Nerve Passes Research Articles

Anatomical study of pterygoid implants: artery and nerve passage through bone dehiscence of the greater palatine canal

PurposePterygoid implants are an alternative approach to avoid sinus-lifting or other grafting procedures. During pterygoid implant placement, dental surgeons risk damaging the greater palatine canal (GPC). However, they do not have sufficient reasons to avoid GPC injury. This study performed a detailed morphological analysis of the GPC to determine susceptibility to damage during pterygoid implant surgery.MethodsTo understand the detailed morphology of the GPC, gross anatomical analysis, histological analysis, and bone morphometry via micro-computed tomography were performed.ResultsWe found that the medial wall of the GPC communicated with the nasal cavity through the bone dehiscence. The dehiscence appeared near the inferior nasal concha in 72.4% of the cadavers. The nerve and artery passed from the GPC to the nasal mucous membrane through the dehiscence. Given that the greater palatine nerve passed medial to the descending palatine artery in the GPC, the descending palatine artery is damaged first rather than the greater palatine nerve during pterygoid implant surgery.ConclusionsDental surgeons who penetrate the GPC using an implant body may extend the bleeding to the nasal mucosa, which seems to spread the inflammation to the nasal cavity.

FORAMEN MAGNUM – A STUDY ON ITS MORPHOMETRY AMONG THE SOUTH INDIAN POPULATION

Objective: Foramen magnum is an oval opening present in the median region of the posterior cranial fossa of the occipital bone. The lower end of the medulla, meninges, spinal arteries, and spinal roots of accessory nerve pass through the foramen. Morphometry of the foramen magnum is studied for better learning of the structure, but this study helps in planning a safe surgery and exploration in the head-and-neck region. Various surgical approaches of the foramen provide access to the foramina on the base of the skull and prevent broad retraction of the neurovascular structures passing through them, so the morphometric study plays an important role in transcondylar approach. Methods: Fifty dry human skulls available in the Department of Anatomy, Amala Medical College and Hospital, and also at Jubilee Medical College and Hospital, Thrissur were studied for this research work, and results were statistically analyzed. Results: The most common shape of the foramen magnum was oval, the mean of anteroposterior diameter was greater than the mean of transverse diameter, p-value of the diameters was found to be significant, p-value of the mean of foramen magnum index was significant. Conclusion: This study will help the surgeons to effectively plan a surgery at the head and neck site

PENGARUH PENGGUNAAN SARUNG TANGAN DENGAN BANTALAN DAN TAPPING TERHADAP PENURUNAN NYERI CARPAL TUNNEL SYNDROME

Carpal tunnel syndrome is a disorder that occurs in the wrist where inside the wrist there is a carpal tunnel through which the median nerve passes, as a result of excessive movement or pressure on the carpal tunnel which causes irritation of the median nerve. The aim of this study is to determine the effect of using gloves with pads and taps to reduce carpal tunnel syndrome pain, this research method used a pre and post experimental design, as many as 50 people were given gloves with pads and taps, the research subject was someone who worked more than 3 hours riding a motorbike in 1 day, in When driving, the wrist gets pressure when slowing down the vehicle and when passing through winding roads. The research subjects used gloves for 10 working days in two weeks, and used tapping for 2 weeks with a duration of 1 day on for 8 hours, 1 day off. The results of this study were 31 men and 19 women with an average age of 32.2 years and a pain average of 4.54 before and after 1.84 on the vas scale. In the statistical tests carried out, the value p=0.0001 was obtained where p< 0.05 so it can be concluded that the use of gloves and taps can reduce pain in cases of carpal tunnel syndrome.

Occurrence of the ossification of petrosphenoid ligament: a retrospective radiologic study from computed tomographic images.

