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.

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.

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.

Occipital condyle screw fixation viability according to age and gender anatomy: A computed tomography-based analysis

OBJECTIVE

To assess the Occipital condyle morphology in an all-age population of Northeastern Mexico, and determine age and gender related changes for surgical viability.

METHODS

A total of 175 consecutive HRCT scans were included and divided into 5 age groups. The condylar length, width, height, sagittal angle, anterior, posterior and medial intercondylar distances, and intercondylar angle of the OC were measured.

RESULTS

Mean condylar length, width, and height in total population were 20.58 mm, 9.42 mm, and 9.02 mm, respectively. Differences were observed in most morphometric parameters when comparing age groups. Significant intergender differences in total population were observed in most parameters, when individualizing each age group the height remained significant in all. The group with the least height measurement was aged 5-9 years, this however, could allow the OC screw (≥6.5 mm) placement.

CONCLUSION

Differences in most morphometric parameters of OC were observed between age groups and gender, particularly patients with 5-9 years. However, all groups presented a minimum height that allows the placement of a standard screw. A preoperative imaging study is always recommended due to the variability and complexity of the region.

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.

Gynecological influencing factors on the rectovaginal septum's morphology

INTRODUCTION AND HYPOTHESIS

The objective was to determine the mean morphometric characteristics of the rectovaginal septum (RVS) and its variations in correlation with the number of pregnancies, method of delivery, parity, and estrogenic exposure.

METHODS

An observational, cross-sectional, retrospective, descriptive, and comparative study was carried out. Pelvic MRI of Hispanic women (≥15 years of age) from the northeast of Mexico were obtained. Age and obstetric and gynecological history were registered and the sample women were categorized by their variables. Length and thickness measurements were standardized.

RESULTS

A total of 102 MRI studies were included, with a mean age of 41; 24.5% were nulligravida, the rest primi- or multigravida. Vaginal delivery was the most common type (49.35%), 16.88% had a cesarean section, and 31.17% had mixed delivery. 74.5% of the women were premenopausal. The mean RVS length was 73.2 ± 15.3 mm, with a thickness of 2.8 ± 1.7, 2.2 ± 1.2, and 2.5 ± 1.3 mm for the upper, middle, and lower thirds respectively. There were tendencies to increase the length of the RVS, and the thickness of the upper and middle thirds in the non-pregnancy and the at-least-one-pregnancy groups; to increase the length and middle-third thickness in those with mixed delivery, and increased upper- and lower-third thickness in those with only a cesarean section. Multiparous women with vaginal delivery had significantly longer and thicker RVS than primiparous. Premenopausal women had significantly longer RVS with a tendency to lose thickness toward postmenopause.

CONCLUSIONS

The morphology of RVS can be modified by different factors such as age, number of pregnancies, number of births, and estrogenic exposure. This structure should be evaluated and taken into account in preoperative management and surgical technique planning.

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 ± 18.63 years. The mean variable measurements (mm) for all the population were 21 ± 4, 16 ± 3, 6 ± 2, 3 ± 2, 2 ± 1 and 35 ± 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.

Origin variations of the superior thyroid, lingual, and facial arteries: a computed tomography angiography study

PURPOSE

To determine the anatomical variations and morphology of the external carotid artery (ECA) and its anterior branches.

METHODS

Using computed tomography angiography (CTA), the origin, internal diameter, and surface laterality emergence of the superior thyroid (STA), lingual (LA), and facial (FA) arteries were evaluated retrospectively evaluated and classified. The bifurcation level of the common carotid artery (CCA) in relation to the cervical vertebrae and disc was also determined.

RESULTS

A total of 76 CTA were included in the study. STA originated from the carotid bifurcation (CB) (type I), CCA (type II) and ECA (type III) in 20.4 (31/152), 17.1 (26/152) and 50.7% (77/152) cases, respectively. Also 10.5% (16/152) arose from a shared trunk with LA as a thyrolingual trunk (TLT) (type IVa), and absent in 1.3% (2/152). LA originated in the CB in only one case. A linguofacial trunk (LFT) was present in 14.5% (22/152). Mean diameters of STA, LA and FA were 1.70, 1.95 and 2.45 mm, respectively. Meanwhile, surface laterality were predominately from anteromedial, medial, and anterior, respectively. CB was mainly on C3 or C3-C4 (55.9% of cases).

CONCLUSIONS

STA origin below the ECA is a common finding. Our population presented the highest percentage of TLT (10.5%) and high CB (9.8%) in literature. Considering these variations are important to prevent complications in neck surgical procedures.

Anatomical variations of the acromial and coracoid process: clinical relevance

PURPOSE

The acromial and coracoid process morphology is of clinical relevance due to associations with functional limitations and shoulder pathology. Our objective was to describe the anatomical characteristics of the acromial and coracoid process using computed tomography (CT).

METHODS

Descriptive, observational, transversal and retrospective study. A total of 155 CT of patients without shoulder pathology, of both genders, and indistinct age were evaluated and grouped by age: Group 1 < 25 years; group 2 25-40 years; group 3 > 40 years. The following parameters were evaluated: Acromial type (AcT), vertical coracoid distance (VCD), acromial tilt (AT), acromial projection (AP), critical shoulder angle (CSA), type of the subcoracoid outlet (TSO), and the area of the subcoracoid outlet (ASO).

RESULTS

Statistically significant differences were found between men and women for VCD (14.44 ± 4.79 vs. 11.76 ± 4.00 mm; p < 0.001) and AP (3.66 ± 4.71 vs. 1.62 ± 4.99 mm; p < 0.05) as well as between age groups 1 and 3 for AT (35.08 ± 11.53 vs. 28.41 ± 6.60; p < 0.05) and ASO (398.99 ± 153.91 vs. 255.56 ± 124.58 mm²; p < 0.001). An unexpected high ASO variation was identified with 11% of S-shaped acromion and 1.3% clock-shaped TSO.

CONCLUSION

The age group between 25-40 years had the most uniform distribution of data. There is a high morphological variability present in an asymptomatic population, which should be considered in the clinical assessment such as shoulder impingement syndrome.

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.

[Vertebral fixation with a transpedicular approach. Relevance of anatomical and imaging studies]

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.