Evaluation of inner ear damage by mastoid drilling with measurement of serum prestin (SLC26A5) levels.

OBJECTIVE: The objective of this study is to demonstrate any inner ear injury caused by drilling in mastoid surgery with prestin, outer hair cell motor protein specific to the cochlea. METHODS: The patients with chronic otitis media requiring mastoidectomy (n = 21) and myringoplasty (n = 21) were included. Serum prestin level obtained from blood samples was measured before surgery and on postoperative days 0, 3, and 7 using Human Prestin (SLC26A5) ELISA Kit. All patients underwent the Pure Tone Audiometry (PTA) test before surgery and on the postoperative 7th day. The drilling time was also recorded for all patients who underwent mastoidectomy. RESULTS: In both mastoidectomy and myringoplasty groups, the postoperative serum prestin levels increased on days 0 and 7 (pday-0 = 0.002, pday-7 = 0.001 and pday-0 = 0.005, pday-7 = 0.001, respectively). There was no significant difference in the serum prestin levels between the two groups, postoperatively. The PTA thresholds at day 7 did not change in either group. A significant decline at 2000 Hz of bone conduction hearing threshold in both groups and a decline at 4000 Hz in the myringoplasty group were found. There was no correlation between the drilling time and the increase of prestin levels in the postoperative day 0, 3, and 7. CONCLUSION: Our results showed that mastoid drilling is not related to a significant inner ear injury. Although the myringoplasty group was not exposed to drill trauma, there was a similar increase in serum prestin levels as the mastoidectomy group. Also, a significant decline at 2000 Hz of bone conduction hearing threshold in both groups and a decline at 4000 Hz in the myringoplasty group were found. These findings suggest that suction and ossicular manipulation trauma can lead to an increase in serum prestin levels and postoperative temporary or permanent SNHL at 2000 and 4000 Hz. LEVEL OF EVIDENCE: Level-4.

Anatomical and Clinical Evaluation of Tympanic Tegmen and Mastoid Bone with Multidetector Computed Tomography / Evaluación Anatómica y Clínica del Tegmen Timpánico y Hueso Mastoideo con Tomografía Computarizada Multidetector

SUMMARY: Tegmen level and mastoid bone thickness are important parameters of surgical risk in middle ear and mastoid region surgeries. This retrospective cohort study was conducted to provide a risk classification for the mastoid and middle ear regions. The study population comprised of 300 patients who underwent multidetector computed tomography (MDCT) for various indications. Patients with no pathology that disrupted the structure of the temporal region were included in the study. A risk classification was generated by analyzing the data obtained from mastoid and tympanic tegmen depths and the mastoid bone thickness by MDCT. The mastoid and tympanic tegmen were lower on the right side than on the left. In women, the right-sided mastoid bone thickness and mastoid tegmen were lower, and low-level tympanic and mastoid tegmen on the left and thin right mastoid bones were more common. According to the risk classifications for mastoid and middle ear region surgeries, women demonstrated a higher risk than men. In addition, as the thickness of the mastoid bone increased, the levels of the mastoid and tympanic tegmen increased. The present study provides a proper risk classification that may be helpful for preoperative risk assessment prior to middle ear and mastoid region surgery.

El nivel del tegmen y el grosor del hueso mastoideo son parámetros importantes del riesgo quirúrgico en las cirugías del oído medio y la región mastoidea. Este estudio de cohorte retrospectivo se llevó a cabo para proporcionar una clasificación del riesgo en las regiones mastoidea y del oído medio. La población de estudio estuvo compuesta por 300 pacientes que se sometieron a una tomografía computarizada multidetector (MDCT) por diversas indicaciones. Se incluyeron en el estudio pacientes sin patología que alterase la estructura de la región temporal. Se generó una clasificación de riesgo analizando los datos obtenidos de las profundidades del tegmen mastoideo y timpánico y el grosor del hueso mastoideo por TCMD. El tegmen mastoideo y timpánico estaban más bajos en el lado derecho que en el izquierdo. En las mujeres, el grosor del hueso mastoideo del lado derecho y el tegmen mastoideo eran más bajos, y eran más frecuente la presencia de tegmen timpánico y mastoideo de bajo nivel en los huesos mastoideos izquierdo y delgados en el lado derecho. Según las clasificaciones de riesgo de las cirugías de la región mastoidea y del oído medio, las mujeres presentaban un mayor riesgo que los hombres. Además, a medida que aumentaba el grosor del hueso mastoides, aumentaban los niveles del tegmen mastoideo y timpánico. El presente estudio proporciona una clasificación de adecuada de riesgo que puede ser útil para la evaluación preoperatoria del riesgo antes de la cirugía del oído medio y la región mastoidea.