Various ligaments present in the skull base are of clinical and surgical importance. One among them, is the petrosphenoid ligament (PSL). PSL may ossify either in a partial or complete form and forms the roof of Dorello's canal underneath which the abducens nerve passes. Studies argued both protective and adverse effects of the ossified PSL. Hence, the incidence of PSL ossification has become a relevant subject in clinical practice to radiologists, neurologists and neurosurgeons for understanding its potential role in abducens nerve compression. We have undertaken this study to investigate the incidence of PSL ossification from multidetector computed tomography (MDCT) images of the patients who had been referred to the Medical Imaging Department of Mubarak Al-Kabeer Hospital in Kuwait. We retrospectively assessed a total of 200 patients' head CT scans (400 petroclival regions) between January 2021 and June 2022 in which 59% were males (n = 118) and 41% were females (n = 82) aged between 18 and 91 years. A total of 37 patients (26 male, 11 female) aged between 18-84 years were presented with ossification of PSL. Among these 37 patients, 28 patients were presented with unilateral ossified PSL, and 9 patients were presented with bilateral ossified PSL, amounting to the total of 46 ossified PSL from 400 CT images of the petroclival regions (11.5%). The genderwise and sidewise occurrence of the PSL ossification seen in different age groups were not statistically significant (p > 0.05). Among all the ossified cases, there was no patient presented with abducens nerve palsy. We believe our results provide baseline data in the region for understanding PSL ossification and its impact on the abducens nerve palsy.

Morphological analysis of the jugular foramen in dry human skulls in northeastern Brazil.

The jugular foramen (JF) is located between the temporal and occipital bones. The JF is a primary pathway for venous outflow from the skull and passage of nerves. Variations are common in this region and may have clinical and surgical implications. To analyze the sexual dimorphism and JF morphology in skulls from Northeastern Brazil. 128 human skulls from the Anatomy Laboratory of the Federal University of Paraíba, 64 male and 64 female, were selected and the JFs analyzed for bone septation and the presence of a dome. Data analysis considered P<0.05 as significant. On at least one side, complete septation was observed in 26 skulls (20.3%), incomplete septation in 93 skulls (72.6%) and 61 skulls (47.6%) did not present septation. In 114 skulls (89%), 47.6% female and 41.4% male, have a unilateral presence of the dome and 71 (55.4%) have it bilaterally. Posterolateral compartment diameters and JF area had higher values on the right side in the total sample and separated by sex (P<0.05). Most morphometric variables of the anteromedial compartment were higher in male than in female (P<0.05), fact that was not observed in the posterolateral compartment (P>0.05). This study showed a higher prevalence of complete septation in males compared to females. Morphometric analysis presented a peculiar morphology of the JF in this study. These results suggests that the surgical approach to diseases that affect the JF may be peculiar to the studied population, confirming the importance of morphological analysis of the skull base.

A bilateral four-headed brachialis muscle with a variant innervation: a cadaveric report with possible clinical implications.

Anterior compartment muscles of the arm present high morphological variability, with possible clinical significance. The current cadaveric report aims to describe a bilateral four-headed brachialis muscle (BM) with aberrant innervation. Emphasis on the embryological background and possible clinical significance are also provided. Classical upper limb dissection was performed on an 84-year-old donated male cadaver. The cadaver was donated to the Anatomy Department of the National and Kapodistrian University of Athens. On the left upper limb, the four-headed BM was supplied by the musculocutaneous and the median nerves after their interconnection. On the right upper limb, the four-headed BM received its innervation from the median nerve due to the musculocutaneous nerve absence. A bilateral muscular tunnel for the radial nerve passage was identified, between the BM accessory heads and the brachioradialis muscle. BM has clinical significance, due to its proximity to important neurovascular structures and frequent surgeries at the humerus. Hence, knowledge of these variants should keep orthopedic surgeons alert when intervening in this area. Further dissection studies with a standardized protocol are needed to elucidate the prevalence of BM aberrations and concomitant variants.

