Publications by authors named "Baran Bozkurt"

24 Publications

  • Page 1 of 1

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

Endoscopic Bilateral Optic Nerve Decompression for Treatment of Idiopathic Intracranial Hypertension.

Brain Sci 2021 Mar 4;11(3). Epub 2021 Mar 4.

Department of Neurosurgery, University of Virginia, Charlottesville, VA 22903, USA.

Objective: To evaluate the results of bilateral endoscopic optic nerve decompression (EOND) with the opening nerve sheath (ONS) technique in patients with idiopathic intracranial hypertension (IIH).

Methods: Between the years of 2017 and 2019, we retrospectively evaluated nine IIH patients with progressive visual impairment despite medical treatment and who were treated with the EOND and ONS techniques. We also demonstrated our surgical technique recipe on postmortem human heads in a stepwise manner.

Results: There were 9 patients (7 females and 2 males) between the ages of 21 and 72 included in this study, and the mean age was 40.8. All patients had an impairment in visual acuity and/or their visual field, with signs of papilledema and/or optic atrophy. The patients were followed up with for 9-48 months. Improvements in visual acuity were observed in 7 out of 9 patients (78%). Visual field defects improved in 5 out of 8 patients (62.5%). Papilledema was resolved in all patients (100%). Headaches improved in all symptomatic patients (100%). No intraoperative or postoperative complications were observed.

Conclusions: EOND is a safe and effective surgical procedure in selected patients with IIH. Bilateral wide bony decompression and nerve fenestration can also be an additional benefit for headache relief. Further clinical series and long-term follow-up are needed for more precise results.
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http://dx.doi.org/10.3390/brainsci11030324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998922PMC
March 2021

Microsurgical Management of the Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Feasibility Study.

ORL J Otorhinolaryngol Relat Spec 2021 Mar 15:1-9. Epub 2021 Mar 15.

Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota, USA.

Background: The proper head positioning decreases the surgical complications by enabling a better surgical maneuverability. Middle cerebral artery (MCA) bifurcation aneurysms have been classified by Dashti et al. [Surg Neurol. 2007 May;67(5):441-56] as the intertruncal, inferior, lateral, insular, and complex types based on dome projection. Our aim was to identify the optimum head positions and to explain the anatomic variables, which may affect the surgical strategy of MCA bifurcation aneurysms.

Methods: The lateral supraorbital approach bilaterally was performed in the 4 cadaveric heads. All steps of the dissection were recorded using digital camera.

Results: The distal Sylvian fissure (SF) dissection may be preferred for insular type and the proximal SF dissection may be preferred for all other types. Fifteen degrees head rotation was found as the most suitable position for the intertruncal, lateral type and subtype of complex aneurysms related with superior trunk. Thirty degrees head rotation was found the most suitable position for the inferior type, insular type, and subtype of complex aneurysms related with inferior trunk.

Conclusions: The head positioning in middle cerebral bifurcation aneurysms surgery is a critical step. It should be tailored according to the projection and its relationship with the parent vessels of the middle cerebral bifurcation.
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http://dx.doi.org/10.1159/000514177DOI Listing
March 2021

The Carotid Endarterectomy Cadaveric Investigation for Cranial Nerve Injuries: Anatomical Study.

Brain Sci 2021 Feb 10;11(2). Epub 2021 Feb 10.

Department of Neurosurgery, Acıbadem Mehmet Ali Aydinlar University, 34662 Istanbul, Turkey.

Cerebral stroke continues to be one of the leading causes of mortality and long-term morbidity; therefore, carotid endarterectomy (CEA) remains to be a popular treatment for both symptomatic and asymptomatic patients with carotid stenosis. Cranial nerve injuries remain one of the major contributor to the postoperative morbidities. Anatomical dissections were carried out on 44 sides of 22 cadaveric heads following the classical CEA procedure to investigate the variations of the local anatomy as a contributing factor to cranial nerve injuries. Concurrence of two variations was found to be important in hypoglossal nerve injury: the presence of a direct smaller vein in proximity of the carotid bifurcation, and the intersection of the hypoglossal nerve (HN) with this vein. Based on the sample investigated, this variation was observed significantly higher on the right side. Awareness of possible anatomical variations and early ligation of any small veins can significantly decrease iatrogenic injury risk.
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http://dx.doi.org/10.3390/brainsci11020211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7916403PMC
February 2021

Probe-based three-dimensional confocal laser endomicroscopy of brain tumors: technical note.