Anatomy of the mastoid triangle and morphometric sex differences.

OBJECTIVE OF THE STUDY: This study aimed to quantify the area of the mastoid triangle (MT) and assess potential morphometric differences between males and females. PATIENTS: The sample consisted of 244 dry human skulls, with biological sex known based on genetic analysis, collected from a medicolegal osteological database from Central-Western Brazil. MATERIALS AND METHODS: The study was observational, analytical, and cross-sectional. The skulls were analyzed using Heron's equation to calculate the area of the MT. The landmarks connecting each of the sides of the triangle were: Porion (Po)>Mastoidale (Ma)>Asterion (Ast). Morphometric references were calculated and compared based on sex. RESULTS: The area of the MT was nearly 14% larger in males compared to females (p<0.05). The mean MT area for the right and left sides of males were 684.11±93.25mm2 and 668.94±111.95mm2, respectively. In females, the mean MT for the right and left sides were 588.93±91.09mm2 and 582.88±102.98mm2, respectively. Right and left side measurements were significantly different (p<0.05), except for Po-Ast (p=0.232). CONCLUSION: Morphometric features regarding the MT were slightly different between males and females. Application of the MT as a dimorphic tool should be adjuvant. Moreover, this tool should be considered carefully, especially because the sex-based differences were statistically significant, but discrete between males and females.

Critical analysis of moderate and severe retractions in the pars tensa and pars flaccida of the tympanic membrane.

OBJECTIVES: Analyze the prevalence of retractions in different areas of the Tympanic Membrane (TM), the correlations between the involvement of the Pars Tensa (PT) and Pars Flaccida (PF), and the air-bone gaps. METHODS: A cross-sectional study. Patients with moderate and/or severe TM retraction of 2200 consecutive patients with chronic otitis media between August 2000 and January 2019 were included. Ears with previous surgery were excluded. Ears were classified as isolated PF and PT retractions and association of both. The degrees of severity and presence of effusion were evaluated. The data were analyzed using the SPSS Statistics software program. RESULTS: 661 ears were included. The prevalence of isolated atical retractions was 24.9%, of isolated posterior quadrants was 10.6%, and of association of quadrants was 64%. There was no correlation between the retractions in the different areas of the TM (posterior and attic quadrants: r = 0.13; p = 0.041; anterior and posterior quadrants: r = 0.23; p = 0.013, anterior and attic quadrants: r = 0.06; p = 0.043). Effusion was present in 30.7% of the ears. ABG median was lower in ears with PF retraction (6.25 dB HL) than PT retraction, isolated (15 dB HL) or not (13.75 dB HL; p < 0.05); 72% of the ears had an ABG ≤ 20 dB HL. For severity of the retraction of PF, the ABG was similar across groups. For the PT, there was a global difference in the medians of ABG in terms of the degree of severity, with a moderate correlation. CONCLUSION: The prevalence of moderate and severe retractions was 24.5%; 64% of the ears had an association of affected regions. There was no correlation between the retraction in the different areas of the TM. We found a significant correlation between the severity of retraction and the worsening of ABG threshold, only for PT. EVIDENCE LEVEL: 4.

Transmastoid exposure of the labyrinthine segment of the facial nerve: an anatomical study.