Factors influencing the spread of local anesthetic during the transverse abdominal plane block (study on unfixed corpses)

Introduction. Despite the proven clinical effectiveness of the transverse abdominal plane block (TAP block), the factors affecting the distribution of local anesthetic in the fascial case have not been fully studied, and there are no clear recommendations regarding the choice of the volume of local anesthetic taking into account anthropometry.The objective was to identify anthropometric factors influencing the choice of an adequate volume of local anesthetic for performing a TAP block.Materials and methods. In the pathology department, 40 upper and 40 lateral TAP blocks were performed in 20 corpses using ultrasound navigation. On the right side, 20 ml (block group A) of diamond green dye solution was injected, on the left side - 30 ml (block group B). The dependence of the area of distribution of the dye solution on the volume of the body, weight and height of the corpse was investigated. The analysis of the effect of damage in the execution zone on the area of dye distribution was carried out.Results. In the group B, the dye in 100 % of cases (n=18) spread to the nerve passage areas Th6 – Th9 in the upper TAP block and Th9 – L1 in the lateral TAP block. In group A, in 38.8 % of cases (n=7), the dye did not spread to the Th8-Th9 nerve passage area with the upper TAP block, as well as to the Th10 and Th12–L1 passage areas with the lateral TAP block. An inverse correlation of the growth and the dye distribution area was revealed (p &lt; 0.01). In all unfixed corpses whose height exceeded 179 cm, the dye could not compromise all the zones of passage of nerve structures. Tissue damage in the area of the block limited the spread of the dye.Conclusion. Adequate distribution of local anesthetic depends on the patient’s height. With the height of &gt;179 cm, 20 ml may not be enough to perform a TAP block, and &lt;177 cm – 30 ml may be excessive.

Hypoglossal canal: an osteological and morphometric study on a collection of dried skulls in an Italian population: clinical implications

BackgroundThe hypoglossal canal is a dual bone canal at the cranial base near the occipital condyles. The filaments of the hypoglossal nerve pass through the canal. It also transmits the meningeal branch of the ascending pharyngeal artery, the venous plexus and meningeal branches of the hypoglossal nerve. The hypoglossal nerve innervates all the intrinsic and extrinsic muscles of the tongue except the palatoglossal and is fundamental in physiological functions as phonation and deglutition. A surgical approach to the canal requires knowledge of the main morphometric data by neurosurgeons.MethodsThe present study was carried out on 50 adult dried skulls: 31 males: age range 18–85 years; 19 females: age range 26–79 years. The skulls came from the ''Leonetto Comparini'' Anatomical Museum. The skulls belonged to people from Siena (Italy) and its surroundings (1882–1932) and, therefore, of European ethnicity. The present study reports (a) the osteological variations in hypoglossal canal (b) the morphometry of hypoglossal canal and its relationship with occipital condyles. One skull had both the right and left hypoglossal canals occluded and, therefore, could not be evaluated. None of the skulls had undergone surgery.ResultsWe found a double canal in 16% of cases, unilaterally and bilaterally in 2% of cases. The mean length of the right and left hypoglossal canals was 8.46 mm. The mean diameter of the intracranial orifice and extracranial orifice of the right and left hypoglossal canals was 6.12 ± 1426 mm, and 6.39 ± 1495 mm. The mean distance from the intracranial end of the hypoglossal canal to the anterior and posterior ends of occipital condyles was 10,76 mm and 10,81 mm. The mean distance from the intracranial end of the hypoglossal canal to the inferior end of the occipital condyles was 7,65 mm.ConclusionsThe study on the hypoglossal canal adds new osteological and morphometric data to the previous literature, mostly based on studies conducted on different ethnic groups.The data presented is compatible with neuroradiological studies and it can be useful for radiologists and neurosurgeons in planning procedures such as transcondilar surgery. The last purpose of the study is to build an Italian anatomical data base of the dimensions of the hypoglossal canal in dried skulls..

