Olivary body exposure through far lateral and lower retrosigmoid approaches. Comparative analysis of the exposed surface and angle of attack.

OBJECTIVES: Throughout neurosurgical history, the treatment of intrinsic lesions located in the brainstem has been subject of much controversy. The brainstem is the anatomical structure of the central nervous system (CNS) that presents the highest concentration of nuclei and fibers, and its simple manipulation can lead to significant morbidity and mortality. Once one of the safe entry points at the medulla oblongata has been established, we wanted to evaluate the safest approach to the olivary body (the most used safe entry zone on the anterolateral surface of the medulla oblongata). The proposed objective was to evaluate the working channel from the surface of each of the far lateral and retrosigmoid approaches to the olivary body: distances, angles of attack and channel content. MATERIAL AND METHODS: To complete this work, a total of 10 heads injected with red/blue silicone were used. A total of 40 approaches were made in the 10 heads used (20 retrosigmoid and 20 far lateral). After completing the anatomical study and obtaining the data referring to all the approaches performed, it was decided to expand the sample of this research study by using 30 high-definition magnetic resonance imaging of anonymous patients without cranial or cerebral pathology. The reference points used were the same ones defined in the anatomical study. After defining the working channels in each of the approaches, the working distances, angle of attack, exposed surface, and the number of neurovascular structures present in the central trajectory were analyzed. RESULTS: The distances to the cranial and medial region of the olivary body were 52.71 mm (SD 3.59) from the retrosigmoid approach and 27.94 mm (SD 3.99) from the far lateral; to the most basal region of the olivary body, the distances were 49.93 (SD 3.72) from the retrosigmoid approach and 18.1 mm (SD 2.5) from the far lateral. The angle of attack to the caudal region was 19.44° (SD 1.3) for the retrosigmoid approach and 50.97° (SD 8.01) for the far lateral approach; the angle of attack to the cranial region was 20.3° (SD 1.22) for the retrosigmoid and 39.9° (SD 5.12) for the far lateral. Regarding neurovascular structures, the probability of finding an arterial structure is higher for the lateral far, whereas a neural structure will be more likely from a retrosigmoid approach. CONCLUSIONS: As conclusions of this work, we can say that far lateral approach presents more favorable conditions for the microsurgical treatment of intrinsic bulbar and bulbomedullary lesions approached through the caudal half of the olivary body. In those cases of bulbar and pontine-bulbar lesions approached through the cranial half of the olivary body, the retrosigmoid approach can be considered for selected cases.

Vermian subtentorial arteriovenous malformation supplied by the artery of Wollschlaeger and Wollschlaeger.

BACKGROUND: The artery of Wollschlaeger and Wollschlaeger is a tentorial branch of the superior cerebellar artery: due to its small diameter, it is not usually seen in normal angiograms except when enlarged in the setting of a dural AVF or tentorial meningioma. Its presence has been rarely described in the Literature. CASE REPORT: herein we describe the first ever reported case of a vermian subtentorial arteriovenous malformation supplied by the artery of Wollschlaeger and Wollschlaeger in 70 year old female patient. CONCLUSION: vermian subtentorial AVMs supplied by the artery of Wollschlaeger and Wollschlaeger are extremely rare vascular malformations. The presence of the artery of Wollschlaeger and Wollschlaeger must be carefully evaluated during preoperative surgical planning due to its key role in the supply of vascular malformation and to decrease the risk of intra operative bleeding during surgery.

Intra- and extradural anterior clinoidectomy: anatomy review and surgical technique step by step.