INTRODUCTION: Compression of the labyrinthine segment of the facial nerve by edema has been considered as an important pathology in the majority of the cases of idiopathic facial nerve paralysis. Hence, it is suggested that total decompression of the facial nerve should also include the labyrinthine segment by a middle fossa approach. However, the middle fossa approach requires craniotomy and temporal lobe retraction, which increases the morbidity. The labyrinthine segment of the facial nerve can also be reached through mastoidectomy. However, many ear surgeons are not familiar with this approach due to the lack of anatomical data on this surgical area. OBJECTIVE: To study the anatomical limitations of decompression of the labyrinthine segment via transmastoid approach. METHODS: Complete mastoidectomy was performed in six adult cadavers heads. Dissection was extended in the zygomatic root and posterior bony wall of the external auditory canal to visualize the incudomallear joint completely. The bone between tympanic segment, lateral and superior semicircular canal's ampullas and middle fossa dural plate was removed. Fine dissection was carried out over tympanic segment of the facial nerve in an anterosuperomedial direction the labyrinthine segment was reached. RESULTS: All the mastoids were well pneumatized. Distances between the labyrinthine segment and middle fossa dura, and between the labyrinthine segment and superior semicircular canal, were 2.5 and 4.5 mm on average, respectively. In addition, distances between the middle fossa dura and dome of the lateral semicircular canal, and between the middle fossa dura and tympanic segment were 4.6 mm and 4.3 mm on average, respectively. CONCLUSION: It is possible to expose the labyrinthine segment of the facial nerve through mastoidectomy by dissecting the bone in the area between the tympanic segment of the facial nerve, middle fossa dural plate and ampullary ends of the lateral and superior semicircular canals.

Determination of age and sex using bimastoid diameter: a cone beam computed tomography Study / Deteminación de la edad y el sexo mediante el diámetro bimastoide: un estudio en tomografía computarizada de haz cónico (CBCT)

Abstract This study aimed to investigate the possibility of age and sex determination using bimastoid diameter with cone-beam computed tomography (CBCT). This retrospective study investigated 100 female and 100 male patients aged 18-83 years (mean age: 45.55±16.28 years). To measure bimastoid diameter, the appropriate image was chosen from sagittal, coronal, and axial images of CBCT in which the measurement points could be best detected. The distance between the points of the mastoid process was measured using three-dimensional coronal reconstruction. The mean bimastoid breadth was 106.12±6.22mm. The bimastoid diameter in male cases was higher than that in female cases (110.69±4.53mm vs. 101.65±4.00mm). There was no significant difference in bimastoid breadth with advancing age. For sex determination, morphometric measurements of bimastoid diameter ensured a high rate of dimorphism in the Turkish subpopulation. CBCT morphometric analysis may be reliable and convenient for evaluating sex and may be recommended to compare population data.

Resumen Este estudio tuvo como objetivo investigar la posibilidad de determinar la edad y el sexo utilizando el diámetro bimastoideo con tomografía computarizada de haz cónico (CBCT). Este estudio retrospectivo investigó a 100 mujeres y 100 hombres de entre 18 y 83 años (edad media: 45,55±16,28 años). Para medir el diámetro bimastoideo, se eligió la imagen adecuada de las imágenes sagital, coronal y axial de CBCT en las que los puntos de medición se podían detectar mejor. La distancia entre los puntos del proceso mastoideo se midió mediante reconstrucción coronal tridimensional. La amplitud media del bimastoide fue de 106,12± 6,22mm. El diámetro del bimastoide en los casos masculinos fue mayor que en los casos femeninos (110,69±4,53 mm frente a 101,65±4,00mm). No hubo diferencias significativas en la amplitud del bimastoide con la edad. Para la determinación del sexo, las mediciones morfométricas del diámetro bimastoide aseguraron una alta tasa de dimorfismo en la subpoblación turca. El análisis morfométrico CBCT puede ser confiable y conveniente para evaluar el sexo y puede recomendarse para comparar datos poblacionales.

Temporal bone pneumatization: A scoping review on the growth and size of mastoid air cell system with age.

