Middle Cranial Fossa Approach: The Incudomalleolar Joint as a Reliable Landmark

Abstract Introduction The middle cranial fossa approach is performed by fewer neurotologists owing to a reduced number of indications. Consistent landmarks are mandatory to guide the surgeon in a narrow field. Objectives We have evaluated the incus and malleus head and the incudomalleal joint (IMJ) as a key landmark for identifying the superior semicircular canal (SSC) and to get oriented along the floor of the middle cranial fossa. Methods A combination of 20 temporal bone dissections and CT imaging were utilized to test and describe these landmarks. Results The blue line of the SSC is consistently identified along the prolongation of a virtual line through the IMJ and the angulation toward the root of zygoma. The mean distance from the zygoma toward the IMJ ranged from 1.60 to 1.90cm. Once the IMJ was identified, the blue line of the SSC was consistently found along the virtual line through the IMJ within 5 to 9mm. Conclusions The IMJ is a safe and consistent anatomical marker in the surgical approach to the middle cranial fossa floor. Opening the tegmen 1.5 to 2cm medial to the root of the zygoma and identifying the joint allows to trace a virtual line toward the SSC within 5 to 9mm. Knowledge of the close relationship between the direction of the IMJ and the superior canal can be used in all transtemporal approaches, thus orienting the surgeon in a rather narrow field with limited retraction of the dura and brain.

Morphometric and Topographic Assessment of Foramen Ovale in Skulls of Jharkhand Population

Foramen ovale, situated in the greater wing of sphenoid, posterolateral to the foramen rotundum, transmits the sensory and motor root of mandibular nerve, accessory meningeal artery, emissary vein and lesser petrosal nerve to the infratemporal fossa. The normal shape of the foramen is oval, but its shape and size is quite variable. It plays an important role in the diagnostic and surgical procedures related to the middle cranial fossa. So, knowledge of the variations, dimensions and the topographic location is of importance to the neurosurgeons while dealing with surgeries in this region. Our study aims at finding the morphological variations in shape, dimensions of foramen ovale and its location in relation to the zygomatic arch.METHODSA cross-sectional observational study was carried out over a period of one year from 1/6/2018 to 31/5/2019, on 46 adult human skulls, taken from the department of Anatomy, RIMS, Ranchi. Fully dried, intact, adult human skulls were included in the study. Foramen ovale was observed for variation in shape, size and location. The presence of any accessory bony structure like bony plate, spine or septa was looked for and prevalence noted. The maximum antero-posterior length and width of foramen ovale and its distance from articular tubercle and the anterior root of zygomatic arch were measured using Vernier callipers. Pathologically malformed and damaged skulls were excluded from the study.RESULTSFour types of shapes were observed – oval (76.08%) , almond (5.43%) , semilunar (8.69%) and triangular (9.78%). The mean anteroposterior dimension of foramen ovale was 6.96 ± 1.17 mm (6.89 ± 1.28 mm on the right side & 7.02 ± 1.05 mm on the left side) and the mean transverse dimension was 3.35 ± 0.66 mm (3.25 ± 0.57 mm on the right side, 3.45 ± 0.73 mm on the left side) . The mean distance of foramen ovale from articular tubercle on zygomatic arch was 32.58 ± 1.29 mm (32.41 ± 1.10 mm on the right side, 32.74 ± 1.45 mm on the left side) and from anterior root of zygomatic arch was 24.75 ± 1.70 (23.91 ± 0.85 mm on the right side, 25.59 ± 1.92 mm on the left side).CONCLUSIONSThere is no significant average difference between FO_AP_RT – FO_AP_LT. There is no significant average difference between FO Width_RT - FO_Width_LT. There is a significant average difference between FO to Art. Tubercle Right - FO to Art Tubercle left. There is a significant average difference FO to ant. root Right - FO to ant. root left.