PURPOSE: The complex relations of the paraclinoid area make the surgical management of the pathology of this region a challenge. The anterior clinoid process (ACP) is an anatomical landmark that hinders the visualization and manipulation of the surrounding neurovascular structures, hence in certain surgical interventions might be necessary to remove it. We reviewed the anatomical relationships that involve the paraclinoid area and detailed the step-by-step techniques of intra and extradural clinoidectomy in cadaveric specimens. MATERIALS AND METHODS: A literature review was done describing the most relevant anatomic relationships regarding the anterior clinoid process. Extradural and intradural clinoidectomy techniques were performed in six dry bone heads and in ten previously injected cadaverous specimens with colored latex (Sanan et al. in Neurosurgery 45:1267-1274, 1999) and each step of the procedure was recorded using photographic material. Finally, an analysis of the anatomical exposure achieved in each of the techniques used was performed. RESULTS: The main advantage of the intradural clinoidectomy technique is the direct visualization of the neurovascular structures adjacent to the ACP when drilling, at the same time, opening the Sylvian fissure will allow the direct visualization of the ACP variants. The main advantage offered by the extradural technique is that the dura protects adjacent eloquent structures while drilling. Among the disadvantages, it is noted that the same dura that would protect the underlying structures also prevents the direct visualization of these neurovascular structures adjacent to the ACP. CONCLUSION: We reviewed the anatomy of the paraclinoid area and made a step-by-step description of the technique of the anterior clinoidectomy in its intra- and extradural variants in cadaveric preparations for a better understanding.

The Smith-Robinson Approach to the Subaxial Cervical Spine: A Stepwise Microsurgical Technique Using Volumetric Models From Anatomic Dissections.

BACKGROUND: The Smith-Robinson1 approach (SRA) is the most widely used route to access the anterior cervical spine. Although several authors have described this approach, there is a lack of the stepwise anatomic description of this operative technique. With the advent of new technologies in neuroanatomy education, such as volumetric models (VMs), the understanding of the spatial relation of the different neurovascular structures can be simplified. OBJECTIVE: To describe the anatomy of the SRA through the creation of VMs of anatomic dissections. METHODS: A total of 4 postmortem heads and a cervical replica were used to perform and record the SRA approach to the C4-C5 level. The most relevant steps and anatomy of the SRA were recorded using photogrammetry to construct VM. RESULTS: The SRA was divided into 6 major steps: positioning, incision of the skin, platysma, and muscle dissection with and without submandibular gland eversion and after microdiscectomy with cage positioning. Anatomic model of the cervical spine and anterior neck multilayer dissection was also integrated to improve the spatial relation of the different structures. CONCLUSION: In this study, we review the different steps of the classic SRA and its variations to different cervical levels. The VMs presented allow clear visualization of the 360-degree anatomy of this approach. This new way of representing surgical anatomy can be valuable resources for education and surgical planning.

Novel Simulation Model with Pulsatile Flow System for Microvascular Training, Research, and Improving Patient Surgical Outcomes.

BACKGROUND: Simulation allows surgical trainees to acquire surgical skills in a safe environment. With the aim of reducing the use of animal experimentation, different alternative nonliving models have been pursued. However, one of the main disadvantages of these nonliving models has been the absence of arterial flow, pulsation, and the ability to integrate both during a procedure on a blood vessel. In the present report, we have introduced a microvascular surgery simulation training model that uses a fiscally responsible and replicable pulsatile flow system. METHODS: We connected 30 human placentas to a pulsatile flow system and used them to simulate aneurysm clipping and vascular anastomosis. RESULTS: The presence of the pulsatile flow system allowed for the simulation of a hydrodynamic mechanism similar to that found in real life. In the aneurysm simulation, the arterial flow could be evaluated before and after clipping the aneurysm using a Doppler ultrasound system. When practicing anastomosis, the use of the pulsatile flow system allowed us to assess the vascular flow through the anastomosis, with verification using the Doppler ultrasound system. Leaks were manifested as "blood" pulsatile ejections and were more frequent at the beginning of the surgical practice, showing a learning curve. CONCLUSIONS: We have provided a step-by-step guide for the assembly of a replicable and inexpensive pulsatile flow system and its use in placentas for the simulation of, and training in, performing different types of anastomoses and intracranial aneurysms surgery.

The pretemporal trans-cavernous trans-Meckel's trans-tentorial trans-petrosal approach: a combo skill in treating skull base meningiomas.

