Neuraxial pathology and regional anesthesia: an education guide to decision-making.

In current clinical practice, spinal anesthesia and analgesia techniques-including epidural and subarachnoid procedures-are frequently executed without imaging like X-ray or epidurography. Unrecognized spinal pathology has resulted in serious morbidity in the context of performing neuraxial anesthesia. Typically, preoperative consultations incorporate a patient's medical history but lack a detailed spinal examination or consideration of recent MRI or CT scans. In contrast, within the domain of pain clinics, a multidisciplinary approach involving anesthesiologists and neuroradiologists is common. Such collaborative settings rely on exhaustive clinical history and scrutinization of recent imaging studies, which may influence the decision to proceed with invasive spinal interventions. There are no epidemiological data concerning rates of the different baseline pathologies that would potentially pose morbidity risks from neuraxial procedures, but the most common among these is canal stenosis, which significantly affects almost 20% of people over 60 years of age. This paper aims to elucidate these critical findings and advocate for incorporating meticulous preoperative assessments for individuals slated for spinal anesthesia or analgesia procedures, thereby attempting to mitigate potential risks.

The size, number, and distribution of nerve endings around and within the human epiglottis, focusing on tracheal intubation maneuvers.

The aim of this study was to examine the distribution of nerve endings in the mucosa, submucosa, and cartilage of the epiglottis and the vallecula area and to quantify them. The findings could inform the choice of laryngoscope blades for intubation procedures. Fourteen neck slices from seven unembalmed, cryopreserved human cadavers were analyzed. The slices were stained, and cross and longitudinal sections were obtained from each. The nerve endings and cartilage were identified. The primary metrics recorded were the number, area, and circumference of nerve endings located in the mucosa and submucosa of the pharyngeal and laryngeal sides of the epiglottis, epiglottis cartilage, and epiglottic vallecula zone. The length and thickness of the epiglottis and cartilage were also measured. The elastic cartilage of the epiglottis was primarily continuous; however, it contained several fragments. It was covered with dense collagen fibers and surrounded by adipose cells from the pharyngeal and laryngeal submucosa. Nerve endings were found within the submucosa of pharyngeal and laryngeal epiglottis and epiglottic vallecula. There were significantly more nerve endings on the posterior surface of the epiglottis than on the anterior surface. The epiglottic cartilage was twice the length of the epiglottis. The study demonstrated that the distribution of nerve endings in the epiglottis differed significantly between the posterior and anterior sides; there were considerably more in the former. The findings have implications for tracheal intubation and laryngoscope blade selection and design.

Corrigendum: Intrathecal drug delivery: Advances and applications in the management of chronic pain patient.

[This corrects the article DOI: 10.3389/fpain.2022.900566.].

Revisiting the Muscular Innervation of the Obturator Nerve: Application to Neurotization Procedures.

BACKGROUND: Our goal was to revisit the innervation of the adductor muscles of the thigh and add new evidence to currently existing knowledge. METHODS: Ten thighs from five fresh frozen cadavers were dissected. Obturator nerve innervation to the pectineus, obturator externus, adductor brevis, adductor magnus, adductor longus, and gracilis was documented. RESULTS: The adductor longus and gracilis were innervated by the anterior branch in 100%, and the adductor magnus was innervated by the posterior branch in 100%. The adductor brevis was supplied by both the anterior and posterior branches in 90%. The obturator externus was innervated by the posterior branch in 60% and a direct branch from the main trunk in 10%. No innervation of the obturator externus by the obturator nerve was found in 30%. CONCLUSIONS: The obturator externus and adductor brevis need to be explored further to clarify their innervation.

Pectorobrachioepicondylaris musculoaponeurotic band: case description with evidence of median nerve compression.

Upper limb muscle variations can be encountered on imaging or at surgery. We report an unusual muscle and band found during routine dissection of the arm in a cadaver. This case is described and salient literature reviewed. A band was found that traveled from the insertion of the pectoralis major tendon distally and obliquely toward the medial intermuscular septum and medical epicondyle. Fibers of the brachialis were found to interdigitate into the band. A tunnel was formed that carried the median nerve and brachial vessels. Evidence of median nerve compression was observed. We considered this an example of a pectorobrachioepicondylaris muscle. However, some can lead to clinical presentations. Although the significance of the case reported herein is not certain, signs of median nerve compression were identified. We believe that the term pectorobrachioepicondylaris bests describes the muscle reported herein and that our case represents a previously unreported variant of this muscle.

Accuracy of injection pressure measurement at peripheral nerves using high-resolution 40 MHz ultrasound in an anesthetized porcine model.