The interest in the mastoid air cell system arose from the association between temporal bone aeration and otitis media. Its size and growth have been considered when planning chronic and middle ear surgeries. The objective of this review was to explore the literature on the size of mastoid air cells with age, highlighting various growth rates reported and mapping out areas yet to be fully understood for further research. A three-step systematic search was conducted for available literature on the subject matter viz; Google Scholar, Medline, Cochrane Library, and PubMed. Eligibility criteria guided the study selection, and eligible studies were subjected to appraisal using screening and quantitative criteria of mixed-method appraisal tool. A data extraction form was developed to extract information from eligible studies. Nine studies met the eligibility criteria. 55.6% of the included studies were conducted among the east and south Asian population, 33.3% were conducted among Scandinavians, and 11.1% in South America. Age groupings varied among studies; 33.3% utilized 1-year age grouping, 33.3% utilized 5-year age grouping, 11.1% utilized 10-year age grouping. In reporting the size of mastoid air cells across age groupings, 66.7% utilized area, 22.2% utilized volume, while 11.1% utilized both area and volume. Findings from this review showed that the mastoid air cells' size with respect to age differs among populations of different origins. The most common measurements were the area of air cells. The highest growth rate was reported up to 30 years. Findings also show the influence of sex on the size of mastoid air cells and growth rate with age, as females were reported to have larger air cells with rapid growth until puberty. However, the male mastoid air cell system continues a steady growth after puberty and becomes larger. Information still lacks in the volume of air cells in pediatric pneumatization.

Absceso mastoideo como presentación de colesteatoma congénito en preescolar ¿cuál es el origen? / Mastoid abscess as congenital cholesteatoma presentation in a child what is the origin?

Resumen El colesteatoma congénito es una entidad que puede manifestarse con una amplia variedad de síntomas o ser silente durante largo tiempo y constituir un hallazgo incidental. Una vez diagnosticada es importante valorar su extensión y el compromiso de estructuras adyacentes, para lograr una adecuada planificación quirúrgica, eliminando la enfermedad y manteniendo la mejor funcionalidad posible. Se presenta un caso de colesteatoma congénito infantil.

Abstract Congenital cholesteatoma is an entity that can manifest with a wide variety of symptoms or be silent for a long time and constitute an incidental finding. Once diagnosed, it is important to assess the extension to apply the most efficient treatment, eliminating the disease and providing functionality if possible. A case of congenital cholesteatoma in a child is presented.

Recurrent Primary Inverted Papilloma of the Mastoid with Intracranial Invasion: A 7-Year Follow-Up.

A 55-year-old man presented to the otolaryngology department complaining of aural fullness in his left ear after an episode of probable otitis 3 months before. magnetic resonance imaging revealed a soft tissue mass within the mastoid cavity that had destroyed the posterior wall of the middle ear with no apparent middle ear or sinonasal origin. The patient underwent a left canal wall-up tympanomastoidectomy, and the pathology report confirmed an inverted papilloma. Inverted papillomas are uncommon benign epithelial tumors related to a high recurrence rate and high risk of secondary malignant transformation after multiple surgeries. The patient has undergone 2 additional surgical interventions involving the neurosurgery team due to recurrent inverted papilloma that exerted a mass effect over the left cerebellar hemisphere. Despite no signs of recurrence on magnetic resonance imaging 5 years after the last surgery, at least 1 radiologic study per year is granted. Clinical multidisciplinary follow-up including nasal endoscopy and head and neck examination as a part of a stringent follow-up is essential to rule out synchronous nasosinusal inverted papillomas.

"Benefits of the pedicled osteoplastic flap as a surgical approach of mastoidectomy in cochlear implant surgery".