Cancer Manag Res 2018 30;10:3109-3123. Epub 2018 Aug 30.

Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA,

Background: Confocal laser endomicroscopy (CLE) is used during fluorescence-guided brain tumor surgery for intraoperative microscopy of tumor tissue with cellular resolution. CLE could augment and expedite intraoperative decision-making and potentially aid in diagnosis and removal of tumor tissue.

Objective: To describe an extension of CLE imaging modality that produces Z-stack images and three-dimensional (3D) pseudocolored volumetric images.

Materials And Methods: Hand-held probe-based CLE was used to collect images from GL261-luc2 gliomas in C57BL/6 mice and from human brain tumor biopsies. The mice were injected with fluorescein sodium (FNa) before imaging. Patients received FNa intraoperatively, and biopsies were imaged immediately in the operating room. Some specimens were counterstained with acridine orange, acriflavine, or Hoechst and imaged on a benchtop confocal microscope. CLE images at various depths were acquired automatically, compiled, rendered into 3D volumes using Fiji software and reviewed by a neuropathologist and neurosurgeons.

Results: CLE imaging, Z-stack acquisition, and 3D image rendering were performed using 19 mouse gliomas and 31 human tumors, including meningiomas, gliomas, and pituitary adenomas. Volumetric images and Z-stacks provided additional information about fluorescence signal distribution, cytoarchitecture, and the course of abnormal vasculature.

Conclusion: 3D and Z-stack CLE imaging is a unique new option for live intraoperative endomicroscopy of brain tumors. The 3D images afford an increased spatial understanding of tumor cellular architecture and visualization of related structures compared with two-dimensional images. Future application of specific fluorescent probes could benefit from this rapid in vivo imaging technology for interrogation of brain tumor tissue.
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http://dx.doi.org/10.2147/CMAR.S165980DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124793PMC
August 2018

Optical Characterization of Neurosurgical Operating Microscopes: Quantitative Fluorescence and Assessment of PpIX Photobleaching.

Sci Rep 2018 08 22;8(1):12543. Epub 2018 Aug 22.

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

Protoporphyrin IX (PpIX) induced by 5-aminolevulinic acid (5-ALA) is increasingly used as a fluorescent marker for fluorescence-guided resection of malignant gliomas. Understanding how the properties of the excitation light source and PpIX fluorescence interact with the surgical microscope is critical for effective use of the fluorescence-guided tumor resection technique. In this study, we performed a detailed assessment of the intensity of the emitted blue light and white light and the light beam profile of clinical grade operating microscopes used for PpIX visualization. These measurements revealed both recognized fluorescence photobleaching limitations and unrecognized limitations that may alter quantitative observations of PpIX fluorescence obtained with the operating microscope with potential impact on research and clinical uses. We also evaluated the optical properties of a photostable fluorescent standard with an excitation-emission profile similar to PpIX. In addition, we measured the time-dependent dynamics of 5-ALA-induced PpIX fluorescence in an animal glioma model. Finally, we developed a ratiometric method for quantification of the PpIX fluorescence that uses the photostable fluorescent standard to normalize PpIX fluorescence intensity. This method increases accuracy and allows reproducible and direct comparability of the measurements from multiple samples.
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http://dx.doi.org/10.1038/s41598-018-30247-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105612PMC
August 2018

Microvascular anastomosis under 3D exoscope or endoscope magnification: A proof-of-concept study.

Surg Neurol Int 2018 4;9:115. Epub 2018 Jun 4.

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

Background: Extracranial-intracranial bypass is a challenging procedure that requires special microsurgical skills and an operative microscope. The exoscope is a tool for neurosurgical visualization that provides view on a heads-up display similar to an endoscope, but positioned external to the operating field, like a microscope. The authors carried out a proof-of-concept study evaluating the feasibility and effectiveness of performing microvascular bypass using various new exoscopic tools.