Foramen venoso órbito cavernoso: foramen de Warwick / Cavernous orbital venous foramen: Warwick´s foramen

El foramen de Warwick o foramen venoso órbito cavernoso, es un foramen inconstante del ala mayor del esfenoides, situado entre la fisura orbitaria superior y el foramen rotundo. Comunica la órbita con la fosa craneal media y/o con la fosa pterigopalatina y permitiría el paso de la vena oftálmica inferior. La presencia del foramen venoso órbito cavernoso varía entre el 0,38 % y el 0,74 %. Se describe con forma redondeada o crescéntica (semilunar), unilateral o bilateral. El objetivo de este trabajo fue evidenciar la presencia y las características de foramen venoso órbito cavernoso en cráneos secos de individuos adultos chilenos de ambos sexos. Se analizaron 138 cráneos de individuos adultos y de ambos sexos, en búsqueda del foramen venoso órbito cavernoso para determinar la frecuencia, localización, forma, tamaño, orientación y distancias con respecto a la fisura orbitaria superior y el foramen rotundo. Los forámenes encontrados fueron fotografiados, explorados y medidos. La presencia del foramen venoso órbito cavernoso fue del 2,17 % de la muestra, encontrándose en forma unilateral (1,45 %) y bilateral (0,17 %). Con forma redondeada en 3 casos y semilunar en 1 caso. Con orientación hacia la órbita (2 casos) y hacia la fosa pterigopalatina (2 casos). También se evidenció que cuando está presente el foramen venoso órbito cavernoso, la separación entre la fisura orbitaria superior y el foramen rotundo es mayor que en su ausencia. Nuestro estudio demuestra la presencia del foramen venoso órbito cavernoso en la población chilena, con una frecuencia más alta que la observada en otras poblaciones. La localización, orientación y formas coinciden con la literatura, pero difiere en el tamaño (en forámenes redondeados). También pudimos determinar que la fisura orbitaria superior y el foramen rotundo tienden a encontrarse más cercanos en ausencia del foramen venoso órbito cavernoso y por lo tanto más distante cuando esta estructura está presente. Este hecho no está descrito en la literatura. Los resultados de este estudio son importantes para la anatomía, oftalmología, traumatología, imagenología, cirugía e identificación humana. Finalmente y en virtud de la TAI, proponemos llamar a este foramen, foramen venoso órbito cavernoso.

The Warwick's foramen or cavernous orbital venous foramen, is an inconstant foramen from the greater wing of the sphenoid bone, located between the superior orbital fissure and the rotundum foramen. It connects the orbit with the middle cranial fossa and/or with the pterygopalatine fossa and allows for the passage of the inferior ophthalmic vein. The presence of the cavernous orbital venous foramen varies between 0.38 % and 0.74 % in human skulls. It is described as having a rounded or crescentic (semilunar), unilateral or bilateral shape. The objective of the present work was to demonstrate the presence and characteristics of the cavernous orbital venous foramen in dry skulls of Chilean adult individuals of both sexes. One hundred and thirty-eight adult skulls of both sexes were analyzed in search of the cavernous orbital venous foramen to determine the frequency, location, shape, size, orientation and distances with respect to the superior orbital fissure and the rotund foramen. Found foramina were photographed, explored and measured. The cavernous orbital venous foramen was present in 2.17 % of the sample, and was both unilateral (1.45 %) and bilateral (0.17 %). It had a rounded and lunate shape in 3 and 1 cases, respectively. Moreover, it was orientated towards the orbit (2 cases) and towards the pterygopalatine fossa (2 cases). It was also evidenced that when the cavernous orbital venous foramen is present, the separation between the superior orbital fissure and the rotund foramen is greater than in its absence. Our study demonstrates the presence of the cavernous orbital venous foramen in the Chilean population, with a higher frequency than described previously. The location, orientation and observed forms agree with the literature, but differ in size (in rounded shape foramen). We could also determine that the superior orbital fissure and the rotundum foramen tend to be closer in the absence of the cavernous orbital venous foramen and, therefore, are more distant when this structure is present. This fact is not described in the literature. The results of this study are important for anatomy, ophthalmology, traumatology, imaging, surgery and human identification. Finally, and by virtue of the International Anatomical Terminology (IAT), we propose to call this structure the cavernous orbital venous foramen.