BACKGROUND: Fluid injection pressure measurement is promoted as a marker of needle tip position that discriminates between tissue layers. However, clinical ultrasound has insufficient resolution to identify the exact position of the needle tip. Our primary objective was to use 40 MHz ultrasound in anesthetized pigs in order to precisely locate the tip of the needle and measure opening injection pressure in muscle, at epineurium and in subepineurium. METHODS: We surgically exposed the axillae of four anesthetized pigs. Two operators placed a 40 MHz ultrasound transducer over the pectoral muscle and imaged axillary, median and radial nerves. Injections (0.5 mL) were randomized to in-plane and out-of-plane needle trajectories and flow rates of 1, 6 and 12 mL/min. RESULTS: We identified 541 fascicles in 23 nerves. The ratio of fascicle area to nerve area remained constant at ~0.30 for all nerves. Axillary nerves were smaller than median and radial nerves, difference in diameter (95% CI) 1.61 (0.87 to 2.36) mm, p<0.001 and 1.59 (0.82 to 2.36) mm, p=0.001, respectively. Axillary nerves had less fascicles per nerve than median nerves, difference 7.63 (2.43 to 12.83) and radial nerves, difference 9.02 (3.64 to 14.40). We visualized the circumneurium and injection within the subcircumneural compartment. Intraneural injection increased nerve area (SD) from 5.7 (2.2) mm2 to 13.7 (5.5) mm2, difference 8.0 (5.4-10.6) mm2, p<0.001. Mean injection pressure was greater in subepineurium compared with muscle, geometric ratio 2.29 (1.30 to 4.10), p<0.001; and greater on epineurium compared with muscle, geometric ratio 1.73 (1.03 to 3.00), p=0.01. Twenty-two out of 23 injections in muscle, 14 out of 23 injections at epineurium and 11 out of 22 injections in subepineurium were <138 kPa (20 psi). CONCLUSION: Needle tip position was not discernible using pressure monitoring. The circumneurium and subcircumneural injection compartment were observed but not intrafascicular injection.

Morphology and morphometry of the human obturator nerve in males and females.

Peripheral nerve injury and the nerves' subsequent repair and regeneration continues to be marked clinically by poor functional recovery. The analysis of nerve morphology is an aspect which may provide an impact on successful clinical outcomes through better prediction of donor and recipient matching. In this study, we evaluated the morphological aspects of the human obturator nerve for a better understanding of its potential in nerve transplantation. Morphological characteristics of donor obturator nerves were analysed, including nerve diameter and length, fascicle count and the ratio of neural to non-neural tissue present within the cross-sectional area of the nerve's epineurium, with respect to laterality and sex. Statistical significance (p < 0.10) was determined for male obturator nerves having an average diameter of 2.67 mm compared to female obturator nerves at 1.91 mm, as well as left obturator nerves having an average of 11.21 fascicles compared to the right having an average of 10.17 fascicles. Strong positive correlations were determined between cross-sectional nerve area and limb size index, as well as between percentage of non-neural tissue and area of non-neural tissue, among males. Separately, strong correlation between percentage of non-neural tissue and area of non-neural tissue among right obturator nerves in males and females was determined . These findings indicate that there are associations and predictions that can be made about nerve morphology and that these when combined with other patient characteristics may enhance patient functional recovery following a peripheral nerve's repair.

Intrathecal Drug Delivery: Advances and Applications in the Management of Chronic Pain Patient.

Advances in our understanding of the biology of spinal systems in organizing and defining the content of exteroceptive information upon which higher centers define the state of the organism and its role in the regulation of somatic and automatic output, defining the motor response of the organism, along with the unique biology and spatial organization of this space, have resulted in an increased focus on therapeutics targeted at this extracranial neuraxial space. Intrathecal (IT) drug delivery systems (IDDS) are well-established as an effective therapeutic approach to patients with chronic non-malignant or malignant pain and as a tool for management of patients with severe spasticity and to deliver therapeutics that address a myriad of spinal pathologies. The risk to benefit ratio of IDD makes it a useful interventional approach. While not without risks, this approach has a significant therapeutic safety margin when employed using drugs with a validated safety profile and by skilled practioners. The present review addresses current advances in our understanding of the biology and dynamics of the intrathecal space, therapeutic platforms, novel therapeutics, delivery technology, issues of safety and rational implementation of its therapy, with a particular emphasis upon the management of pain.

Entropy Method for Decision-Making: Uncertainty Cycles in Tourism Demand.

A new methodology is presented for measuring, classifying and predicting the cycles of uncertainty that occur in temporary decision-making in the tourist accommodation market (apartments and hotels). Special attention is paid to the role of entropy and cycles in the process under the Adaptive Markets Hypothesis. The work scheme analyses random cycles from time to time, and in the frequency domain, the linear and nonlinear causality relationships between variables are studied. The period analysed is from January 2005 to December 2018; the following empirical results stand out: (1) On longer scales, the periodicity of the uncertainty of decision-making is between 6 and 12 months, respectively, for all the nationalities described. (2) The elasticity of demand for tourist apartments is approximately 1% due to changes in demand for tourist hotels. (3) The elasticity of the uncertainty factor is highly correlated with the country of origin of tourists visiting Spain. For example, it has been empirically shown that increases of 1% in uncertainty cause increases in the demand for apartments of 2.12% (worldwide), 3.05% (UK), 1.91% (Germany), 1.78% (France), 7.21% (Ireland), 3.61% (The Netherlands) respectively. This modelling has an explanatory capacity of 99% in all the models analysed.