Methods: We evaluated microsurgical procedures using a three-dimensional (3D) endoscope, hands-free robotic automated positioning two-dimensional (2D) exoscope, and an ocular-free 3D exoscope, including surgical gauze knot tying, surgical glove cutting, placental vessel anastomoses, and rat vessel anastomoses. Image quality, effectiveness, and feasibility of each technique were compared among different visualization tools and to a standard operative microscope.

Results: 3D endoscopy produced relatively unsatisfactory resolution imaging. It was shown to be sufficient for knot tying and anastomosis of a placental artery, but was not suitable for anastomosis in rats. The 2D exoscope provided higher resolution imaging, but was not adequate for all maneuvers because of lack of depth perception. The 3D exoscope was shown to be functional to complete all maneuvers because of its depth perception and higher resolution.

Conclusion: Depth perception and high resolution at highest magnification are required for microvascular bypass procedures. Execution of standard microanastomosis techniques was unsuccessful using 2D imaging modalities because of depth-perception-related constraints. Microvascular anastomosis is feasible under 3D exoscopic visualization; however, at highest magnification, the depth perception is inferior to that provided by a standard operative microscope, which impedes the procedure.
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http://dx.doi.org/10.4103/sni.sni_36_18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070836PMC
June 2018

Quantitative Anatomic Analysis of the Transcallosal-Transchoroidal Approach and the Transcallosal-Subchoroidal Approach to the Floor of the Third Ventricle: An Anatomic Study.

World Neurosurg 2018 Oct 11;118:219-229. Epub 2018 Aug 11.

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

Objective: To compare transcallosal-transchoroidal and transcallosal-subchoroidal approaches to the ipsilateral and contralateral edges of the floor of the third ventricle using quantitative analyses.

Methods: Five formalin-fixed cadaveric human heads (10 sides) were examined under the operating microscope. Quantitative measurements (area of surgical freedom and angle of attack) were obtained using 3-T magnetic resonance imaging and a StealthStation image guidance system. The limits of the surgical approaches were shown by touching a probe to 6 designated points on the floor of the third ventricle.

Results: The transchoroidal approach provided greater surgical freedom than the subchoroidal approach to access ipsilateral and contralateral middle landmarks at the edges of the floor of the third ventricle in both longitudinal and horizontal planes (P ≤ 0.03). No significant difference between the 2 approaches was found in accessing the anterior and posterior landmarks of the third ventricle in each plane. The surgical freedom to the contralateral anterior, middle, and posterior landmarks was greater than to the ipsilateral landmarks in both the transchoroidal and subchoroidal approaches.

Conclusions: The transcallosal-transchoroidal approach, compared with the transcallosal-subchoroidal approach, may provide better exposure and require less retraction for removal of ipsilateral or contralateral lesions located in the midbrain or hypothalamus and situated near the floor of the third ventricle. The contralateral transcallosal approach with either the transchoroidal or subchoroidal approach may provide good surgical freedom for removal of lesions located near the floor of the third ventricle, such as lesions in the midbrain.
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http://dx.doi.org/10.1016/j.wneu.2018.05.126DOI Listing
October 2018

The oculomotor-tentorial triangle. Part 1: microsurgical anatomy and techniques to enhance exposure.

J Neurosurg 2018 Jun 1:1-9. Epub 2018 Jun 1.

