society, he has completed many advanced neuromodulation procedures. His work has led to high patient satisfaction and strong results in complex neurological cases.

Prof. Erkan Kaptanoğlu, M.D. was born in Balikesir, Turkey in 1966. After completing his primary school, secondary school and high school education in Balikesir, he graduated from Istanbul University, Cerrahpasa Faculty of Medicine in 1990. He completed his internship at Peterborough District Hospital and Lincoln County Hospital in the United Kingdom. After a year of compulsory medical service, he completed his residency, which he had started in 1992, at Ankara Numune Training and Research Hospital in 1997 and became a Neurosurgery Specialist. After being assigned at the same hospital as Chief Resident in the same year, he studied “spinal cord injury and spinal cord regeneration” as a “research fellow” alongside Prof. Charles Tator, M.D., at the University of Toronto Faculty of Medicine in 1998-1999. After returning from Canada in 1999, he was tasked by the Ministry of Health to establish a Field Hospital and to work in cooperation with the Turkish Red Crescent Society at Hakkari, Şemdinli for two months. Following this assignment, he volunteered to work for the 1999 Marmara Earthquake relief effort.

He became an Associate Professor of Neurosurgery in 2004. He earned the title Doctor of Science (Ph.D.) by completing a doctorate program on Advanced Neuroscience between 2000-2005, at Hacettepe University Institute of Medical Sciences. He joined the project for autologous stem cell therapy in human spinal cord injuries with the Departments of Neurosurgery and Hematology at the Ankara University Faculty of Medicine. In 2009, he was appointed as Deputy Chief to the 1st Neurosurgery Clinic at the Ankara Numune Hospital, where he had been working.

At this hospital, in which he worked until 2010, he supervised and attended complex cranial, pediatric, spinal, trauma and vascular neurosurgery operations. He continued his academic research at Ankara University, Department of Anatomy and research laboratories of Ankara University and Hacettepe University for the purpose of developing strategies for complex spinal surgery operations.

With his research on spinal cord injuries and spinal anatomy, he won many awards such as the Acibadem Hospital Medical Research Award, 1st Place in 2000, Turkish Neurosurgical Society Dr. Mahir Tevruz Scientific Research Award, Tübitak and Brain Research Society Wheyt Award in 2001, Turkish Neurosurgical Society Hamit Ziya Gokalp Young Neurosurgeons Research Award, 2nd Place in 2002, Turkish Neurosurgical Society Yildiz Yalcinlar Scientific Research Award in 2004.

In 2010, he went to Cyprus to found the Near East University Faculty of Medicine Hospital with the guidance of Hacettepe University, and was appointed as full Professor. Between 2010-2015, he served as the Founder and Head of Department at the Near East University and Founder and Deputy Chief Physician at the University Training and Research Hospital in TRNC.

In 2000-2001, he served as a member of the editorial board for Türk Nöroşirurji Dergisi and Turkish Neurosurgery journal. Between the years 2001-2006, he served as an assistant editor for Türk Nöroşirurji Dergisi and Turkish Neurosurgery journals. In 2002-2003, he served as the Chairman of the Young Neurosurgeons Committee under the Turkish Neurosurgical Society. He was elected to the Turkish Neurosurgical Society Spinal and Peripheral Nerve Surgery Group Board of Directors to serve between 2003-2009. In 2013, he was again elected as a member to the Turkish Neurosurgical Society Spinal and Peripheral Nerve Surgery Group Board of Directors. In 2015, he became the Chairman of the Turkish Neurosurgical Society Spinal and Peripheral Nerve Surgery Group Board of Directors. In 2018, he was elected as a member to the Board of Turkish Neurosurgery Academy.

In 2015, he was appointed to the Marmara University Faculty of Medicine, Department of Neurosurgery and was elected as the Head of Department. During the same period, he also served as the Director of the Institute of Neuroscience. In 2018, he completed his tenure as the Head of Department. Reaching the end of this tenure in 2019, he retired from his duties as the Director of the Institute of Neuroscience and as a Member of the Faculty of Medicine. During his tenure at Marmara University, he supervised and accompanied surgical operations for complex cases from cranial patients to brain tumors (gliomas, meningiomas and hypophysis adenomas in particular), cerebral hemorrhages, Parkinson’s disease, trauma and vascular neurosurgery. He performed complex spinal surgery operations such as surgeries for spinal deformities (e.g. scoliosis and kyphosis), thoracoscopic spinal surgeries and sacral tumor surgeries. He conducted research and experimental studies on stem cell therapy and regeneration in spinal cord injuries. Between 2019-2020, currently He continues his clinical practice and surgeries along with his local and international academic studies, from his private clinic and Istanbul Brain and Spine Center.