Anatomical variations and coding of the intra-trunk pathways in the thoracodorsal nerve

Aim. To study anatomical variations of the intra–trunk pathways in the thoracodorsal nerve bundles and to develop a system for their coding.Materials and methods. After fixation in a 2% solution of acetic acid using the MBS-10 stereomicroscope, we performed macro- and microscopic intra-trunk dissection of thoracodorsal nerve bundles in 121 specimens obtained from 105 corpses of males and females who died at the age of 40–97 years. Using the obtained findings, we compiled a database in the MS Excel 12.0 software and determined the number of anatomical variations in absolute and relative (% from 121 specimens) units.Results. The study revealed that the thoracodorsal nerve is a mixed nerve, which consists of 1 motor and 1– 3 sensory bundles that variously pass through the spinal nerves, trunks, and the axillary nerve with the formation of 20 intra-trunk pathways. In 77% of cases, sensory bundles arising from the thoracodorsal nerve pass through the posterior bundle, the posterior division, the middle trunk, and the C7 spinal nerve or the inferior trunk and the C8 spinal nerve. In 22% of cases, the thoracodorsal nerve has one or, rarely, two duplicate sensory pathways besides the main one. In 93% of cases, the motor bundle to the thoracodorsal nerve passes through the C7 spinal nerve and the middle trunk, the posterior division, and the posterior bundle. Coding the anatomical variations of the intra-trunk pathways in the direction of sensory bundle «posterior bundle → posterior division → trunk → spinal nerve; motor bundle ← posterior bundle ← posterior division ← trunk ← spinal nerve allows to briefly yet clearly and fully display the morphological diversity of the nerve anatomy.Conclusion. The identified anatomical variations of the intra-trunk pathways can be useful in the diagnosis of injuries and diseases. They expand indications for the use of spinal nerves, trunks of the brachial plexus, and the thoracodorsal nerve in reconstructive surgery.

Evaluation and Classification of Supraorbital Nerve Emerging Patterns.

Numerous significant variations in the supraorbital nerve (SON) pass through the notches and foramina. During endoscopic forehead lifting, the passage and the location of the nerve against the frontal bone render it susceptible to injury, resulting in diminished or absent sensation in the corresponding location. We attempted to obtain accurate knowledge of the SON emergence routes. Data of patients who underwent an endoscopic forehead lift in a plastic surgery clinic between November 2015 and August 2021 were retrospectively analyzed. Deep and superficial branch pathways of SONs were identified and compared according to side and gender. We also classified the nerve patterns into six types. Altogether, 942 patients (1884 SON cases) were evaluated. Out of the patients, 86 patients were male, and 856 were female. The overall mean age was 48.6 (± 13.1) years. In the deep branches, 49% came from the notch, and 51% came from the foramen. In the superficial branches, 67% came from the notch, and 33% of superficial branches came from the foramen. Unlike the deep branch, superficial branches from the notch were significant. Deep and superficial branches of male patients were much more notched than those of female patients. Branches emerged together in 56% and separately in 44% of the cases. The absolute number of SON notches was higher than that of SON foramina. This study with the largest number of SON cases will help surgeons understand the variation and course of SON. This journal requires that authors 38 assign a level of evidence to each article. For a full 39 description of these Evidence-Based Medicine ratings, 40 please refer to the Table of Contents or the online 41 Instructions to Authors www.springer.com/00266 .

The potential role of a narrow foramen rotundum and foramen ovale in the development of concomitant continuous pain in trigeminal neuralgia