OBJECTIVE: To evaluate the esthetic and functional results of an osteoplastic flap for mastoid cavity closure in cochlear implant surgery. STUDY DESIGN: Double-blind, prospective, randomized clinical trial. SETTING: tertiary referral center. INTERVENTION(S): On hundred and twenty-six patients were randomized in 2 groups for cochlear implant surgery. Cases (n: 63) underwent simple mastoidectomy using an anteriorly pedicled osteoplastic flap for mastoid closure. In controls (n: 63), a traditional periosteal flap was used. Evaluation with the POSAS questionnaire was performed 1 year after surgery to assess surgical wound esthetics. Sixteen patients from each group had postoperative CT-scans and wideband tympanometry to assess mastoid aeration and middle ear absorbance. Gender and time after surgery were correlated. MAIN OUTCOME MEASURE(S): Evaluation of the quality of the surgical wound with the application of a questionnaire validated in the medical literature and translated into Portuguese language called POSAS, considering the perception of the blinded patient and doctor regarding the surgical technique proceeded. A lower POSAS score suggests better esthetics of the surgical wound. Secondary outcomes are volumetric measurement of aeration inside mastoid cavity using 3D computer tomography exam, which aims to analyze the influence of fibrocicatricial retraction in the surgical wound into the mastoid and the interference of its aeration volume in the absorption of sound in the middle ear, using the wideband tympanometry exam. RESULTS: The POSAS questionnaire in the Case group showed a lower level of local pain and itchiness, a skin color and thickness more similar to the surrounding skin and less irregularity and stiffness, with no influence from time after surgery and gender compared to the Control group. The median tomographic volume was 6.37 cc in the cases and 4.60 cc in controls. Wideband tympanometry showed general smaller sound absorbance in the Case group results, specially, at 1000 Hz frequency. No intraoperative or postoperative complications were observed with the osteoplastic flap. CONCLUSIONS: This technique is an effective and safe alternative to alleviate common problems of mastoid surgery for cochlear implantation. In addition to esthetic benefits, it has less interference in middle ear physiology of sound absorbance and less fibrous tissue into the mastoid cavity during the follow-up of more than 1 year.

Mastoid and opisthion-bimastoid triangles for sex determination in a Brazilian sample / Triangulos mastoideo y opistión-bimastoideo para la determinación del sexo en una muestra brasileña

SUMMARY: Human identification involving mutilation, advanced decomposition, and skeletonized materials is a challenge for professionals in forensic medicine and dentistry. This study was aimed at a morphometric analysis of the mastoid and bimastoid triangles to determine sex in a Brazilian population. The sample included 80 human skulls (34 females and 46 males; age: 18 to 60 years) from individuals with death certificates. Linear measurements (mm) of the mastoid process - right (n=3) and left (n=3) - and the opisthion- bimastoid (n=3) triangles were taken (digital caliper) by two previously trained researchers. Three cranial points - asterion, porion and process - were determined for the right and left mastoid triangle and three others - (1) opisthion and (2) right and (3) left mastoid - for the bimastoid triangle. Heron's formula was used to calculate the area of the triangles assessed. Data were submitted to the Shapiro- Wilk normality test, followed by the unpaired Student's t test or the Mann-Whitney U test, depending on the data distribution verified in the normality test (GraphPad Prism 5.01; p<0.05). The ROC curve was used to measure the accuracy of the variables toward sex determination. The opisthion-bimastoid triangle showed high accuracy and significant differences in all the variables assessed and thus was considered a potential element for sex determination in the Brazilian population assessed.

RESUMEN: La identificación humana que comprende la mutilación, descomposición avanzada y materiales esqueletizados, es un desafío para los profesionales de la medicina forense y de la odontología. Este estudio tuvo como objetivo un análisis morfométrico de los triángulos mastoideo y bimastoideo para determinar el sexo en una población brasileña. La muestra incluyó 80 cráneos humanos (34 mujeres y 46 hombres; edad: 18 a 60 años) de sujetos con certificado de defunción. Se tomaron las medidas lineales (mm) del proceso mastoides - derecha (n = 3) e izquierda (n = 3) - y los triángulos opistion-bimastoide (n = 3) (caliper digital) por dos investigadores previamente entrenados. Se determinaron tres puntos craneales - asterion, porion y proceso mastoides - para el triángulo mastoideo derecho e izquierdo y otros tres - (1) opistion y (2) proceso mastoides derecho e izquierdo - para el triángulo bimastoideo. Se utilizó la fórmula de Heron para calcular el área de los triángulos evaluados. Los datos se analizaron con la prueba de normalidad de Shapiro-Wilk, seguida de la prueba t de Student para datos no apareados o la prueba U de Mann-Whitney, según la distribución de datos verificada en la prueba de normalidad (GraphPad Prism 5.01; p <0.05). La curva ROC se utilizó para medir la precisión de las variables hacia la determinación del sexo. El triángulo opistion-bimastoide mostró una alta precisión y diferencias significativas en todas las variables evaluadas, por lo que se consideró un elemento probable para la determinación del sexo en la población brasileña evaluada.

Postoperative Imaging of the Temporal Bone.