Localization of internal auditory canal in the middle cranial fossa approach: a study in Chinese based on CT reconstruction technique / 上海交通大学学报（医学版）

Objective • To study how to localize the internal auditory canal in the middle cranial fossa approach in Chinese using CT reconstruction technique. Methods • Forty-four cases (88 sides) of normal temporal bone CT data were selected, including 22 males and 22 females. The anatomical structures of the middle cranial fossa including the skull base, the internal auditory canal and the superior semicircular canal were reconstructed in 3D. The angle between great superficial petrosal nerve and internal auditory canal, the angle between superior semicircular canal and internal auditory canal and the osseous thickness above internal auditory canal were measured. The angle and distance were statistically analyzed in different sex and side groups. Results • On the reconstructed 3D middle cranial base, the arcuate eminence could only be identified in 43% cases. The angle between great superficial petrosal nerve and internal auditory canal was 51.46˚±9.28˚; the angle between superior semicircular canal and internal auditory canal was 49.22˚±7.32˚; the osseous thickness above internal auditory canal was (4.38±0.97) mm. No gender or side difference was noticed. Conclusion • There are significant individual differences in angulation and distance between the internal auditory canal and its related anatomical structures. CT reconstruction technique is helpful for accurate localization of the internal auditory canal.

Superior Semicircular Canal Dehiscence Syndrome - Diagnosis and Surgical Management

Abstract Introduction Superior semicircular canal dehiscence syndrome was described by Minor et al in 1998. It is a troublesome syndrome that results in vertigo and oscillopsia induced by loud sounds or changes in the pressure of the external auditory canal or middle ear. Patients may present with autophony, hyperacusis, pulsatile tinnitus and hearing loss. When symptoms are mild, they are usually managed conservatively, but surgical intervention may be needed for patients with debilitating symptoms. Objective The aim of this manuscript is to review the different surgical techniques used to repair the superior semicircular canal dehiscence. Data Sources PubMed and Ovid-SP databases. Data Synthesis The different approaches are described and discussed, as well as their limitations.We also review the advantages and disadvantages of the plugging, capping and resurfacing techniques to repair the dehiscence. Conclusions Each of the surgical approaches has advantages and disadvantages. The middle fossa approach gives a better view of the dehiscence, but comes with a higher morbidity than the transmastoid approach. Endoscopic assistance may be advantageous during the middle cranial fossa approach for better visualization. The plugging and capping techniques are associated with higher success rates than resurfacing, with no added risk of hearing loss.

An osteometric evaluation of the foramen spinosum and venosum / Una evaluación osteométrica de los forámenes espinoso y venoso

The foramen spinosum (FS) and foramen venosum (of Vesalius) (FV) are alisphenoid apertures situated within the hub of the middle cranial fossa in close proximity to foramen ovale (FO). The FS and FV provide a passage to important neurovascular structures. An accurate knowledge of the morphometric details of the FS and FV including their shape, incidence, relation to other foramina and/or presence of any anomalies may represent a reliable anatomical landmark during surgical explorative maneuvers. Therefore, the aim of this study was to investigate the morphologic and morphometric features of the FS and FV. The study was conducted on 100 dry human skulls (n= 200) obtained from the osteological bank at the University of KwaZulu-Natal, to produce a database which may serve as a useful guideline to surgeons and anesthetists. Although single (95%), duplicate (2.5%) and triplicate (0.5%) FS were identified; only single (5%) and duplicate (0.5%) FV were found. Oval (FS: 43.5%; FV: 4.5%) and round (FS: 58%; FV: 0.5%) foramina were observed. In addition, the relationship of the FS and FV to FO was recorded: postero-lateral (FS: 93%; FV: 0%); posterior (FS: 1.9%; FV: 0%); postero-medial (FS: 0.5%; FV: 0%); anterior (FS: 0%; FV: 0.5%); antero-medial (FS: 0%; FV: 4.5%). The mean morphometric parameters of the FS and FV included the internal diameter (FS: 2.53±0.76 mm; FV: 1.93±0.46 mm), external diameter (FS: 2.50±0.74 mm; FV: 2.81±1.53 mm) and distance to the FO (FS: 3.45± 1.29 mm; FV: 2.63±1.24 mm). In light of the morphometric and morphological variations of skull-based foramina, the evaluation of the FS and FV in our study may provide a reliable osteometric reference in clinical practice which may be beneficial during interpretation of imaging and surgical intervention.

