Surgical Approach to Thalamic Tumors.

Thalamic tumors are deep-seated lesions. Recent improvements in therapeutic approaches and surgical techniques have allowed a more accurate approach to these lesions and a reduction in morbidity and mortality. In this article, the various surgical approaches for the resection of thalamic tumors are described. Each of these approaches has its own indications and risk of complications. Resection of thalamic tumors needs specific anatomical knowledge, especially the vascular anatomy of the region and the thalamic peduncles.

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

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.

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

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.

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

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.

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

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.

Endoscopy-assisted high cervical anterolateral retropharyngeal approach to clivus: a cadaveric study.

Introduction: The surgical management of pathologies involving the clivus and craniocervical junction has always been considered a complex procedure because of the deeply located surgical targets and the surrounding complex neural and vascular anatomical structures. The most commonly used approaches to reach this area are the transnasal, transoral, and transcervical approaches. Material and Methods: This approach was performed unilaterally on five cadaver heads and bilaterally on one cadaver head. Results: We described a modified endoscope-assisted high cervical anterolateral retropharyngeal approach in which each stage of the procedure was demonstrated on human cadavers in a step-by-step manner using endoscopic camera views. This approach was broken down into nine steps. The neurovascular structures encountered at each step and their relationships with each other are demonstrated. Discussion: The advantages and disadvantages of our modified approach were compared to the conventional transcervical, transoral, and endoscopic endonasal approaches.

The parietooccipital interhemispheric transtentorial approach for pineal tumors.

Access to the pineal region has always been a challenge for neurosurgeons. The parietooccipital interhemispheric transtentorial approach is a slight variation of the traditional occipital transtentorial approach that provides adequate exposure to the lesions of the pineal region without introducing additional risks. In this study, the modified parietooccipital interhemispheric transtentorial approach is discussed including step-by-step anatomical cadaveric dissections and operative images. 27 adult patients (age > 18) who were operated over a 30-year period (1992-2022) by the senior author (M.N.P.) at two clinics, Marmara University, Department of Neurosurgery, Istanbul, Turkey and Acibadem Mehmet Ali Aydinlar University, Department of Neurosurgery, Istanbul, Turkey were analyzed. Only pineal region tumors were included in the analysis. Falcotentorial meningiomas and vascular lesions including cavernomas were excluded. 5 cadaveric specimens were dissected step by step following the surgical approach. Each step was documented using a Canon EOS 5D Mark II camera with Canon 100 mm Macro Lens. Step by step images of the dissections were presented including comparison with surgical images. Additional illustrations were used to describe the surgical corridor. The surgical corridor is maintained anterior to the parietooccipital sulcus along the medial of the precuneus. No retraction to the calcarine sulcus resulted in no postoperative hemianopsia. The neurovascular structures along the surgical corridor along with the nuances of the tentorium incision and splenium resection are discussed. The parietooccipital interhemispheric transtentorial approach provides a wide and safe corridor for surgical resection of pineal tumors.

Impact of COVID-19 on interest in pediatric neurosurgery related symptoms, diseases, and treatments.

BACKGROUND: More and more often, patients use online resources to increase their knowledge/confidence in conventional medicine. Thus, the evaluation of the internet search trends may offer an insight into patients' perception of the healthcare system during the pandemic, especially for medical specialties with invasive interventions such as pediatric neurosurgery. METHODS: A total of 140 keywords representing a wide range of pediatric neurosurgery related symptoms/signs, diseases, and treatments were defined. Google Trends tool was queried for the predefined keywords within the United States from January 01, 2016, to November 17, 2020. Two periods in 2020, March 15 to July 4 and July 5 to October 31, were compared with similar periods over the preceding four years (2016-2019). We performed analyses in three sections: symptoms/signs, diseases, and treatments. RESULTS: Public interest has shifted from regular pediatric neurosurgery related symptoms/signs, diseases, and treatments to the ones related with neurological aspects of COVID-19 both in initial and short-term stages of the pandemic. CONCLUSIONS: Google Trends highlights that the link between neurosurgeon/pediatric patients/caregivers needs to be further empowered by growing educational efforts.