OBJECTIVEAccess to the ventrolateral pontomesencephalic area may be required for resecting cavernous malformations, performing revascularization of the upper posterior circulation, and treating vascular lesions such as aneurysms. However, such access is challenging because of nearby eloquent structures. Commonly used corridors to this surgical area include the optico-carotid, supracarotid, and carotid-oculomotor triangles. However, the window lateral to the oculomotor nerve can also be used and has not been studied. The authors describe the anatomical window formed between the oculomotor nerve and the medial tentorial edge (the oculomotor-tentorial triangle [OTT]) to the ventrolateral pontomesencephalic area, and assess techniques to expand it.METHODSFour cadaveric heads (8 sides) underwent orbitozygomatic craniotomy. The OTT was exposed via a pretemporal approach. The contents of the OTT were determined and their anatomical features were recorded. Also, dimensions of the brainstem surface exposed lateral and inferior to the oculomotor nerve were measured. Measurements were repeated after completing a transcavernous approach (TcA), and after resection of temporal lobe uncus (UnR).RESULTSThe s1 segment and proximal s2 segment of the superior cerebellar artery (SCA) and P2A segment of the posterior cerebral artery (PCA) were the main contents of the OTT, with average exposed lengths of 6.4 ± 1.3 mm and 5.5 ± 1.6 mm for the SCA and PCA, respectively. The exposed length of the SCA increased to 9.6 ± 2.7 mm after TcA (p = 0.002), and reached 11.6 ± 2.4 mm following UnR (p = 0.004). The exposed PCA length increased to 6.2 ± 1.6 mm after TcA (p = 0.04), and reached 10.4 ± 1.8 mm following UnR (p < 0.001). The brainstem surface was exposed 7.1 ± 0.5 mm inferior and 5.6 ± 0.9 mm lateral to the oculomotor nerve initially. The exposure inferior to the oculomotor nerve increased to 9.3 ± 1.7 mm after TcA (p = 0.003), and to 9.9 ± 2.5 mm after UnR (p = 0.21). The exposure lateral to the oculomotor nerve increased to 8.0 ± 1.7 mm after TcA (p = 0.001), and to 10.4 ± 2.4 mm after UnR (p = 0.002).CONCLUSIONSThe OTT is an anatomical window that provides generous access to the upper ventrolateral pontomesencephalic area, s1- and s2-SCA, and P2A-PCA. This window may be efficiently used to address various pathologies in the region and is considerably expandable by TcA and/or UnR.
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http://dx.doi.org/10.3171/2018.1.JNS173139DOI Listing
June 2018

Diagnostic Accuracy of a Confocal Laser Endomicroscope for In Vivo Differentiation Between Normal Injured And Tumor Tissue During Fluorescein-Guided Glioma Resection: Laboratory Investigation.

World Neurosurg 2018 Jul 17;115:e337-e348. Epub 2018 Apr 17.

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

Objective: Glioma resection with fluorescein sodium (FNa) guidance has a potential drawback of nonspecific leakage of FNa from nontumor areas with a compromised blood-brain barrier. We investigated the diagnostic accuracy of in vivo confocal laser endomicroscopy (CLE) after FNa administration to differentiate normal brain, injured normal brain, and tumor tissue in an animal glioma model.

Methods: GL261-Luc2 gliomas in C57BL/6 mice were used as a brain tumor model. CLE images of normal, injured normal, and tumor brain tissues were collected after intravenous FNa administration. Correlative sections stained with hematoxylin and eosin were taken at the same sites. A set of 40 CLE images was given to 1 neuropathologist and 3 neurosurgeons to assess diagnostic accuracy and rate image quality (1-10 scale). Additionally, we developed a deep convolution neural network (DCNN) model for automatic image classification.

Results: The mean observer accuracy for correct diagnosis of glioma compared with either injured or uninjured brain using CLE images was 85%, and the DCNN model accuracy was 80%. For differentiation of tumor from nontumor tissue, the experts' mean accuracy, specificity, and sensitivity were 90%, 86%, and 96%, respectively, with high interobserver agreement overall (Cohen κ = 0.74). The percentage of correctly identified images was significantly higher for images with a quality rating >5 (104/116, 90%) than for images with a quality rating ≤5 (32/44, 73%) (P = 0.007).

Conclusions: With sufficient FNa present in tissues, CLE was an effective tool for intraoperative differentiation among normal, injured normal, and tumor brain tissue. Clinical studies are warranted to confirm these findings.
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http://dx.doi.org/10.1016/j.wneu.2018.04.048DOI Listing
July 2018

Erratum to "Low Retrosigmoid Infratonsillar Approach to Lateral Medullary Lesions" [World Neurosurgery 111 (2018) 311-316].

World Neurosurg 2018 06 3;114:438. Epub 2018 Apr 3.

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

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http://dx.doi.org/10.1016/j.wneu.2018.03.127DOI Listing
June 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

A Rare History: an Intracranial Nail Present for Over a Half-Century.

Acta Medica (Hradec Kralove) 2017;60(3):124-126

Tepecik Research and Training Hospital, Department of Neurosurgery, Izmir, Turkey.