The most characteristic symptom of trigeminal neuralgia (TN) is paroxysmal and lancinating pain along the sensory distribution of the trigeminal nerve. Notably, a proportion of TN patients also experience persistent throbbing or burning in the same territory as their paroxysmal pain, termed concomitant continuous pain (CCP). The neurovascular compression (NVC) theory has been regarded as the primary cause of paroxysmal pain in TN. In contrast, the mechanisms underlying CCP can hardly be explained by NVC and have yet to be clearly elucidated. Both the foramen rotundum (FR) and foramen ovale (FO) are substantial bony apertures in the middle cranial fossa, through which the second (V2) and third divisions (V3) of the trigeminal nerve pass, respectively. Prior studies have proposed that a narrow FR and FO on the right side may result in a greater incidence of right-sided symptoms and be involved in the development of TN. However, given the nature of CCP and certain anatomical findings, we postulate that secondary compression of V2 and V3 by narrow foramina is more likely to be the primary cause of the persistent pain instead of the paroxysmal pain in cases of TN with CCP. TN with CCP may be the combination of trigeminal neuralgia induced by NVC and trigeminal neuropathic pain resulting from constant entrapment of V2 and V3. Therefore, considering that microvascular decompression cannot resolve all causes of TN with CCP, percutaneous ablative procedures and stereotactic radiosurgery may be more appropriate for patients with narrow foramina.

Morphometric Study of Atlas Vertebra In Relation to Sulcus Arteriae Vertebralis

Background: Atlas(C1) is an atypical cervical vertebra shaped like a ring. Important structures like the vertebral artery, suboccipital plexus of veins and first cervical nerve pass through it. Knowledge of the variability of C1 is important for neurosurgeons, orthopaedicians, otorhynologists and other physicians who in everyday practice are in contact with disorders of the spine and their consequences. So, this study was undertaken to assess the various dimensions of the C1 in relation to the vertebral artery groove. Methods and materials: fifty dried human atlas vertebrae were studied. Various measurements were done and statistically analysed. Results: Antero-posterior diameter (APD) of Foramen transversarium(FT) was measured as 7.73  1.04mm on the right and 7.62  0.90mm on left side. Transverse Diameter(TD) of FT was observed as 6.12  0.97mm on the right side and 6.02  0.97mm on the left side. Outer Distance of Vertebral Artery Groove(VAG) was measured as 26.22  2.32mm and 25.84  1.85mm on the right and left sides, respectively. Inner Distance of VAG was observed as 13.10  1.66mm on right and 13.17  1.57mm on the left side. APD of Superior Articular Facet(SAF) was 21.52  2.36mm on right and 21.51  2.07mm on left side.TD of SAF was 11.21  1.47mm on right and 11.32  1.53mm on left side. APD of Inferior Articular Facet(IAF) was observed as 17.54  1.50mm on right and 17.701.60mm on left side. TD of IAF was observed as 14.99 ± 1.65mm on the right side and 14.94 ± 1.51mm on left side. Distance between lateral-most edge of both Foramen Transversaria was measured as 56.37  4.11mm and distance between medial-most edge of both Foramen Transversaria was 44.78  3.67mm. MaximumTD of Atlas was measured as 72.09 5.59mm. Conclusion: The study will generate information that would be useful for geometric modelling of vertebrae and give necessary morphometric data on human atlas vertebra in Indian population. KEYWORDS: Atlas vertebra, Foramen transversarium, Vertebral Artery.

Morphological features of basivertebral foramen among different age groups: Recognition in spine.

Basivertebral foramen (BF) is a vessel and nerve passage in the posterior wall of vertebral body (VB). Our goal was to report BF's morphological characteristics in different age groups of mainland Chinese adults and to evaluate the relationship between BF's morphology and factors such as age, gender, heavy work, size and level of VB. We enrolled 300 adults among persons who came to our hospital for health examination. We measured BFs and VBs' parameters on T1 weighted sagittal lumbar spine MR images. We also assessed following potential predictors: gender, body height, body weight, body mass index, alcohol use, habits of smoking and drinking, type of work (physical work or non-physical work). A stepwise multivariate linear regression analysis was conducted to identify predictors of BF's height. People above 60 have significantly bigger BFHr than those in young adulthood and in the middle ages at all five levels, while they have shallowest BFs, especially at L3. Multiple linear regression resulted in a formula that accounted for 30.1% of the variability in the height of basivertebral foramen. Significant predictors included: gender, age, level, vertebral height and heavy work. Age is the highest weight in all factors on the height of BF. BF is closer to the upper endplate. The BF was relatively higher and deeper in the female lumbar spine. Heavywork results in lower BF. Last but not the least, as we supposed, BF gets shallower and higher compare to VB with age. Prognostic level III. See instructions for authors for a complete description of levels of evidence.

