Cochlear morphometry in healthy ears of a mexican population: A comparison of measurement techniques.

OBJECTIVE: This study describes the cochlear morphometry of a mexican population analysed by laterality and sex. The objective is to compare Cochlear Length (CL) evaluation between Alexiades et al. formula and manual method described by Würfel et al. PATIENTS: Hispanic patients from Mexico, with an age of 18 years or older, were included. Morphometric examination was performed retrospectively on 200 subjects who underwent previously temporal bone imaging for clinical purposes. MATERIALS AND METHODS: Horos for Mac program was used to measure CL, cochlear height, distance A, and distance B. WorkStation AW Volume Share 2 was used to obtain volume. CL was measured in 400 temporal bones (228 females, 172 males). RESULTS: The mean CL was 34.02mm±2.15mm. A significant difference was found in all variables between sex (P=≤0.05) and laterality (P=≤0.05). The Alexiades equation was used for determining CL and compared with the manual formula, with no significant differences (κ=0.71). However, the time consumption was 5 times faster with the calculated method. The Alexiades formula was demonstrated to be a reliable method measurement. CONCLUSION: Preoperative Computed Tomography evaluation of the internal ear helps to plan the Cochlear Implants (CI) surgical approach and allows to choose an appropriate electrode length for each necessity. Our findings may be useful to facilitate and adapt preoperative management of CI surgery by considering the characteristics of cochlear morphology of Latin-American populations.

A proposed extension to the elongated styloid process definition: A morphological study with high-resolution tomography computer.

The objective of the present study was to evaluate the morphology and angulation of the styloid process (SP), analyzing results stratified by gender, side and age on asymptomatic patients. We retrospectively analyzed 99 high-resolution computed tomography study images from asymptomatic patients. The images were assessed intra-observatory by a head and neck expert radiologist. Data for length, morphology, and angulation in a coronal and sagittal plane were recorded and stratified by age and gender. Morphology was classified according to the Langlais modified by Guimares classification. The mean lengths were 31.67±0.97mm and 31.64±0.90mm for the right and left sides respectively. Using the Langlais modified by Guimares classification, the normal type was the most prevalent and without a statistically significant difference when comparing between genders. A total of 27.6% presented a morphologically elongated SP (>25mm of continuous process), 49.5% presented a radiologically elongated SP (>30mm), and a total of 9.59% had a longer length than the proposed≤45mm. The right transverse angle was greater in men than women, and a statistically significant difference was found (P=0.010). We show the morphological variability of the SP. Although our results are reported with the traditional definition, the high prevalence supports the need for a new definition of elongated SP and a normal angulation ranges.

Safety window for the transsphenoidal approach for pituitary tumours: a computed tomographic angiography study.

BACKGROUND: The aims are to evaluate the morphometry of the sellar region and propose a safety window on the floor of the sella turcica for the transsphenoidal approach in a Hispanic population. MATERIALS AND METHODS: We retrospectively analysed 150 computed tomographic angiography sellar region images from asymptomatic patients. The images were evaluated intraobservatory by an expert radiologist. We measured: intercarotid distance of cavernous segment; depth of sella turcica; skull base angle; anterior distance, the distance between anterior spinal nasal and floor of the sella turcica; posterior distance, the distance between anterior spinal nasal and posterior wall of the sella turcica; anterior surgical angle, formed between the floor of the nostril and superior limit of the anterior wall of the sella turcica; and posterior angle, formed between the floor of the nostril and the inferior limit of the posterior wall of the sella turcica. RESULTS: Safety window was based on two measures: the intercarotid distance and depth. The mean of the safety window is 151.13 mm² and 147.60 mm² for men and women, respectively. The intercarotid distance was 17.83 mm. The depth of the sella turcica was 8.46 mm. The skull base angle was 112.13 grades. The anterior distance was 76.34 mm. The posterior distance was 87.59 mm. The anterior surgical angle was 32.76 grades. The posterior surgical angle was 87.59 grades. CONCLUSIONS: The surgical approach space is smaller in females. It could significate a more complicated surgery in this population. Anatomical understanding could reduce complications in hospitals without a neuronavigation system.

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.

Volumetric assessment of the sella turcica: a re-evaluation.

BACKGROUND: The sella turcica volume is widely measured by the Di Chiro-Nelson method. The purpose is to compare the fidelity of a proposed volumetry method vs. the Di Chiro-Nelson method, using computed tomography (CT) images. MATERIALS AND METHODS: Morphometric examination of 173 CT scans were included, of which 52.6% were female. The mean age was 53.2 ± 17.6 years. Considering the Di Chiro-Nelson method, two measurements were added for each axis in the CT evaluation: length (central, left, and right), width (central, anterior, and posterior), and height (central, left, and right). RESULTS: The mean measurements were length: central 10.11 ± 1.44, left 7.45 ± 1.67, right 7.53 ± 1.59; width: central 12.27 ± 2.11, anterior 10.99 ± 1.92, posterior 10.10 ± 1.74; height: central 7.68 ± 1.38, left 7.16 ± 1.35, right 7.40 ± 1.41. A statistically significant difference between sexes was found only in the anterior width (p = 0.01). Using the proposed method, the volume was 342.2 ± 88.5 and 378. 6 ± 113.9 mm³, respectively for females and males (p = 0.02) vs. 476.1 ± 132.4 and 523.8 ± 186.0 mm3 (p = 0.05) using the Di Chiro-Nelson's method. CONCLUSIONS: Women had significantly smaller sella turcica volume than men. This proposed method considers the sella turcica as a not strictly symmetrical structure and indicates reduced variation between the maximum and minimum values, compared to the Di Chiro-Nelson's. Our findings may be useful for reassessment the volume of the sella turcica as the measurements indicate a higher precision.

Morphometry of the aortic arch and its branches. A computed tomography angiography-based study.

BACKGROUND: The current study aims to determine the prevalence of variations of the aortic arch using computed tomography angiography (CTA), as well as morphometries and gender correlations. MATERIALS AND METHODS: A retrospective, transverse, observational and descriptive study of 220 CTA was performed. The branching pattern, most cranial vertebral level of the aortic arch, area of the proximal, middle and distal segments of the arch, area of each branch, and the path of atypical arteries were recorded. Results were analysed and stratified by gender. RESULTS: The typical aortic arch branching pattern was present in 77.7% without statistical significance between genders. The most common variant was a two-branch pattern with a common trunk and a left subclavian (13.6%), followed by a typical branching pattern with an added left vertebral artery (7.3%). T3 was the most frequent cranial level (32.3%), followed by T2-T3 (26.8%), and T3-T4 (23.2%). The mean areas of the aortic arch were 685.5 ± 183.9, 476.1 ± 124.1, and 445.0 ± 145.1 mm2 for the proximal, middle and distal segments, with statistical difference between men and women in the middle and distal segments. Three paths of atypical arteries were identified: bifurcated vertebral artery (0.5%), aberrant right subclavian artery (0.5%), and left subclavian ostium obstruction (0.5%). CONCLUSIONS: Mexican population has one of the highest prevalence of variations in the aortic arch branching pattern. The high probability of finding these should be taken into consideration when assessing patients. A standardised classification method would contemplate future un-reported findings, without causing confusion by the different numbers assigned by each author.

[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.