He has attended numerous national and international courses and meetings as an instructor and speaker, was a guest speaker in over 100 events and conferences. He has published 65 international, 35 national scientific articles, edited 7 books, written 52 book chapters. He has served in the organizational committee 5 times in international meetings and 22 times in national meetings.

He is a member of the Turkish Medical Association, Turkish Cypriot Medical Association, Turkish Neurosurgical Society, Turkish Spine Society, EUROSPINE, AO Spine, Turkish Neurosurgery Academy.

Medical Area of Interest and Activities 

Functional Neurosurgery (Parkinson’s, Deep Brain Stimulation) 

Brain and Spinal tumors 

Spinal degenerative diseases Education 

Istanbul University Cerrahpaşa Faculty of Medicine 

Trakya University Faculty of Medicine Brain and Nerve Surgery

Education 

Istanbul University Cerrahpaşa Faculty of Medicine 

Trakya University Faculty of Medicine Brain and Nerve Surgery

Experience 

Ankara Gülhane Military Medical Academy Brain and Nerve Surgery 

Osmaniye State Hospital 

Bolu State Hospital 

Private Taksim German Hospital 

Taksim Training and Research Hospital 

Istanbul University Faculty of Medicine Brain and Nerve Surgery 

Liv Hospital Ulus

Memberships 

Turkish Neurosurgery Society 

Turkish Medical Association

Research and Publications 

Development of micro-neurosurgery laboratory training model for orbita and optical nerves on fresh lamb cadaver (2007) • 

Effect of Astaxanthin on NMDA sub units and MRNA expression levels in Primary Cortical Neurons 

Articles in International Journals (18)  

Chapters in International Books (1) 

Articles in National Journals (5) 

International Papers (12) 

National Papers (24) 

Specializations

Brain Tumors

Aneurysm Surgery

Pituitary Surgery

Spine Surgery

Waist neck and back hernias

Spine Tumors

Spinal Fractures

Peripheral Nerve Surgery

Education and Specialization:

• Medical Degree: Istanbul University Cerrahpaşa Faculty of Medicine (1991-1998)
• Specialization in Neurosurgery: Karadeniz Technical University Faculty of Medicine (1999-2005)
• Associate Professorship: (2015)
• Professorship: (2020)

Professional Experience:

• 2007-2008: Ankara GATA
• 2009-2011: Özel Ordu Medical Park Hospital
• 2011-2013: Ankara Keçiören Training and Research Hospital
• 2013-2015: Giresun University Faculty of Medicine
• 2014: Clinical Observer at Helsinki University Central Hospital
• 2015-2023: Karadeniz Technical University Faculty of Medicine
• Current Position: Neurosurgeon at VM Medical Park Pendik Hospital

Areas of Expertise:

• Brain Aneurysm and Repair
• Brain Tumor/Cancer Surgery
• Spinal Canal Stenosis Surgery
• Lumbar and Cervical Disc Herniation
• Spinal Cord Surgery
• Minimally Invasive Neurosurgery
• Pediatric Neurosurgery
• Congenital Anomalies

Research and Publications: Prof. Dr. Arslan has numerous publications in prestigious journals, covering topics such as the treatment of brain and spinal tumors, innovative neurosurgical techniques, and outcomes of neurosurgical interventions. His work includes studies on brain ischemia/reperfusion injury, spinal cord ischemia, and various other neurosurgical conditions.

Professional Memberships:

• Turkish Neurosurgery Association
• Turkish Society of Neurological Surgery

2002-2007 Istanbul University Istanbul Faculty of Medicine Department of Brain and Nerve Surgery

1988-1995 Trakya University Faculty of Medicine

2015- Atlas University Medicine Hospital

2014-2015 Private Pendik Yüzyıl Hospital Brain and Neurosurgery Clinic

2009-2014 Medicine Hospital Brain and Neurosurgery Clinic

2009-2009 Nisa Hospital Brain and Neurosurgery Clinic

2007-2009 Mardin State Hospital Brain and Neurosurgery Clinic

2002-2007 Istanbul University Istanbul Faculty of Medicine Brain and Neurosurgery

1997-2001 Enez Health Center and Enez State Hospital

Cervical, Thoracic and Lumbar Disc Surgery (endoscopic/microsurgery)

Far lateral (non-canal) lumbar disc surgery (lateral microsurgical approach)

Neurovascular surgery

Cerebrovascular diseases (vascular diseases of the brain)