El foramen espinoso (FE) y foramen venoso (FV) son aberturas situadas en el centro de la fosa craneal media en las proximidades de un foramen oval permeable (FO). El FE y FV proporcionan el acceso a importantes estructuras neurovasculares. Un conocimiento preciso de los datos morfométricos del FE y FV, incluyendo su forma, incidencia, relación con otros forámenes o presencia de cualquier anomalía puede representar un punto de referencia anatómica fiable durante las maniobras exploratorias quirúrgicas. El objetivo de este estudio fue investigar las características morfológicas y morfométricas del FE y FV. El estudio se realizó sobre 100 cráneos humanos secos (n= 200) obtenidos del banco osteológico de la Universidad de KwaZulu-Natal, para producir una base de datos que pueda servir como guía útil para los cirujanos y anestesistas. Se identificaron FE únicos (95%), dobles (2,5%) y triples (0,5%); junto a FV únicos (5%) y dobles (0,5%). Según forma, se encontraron forámenes de tipo oval (FE: 43,5%; FV: 4,5%) y circular (FE: 58%; FV: 0,5%). Además, se registró la relación entre FE, FV y FO: postero-lateral (FE: 93%; FV: 0%); posterior (FE: 1,9%; FV: 0%); postero-medial (FE: 0,5%; FV: 0%); anterior (FE: 0%; FV: 0,5%) y antero-medial (FE: 0%; FV: 4,5%). Los parámetros morfométricos medios de los FE y FV incluyeron el diámetro interno (FE: 2, 53±0,76 mm; FV: 1,93±0,46 mm), diámetro externo (FS: 2,50±0,74 mm; FV: 2,81±1,53 mm) y distancia al FO (FS: 3,45±1,29 mm; FV: 2,63±1,24 mm). Considerando la morfometría y las variaciones morfológicas de los forámenes en la base del cráneo, la evaluación del FE y FV puede proporcionar una referencia osteométrica fiable en la práctica clínica, que puede ser beneficiosa durante la interpretación imagenológica y la intervención quirúrgica.

Foramen of Vesalius: Prevalence, Morphology, Embryological Basis and Clinical Implications

The objectives of the present study were to find the prevalence of foramen of Vesalius and to discuss its morphology. The embryological basis of this foramen and its surgical highlights are emphasized. The study comprised 78 human adult dried skulls, which were obtained from the anatomy laboratory of our institution. The greater wing of the sphenoid bone was macroscopically observed for the presence of foramen of Vesalius. It was observed that the foramen was present in 29 skulls (37.2%). It was seen bilaterally in 13 (16.7%) skulls and unilaterally in 16 (20.5%) specimens.Anatomical literature has explained the variation of this foramen by the developmental considerations. We believe that the details of this foramen are known to have significant implications for the medical and surgical literature. The details are also enlightening to the clinical anatomists and other broad specialties of medicine.This sphenoidal emissary foramen contains a bridging vein, which connects the pterygoid venous plexus with the cavernous sinus. This communication is clinically important, since an extra cranial infection may sometimes reach the cavernous sinus through this foramen, which may lead to cavernous sinus thrombosis. Foramen of Vesalius can get injured during the trigeminal nerve block technique performed for the trigeminal neuralgia. In this procedure, the foramen can get hurt by a displaced instrument, which would end up in intracranial bleeding, which can spread the extracranal infection into the cavernous sinus. This may lead to serious disorders like Tolosa Hunt and Gradenigo syndromes. Keywords: Foramen ovale, middle cranial fossa, morphology, skull base, sphenoid bone