Morphometric analysis of the optic canal and the superior orbital fissure in a Brazilian sample – study in CT scans

The posterior wall of the orbit is composed by the sphenoid bone and exhibits the optic canal (OC) and the superior orbital fissure (SOF). The comprehensive knowledge of anatomical and morphometric observations of OC and SOF is vital for an accurate diagnosis and management of local pathology. The aim of this study was to conduct a morphometric analysis of the OC and the SOF in CT scans in a Brazilian population. A total of 40 computed tomography (CT) scans of dry human skulls were used (20 males and 20 females). The images were submitted to a segmentation in which the bony structures of interest in the orbit were selected. A three-dimensional reconstruction of the region and the measurements of the perimeter (mm) of the SOF and the volume (mm3) of the OC were performed. The statistical analysis was performed to verify if there was a difference in sex on each side for each anatomical structure. Regarding the OC, for the left side, there was a statistical difference between the sexes. For the SOF, neither the right side nor the left side showed statistical difference between the sexes. The present study showed new data about anatomical structures of the human orbit, bringing relevant knowledge for surgical and diagnostic procedures in the region. Especially for those anatomical structures evaluated that allow the passage of blood vessels and nerves, specific knowledge of their dimensions in different populations is valuable to avoid injuries during procedures in the orbital region.

Quantification of global orbital shape variation.

The complex anatomy of the orbit generates a complex orbital shape that can only be quantified approximatively by classic linear measurements such as maximum width and height. There is no global three-dimensional quantification of variations in orbital shape. The purpose of this study was to develop a method to quantify a global three-dimensional orbital shape variation in a healthy population and to test a series of explanatory factors. We investigated the hypotheses that orbital shape is related to gender(H1), orbital size(H2) and/or age(H3). Medical computed tomography(CT) images of 60 adult individuals were studied. The study sample consisted of 30 males and 30 females with a mean age of 25.1 years. Four anatomical landmarks and 140 semi-landmarks were measured on both positive and negative 3D reconstructed orbits and analyzed with geometric morphometrics. A principal component analysis(PCA) was computed to define a morphological space. Shape variation was visualized using vector distance maps and diagrams. The greatest variation was seen in the length of the superior orbital fissure. There was a gradient in terms of orbital shape ranging from short, wide orbits to tall, narrow orbits. The analysis did not highlight any significant age-, gender- or size-related impact in terms of orbital shape variation. Future avenues to explore include the study of other potential explanatory factors such as the different embryological origins of the orbital bones, the passage of vessels and nerves, and ethnic origins. This method can also be applied to the study of pathological orbits.

Магнитно-резонансно-томографическая анатомия половых нервов у мужчин зрелого возраста после выполнения оперативных вмешательств на органах малого таза

The work studied the magnetic resonance imaging (MRI) anatomy of the pudendal nerves in mature men who underwent surgery on pelvic organs. The study included 75 patients (30 patients in the first period of adulthood and 45 patients in the second period of adulthood). Thirty-seven patients underwent prostatectomy and 38 respondents underwent rectal resection. The single-trunk nature of the branching of the nerve, in which the pudendal nerve passes under the sacrospinous ligament, was found in the majority of patients (65.3%). The sources of formation of the pudendal nerves in 45 (60.0%) cases were the roots S2, S3 and S4, in 19 (25.3%) respondents the pudendal nerves were formed from the roots S2 and S4 and in 11 (14.6%) of respondents, the nerves originated from the S3 and S4 roots. The genital canals originate 22.5±3.2 mm below the ischial tuberosity and lie 39.8±9.5 mm anterior to it, the canals end at the level of the lower edge of the pubic symphysis 24.4±10.9 mm behind it. The average cross-sectional area of the genitals was 27.9±9.2 mm2. The average diameters of the pudendal nerve trunks at a level of 2 cm distal to the piriformis muscle were 4.63 mm, 1.85 mm, and 1.64 mm for the first, second, and third trunks, respectively. The average length of the pudendal nerve trunks before division into terminal branches was 25.23 mm. A comparison of the skeletotopic characteristics of the genital canals between patients with a conditional norm and patients after surgery on the pelvic organs demonstrated the presence of significant differences (p=0.023).