The anatomy of the temporal bone is complex, and postoperative imaging evaluation of this bone can be challenging. Surgical approaches to the temporal bone can be categorized didactically into tympanoplasty and ossicular reconstruction, mastoidectomy, and approaches to the cerebellopontine angle and internal auditory canal (IAC). In clinical practice, different approaches can be combined for greater surgical exposure. Postoperative imaging may be required for follow-up of neoplastic lesions and to evaluate unexpected outcomes or complications of surgery. CT is the preferred modality for assessing the continuity of the reconstructed conductive mechanism, from the tympanic membrane to the oval window, with use of grafts or prostheses. It is also used to evaluate aeration of the tympanic and mastoid surgical cavities, as well as the integrity of the labyrinth, ossicular chain, and tegmen. MRI is excellent for evaluation of soft tissue. Use of a contrast-enhanced fat-suppressed MRI sequence is optimal for follow-up after IAC procedures. Non-echo-planar diffusion-weighted imaging is optimal for detection of residual or recurrent cholesteatoma. The expected imaging findings and complications of the most commonly performed surgeries involving the temporal bone are summarized in this review. Online supplemental material is available for this article. ©RSNA, 2021.

Sex determination by osteometric assessment of the mastoid process using Cone Beam Computed Tomography / Determinação do sexo em uma população Iraniana por avaliação osteométrica do processo mastóide em imagens de TCFC

Objective: Sex determination is one of the most important parameters to identify in forensic science. Because the mastoid process is the most resistant to damage due to its position in the skull base, it can be used for sex determination. The purpose of this study was to measure the dimensions and convexity and internal angles of the mastoid process to present a model of sex determination in Iranian population. Material and methods: This study was performed on three-dimensional images of 190 Cone Beam Computed Tomography (CBCT) of 105 women and 85 men. On each CBCT the distance between the porion and the mastoid (PM), mastoid length (ML), the distance between the mastoidale and the mastoid incision (M-I), the mastoid height (MH), the mastoid width (MW), intermastoidale distance (IMD) the lateral surfaces of the left and right mastoids (IMLSD) and the Mastoid medial convergence angle (MMCA) was measured on both the right and the left. The data were analyzed by descriptive statistics, t-test, and discriminant function analysis. Results: Significant differences were found for all variables except MMCA and MF in both sex. All measured variables except MW were greater for men than women. The discriminant model achieved a total accuracy of 93.7%. Among the measured factors IMD and IMSLD had the most influence on sex determination. Conclusion: Measuring the dimensions of the mastoid process is a very good method for sex determination with high accuracy of 90% (AU)

Objetivo: A determinação do sexo é um dos parâmetros mais importantes para identificação na ciência forense. Por ser o processo mastóide resistente a danos, devido a sua posição na base do crânio, este poderia ser usado na determinação do sexo. O objetivo deste estudo foi mensurar as dimensões, convexidade e ângulos internos do processo mastóide para apresentar um modelo de determinação do sexo em uma população Iraniana. Material e métodos: Este estudo foi realizado em 190 imagens de tomografia computadorizada de feixe cônico (TCFC), sendo 105 mulheres e 85 homens. Em cada TCFC foram realizadas medidas no processo mastóide em comprimento (ML), altura (MH), largura (MW) em ambos os lados direito e esquerdo, também foi medida a distância entre o Pórion e o processo mastóide (PM), distância até incisura mastoidea (M-I), distância entre as superfícies mediais (IMD) distância entre as superfícies laterais dos processos direito e esquerdo (IMLSD) e o ângulo de convergência medial (MMCA). Os dados foram analisados por estatística descritiva, teste t e análise de função discriminante. Resultados: Diferenças significativas foram encontradas para todas as variáveis, exceto MMCA e MF em ambos os sexos. Todas as variáveis medidas, exceto MW, foram maiores para os homens do que para as mulheres. O modelo de análise de função discriminante alcançou uma precisão total de 93,7%. Entre os fatores medidos, o IMD e o IMSLD tiveram a maior influência na determinação do sexo. Conclusão: Podemos concluir que as dimensões do processo mastóide constituem um método para determinação do sexo, em população Iraniana, com precisão de 90% (AU)

Prevalence of facial canal dehiscence and other bone defects by computed tomography.