A Case of Vestibular Schwannoma with Acute Spontaneous Vertigo / 대한이비인후과학회지

Vestibular schwannoma (VS) is a rare benign tumor arising from the vestibular portion of the 8th cranial nerve. Patients with VS complain of diverse symptoms, such as asymmetrical hearing loss, tinnitus, vertigo, and unsteadiness. The most common symptom of VS is unilateral and gradual loss of hearing, which may also be associated with tinnitus. We experienced an unusual case of 62-year-old woman, who presented with acute vertigo without any typical otologic symptoms of hearing loss and tinnitus. Because of the unusual symptom, the patient was initially diagnosed with vestibular neuronitis. However, atypical nystagmus was presented after head shaking test. Internal auditory canal MRI scanning confirmed the diagnosis of VS. We removed the patient's VS by middle cranial fossa approach. We present this case with a review of relevant peer-reviewed medical articles and literature.

A Case of Recurred Cholesteatoma Removal via Middle Cranial Fossa Approach / 대한이비인후과학회지

Cholesteatoma is a benign disease but it has an aggressive feature that may lead to serious conditions. Many strategies have been introduced for the treatment cholesteatoma, yet no definite single method has been established: it should be treated respectively regarding the completion of cholesteatoma, conservation of tympanic mucosa, proper ventilation of middle ear and preservation of hearing. A 25-year old patient visited our clinic for right-sided facial paralysis of 5 days. The patient underwent canal wall down mastoidectomy 10 years ago due to cholesteatoma and a few revision surgeries under local anesthesia for recurrence. Pre-operative temporal bone CT showed suspected recurred cholesteatoma in internal auditory canal and labyrinthine segment of facial nerve nearby. The patient underwent a removal of cholesteatoma via middle cranial fossa approach. This case report is a successful completion of recurred cholesteatoma, for which no recurrence is shown. Facial nerve function is improved at postoperative 1 year.

Preoperative malignant looking retrobulbar, infratemporal and middle cranial fossa tuberculoma in a young child - a case report.

Tuberculosis involving skull base and brain is relatively common in developing countries. Preoperative neuro-radiological features of such lesions mimic neoplastic lesions of brain & skull base and postoperative histopathological study brings the ultimate diagnosis. Here we present a case of large tubercular lesion involving retrobulbar, infratemporal and middle cranial fossa that preoperatively thought to be a malignant lesion in a young child and was managed surgically with anti-tubercular drugs having a happy termination. Even radiologically malignant looking mass lesion in brain and skull base can be proved as tuberculosis that can bring happiness to the patient and also to the treating neurosurgeons.

Trigeminal cave and ganglion: an anatomical review / Cavo y ganglio trigeminal: una revisión anatómica

The trigeminal cave (TC) is a special channel of dura mater, which extends from the posterior cranial fossa into the posteromedial portion of the middle cranial fossa at the skull base. The TC contains the motor and sensory roots of the trigeminal nerve, the trigeminal ganglion (TG) as well as the trigeminal cistern. This study aimed to review the anatomy of the TC and TG and determine some parameters of the TC. The study comprised two subsets: A) Cadaveric dissection on 30 sagitally sectioned formalin fixed heads and B) Volume injection. We found the dura associated with TC arranged in three distinct layers. TC had relations with internal carotid artery, the cavernous sinus, the superior petrosal sinus, the apex of petrous temporal bone and the endosteal dura of middle cranial fossa. The mean volume of TC was 0.14 ml. The mean length and breadth of TG were 18.3 mm and 7.9 mm, respectively, mean width and height of trigeminal porus were 7.9 mm and 4.1 mm, respectively, and mean length of terminal branches from TG to point of exit within skull was variable. An understanding of the precise formation of the TC, TG, TN and their relations is important in order to perform successful surgical procedures and localized neural block in the region of the TC.