PURPOSE: Surgical treatments for skull base meningiomas are challenging. We found that most of these lesions (75%), despite locating at the anterior, middle or posterior fossa, could be dealt with a combo skill-the pretemporal trans-cavernous trans-Meckel's trans-tentorial trans-petrosal approach (PCMTP), which adopted the same curvilinear skin incision as for the classic pterional approach. Our aim of this study is to validate the application of this technique in treating skull base meningiomas. METHODS: Patients underwent surgical intervention at our institute during 2010-2018 were retrospectively reviewed. We statistically analyzed the clinical, radiological, and pathological outcomes. RESULTS: In total, 109 patients operated with at least part of the PCMTP combo technique were included. The median follow-up time was 26.6 months. Tumor locations were categorized into: Zone I-sphenoid ridge, olfactory groove, and juxtasellar meningiomas which could be dealt with pterional approach. Zone II-clinoidal and cavernous sinus meningiomas which could be dealt with pretemporal trans-cavernous approach. Zone III-Meckel's and Incisura meningiomas which could be dealt with trans-Meckel's trans tentorial approach. Zone IV-petroclival menigiomas which could be dealt with trans-petrosal approach. When an extensive tumor occupied the anterior, middle, and posterior fossa, the whole combination of the PCMTP technique was applied. The mortality rate is 3.7% (4 patients). Three patients (2.8%) suffered from postoperative deterioration and required occasional assistance. The location of tumor was associated with different Simpson grade removal (p = 0.0015) and resection rate (p < 0.001). CONCLUSION: The PCMTP is effective in treating skull base meningiomas.

Side-to-End Hypoglossal-Facial Neurorrhaphy for Treatment of Complete and Irreversible Facial Paralysis after Vestibular Schwannoma Removal by Means of a Retrosigmoid Approach: A Clinical and Anatomic Study.

BACKGROUND: Facial paralysis secondary to a complete and irreversible anatomic or functional lesion of the facial nerve (FN) causes severe functional and psychological disorders for the patient. A large number of surgical techniques have therefore been developed for FN repair. Our objective was to propose a surgical FN reanimation protocol for patients with irreversible anatomic or functional postsurgical injury of the FN in the cerebellopontine angle after vestibular schwannoma resection. METHODS: The clinical study included a total of 16 patients undergoing side-to-end hypoglossal-facial neurorrhaphy (SEHFN) since 2010, in which the FN injury was always secondary to vestibular schwannoma surgery in the cerebellopontine angle using a retrosigmoid approach. All patients had complete clinical facial paralysis at the time of the SEHFN. The anatomic study was conducted using 3 heads and necks (6 SEHFN). RESULTS: Twelve months after surgery, FN function assessment with the House and Brackmann scale showed 2 patients with grade II, 13 patients with grade III, and only 1 patient with grade IV, and after 2 years, 4 patients had grade II, 11 patients had grade III, and 1 patient had grade IV. The average length of the anastomotic translocation portion of the FN in the anatomic study was 34.76 mm. CONCLUSIONS: Side-to-end epineural suture of the FN, mobilizing its mastoid segment on the hypoglossal nerve with partial section of the dorsal aspect of the hypoglossal nerve, is a safe anatomic surgical technique for FN reanimation with outstanding clinical results.

White Matter Relationships Examined by Transillumination Technique Using a Lateral Transcortical Parietal Approach to the Atrium: Three-Dimensional Images and Surgical Considerations.

BACKGROUND: Numerous lesions are found in the ventricular atrium (VA). Access is gained through many white matter tracts with great relevance and specific neurologic functions. It is important to understand the configuration of the most relevant structures surrounding this zone and, thus, select the safest entry zone on the lateral cerebral surface. OBJECTIVE: We studied the white matter layers traversed in the lateral transcortical parietal approach through the intraparietal sulcus (IPS), adding a transillumination technique. With this knowledge, we selected the safest highway to improve this particular approach. METHODS: An in-depth study of the white matter tracts was performed on 24 cerebral hemispheres (12 human whole brains). The Klingler technique and microsurgical dissection techniques were used under ×6 to ×40 magnification. The transillumination technique (torch illuminating the ventricular cavity) was used to expose the layers surrounding the VA and, thus, guide the dissection. RESULTS: Taking the IPS on the cerebral surface as a reference, we identified the following white matter layers ordered from the surface to the ependyma: U fibers, superior longitudinal fascicle, arcuate fascicle, vertical occipital fascicle, sagittal stratum with the optic radiations, and tapetum fibers. The transillumination technique allowed for the easier identification of the white matter deep periventricular layers. CONCLUSIONS: Knowledge of the main fascicles in the path and neighborhood of the VA allowed us to understand how certain neurologic functions can be affected by lesions at this level and to select the most appropriate way to avoid damaging relevant fascicles.