We present a rare case of a patient with a persistent headache for many years found to have an intracranial nail present for nearly 65 years. The nail was found entering approximately 1 cm from the midline on the left side, passing below the superior sagittal sinus, with the tip 1.5 mm right of the frontal horn of the lateral ventricle. Treatment strategies designed to optimize outcome for intracranial foreign bodies and possible complications are discussed in this report. We also discuss the decision for surgical intervention for foreign bodies and the relevance of position of the foreign body.
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http://dx.doi.org/10.14712/18059694.2018.5DOI Listing
April 2018

Low Retrosigmoid Infratonsillar Approach to Lateral Medullary Lesions.

World Neurosurg 2018 Mar 16;111:311-316. Epub 2017 Dec 16.

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

Objective: In our study, we comprehensively detail the technique of the low retrosigmoid approach to the lateral medullary area, including the inferior cerebellar peduncle, postolivary sulcus, pontomedullary sulcus, and inferior olivary nucleus, as well as the lateral recess of the fourth ventricle.

Methods: Four formalin-fixed, silicone-injected, cadaveric human heads were examined under the operating microscope to demonstrate pertinent descriptive anatomy using the low retrosigmoid approach in a stepwise manner. Clinical parameters of a patient with a lateral medullary lesion were reviewed retrospectively to describe preoperative and postoperative examination and surgical details of the approach to the lateral medulla.

Results: The clinical case report describes a low retrosigmoid craniotomy performed to access the exiting points of cranial nerves IX (glossopharyngeal) and X (vagus), foramen of Luschka, inferior cerebellar peduncle (lateral medullary zone), postolivary sulcus, and olivary nucleus. The lesion was exposed using the inferior cerebellar peduncle and removed using standard microsurgical technique.

Conclusions: The lower retrosigmoid infratonsillar approach provides excellent exposure to medullary safe entry zones, including the transolivary, postolivary sulcus, pontomedullary sulcus, and lateral medullary (inferior cerebellar peduncle) zones, for removal of lesions in this area.
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http://dx.doi.org/10.1016/j.wneu.2017.12.064DOI Listing
March 2018

A morphometric and analytical cadaver dissection study of a tumor-simulation balloon model.

J Clin Neurosci 2018 Mar 14;49:76-82. Epub 2017 Dec 14.

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

We quantified the effects on anatomical cadaver dissection of a balloon-inflation tumor model positioned in the parasellar region and approached through an orbitozygomatic (OZ) craniotomy. A modified supraorbital OZ was performed bilaterally on 5 silicon-injected cadaver heads. Ten predetermined anatomical points assigned using a frameless stereotactic device were used to measure the working area of exposure, degree of surgical freedom, and horizontal and vertical angles of attack to specific target points before and after inflation of a balloon catheter mimicking a parasellar tumor. Balloon inflation displaced the central anatomical structures (pituitary stalk, lamina terminalis, anterior chiasm, and internal carotid artery [ICA]-posterior communicating artery and ICA-A1 junctions) by 14-51% (p ≤ .05). With tumor simulation, the vertical angle of attack increased by 67% (p < .01), while the area of exposure increased by 83% (p < .01) and surgical freedom increased by 58% (p < .01). This tumor model also significantly displaced central anatomical sella-associated structures. Compared to a normal anatomical configuration, the tumor simulation (balloon) opened surgical corridors (especially vertical) and acted as a natural retractor, widening the angle of access to the infundibular apex-hypothalamic junction. Although this model cannot exactly mimic a tumor mass in a patient, the effects of tumor compression and sequential displacement of important structures can be combined into and then assessed in a cadaveric neurosurgical anatomical scenario for training and research.
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http://dx.doi.org/10.1016/j.jocn.2017.12.005DOI Listing
March 2018

Anterior temporal artery to posterior cerebral artery bypass for revascularization of the posterior circulation: An anatomical study.

J Clin Neurosci 2018 Jan 27;47:337-340. Epub 2017 Oct 27.

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

We describe a novel intracranial-to-intracranial bypass technique between the anterior temporal artery and the posterior cerebral artery for revascularization of the posterior circulation. Four formalin-fixed human heads were examined to demonstrate the detailed anatomy of the middle cerebral artery and the posterior cerebral artery, and to illustrate the step-by-step bypass procedure. The anterior temporal artery, a branch of the middle cerebral artery, can be anastomosed to the P2 segment of the posterior cerebral artery as an alternative to extracranial bypass donor segments for treatment of complex aneurysms requiring revascularization. The anastomosis of the anterior temporal artery as a pedicled donor to the posterior cerebral artery provides a shorter graft, due to its close anatomical position to the posterior cerebral artery, for posterior circulation revascularization.
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http://dx.doi.org/10.1016/j.jocn.2017.10.047DOI Listing
January 2018

Contralateral anterior interhemispheric-transcallosal-transrostral approach to the subcallosal region: a novel surgical technique.