El cavo trigeminal (CT) de la duramadre es un conducto especial que se extiende desde la fosa craneal posterior a la parte posteromedial de la fosa craneal media en la base del cráneo. El CT contiene las raíces motoras y sensoriales del nervio trigémino (NT), ganglio trigeminal (GT), así como la cisterna trigeminal. Este estudio tuvo como objetivo examinar la anatomía del CT y GT y para determinar algunos parámetros del CT. El estudio se realizó en dos etapas: A) la disección anatómica de 30 cabezas seccionadas sagitalmente y B) la inyección para estimar volumen. Fueron encontrados tres capas distintas de duramadre asociadas al CT. El CT se relacionó con la arteria carótida interna, el seno cavernoso, el seno petroso superior, el vértice de la porción petrosa del hueso temporal y la dura endosteal de la fosa craneal media. El volumen medio del CT fue de 0,14 ml. La longitud media y la amplitud del GT fueron 18,3 mm y 7,9 mm, respectivamente. La media del ancho y alto del poro trigeminal fueron 7,9 mm y 4,1 mm, respectivamente; la longitud media de las ramas terminales del GT al salir del cráneo fue variable. El conocimiento preciso de la formación del CT, GT, NT y sus relaciones es necesario para realizar procedimientos quirúrgicos exitosos o el bloqueo nervioso localizado en la región del CT.

Repair of Spontaneous Cerebrospinal Fluid Otorrhea from Defect of Middle Cranial Fossa

Spontaneous cerebrospinal fluid (CSF) otorrhea is defined as CSF otorrhea where there are no identifiable causes including previous trauma, surgery, infection, neoplasm or congenital anomaly. The condition is rare. The origin of CSF leak is commonly a defect in the tegmen of the middle cranial fossa. The pathophysiology of spontaneous CSF otorrhea is unclear. Two theories of the etiology of bony defects of the temporal bone are the congenital bony defect theory and arachnoid granulation theory. The authors experienced a case of a 49-year-old female patient admitted with the complaint of persistent right ear fullness. Computed tomography revealed a large defect of the middle fossa and suspicious CSF otorrhea through the defect of tegmen tympani. Repair was successful with multiple bone chips using the transmastoid approach. The postoperative course was good and there has been no recurrence of the CSF leakage.

Anatomic and morphometric consideration for external landmarks of foramen spinosum in Thai dry skulls.

Background and Objectives: The foramen spinosum (FS) is an important opening on the greater wing of the sphenoid bone and transmits the middle meningeal artery to the middle cranial fossa. Because the presence of FS is important in microsurgery of this area, the anatomic and morphometric consideration for localizing the FS using external landmarks were studied. Methods: One hundred and three dry skulls were examined for the FS in the middle cranial fossa and at the extracranial view of the skull base. The type of FS was classified according to its shape. Its diameter and the distances to the zygomatic arch (ZA) and the external acoustic meatus (EAM) were also measured. Results: The FS in both views of the skull base was mostly round in shape (43.2% intracranially and 49.5% extracranially) and was present bilaterally 30.1% extracranially. The maximum and minimum diameters of the FS and the FS-ZA distance were greater in males than females and the ZA-EAM distance was greater on the right than the left sides significantly. (P<0.05) Conclusion: Although a great variation was found in the shapes of the FS, prior estimation of the location of FS was suggested using external landmarks as the point on the ZA 16.42 mm anterior to the EAM and 34.19 mm from that point medial and perpendicular to the ZA. These findings may help neurosurgeon to approach the middle cranial fossa more precisely and gain better preservation of surrounding neurovascular structures.

Prevalencia y características morfométricas del foramen venoso en cráneos del Noreste de México / Prevalence and morphometric characteristics foramen venosum in Northeastern Mexico skulls