Microsurgical Anatomy of the Insular Region and Operculoinsular Association Fibers and its Neurosurgical Application.

OBJECTIVE: To analyze the three-dimensional relationships of the operculoinsular compartments, using standard hemispheric and white matter fiber dissection and review the anatomy of association fibers related to the operculoinsular compartments of the Sylvian fissure and the main white matter tracts located deep into the insula. The secondary aim of this study was to improve the knowledge on this complex region to safely address tumor, vascular, and epilepsy lesions with an integrated perspective of the topographic and white matter fiber anatomy using 2D and 3D photographs. METHODS: Six cadaveric hemispheres were dissected. Two were fixed with formalin and the arteries were injected with red latex dye; the remaining four were prepared using the Kingler method and white fiber dissections were performed. RESULTS: The insula is located entirely inside the Sylvian fissure. The topographic hemispheric anatomy, Sylvian fissure, opercula, surrounding sulci and gyri, as well as the M2, M3, and M4 segments were identified. The anatomy of the insula, with the sulci and gyri and the limiting sulci, were also identified and described. The main white matter fiber tracts of the operculoinsular compartments of the Sylvian fissure as well as the main association and commissural fibers located deep in the insula were dissected and demonstrated. CONCLUSIONS: Complementing topographic anatomy with detailed study of white matter fibers and their integration can help the neurosurgeon to safely approach lesions in the insular region, improving postoperative results in the microsurgical treatment of aneurysmal lesions, insular tumors, or epilepsy surgery.

Variabilidad pronóstica del meningioma atípico con resección completa. Propuesta de algoritmo de tratamiento / Prognostic variability in atypical meningioma with complete resection. Proposed treatment algorithm

Objetivo: Los autores pretenden evidenciar que los factores pronósticos actuales que intentan evaluar el riesgo de recidiva de los meningiomas atípicos se muestran insuficientes para predecir el devenir de dicha patología. Material y método: Mediante los datos obtenidos de las bases de datos hospitalarias se adquiere una muestra de 27 pacientes con un diagnóstico anatomopatológico de meningioma atípico, con un tiempo mínimo de seguimiento de 6meses tras el diagnóstico. Posteriormente se evalúan los factores pronóstico (edad < 50años, sexo masculino, afectación ósea, edema perilesional, volumen tumoral, localización, Ki67/MIB-1) tras la estratificación de los pacientes sometidos a resección completa en recidivantes y no recidivantes. El análisis univariante se realiza mediante test de Mann-Whitney, test χ2 de homogeneidad/test exacto de Fisher. Finalmente se realiza el análisis multivariante mediante regresión logística binaria, obteniéndose los valores correspondientes a la R2 de Nagelkerke y el test de Hosmer-Lemeshow para evaluar la bondad del ajuste. Resultados: Los análisis uni y multivariante no muestran diferencias estadísticamente significativas entre los subgrupos recidivante y no recidivante de los pacientes sometidos a resección completa. Como resultado destacable se objetiva que por cada año de edad por encima de los 50años se disminuye el riesgo de recidiva un 5,8%. Conclusiones: Aunque los factores pronósticos actuales puedan mostrar un incremento del riesgo de recidiva una vez se estratifica a los pacientes por los 2 factores más importantes (anatomía patológica y grado de resección), dichos factores se muestran insuficientes para predecir el pronóstico final de los pacientes afectos por dicha patología

