Magnetic resonance based morphometric analysis of the tentorial notch.

BACKGROUND: The study of the tentorial notch can improve the understanding of brain injury mechanisms. Tentorial morphology has been analysed primarily in cadaveric studies. However, the postmortem effect can cause variability in the measurements. The objective was to evaluate the morphometry of the tentorial notch and the third cranial nerve on living subjects using magnetic resonance imaging (MRI). MATERIALS AND METHODS: A retrospective cross-sectional study was performed. Using consecutive cases, 60 MRI scans were analysed for tentorial notch morphology. Maximum notch width (MNW), notch length (NL), interpedunculoclival (IC) distance, apicotectal (AT) distance, third cranial nerve (CN-III) distance, and inter- CN-III angle, were obtained. For the classification of the tentorial notch quartile distribution technique for MNW, NL, AT distance, and IC distance were used. RESULTS: According to the quartile of the MNW, patients were stratified into narrow, midrange, and wide groups. Using the NL quartile groups, they were also classified as short, midrange, and long. With these, the tentorial notch could be classified into eight types. Statistical differences between genders in the MNW and inter-CN-III angle were found, as well as a strong positive correlation between NL and AT distance, and between right and left CN-III distances. CONCLUSIONS: There were differences between the cadaveric samples and living subjects in the CN-III distances. This difference could be explained by the dehydration of brain volume in the postmortem process which may cause nerve elongation. Morphometry of the tentorial notch and its neurovascular relations allows a better understanding of the mechanisms of brain herniation.

Prevalence, topographic and morphometric features of femoral cam-type deformity: changes in relation to age and gender.

Femoroacetabular impingement (FAI) syndrome is a frequent cause of pain and in recent years considered to be a precursor of premature hip osteoarthritis. The structural abnormalities which characterize FAI syndrome, such as the cam-type deformity, are associated with morphological alterations that may lead to hip osteoarthritis. The aim of this study was to determine the prevalence and topographic and morphometric features of the cam deformity in a series of 326 femur specimens obtained from a Mexican population, as well as changes in prevalence in relation to age and gender. The specimens were subdivided into groups according to gender and age. A standardized photograph of the proximal femur of each specimen was taken, and the photograph was used to determine the alpha angle using a computer program; the location of the lesion was determined by quadrant and the morphometric characteristics were determined by direct observation. The overall prevalence of cam deformities in the femur specimens was 29.8 % (97/326), with a prevalence by gender of 35.2 % (64/182) in men and 22.9 % (33/144) in women. The mean alpha angle was 54.6° ± 8.5° in all of the osteological specimens and 65.6° ± 7.5° in those specimens exhibiting a cam deformity. Cam deformities were found topographically in the anterior-superior quadrant of the femoral head-neck junction in 86.6 % (84/97) of the femurs. Deformities were found in 28.2 % of the right femurs and 31.3 % of the left femurs. The prevalence of cam deformity was higher in the femur specimens of young men and in those of middle-aged and older women. There were no significant differences in this deformity in relation to the alpha angle according to age and gender.

[Vertebral fixation with a transpedicular approach. Relevance of anatomical and imaging studies]. / Fijación vertebral por vía transpedicular. Importancia de los estudios anatómicos y de imagen.

The number of patients with spine conditions has grown exponentially in recent years leading to an increase in the number of cases requiring surgical treatment. Currently vertebral fusion surgery with a transpedicular approach represents the most commonly used technique to treat any type of vertebral disorder. The morphometric characteristics of vertebrae, particularly the pedicle, determine the size of pedicular implants, including width and length, as well as the shape and direction of the screw and its ideal angulation at the time of introduction. Knowing these characteristics is important to prevent injuring important adjacent structures and to decrease the postoperative complication rate. In recent decades numerous studies on the morphometric characteristics of the vertebral pedicle have been conducted in different populations to determine its real dimensions by means of direct measurement and imaging methods. These studies have concluded that there are significant differences in these measurements among the different ethnic groups, races, genders, ages and the vertebral regions studied. This paper analyzes the different morphometric studies of the pedicle and all the other vertebral elements studied in Mexico and the rest of the world and explain the importance of their knowledge and surgical application for the correct development of vertebral fusion surgery with a transpedicular approach.

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.