El foramen venoso es una estructura inconstante que se encuentra posterior al foramen redondo y medial al foramen oval, y da paso a una vena que anastomosa al plexo venoso pterigoideo con el seno cavernoso. La existencia de éste foramen puede ser motivo de complicaciones clínicas, entre ellas que es una potencial vía de acceso al seno cavernoso de trombos infectados y constituye una posible falsa vía durante la rizotomía percutánea del trigémino pudiendo puncionar la vena y ocasionar hematomas subdurales. Se utilizó la colección de cráneos del Departamento de Anatomía de la Facultad de Medicina UANL. Se observó la frecuencia y se midieron los siguientes parámetros del foramen: Ancho y largo; en la cara interna de la base del cráneo se midieron las distancias a: foramen redondo, foramen oval, plano sagital mediano y entre forámenes venosos; en la cara externa de la base del cráneo se midieron las distancias con: foramen oval, plano sagital medio y entre los forámenes venosos. Las medidas fueron llevadas a cabo por tres observadores distintos a través de medición directa con vernier y con microfotografías con escalas milimétricas. Se encontró una frecuencia del 20 por ciento con medidas medias de 1,66mm de largo, 1,06mm de ancho; en la cara interna de la base del cráneo: 11,31mm de distancia al foramen redondo, 4,13mm al foramen oval, 17,75mm al plano sagital medio y 31,91mm entre los forámenes; en la cara externa de la base: 2,50mm al foramen oval, 19,54mm al plano sagital medio y 36,05mm entre forámenes venoso. La distancia al foramen oval varía en la cara interna y la cara externa de la base del cráneo debido a un trayecto oblicuo del foramen que tiende a aproximarse al foramen oval y por tanto a separarse del plano sagital medio. Los forámenes derechos fueron generalmente más grandes.

Foramen venosum (foramen Vesalius) is an inconstant structure which is located posterior to the foramen rotundum and medial to the foramen ovale, and it gives pace to an emissary vein that communicates the plexus pterigoideus and the sinus cavernosus. The existence of this anatomical structure can be of interest in certain procedures like percutaneous trigeminal rhizotomy where this foramen can be the cause of a false pathway and be punctured causing a subdural hematoma. It also can be an access to the sinus cavernosus for infected thrombus coming from dental and facial infections. For this study the skull collection of the Anatomy Department, Faculty of Medicine UANL, was used. We observed the frequency and measured the following parameters: Length and width; in the basis cranii we measured: Distances to the foramen rotundum, foramen ovale, planum medianum and between two foramina venosum (one on each side). In basis cranii externa we measured: distances to foramen ovale, planum medianum, and between two foramina venosum. Three independent observers blinded among them, measured the parameters using a Vernier and microphotographs with milimetrical scales. A 20 percent frequency was found and the following median measures: Length 1.66mm, width 1.06mm; basis cranii: distance to foramen rotundum 11.31mm, distance to foramen ovale 4.13mm, distance to planum medianum 17.75mm and 31.91mm between both foramina venosum. Basis cranii externa: distance to foramen ovale 2.49mm, distance to planum medianum 19.54mm and distance between foramenina venosum 36.05. The distance to the foramen ovale varies between basis cranii and basis cranii externa because the foramen has an oblique trajectory and it approximates to the foramen ovale (from superior to inferior) and separates from the planum medianum. It was found bilaterally only in one skull. There are differences between the left and right foramens, the latter being generally larger.

Anatomic study to posterior-middle cranial fossa via retrosigmoid keyhole approach / 中华显微外科杂志

@#Objective To explore and evaluate the micro-anatomic structure of posterior-middle cra nial fossa in the retrosigmoid keyhole approach for clinical application. Methods Ten formalin-fixed adult cadaver heads of 20 sides were used to apply the retrosigmoid keyhole approach to reach and observe the structure of posterior-middle cranial fossa.Results The retrosigmoid keyhole approach can reach petroclival region from post-lateral aspect and through this approach the lateral potion of cerebellar hemisphere、petrosal bone,CN Ⅴ,Ⅶ,Ⅷ,part of CN Ⅸ-Ⅻ,lateral potion of pons、vertebral artery and anterior inferior cerebellavar artery can be exposed cleady.Resecting part of supra-tubercle of IAM can enlarge the exposure of IAM and CN V.After cutting off the edge of tentorial part of CN Ⅳ and middle cranial fossa can be exposed.Conclusion Through retrosigmoid keyhole approach we can use the small but compatible bone hole to diminish the ineffective exposure of the cerebellum.Meanwhile the wound because of the approach and complication can be cut down.It's an effective,safe and convenience approach in clinical application to resect the tumor mainly located in posterior cranial fossa.