Objective: The authors attempt to show how the current prognostic factors that try to assess the risk of recurrence of atypical meningiomas are insufficient to predict the future of this disease. Materials and method: Using data obtained from hospital databases, a sample of 27 patients was obtained with pathological diagnosis of atypical meningioma, and who had a minimum follow-up time of 6months after diagnosis. Later prognostic factors (age <50years, male gender, bone involvement, peri-lesional swelling, tumour volume, location, Ki67/MIB-1) were evaluated after the stratification of patients undergoing complete resection in recurrencies and non-recurrencies. Univariate analysis was performed using Mann-Whitney test, χ2 homogeneity test/Fisher exact test. Finally, multivariate analysis was performed using binary logistic regression to obtain the values for R2 Nagelkerke and the Hosmer-Lemeshow to evaluate the goodness of fit. Results: The uni- and multivariate analysis showed no statistically significant differences between recurrent and non-recurrent subgroups of patients undergoing complete resection. It is noted in the results that for each year of age above 50years, the risk of recurrence is decreased by 5.8%. Conclusions: Although current prognostic factors may show an increased risk of recurrence once patients are stratified by the two most important factors (pathology and extent of resection), those factors are insufficient to predict the ultimate outcome of patients affected by this pathology

The cochlea in skull base surgery: an anatomy study.

OBJECTIVE The object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea. METHODS Twenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40. RESULTS The cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial nerve and greater petrosal nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem. CONCLUSIONS An understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.

[Prognostic variability in atypical meningioma with complete resection. Proposed treatment algorithm]. / Variabilidad pronóstica del meningioma atípico con resección completa. Propuesta de algoritmo de tratamiento.

OBJECTIVE: The authors attempt to show how the current prognostic factors that try to assess the risk of recurrence of atypical meningiomas are insufficient to predict the future of this disease. MATERIALS AND METHOD: Using data obtained from hospital databases, a sample of 27 patients was obtained with pathological diagnosis of atypical meningioma, and who had a minimum follow-up time of 6months after diagnosis. Later prognostic factors (age <50years, male gender, bone involvement, peri-lesional swelling, tumour volume, location, Ki67/MIB-1) were evaluated after the stratification of patients undergoing complete resection in recurrencies and non-recurrencies. Univariate analysis was performed using Mann-Whitney test, χ(2) homogeneity test/Fisher exact test. Finally, multivariate analysis was performed using binary logistic regression to obtain the values for R(2) Nagelkerke and the Hosmer-Lemeshow to evaluate the goodness of fit. RESULTS: The uni- and multivariate analysis showed no statistically significant differences between recurrent and non-recurrent subgroups of patients undergoing complete resection. It is noted in the results that for each year of age above 50 years, the risk of recurrence is decreased by 5.8%. CONCLUSIONS: Although current prognostic factors may show an increased risk of recurrence once patients are stratified by the two most important factors (pathology and extent of resection), those factors are insufficient to predict the ultimate outcome of patients affected by this pathology.

[Transzygomatic pterional approach. Part 1: anatomical study]. / Abordaje pterional transcigomático. Parte 1: estudio anatómico.

OBJECTIVE: Cadaveric study of the anatomical structures of the temporal region, as well as the technical aspects of the transzygomatic pterional approach. MATERIAL AND METHODS: Six human formalin-fixed heads, whose arterial circulatory system was injected with red-dyed silicone, were studied (12 temporal regions). Dissections were performed using standard microsurgical techniques and instruments. RESULTS: We confirm the existence of a double superficial and deep layer within the superficial temporal fascia, which makes possible to perform the zygomatic arch osteotomy without damaging the temporal muscle and the branches of the superficial temporal artery and the facial nerve. The shape and location of the osteotomies to preserve the témporo-mandibular joint and ligaments and to provide correct reconstruction of the bone flap are described. We compare the exposure of intracranial structures obtained by this approach with those obtained by the conventional pterional approach and the orbitozygomatic approach. CONCLUSIONS: The transzygomatic pterional approach provides wide exposure of the temporal lobe for trans-sylvian, pre-temporal and/or subtemporal approaches in selected cases of neurosurgical pathology. A detailed anatomical knowledge of the temporal region is necessary to achieve the best surgical, functional and cosmetic results.