J Neurosurg 2018 08 3;129(2):508-514. Epub 2017 Nov 3.

3Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona.

OBJECTIVE The authors report a novel surgical route from a superior anatomical aspect-the contralateral anterior interhemispheric-transcallosal-transrostral approach-to a lesion located in the subcallosal region. The neurosurgical approach to the subcallosal region is challenging due to its deep location and close relationship with important vascular structures. Anterior and inferior routes to the subcallosal region have been described but risk damaging the branches of the anterior cerebral artery. METHODS Three formalin-fixed and silicone-injected adult cadaveric heads were studied to demonstrate the relationships between the transventricular surgical approach and the subcallosal region. The surgical, clinical, and radiological history of a 39-year-old man with a subcallosal cavernous malformation was retrospectively used to document the neurological examination and radiographic parameters of such a case. RESULTS The contralateral anterior interhemispheric-transcallosal-transrostral approach provides access to the subcallosal area that also includes the inferior portion of the pericallosal cistern, lamina terminalis cistern, the paraterminal and paraolfactory gyri, and the anterior surface of the optic chiasm. The approach avoids the neurocritical perforating branches of the anterior communicating artery. CONCLUSIONS The contralateral anterior interhemispheric-transcallosal-transrostral approach may be an alternative route to subcallosal area lesions, with less risk to the branches of the anterior cerebral artery, particularly the anterior communicating artery perforators.
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http://dx.doi.org/10.3171/2017.4.JNS16951DOI Listing
August 2018

Quantitative Comparison of Three Endoscopic Approaches to the Parasellar Region: Laboratory Investigation.

World Neurosurg 2017 Dec 5;108:383-392. Epub 2017 Sep 5.

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

Background: Endoscopic endonasal transsphenoidal and contralateral sublabial transmaxillary approaches are used for approaching parasellar lesions. The aim of this anatomical study was to compare endoscopic endonasal uninostril and binostril (contralateral) and contralateral sublabial transmaxillary approaches via a quantitative analysis of exposure limits and instrument working avenues.

Methods: Six formalin-fixed silicone-injected adult cadaveric heads (12 sides) were studied. The surgical working area, depth of the surgical corridor, angle of attack, and surgical freedom were measured and compared for the 3 approaches.

Results: The endoscopic binostril endonasal approach to the parasellar area provided greater surgical freedom in the opticocarotid recess (OCR) and superior orbital fissure (SOF) compared with that of the uninostril endonasal approach (OCR, P < 0.01; SOF, P = 0.01) and the contralateral sublabial transmaxillary approach (OCR, P = 0.01; SOF, P = 0.03). The horizontal and vertical angles of attack with the binostril endonasal approach also were greater than those of the uninostril approach (OCR, P ≤ 0.05; SOF, P ≤ 0.01) and the contralateral transmaxillary approach (OCR, P ≤ 0.01; SOF, P ≤ 0.01). However, the contralateral sublabial transmaxillary approach provided more lateral exposure than the uninostril or binostril endonasal approach to the parasellar area, and it enabled a shorter surgical trajectory to the contralateral parasellar area (P < 0.01).

Conclusions: An anatomical comparison of the 3 endoscopic approaches to the parasellar area showed that the binostril approach provides greater exposure and freedom for instrument manipulation. The contralateral transmaxillary route provided a more lateral view, increasing exposure on average by 48%, with shorter surgical depth; however, surgical freedom was inferior to that of the binostril approach.
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http://dx.doi.org/10.1016/j.wneu.2017.08.180DOI Listing
December 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

C1 lateral mass screw insertion from the caudal-dorsal to the cranial-ventral direction as an alternate method for C1 fixation: A quantitative anatomical and morphometric evaluation.

J Clin Neurosci 2017 Aug 15;42:176-181. Epub 2017 May 15.

Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA. Electronic address:

Object: C1 lateral mass screw has been widely used for fixation of the upper cervical spine. However, traditional fixation methods are not without complication. Morphometric measurement of an alternative approach is conducted.

Methods: Three-dimensional CT scans of the cervical spine obtained in 100 adults were evaluated, and key measurements were determined for screw entry points, trajectories, and screw lengths for placement of a C1 screw via this alternate approach. Additional measures were included to account for relevant anatomic variation, including the size of the dangerous lateral zone of the C1 entry point and depth of the atlantooccipital joint surface. Twenty dried atlantal specimens were evaluated to determine corresponding ex vivo measurements.

Results: The mean maximum angle of medialization was 20.8°±2.8° (right) and 21.1°±2.8° (left), as measured in the axial CT images. Sagittal CT images show the mean maximum superior angulation was 24.7°±4.3° (right) and 24°±4.0° (left), and the mean minimum superior angulation was 13.6°±4.4° (right) and 13.6°±3.9° (left). The mean screw length within the lateral mass was 21.2±1.9mm (right) and 21.3±2.0mm (left). Given an additional 10-15mm needed for rod adaptation, an ideal screw length of 30-35mm was determined.

Conclusion: The C1 insertion caudally from the C2 nerve root may become an alternate method. Preoperative consideration of the ideal screw insertion point, trajectory, and length are vital for safe and effective surgical intervention.
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http://dx.doi.org/10.1016/j.jocn.2017.04.041DOI Listing
August 2017

Cortical Bone Trajectory Screw for Lumbar Fixation: A Quantitative Anatomic and Morphometric Evaluation.

World Neurosurg 2017 Jul 3;103:694-701. Epub 2017 May 3.

Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota, USA.

Background: Lumbar cortical bone trajectory (CBT) screw constructs provide an alternative method of pedicle screw fixation in minimally invasive spine surgery. In this study, we explored the CBT technique in further anatomic detail. The primary aims were to evaluate variations in anatomy relevant to CBT screw placement and to determine optimal screw location, trajectory, and length using measures obtained from computed tomography (CT) scans.

Methods: One hundred CT scans of the lumbar spine were reviewed, and 14 total measurements of entry points, trajectories, and lengths for placement of CBT screws were evaluated.

Results: Across all lumbar levels, the mean right pedicle-pars interarticularis junction length ranged from 7.58 ± 1.18 mm to 8.37 ± 1.42 mm, and the mean left pedicle-pars interarticularis junction length ranged from 7.95 ± 1.42 mm to 8.6 ± 1.74 mm. The pedicle-pars interarticularis junction from L1 to L5 was deemed too small for a 5-mm-diameter CBT screw in 35%, 24%, 17%, 17%, and 19%, respectively, on the right, and in 30%, 17%, 17%, 17%, and 20%, respectively, on the left. The average length of a screw placed along the cranial cortical bone of the pedicle ranged from 27 ± 2.5 mm to 30.5 ± 3.4 mm, and the angle of the screw with respect to the vertebral body endplate ranged from 44 ± 4.1° to 48 ± 6.2°.

Conclusions: Improved anatomic knowledge relevant to CBT screw placement for lumbar fixation offers the potential for improving outcomes and reducing complications. Moreover, detailed analysis of the anatomy of the pedicle-pars interarticularis junction via preoperative CT can aid in determining the ideal fixation method.
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http://dx.doi.org/10.1016/j.wneu.2017.03.137DOI Listing
July 2017

A contemporary framework of language processing in the human brain in the context of preoperative and intraoperative language mapping.

Neuroradiology 2017 Jan 22;59(1):69-87. Epub 2016 Dec 22.

Department of Neurosurgery, University of Minnesota, Minneapolis, MN, USA.

Introduction: The emergence of advanced in vivo neuroimaging methods has redefined the understanding of brain function with a shift from traditional localizationist models to more complex and widely distributed neural networks. In human language processing, the traditional localizationist models of Wernicke and Broca have fallen out of favor for a dual-stream processing system involving complex networks organized over vast areas of the dominant hemisphere. The current review explores the cortical function and white matter connections of human language processing, as well as their relevance to surgical planning.

Methods: We performed a systematic review of the literature with narrative data analysis.