INTRODUCTION: The facial nerve is the most vulnerable structure during otological surgeries. Facial canal dehiscence (FCD) is the main risk factor for iatrogenic injuries. Its prevalence in clinical studies ranges between 6 and 33.3%, while anatomical studies report 25-57%. The objective was to determine the prevalence of FCD stratified by age and gender in a healthy population. MATERIALS AND METHODS: Temporal bones from high-resolution computed tomography (CT) were analyzed. Patients with a history of trauma or tumors of the temporal bone, cholesteatomas, chronic middle ear disease, and any pathology that could modify the bone's anatomy, were excluded. RESULTS: A total of 184 temporal bones were included. FCD was observed in 94 (51.2%) of the analyzed bones. The tympanic portion was the most frequently affected site with 91 (49.5%), followed by the mastoid segment with 3 (1.6%). No dehiscence was found in the labyrinth portion. We observed 30 (31.9%) of the FCD involved the oval window. Other bone defects identified with the FCD included: 11 (11.7%) with a lateral semicircular canal fistula and 7 (7.4%) with tegmen tympani erosions. CONCLUSION: FCD has a high prevalence among healthy patients. A pre-surgical otological evaluation using high-resolution CT should be indicated to properly assess the patient and reduce the risk of injury.

Estudio morfométrico del punto asterional y su relación con los senos venosos durales / Morphometric study of the asterional point and its relationship with the dural venous sinuses

INTRODUCCIÓN: la importancia de conocer las diferentes reparaciones anatómicas que involucran la parte ósea de la fosa posterior con estructuras neurovasculares, disminuye la incidencia de complicaciones relacionadas con su acceso dentro del procedimiento neuroquirúrgico. MATERIALES Y MÉTODOS: estudio descriptivo basado en la evaluación de 90 hemicráneas secas, del Museo de Anatomía de la Universidad Mayor de San Andrés. RESULTADOS: la prevalencia de asterión tipo I fue de 28.9%, mientras que la de tipo II fue de 71.1%. La prevalencia del número de venas emisarias fue: una vena 54.4%, dos venas 42.2% y tres venas 3.3%. Los promedios para las características morfométricas son los siguientes: de Asterion a protuberancia occipital externa de 68.8 mm, de Asterion a cresta suprameatal de 50.1 mm, de Asterion a vena emisaria de 54.1 mm, de Asterion a Vértice del proceso mastoideo de 54.1 mm y de asterion a plano horizontal de Francfort 14.6 mm. La ubicación del asterión en el seno transverso fue la siguiente: al mismo nivel del seno, 47.8% de los casos, en el codo en 13.3%, superior al seno 31.1% e inferior a este en el 7.8%. CONCLUSIONES: hay una diferencia en algunos resultados morfométricos del asterión con respecto a otros autores, lo que podría determinar una configuración craneal diferente para nuestra población. Esto debe considerarse para evitar complicaciones durante el período transoperatorio en una cirugía de fosa posterior. Estos resultados reflejan la necesidad de realizar un estudio con una población más grande para obtener resultados reales, estableciendo así parámetros de corte que nos permitirán tener nuestra propia bibliografía sobre cómo proceder en nuestra actividad quirúrgica.

INTRODUCTION: the importance of knowing the different anatomical repairs that involve the bony part of the posterior fossa with neurovascular structures, decreases the incidence of complications related to its access within the neurosurgical procedure. MATERIALS AND METHODS: descriptive study based on the evaluation of 90 dry hemicranial, from the Anatomy Museum of the Universidad Mayor de San Andrés. RESULTS: the prevalence of asterion type I was 28.9%, while that of type II was 71.1%. The prevalence of the number of emissary veins was: One vein 54.4%, Two veins 42.2% and Three veins 3.3%. The averages for morphometric characteristics are as follows: from Asterion to external occipital protuberance 68.8 mm, from Asterion to suprameatal crest 50.1 mm, from Asterion to emissary vein 54.1 mm, from Asterion to Vertex from the mastoid process 54.1 mm and from asterion to horizontal plane of Frankfurt 14.6 mm. The location of asterion in the transverse sinus was the following: at the same level of the sinus 47.8% of the cases, in the elbow in 13.3%, superior to the sinus 31.1% and inferior to this in the 7.8%. CONCLUSIONS: there is a difference in some morphometric results of the asterion with respect to other authors, which could determine a different cranial configuration for our population. This should be considered to avoid complications during the transoperative period in a posterior fossa surgery. These results reflect the need to carry out a study with a larger population, in order to have real results, thus establishing cutting parameters that will allow us to have our own bibliography on how to proceed in our surgical activity.