[Transzygomatic pterional approach. Part 2: Surgical experience in the management of skull base pathology]. / Abordaje pterional transcigomático. Parte 2: Experiencia quirúrgica en la patología de base de cráneo.

OBJECTIVES: To present our experience with the transzygomatic pterional approach in the treatment of neurosurgical pathology of the base of the skull located in the middle cranial fossa and surrounding areas. METHOD: A retrospective study of pathological findings, surgical outcomes and complications in a series of 31 cases operated on between 2009 and 2011 using a transzygomatic pterional approach. RESULTS: The lesions involved the sphenoid wing (25.9%), several regions due to invasive growth pattern (19.5%), the temporal lobe (16.1%) and cavernous sinus (12.9%). The others were located in the floor of the middle fossa, Meckel's cave, incisural space, cisterns and infratemporal region. The pathological nature of the lesions was: benign meningioma (42%), temporal lobe tumour (19.5%), vascular disease (12.9%), inflammatory lesions (6.4%), atypical meningioma (6.4%), epidermoid cyst (6.4%), neurinoma (3.2%) and poorly differentiated infratemporal carcinoma (3.2%). The approach was usually combined extra-intradural (58.1%) and, less frequently, just extradural (16.1%) or intradural (25.8%). Approach-related complications were minor: haematomas in the wound not requiring treatment (67.8%), superior transient facial paresis (9.7%), transient temporomandibular joint dysfunction (12.9%) and atrophy of the temporal muscle (16.2%). There were no hardware-related complications or cosmetic issues related to the osteotomy and posterior osteosynthesis of the zygomatic arch. CONCLUSIONS: The pterional approach combined with osteotomy of the zygomatic arch allows mobilising the temporalis muscle away from the temporal fossa, consequently exposing its entire surface to complete the temporal craniotomy up to the middle fossa; it helps to access and treat pathology in this region or it can be used as a corridor to approach surrounding areas.

Abordaje pterional transcigomático. Parte 2: Experiencia quirúrgica en la patología de base de cráneo / No disponible

Objetivos Exponer la experiencia con el abordaje pterional transcigomático en el tratamiento de la patología neuroquirúrgica de la base de cráneo situada en la fosa craneal media y zonas vecinas. Material y método Estudio retrospectivo de la patología, resultados quirúrgicos y complicaciones obtenidos en 31 casos intervenidos entre 2009 y 2011 usando un abordaje pterional transcigomático. Resultados Se han intervenido lesiones del ala del esfenoides (25,9%), afectando varias regiones por su crecimiento invasivo (19,5%), del lóbulo temporal (16,1%) y del seno cavernoso (12,9%), involucrando el resto al suelo de la fosa media, cavum de Meckel, región incisural, cisternas y región infratemporal. La naturaleza de las lesiones intervenidas fue la siguiente: meningioma benigno (42%), tumor parenquimatoso (19,5%), patología vascular (12,9%), lesiones inflamatorias (6,4%), meningioma atípico (6,4%), tumor epidermoide (6,4%), neurinoma (3,2%) y carcinoma pobremente diferenciado infratemporal (3,2%). La mayor parte de las veces el abordaje fue combinado extra-intradural (58,1%), y con menor frecuencia extradural (16,1%) o intradural (25,8%) puro. Las complicaciones relacionadas con el abordaje fueron menores: hematomas en la herida que no requirieron tratamiento (67,8%), paresia facial superior transitoria (9,7%), de disfunción transitoria de articulación temporomandibular (12,9%) y atrofia del músculo temporal (16,2%). No hubo ningún caso de aflojamiento de material ni problemas estéticos relacionados con la osteotomía y osteosíntesis del arco cigomático. Conclusiones La modificación del abordaje pterional asociando una osteotomía del arco cigomático, que permite rebatir el músculo temporal de toda la fosa temporal y exponer así toda su superficie para completar la craneotomía temporal hasta la base de la fosa media, nos facilita el acceso para tratar patología de la misma o utilizarla como corredor para el acceso a zonas vecinas (AU)