Results: Although there is significant heterogeneity in the literature over the past century of exploration, modern evidence provides new insight into the true cortical function and white matter anatomy of human language. Intraoperative data and postoperative outcome studies confirm a widely distributed language network extending far beyond the traditional cortical areas of Wernicke and Broca.

Conclusions: The anatomic distribution of language networks, based on current theories, is explored to present a modern and clinically relevant interpretation of language function. Within this framework, we present current knowledge regarding the known effects of damage to both cortical and subcortical components of these language networks. Ideally, we hope this framework will provide a common language for which to base future clinical studies in human language function.
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http://dx.doi.org/10.1007/s00234-016-1772-0DOI Listing
January 2017

Transcortical selective amygdalohippocampectomy technique through the middle temporal gyrus revisited: An anatomical study laboratory investigation.

J Clin Neurosci 2016 Dec 4;34:237-245. Epub 2016 Aug 4.

Department of Neurosurgery, University of Minnesota, Mayo Building, 4th floor 420 Deliware St., SE Minneapolis, MN 55455, USA.

The anterior temporal lobectomy (ATL) and selective amygdalohippocampectomy (SelAH) have been used for surgical treatment of mesial temporal lobe epilepsy. We examined the comprehensive white matter tract anatomy of the temporal lobe to gain an insight into the trans-middle temporal gyrus, a lateral approach which has been commonly used. The transmiddle temporal gyrus approach was performed in a stepwise manner on cadaveric human heads to examine the traversing white matter pathways through it and the structures located in the temporal horn. We reviewed the literature to compare the trans-middle temporal gyrus approach with other SelAH techniques based on surgical outcomes. There does not appear to be a significant difference in seizure outcome between SelAH and ATL. However, the SelAH provides a better neuropsychological outcomes than the ATL in selected patients. Each SelAH approach has individual advantages and disadvantages. Based on our anatomical study, in the transcortical amygdalohippocampectomy technique through the middle temporal gyrus the white matter pathways to be encountered. In the temporal horn, the collateral eminence, hippocampus, lateral ventricular sulcus, choroidal fissure, inferior choroidal point, choroid plexus, fimbria of the fornix, and amygdala are exposed. The subpial dissection is performed along the lateral ventricular sulcus from the collateral eminence on lateral side and from the choroidal fissure on medial side by microdissector for en bloc resection of the hippocampus proper. The trans-middle temporal gyrus approach is commonly used in treatment of mesial temporal lobe epilepsy patients. A better anatomical and functional understanding of the structures of the temporal lobe is crucial for safer and more accurate surgery.
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http://dx.doi.org/10.1016/j.jocn.2016.05.035DOI Listing
December 2016

Microsurgical and Tractographic Anatomy of the Supplementary Motor Area Complex in Humans.

World Neurosurg 2016 Nov 28;95:99-107. Epub 2016 Jul 28.

Department of Neurosurgery, University of Minnesota, Minneapolis, Minnesota, USA. Electronic address:

Objective: To evaluate the microsurgical anatomy of the fiber tract connections of the supplementary motor area (SMA) and pre-SMA, and examine its potential functional role with reference to clinical trials in the literature.

Methods: Ten postmortem formalin-fixed human brains (20 sides) and 1 cadaveric head were prepared following Klingler's method. The fiber dissection was performed in a stepwise fashion, from lateral to medial and also from medial to lateral, under an operating microscope, with 3D images captured at each stage. Our findings were supported by in vivo magnetic resonance imaging tractography in 2 healthy subjects.

Results: The connections of the SMA complex, composed of the pre-SMA and the SMA proper, are composed of short "U" association fibers and the superior longitudinal fasciculus I, cingulum, claustrocortical fibers, callosal fibers, corticospinal tract, frontal aslant tract, and frontostriatal tract. The claustrocortical fibers may play an important role in the integration of motor, language, and limbic functions of the SMA complex. The frontostriatal tract connects the pre-SMA to the putamen and caudate nucleus, and also forms parts of both the internal capsule and the dorsal external capsule.

Conclusions: The SMA complex has numerous connections throughout the cerebrum. An understanding of these connections is important for presurgical planning for lesions in the frontal lobe and helps explain symptoms related to SMA injury.
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http://dx.doi.org/10.1016/j.wneu.2016.07.072DOI Listing
November 2016