Study of Sigmoid Sinus Variations in the Temporal Bone by Micro Dissection and its Classification - A Cadaveric Study

Abstract Introduction Sigmoid sinus (SS) variations have been classified variously in the literature. These classifications suffer from some form of shortcoming from a clinical point of view for their application. Objective We propose a clinically relevant classification of the SS in relation to the posterior semicircular canal (PSCC) and to the exposure of the presigmoid dural plate. The positioning of the SS was analyzed with reference to the volume of themastoid and to the level of mastoid pneumatization. Methods A total of 94 formalin-preserved human cadaveric temporal bones were microdissected to carry out a complete mastoidectomy. The SS, the presigmoid dural plate, and the PSCCwere exposed, and the position of the former was analyzed in relation to the latter two in order to classify the position of the SS into three grades. Results GradeI hadthebest exposureof the presigmoid dura andof the PSCC,while grade III had the poorest exposure of the presigmoid dura and of the PSCC. Grade I SS was associated with good pneumatization and highermastoid volumescompared with grades II and III. Conclusions The SS exhibits considerable anatomic variability. A favorable positioning of the SS is associated with a large mastoid volume and pneumatization. A careful preoperative study of the imaging may help in understanding the positioning of the SS and the safety of various transmastoid approaches.

Tympanic-mastoid and parotid schwannomas of the facial nerve: clinical presentation related to the anatomic site of origin.

Objective: To describe the clinical presentation of the facial nerve schwannomas according to the anatomical site of origin. Method: A retrospective study in which the clinical presentation, diagnostic protocol and treatment of facial nerve tumors in adults was evaluated. Results: We found 6 cases, 4 cases of tympanic-mastoid location at the spectrum of its possible clinical presentation: from symptomatic cases with facial paralysis, to an asymptomatic case in the tympanic portion found as intraoperative finding; and also found two cases located at the parotid gland, one with complete facial paralysis and one without facial palsy. Conclusions: For the diagnosis of intratemporal and parotid schwannomas of the facial nerve, a high clinical suspicion is required given its heterogeneous presentation; its clinical course depends on the segment of origin and expansion: more frequently asymptomatic at the tympanic horizontal portion and symptomatic at the mastoid vertical portion. These tumors must be assessed with imaging studies, incisional biopsy is not recommended. The treatment is surgical resection in symptomatic patients with facial paralysis greater than grade III of House-Brackmann, with immediate reconstruction of the nerve.

Objetivo: Describir la presentación clínica de los schwannomas del nervio facial de acuerdo con el sitio anatómico de origen. Método: Se realizó un estudio retrospectivo en el que se evaluó la presentación clínica, el protocolo diagnóstico y el tratamiento de tumores del nervio facial en adultos. Resultados: Se encontraron seis casos, cuatro de ellos de localización tímpano-mastoidea en los extremos de su posible presentación clínica: desde casos sintomáticos con parálisis facial, hasta un caso asintomático de la porción timpánica encontrado como hallazgo transoperatorio; y se encontraron dos casos de localización parotídea, uno con parálisis facial completa y otro sin parálisis facial. Conclusiones: Para el diagnóstico de tumores intratemporales y parotídeos del nervio facial se requiere una elevada sospecha clínica dado lo heterogéneo de su presentación; su curso clínico depende del segmento de origen y de su extensión: más frecuentemente son asintomáticos los de la porción timpánica y son sintomáticos los de la porción mastoidea. Estos tumores deben evaluarse con estudios de imagen; no se recomienda realizar biopsia incisional. El tratamiento es la resección quirúrgica en los casos sintomáticos con parálisis facial de grado IV o mayor de House-Brackmann, con reconstrucción inmediata del nervio.