Microanatomy,histology and CT of arachnoid granulations in middle cranial fossa / 解剖学报

Objective To further improve the morphological materials of AGs by micro-dissection, histology and CT, we observed the arachnoid granulations (AGs) in middle cranial fossa. Methods Thirty-three adult cadaveric heads were used for microsurgical dissection;Histological sections of AG specimens from 3 cadaver heads were examined. Forty patients who had both normal conventional brain CT and computed tomographic venography (CTV) were retrospectively reviewed. Results In middle cranial fossa the AGs occur in the following situations in order of frequency: the middle meningeal sinus, sphenoparietal sinus, lateral foramen rotundum and cavernous sinus. AGs usually show round, oval in shape and irregular in shape. AGs can be divided into individual type and leaflet type under light microscope. The numbers of AGs were observed by microanatomy and CTV were 8.72 and 3.52 respectively. The AGs of cavernous sinus was not localized precisely on CTV. Conclusion Study of the AGs in the middle cranial fossa systematically and comprehensively enriches anatomy and image knowledge. It is helpful in neurosurgical planning and choosing operalion procedure to avoid postoperative complications.

A Case of Vestibular Schwannoma Treated with Revision Middle Cranial Fossa Approach to Preserve Facial Nerve Function and Hearing Ability / 대한이비인후과학회지

The aim of surgery for vestibular schwannoma is to accomplish complete tumor removal while preserving facial function and hearing ability. The middle cranial fossa approach represents one such surgical approach for resection of vestibular schwannoma with hearing preservation. As more experience has been gained with this approach, hearing preservation rates have increased. However, even if gross tumor removal is done completely, residual tumor can show regrowth microscopically. Such residual vestibular schwannoma may be treated by different options. We present a case of residual vestibular schwannoma treated with revision middle cranial fossa approach to preserve facial function and hearing ability.

A Case of Image-Guided Acoustic Neuroma Surgery via Middle Cranial Fossa Approach / 대한이비인후과학회지

Acoustic tumor which originates from the vestibular nerve is the most common neoplasm to be found at the cerebellopontine angle. The surgical approaches currently used for the acoustic tumor are the middle cranial fossa, the translabyrinthine, the suboccipital, and the combined approaches depending on the size, location, and growth rate of the tumor and the hearing level, age, and general health condition of the patient. The complex and variable anatomy and the proximity of important structures encountered during acoustic tumor surgery especially when using the middle cranial fossa approach, may make it a tough job even for the experienced surgeon. Recently, developed image-guided system may be an important step in reducing the incidence of the complication. In the present research, authors used image-guided system during acoustic tumor surgery via middle cranial fossa approach, and with good result.

A Case of Dumbbell-Shaped Facial Nerve Schwannoma of the Internal Auditory Canal / 대한이비인후과학회지

Schwannoma is a benign neoplasm of the nerve sheath and is the most common neoplasm of the internal auditory canal (IAC) and cerebellopontine angle. A dumbbell-shaped schwannoma is defined as a mass with two bulbous segments, one in the IAC fundus and the other in the membranous labyrinth of the inner ear or the geniculate ganglion of the facial nerve connected to labyrinth segment. This kind of schwannoma should not be missed because it can affect the type of surgery and so the prognosis of the patient. We present one case of dumbbell-shaped facial nerve schwannoma which was completely excised without any complication.

Comparative Study on Two Surgical Procedures for Middle Cranial Fossa Arachnoid Cysts / 华中科技大学学报（医学）（英德文版）

In this study, we explored the operation options for middle cranial fossa arachnoid cysts(MCFAC). One hundred and forty-nine patients who were operated for a symptomatic MCFAC between 1993 and 2006 in our hosptial were analyzed. Follow-up time ranged from 1 y to 14 y(mean=5.4 y). All these patients were divided into three subgroups according to Galassi classification.Long-term outcome and complications were studied respectively. Fenestration (F) resulted in a more favorable long-term outcome and less complication for cysts of types Ⅰ and Ⅱ, whereas a favorable outcome was noted in type Ⅲ patients who underwent cysto-peritoneal shunting (S). We are led to conclude that Fenestration is suitable for cysts of types Ⅰ and Ⅱ (Galassi classification),cysto-peritoneal shunting is better for cysts of type Ⅲ.