Abordaje pterional transcigomático. Parte 1: estudio anatómico / Transzygomatic pterional approach. Part 1: anatomical study

Objetivo: Estudio cadavérico de las estructuras anatómicas de la región temporal, así como de los aspectos técnicos del abordaje pterional transcigomático. Material y métodos: Fueron utilizados 6 especímenes cadavéricos (12 regiones temporales) previamente formolizados, cuyo sistema circulatorio arterial fue inyectado con silicona teñida de rojo. Las disecciones se realizaron utilizando el instrumental y la técnica microquirúrgica estándar. Resultados: Se confirma la existencia de una doble capa superficial y profunda en la fascia temporal superficial, lo que permite la osteotomía cigomática respetando la integridad del músculo temporal y de las ramas de la arteria temporal superficial y del nervio facial. Se detallan las líneas de la osteotomía para preservar la articulación témporo-mandibular y una correcta reposición del colgajo óseo. La exposición de estructuras intracraneales obtenida mediante dicho abordaje se compara favorablemente con aquellas obtenidas mediante el abordaje pterional convencional y el abordaje órbito-cigomático. Conclusiones: El abordaje pterional transcigomático ofrece una amplia exposición del lóbulo temporal para la realización de abordajes transsilvianos, pretemporales y/o subtemporales en casos seleccionados de patología neuroquirúrgica. Es necesario un detallado conocimiento anatómico de la región temporal para obtener los mejores resultados quirúrgicos, estéticos y funcionales (AU)

Objective: Cadaveric study of the anatomical structures of the temporal region, as well as the technical aspects of the transzygomatic pterional approach. Material and methods: Six human formalin-fixed heads, whose arterial circulatory system was injected with red-dyed silicone, were studied (12 temporal regions). Dissections were performed using standard microsurgical techniques and instruments. Results: We confirm the existence of a double superficial and deep layer within the superficial temporal fascia, which makes possible to perform the zygomatic arch osteotomy without damaging the temporal muscle and the branches of the superficial temporal artery and the facial nerve. The shape and location of the osteotomies to preserve the témporo-mandibular joint and ligaments and to provide correct reconstruction of the bone flap are described. We compare the exposure of intracranial structures obtained by this approach with those obtained by the conventional pterional approach and the orbitozygomatic approach. Conclusions: The transzygomatic pterional approach provides wide exposure of the temporal lobe for trans-sylvian, pre-temporal and/or subtemporal approaches in selected cases of neurosurgical pathology. A detailed anatomical knowledge of the temporal region is necessary to achieve the best surgical, functional and cosmetic results (AU)

Microsurgical Relations between Internal Carotid Artery-Posterior Communicating Artery (ICA-PComA) Segment Aneurysms and Skull Base: An Anatomoclinical Study.

Purpose The study of the clinical, anatomic, imaging, and microsurgical characteristics of the aneurysms of the internal carotid-posterior communicating artery (ICA-PComA) segment and their relationships with the skull base structures. Methods The anatomic relationships of PComA with neurovascular elements and skull base structures were studied in cadavers. The clinical, imaging, and microsurgical findings of 84 microsurgically treated ICA-PComA aneurysms compiled in a prospective database were reviewed. Results The most important anatomic relations of the PComA and ICA-PComA aneurysms are with the oculomotor nerve around the oculomotor triangle that forms the roof of the cavernous sinus. Aneurysms of the ICA-PComA are classified according to the orientation of the aneurysmal sac in infratentorial, supratentorial, and tentorial. Infratentorial aneurysms frequently present with subarachnoid hemorrhage (SAH) and oculomotor nerve paralysis. They have relations with skull base structures that often make it necessary to totally or partially resect the anterior clinoid process (6.7%) or anterior petroclinoid dural fold (15%). Supratentorial aneurysms course with SAH and without oculomotor nerve involvement, but they often are associated with intracranial hematoma. Conclusion ICA-PComA aneurysms have complex anatomic relations. The orientation of the aneurysmal fundus induces relevant differences in the anatomic relations, clinical presentation, and microsurgical approach to ICA-PComA aneurysms.