Anatomical Variations of the Trigeminal Nerve, Trigeminal Ganglion and Foramen Ovale: A Systematic Review

Introduction: The trigeminal nerve is principally responsible for controlling the sensory modalities of the face. The Foramen Ovale (FO) is one of the apertures present in the skull base, through which the mandibular nerve, a branch of the trigeminal nerve passes. Aim: To deliver a thorough understanding of the anatomical variations of the trigeminal ganglion and FO that would be beneficial to neurologists and neurosurgeons when performing various treatments involving these structures. Materials and Methods: The present systematic review was formulated according to Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines. Major electronic databases were screened and all types of studies including descriptive studies, surveys, full-text literature providing information about the variations in trigeminal ganglion and FO, were incorporated in the current review. Studies from 2001 to 2022 were included in this review. The risk of bias evaluation in the present study was conducted by using the review manager software (Rev Man version 5.4) and risk assessment domains were classified as high, indeterminate, or low risk. The recommended approach to check biases such as selection, performance, attrition, reporting, and other biases was done. Results: A total of 12 studies were examined. The studies measured the proper location and the size (diameter) of the trigeminal ganglion and FO using the MRI-based findings in 1,341 subjects in total. It was observed that the length of the trigeminal nerve was found to be about 9.66 mm in the cistern (range 6.04-20.74 mm) in 50% of studies, whereas in 16.67% of the studies trigeminal nerve was longer in the older patients as compared to the normal anatomy. Additionally, the distinctive form of the FO was noted in the current investigation. In total, (n=4) 66.66% of the studies demonstrated the oval shape of the FO, and (n=3) 50% of studies noticed an almond shape, 50% identified a round shape; (n=2) (33%; n=2) displayed a slit form. Only one investigation demonstrated a bony bridged of FO whereas 33% showed tubercle and triangular shapes. Conclusion: Majority of the studies showed that the length of the trigeminal nerve was found to be about 9.66 mm. Whereas, only one author reported that the trigeminal nerve is longer in the older patients as compared to the normal anatomy. The majority of studies demonstrated that the variations were observed in the shape of the FO, i.e., oval, round, almond, slit, spine.

Can sural nerve injuries be prevented in posterior leg approaches? Stage 1: Ultrasound evaluation of a new method based on surface anatomical landmarks and sural nerve pathway

Category: Other; Other Introduction/ Purpose: The risk of sural nerve intersection with posterior leg approaches, and its potential risk of injury in some surgeries can range from 60% to 100%. Several authors have described methods to predict the path of the sural nerve through metric units of non-proportional distances, however these distances are altered by patient's height, leg length and body mass index (BMI); none has proposed a reproducible method, proportional to each person based on anatomical references. The aim is to describe ultrasonographically the distance and crossing zone between a new method, proportional to each person, based on a surface reference line and the position of the sural nerve. Methods: Descriptive cross-sectional study, performed between January to April 2022 in patients requiring foot surgery who met inclusion criteria. We located and marked by ultrasound the course of the sural nerve in the posterior aspect of the leg. Landmarks were drawn and marked with a straight line from the posterior aspect of the medial femoral condyle to the tip of the fibula. This line was divided into two equal segments and the distal half was subdivided into 4 zones, this way, we studied areas based on simple anatomical proportions for each patient. The distance between the references and the ultrasound position of the nerve was measured in these 4 zones, creating intersection points and safety areas. Location and distances of the sural nerve from the proposed landmarks were assessed. A size of 96 lower limbs (48 patients) was determined with 95% confidence interval and 80% power to SN concordance between the two legs greater than 15% of that reported in the literature. Results: 100 lower limbs (50 left; 50 right) assessed in 50 patients were included. Forty-four percent female (44/100) and 56% male (56/100). The median age was 45 (range: 22 - 74) years. The median height was 164 (range: 150 - 180) cm with a median BMI of 23.3 (range: 17.7 - 39.7) kg/cm2. The shortest median distance of the nerve passage was 2.9 mm from Point 2. The sural nerve intersection was 59% in Zone B, 19% in Zone C and 20% in Zone A. Safety zones were established. Average 80% of coincidence in sural nerve localization, in the distal half of the leg, in relation to the surface reference line when comparing both legs of each patient. Conclusion: This study proposes a simple, reproducible, non-invasive, and for the first time, person-proportional method that describes the distance and location of the main areas of intersection of the sural nerve with points and areas determined by a line guided by superficial anatomical landmarks.

