Avoiding iatrogenic injuries to the vertebral artery: A morphometric study of the vertebral artery-free dissection area.

OBJECTIVE: To determine the area of a safety window that excludes the vertebral artery for the safe access of the occipital condyle screws during occipitocervical fixation. METHODS: This study included 138 cervical computed tomography angiograms. Six measurements per side were made in each imaging study. These measurements are from the vertebral artery to (A) the mastoid process, (B) the mastoid incisura, (C) the posterior condylar fossa, (D) the occipital condyle in its midline, and (E) the medial border of the condyle. We also measured from the tip of the mastoid process to the lower border of the occipital condyle on its lateral side (F). RESULTS: A total of 276 areas from 138 individuals were included, of which 51.4 % were men. The mean age was 54.2 ±â€¯18.63 years. The mean variable measurements (mm) for all the population were 21 ±â€¯4, 16 ±â€¯3, 6 ±â€¯2, 3 ±â€¯2, 2 ±â€¯1 and 35 ±â€¯4 for variables A-F, respectively. We found significant differences between sex when we compared measurements A (p = 0.003), C (p = 0.001), D (p = 0.000) and F (p = 0.000). The incidence rate of dominance for the vertebral artery was 18.8 % and 30.4 % for right and left respectively. CONCLUSION: Women had significantly smaller measures than men. This could indicate a higher risk of iatrogenic injury secondary to a smaller vertebral artery-free area. Results may guide surgeons in the pre-surgical planning aiming to reduce the risk of iatrogenic injuries to the vertebral artery.

Sex and age morphometric variations in bony nasolacrimal duct and fossa for lacrimal gland in Mexican population / Variaciones morfométricas de sexo y edad en el conducto nasolagrimal óseo y la fosa de la glándula lagrimal en la población mexicana

Primary acquired nasolacrimal duct obstruction is greater in women over 40 years and has been associated with morphometric variations in the osseous nasolacrimal duct, which varies according to age and sex. The objective is to determine variations regarding sex and age of the nasolacrimal duct and osseous fossa for lacrimal gland. One hundred sixteen dry orbits from Mexican population were analyzed; subdivided into four groups based on age and sex. The length, transverse and anteroposterior diameters of the bone entrance of the nasolacrimal duct, and the length and width of the fossa for lacrimal gland were determined. Statistical tests were applied to determine the significance of the differences found between groups. The nasolacrimal duct in women had shorter length than men in both age groups. The entrance had a wider transverse diameter in women than men independently of age and its anteroposterior diameter was shorter in men under 40 years than over 40 years. The fossa for lacrimal gland was larger in women under 40 years than in men of same age group and women over 40 years old. The lower third of the was wider in women under 40 years than in women over 40 years. Our study confirms significant differences between sex and age groups in some of the morphometric measurements of bony nasolacrimal duct and fossa for lacrimal gland in Mexican population. Comparative studies with and without clinical illness are needed to clarify if the bony characteristics of those structures participate in the etiopathogenesis and distribution differences observed in sex, age and ethnicity of thisillness.

La obstrucción de la vía lagrimal inferior es mayor en mujeres mayores de 50 años y se ha asociado a variaciones morfométricas en la entrada ósea del conducto nasolagrimal (CNL), las cuales varían según edad y sexo. El objetivo del presente estudio es determinar las variaciones respecto a sexo y edad de los diámetros de la entrada ósea del CNL, longitud del CNL y fosa de la glángula lagrimal (FL) ósea. Se analizaron 116 órbitas secas de población mexicana, los cuales a su vez fueron subdivididos en dos subgrupos en base a la edad y sexo. Se determinaron los diámetros transverso y anteroposterior de la entrada ósea del CNL, la longitud del CNL y la longitud y anchura de la FL. Se aplicaron pruebas estadísticas para determinar la significancia de las diferencias entre los grupos de estudio. La longitud del CNL fue menor en mujeres que en hombres en ambos grupos de edad. En cuanto a la entrada ósea del CNL, el diámetro transverso de fue significativamente menor en hombres que en mujeres independientemente de la edad y el diámetro anteroposterior fue menor en hombres < 40 que en > 40. La longitud de la FL fue mayor en mujeres < 40 años que en hombres del mismo rango de edad y que en mujeres > 40 años. La anchura de la FL en el tercio inferior fue menor en mujeres > 40 años que < 40 años. El resto de las mediciones de la FL no presentó diferencias significativas por sexo ni grupo de edad. Nuestro estudio confirmó que existen diferencias entre sexo y grupo de edad en algunas mediciones morfométricas del CNL y FL óseas en población mexicana. Se necesitan estudios comparativos entre personas con y sin obstrucción clínica de vía lagrimal inferior para esclarecer si las características óseas de estas estructuras participan o no en la etiopatogenia y las diferencias de distribución en género, edad y etnia de esta enfermedad.

Clinical and surgical implications regarding morphometric variations of the medial wall of the orbit in relation to age and gender.

The ethmoidal foramens are located on the medial wall of the orbit and are key reference points for intraoperative orientation. Detailed knowledge of the anatomy, bony landmarks and morphometric characteristics of the medial wall of the orbit is essential for various surgical procedures. The aim of this study was to determine the morphometric variations in the medial wall of the orbit and establish significant variations regarding age and gender. A total of 110 orbits were analyzed and subdivided by age (over or under 40 years) and gender. The distances of the medial wall of the orbit between the anterior lacrimal crest, the ethmoidal foramen, the optic canal and the interforamina were determined. Safe surgical areas were sought. Statistical tests were used to determine the differences between groups. In men, there is a safe surgical area proximal to the anterior and posterior ethmoidal foramen. In women, this area is in the posterior third of the medial wall of the orbit between the posterior ethmoidal foramen and the optic canal. Regarding variation according to age, the results of this study suggested that the anteroposterior diameter of the medial wall increases with age. This study showed that the anteroposterior total length of the medial orbit wall is similar between genders of similar age, increases with age, and has significant variations in the distances between the various structures that make up the medial orbit wall with regard to gender and age.