Aneurysms

Arteriovenous malformations

Cavernomas

Neuro-oncological surgery

Brain tumors

Glial tumors

Meningiomas

Pituitary gland tumors

Metastatic brain tumors

Skull base tumors

Pontocerebellar angle tumors

Pineal tumors

Intraventricular tumors

Spinal disease surgery

Cervical, thoracic and lumbar spine fractures

Spine and spinal cord tumors

Scoliosis

Degenerative spine diseases

Peripheral nerve disease surgery

Peripheral nerve tumors

Entrapment neuropathies

Carpal tunnel syndrome

Ulnar groove syndrome

Tarsal tunnel syndrome

Functional neurosurgery and pain surgery

Trigeminal neuralgia

Microvascular decompression

Epilepsy surgery

Spasticity surgery

Epiduroscopic interventions

Hydrocephalus surgeries

Endoscopic 3rd ventriculostomy

VP shunt surgeries

LP shunt surgeries

Developmental anomalies

Meningomyelocele

Tethered cord syndrome

Arachnoid cyst

Craniosynostosis surgeries

Chiari malformation

Head trauma

Subdural hematomas

Intracerebral hematomas

Article published in internationally refereed journals

Cansever T, Civelek E, Sencer A, Karasu A, Kiris T, Hepgül K, Can H, Canbolat A: Spinal cavernous malformations: a report of 5 cases. Surg Neurol Jun 69 

Effects of combined and individual use of N-methyl-D aspartate receptor antagonist magnesium sulphate and caspase-9 inhibitor z-LEDH-fmk experimental spinal cord injury. A.Sencer, A.Aydoseli, Y.Aras, M.Osman Akçakaya, C.Gömleksiz, H.Can, A.Canbolat. Turkısh Joumal of Trauma&Emergency Surgery 2013

Aydoseli A, Can H, Aras Y, Sabanci PA, Akcakaya MO, Unal OF. Memantine and Q-VD-OPh Treatments in Experimental Spinal Cord Injury: Combined Inhibition of Necrosis and Apoptosis. Turk Neurosurg. 2016

Can H, Kircelli A, Kavadar G, Civelek E, Cansever T, Aydoseli A, Onal MB, Yilmaz C. Lumbosacral Conjoined Root Anomaly: Anatomical Considerations of Exiting Angles and Root Thickness. Turk Neurosurg. 2017

Kırcelli A, Özel Ö, Can H, Sarı R, Cansever T, Elmacı İ. Is the presence of linear fracture a predictor of delayed posterior fossa epidural hematoma? Ulus Travma Acil Cerrahi Derg. 2016 Jul

Kavadar G, Demircioğlu DT, Can H, Emre TY, Civelek E, Senyigit A. The clinical factors associated with benefit finding of complementary medicine use in patients with back pain: A cross-sectional study with cluster analysis. J Back Musculoskelet Rehabil. 2017

Ozer AF, Suzer T, Can H, Falsafi M, Aydin M, Sasani M, Oktenoglu T. Anatomic Assessment of Variations in Kambin’s Triangle: A Surgical and Cadaver Study. World Neurosurg. 2017 Apr

Can H, Aydoseli A, Gömleksiz C, Göker B, Altunrende ME, Dolgun M, Sencer A. Combined and individual use of pancaspase inhibitor Q-VD-OPh and NMDA receptor antagonist riluzole in experimental spinal cord injury. Ulus Travma Acil Cerrahi Derg. 2017

Gomleksiz C, Erbulut DU, Can H, Kodigudla MK, Kelkar AV, Kasapoglu E, Ozer AF, Goel VK. A new lumbar fixation device alternative to pedicle-based stabilization for lumbar spine: In vitro cadaver investigation. J Spinal Cord Med. 2018 Jul 16:1-8.

Aydoseli A, Özgen U, Akgül T, Orhan EK, Adıyaman AE, Can H, Karadağ C. Subacute Traumatic Ascending Myelopathy in a 28-year-old man: A rare case. World Neurosurg. 2019 Apr 28

Article published in national refereed journals

1) Intracranial Hemangioblastomas: Clinical Evaluation of 32 Patients T. Cansever, A. Karasu, K. Hepgül, H. Can, A. Sencer Turkish Neurosurgical Journal 2007, Volume:17 

2) Halil Can, Müge Dolgun, Utku Özgen, Cengiz Gömleksiz, Furkan Diren, Aydın Aydoseli, Yavuz Aras, Altay Sencer. Microsurgical Results in Vestibular Schwannoma Patients; Retrospective Clinical Study. JAREM 2019

3) Furkan Diren , Özcan Gayretli , Halil Can , İlke Ali Gürses , Orhan Barlas. Examination of Pons-Cerebellum Cisterna Anatomy with Endoscopic Retrosigmoid Suboccipital Approach: Cadaver Study. JAREM 2019