Ultrasound evaluation of a new surface reference line to describe sural nerve location and safe zones to consider in posterior leg approaches

PurposeSeveral authors have described methods to predict the sural nerve pathway with non-proportional numerical distances, but none have proposed a person-proportional, reproducible method with anatomical references. The aim of this research is to describe ultrasonographically the distance and crossing zone between a surface reference line and the position of the sural nerve.MethodsDescriptive cross-sectional study, performed between January and April 2022 in patients requiring foot surgery who met inclusion criteria. The sural nerve course in the posterior leg was located and marked using ultrasound. Landmarks were drawn with a straight line from the medial femoral condyle to the tip of the fibula. Four equal zones were established in the leg by subdividing the distal half of the line. This way, areas based on simple anatomical proportions for each patient were studied. The distance between the marking and the ultrasound nerve position was measured in these 4 zones, creating intersection points and safety areas. Location and distances from the sural nerve to the proposed landmarks were assessed.ResultsOne-hundred and four lower limbs, 52 left and 52 right, assessed in 52 patients were included. The shortest median distance of the nerve passage was 2.9 mm from Point 2. The sural nerve intersection was 60/104 (57.7%) in Zone B, 21/104 (20.1%) in Zone C and 19/104 (18.3%) in Zone A. Safety zones were established. Average 80.5% of coincidence in sural nerve localization was found in the distal half of the leg, in relation to the surface reference line when comparing both legs of each patient.ConclusionsThis study proposes a simple, reproducible, non-invasive and, for the first time, person-proportional method, that describes the distance and location of the main areas of intersection of the sural nerve with points and zones (risk and safe zones) determined by a line guided by superficial anatomical landmarks. Its application when surgeons plan and perform posterior leg approaches will help to avoid iatrogenic nerve injuries.Level of evidenceIV.

Visualization of human optic nerve by diffusion tensor mapping and degree of neuropathy.

Diffusion-weighted magnetic resonance imaging of the human optic nerve and tract is technically difficult because of its small size, the inherent strong signal generated by the surrounding fat and the cerebrospinal fluid, and due to eddy current-induced distortions and subject movement artifacts. The effects of the bone canal through which the optic nerve passes, and the proximity of blood vessels, muscles and tendons are generally unknown. Also, the limited technical capabilities of the scanners and the minimization of acquisition times result in poor quality diffusion-weighted images. It is challenging for current tractography methods to accurately track optic pathway fibers that correspond to known anatomy. Despite these technical limitations and low image resolution, here we show how to visualize the optic nerve and tract and quantify nerve atrophy. Our visualization method based on the analysis of the diffusion tensor shows marked differences between a healthy male subject and a male subject with progressive optic nerve neuropathy. These differences coincide with diffusion scalar metrics and are not visible on standard morphological images. A quantification of the degree of optic nerve atrophy in a systematic way is provided and it is tested on 9 subjects from the Human Connectome Project.