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

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.

Neurosurgical follow-up and treatment of a series of 26 WHO grade III meningiomas.

Meningiomas are the most common primary intracranial tumors. They have three pathologic grades. Surgical resection aiming Simpson I resection is the standard treatment for meningiomas. Radiotherapy and Gamma Knife radiosurgery are the main adjuvant and salvage treatments. Chemotherapy has limited use. Grade II, and III meningiomas have a higher recurrence rate, and adjuvant radiotherapy is usually the standard treatment for grade III meningiomas. In this paper, we analyzed our meningioma series of 1401 patients and presented the treatment and follow-up results of 26 grade III meningioma cases. Median follow-up of grade III meningiomas was 40.5 (range, 1-154) months. The mean age of patients was 51.7 ± 15.7 years; 12 of them were female and 14 were male (female/male ratio = 0.9). The median progression-free survival (PFS) of them was 22 months, and overall survival (OS) was 62 months. Meningiomas with gross total resection (GTR), non-skull base meningiomas, and primary grade III meningiomas had longer PFS, while meningiomas with GTR, non-skull base meningiomas, and primary meningiomas had longer OS with a statistical significance.

Treatment and follow-up results of WHO grade II meningiomas.

Meningiomas are the most common primary intracranial tumors. They have three pathologic grades. Surgical resection aiming Simpson I resection is the standard treatment for meningiomas. Radiotherapy and Gamma Knife radiosurgery are the main adjuvant and salvage treatments. Chemotherapy has limited use. Grade II, and III meningiomas have a higher recurrence rate, and adjuvant radiotherapy is usually the standard treatment for grade III meningiomas but there is not a consensus regarding grade II meningiomas. In this paper, we analyzed our meningioma series of 1401 patients and presented the treatment and follow-up results of 170 grade II meningioma cases. The median follow-up of grade II meningiomas was 61 (range = 1-231) months. The mean age of patients was 52.5 ± 15.0 years, 102 of them were female and 68 were male (female/male ratio = 1.5). The median progression-free survival (PFS) of them was 109 months, and the cumulative overall survival (OS) rate was 85% at 10 years. Meningiomas with gross total resection, non-skull base meningiomas, and primary grade II meningiomas had longer PFS with statistical significance, while non-skull base meningiomas, younger group of patients, and primary grade II meningiomas had longer OS with a statistical significance.

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

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.

Could gas-filled pseudocyst mimick extruded disc herniation?

There are case reports and small case series in the literature reporting gas-filled pseudocysts (GFP). However, a systematic review presenting overall view of the disease and its management is still lacking. In the present study, we aimed to make a systematic review of GFP cases, and present an exemplary case of ours. Our second aim was to discuss current theories for pathogenesis of GFP. A systematic review of GFP was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. Two large-scaled data search engines were used. A total of 53 articles were retrieved from the literature and presented with an exemplary case of ours. Mean age of the historical cohort was 59.47 years. There were 66 male (54.1%) and 56 female (45.9%) patients. The most prevalent clinical presentation was radicular sign/symptom in lower limbs with (29.1%) or without low back pain (LBP) (67%). Gas-filled pseudocyst has most commonly been diagnosed at the lower lumbar spine (L4-L5, 45.3%; L5-S1, 37.7%). Surgery was the treatment of choice in most of the patients (80%). In the whole cohort, 79.1% of the patients had complete recovery. Gas-filled pseudocysts are rarely observed in daily practice. They present mostly in men at the age of 60s. Precise differential diagnosis determination using appropriate imaging would help clinicians treat the patients properly. Gas-filled pseudocysts should be treated similarly to other spinal pathologies causing nerve root compression.

Low Retrosigmoid Infratonsillar Approach to Lateral Medullary Lesions.

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.

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

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.

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

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 mm2) 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.

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

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.

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

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.

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

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.

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

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.