A reliable septum exists between the lateral cord and medial and posterior cords in the costoclavicular region: Clinical and microanatomical considerations in brachial plexus anesthetic blockade.

BACKGROUND AND OBJECTIVES: The ultrasound-guided proximal infraclavicular costoclavicular block (PICB) appears popular but its results are inconsistent. We sought an accurate demonstration of septae formed between the brachial plexus cords. METHODS: We performed in-plane, lateral-to-medial PICBs on 120 patients and recorded images. Once the most superficial lateral cord component was entered, a 0.4-0.6 mA current was applied to confirm needle placement; 5 ml of local anesthetic (LA) solution was then injected and its spread was observed and recorded. As the needle was advanced, the presence or absence of a hyperechoic linear structure was noted before the deeper compartment was reached, specifically looking for the possible displacement of such a septum. RESULTS: Upon initial scanning, a septum was observed in 67 of the 120 patients (46.2%). However, there was clear displacement of a linear septum between the lateral cord compartment and the medial and posterior cord compartments that prevented spread between the compartments in 94.16% of patients. Piercing the septum evoked motor responses from the medial or posterior cord. The same anatomical regions were studied microanatomically by analyzing cross-sections obtained with the same approach angle as the ultrasound probe. CONCLUSIONS: Intraplexus fascial septae that bundled the medial and posterior cords into one compartment and separated them from the lateral cord were demonstrated and confirmed microanatomically. This suggests the need for two separate injections (or two separate catheter placements for continuous peripheral nerve blockade) into the superficial and deep compartments to ensure LA spread around all three cords of the brachial plexus at this level.

Venous Drainage of Lumbar Vertebral Bodies: Anatomic Study with Application to Kyphoplasty, Vertebroplasty, and Pedicle Screw Complications.

BACKGROUND: Bone cement augmentation with polymethylmethacrylate is a reliable method for stabilizing osteoporotic compression fractures and improving fixation of pedicle screws. However, cement extrusion into the vertebral venous system can result in pulmonary cement embolism. The goal of this anatomic study was to identify the relationship between the internal/external vertebral plexus and neighboring abdominal caval system. METHODS: Thirty-two lumbar vertebral levels were used in this study. Anterior abdominal dissection was performed to access the lumbar vertebral bodies through the peritoneal cavity, and a 16-gauge needle was placed into the center of each lumbar vertebral body at its anterior aspect. Fluoroscopy was used to confirm if the needle was correctly placed. Next, latex and/or continuous air injections were performed into each lumbar vertebral level (L1-L5). Observations confirmed if the latex or air traveled into the inferior vena cava. In addition, the spinal canal was opened to see if any latex was found to enter inside the vertebral canal in cadavers injected with the latex. RESULTS: Latex or air was found to flow into the inferior vena cava at all the lumbar vertebral levels. The latex/air was not observed in the spinal canal in any specimen. CONCLUSIONS: An exact knowledge of the lumbar vertebral venous anatomy is essential when procedures that could affect the vertebral venous system are involved. Its complexity and anatomic variability necessitate such an understanding to better prevent/understand possible complications associated with polymethylmethacrylate extrusion.

The Lumbar Ligamentum Flavum Does Not Have Two Layers and Is Confluent with the Interspinous Ligament: Anatomical Study with Application to Surgical and Interventional Pain Procedures.

Numerous authors over the years have reported that the lumbar ligamentum flavum has two layers. Our routine cadaveric dissections raised the question whether this understanding is correct, as we always have observed only one layer. Thus, the goal of this cadaveric study was to reevaluate the layers of the ligamentum flavum. Twenty lumbar levels from five fresh-frozen cadaveric specimens were used in this study. After dissection of the lumbar spine, the ligamentum flavum and interspinous ligament were exposed. Each lumbar level was transected through the zygapophyseal joint, and hematoxylin and eosin staining, Masson's trichrome staining and Verhoeff-van Gieson staining were performed. Continuation of the interspinous ligament and ligamentum flavum were observed invariably. There was no evidence of the existence of a two-layered ligamentum flavum. The lumbar ligamentum flavum does not consist of two layers, but is confluent instead with the interspinous ligament that attaches to the zygapophyseal joints. To convey this anatomy better, we suggest describing the lumbar ligamentum flavum as a structure that consists of interlaminar and interspinous parts. Precise knowledge of the ligamentum flavum's anatomy can be of clinical value, particularly when epidural anesthesia or lumbar puncture are performed. Clin. Anat. 32:34-40, 2019. © 2019 Wiley Periodicals, Inc.

Microanatomy Relevant to Intrathecal Drug Delivery.

This chapter describes the microanatomy of the spinal cord that is relevant to intrathecal drug delivery started with covering of the spinal cord that are pierced to enter the intrathecal space. The dural sac is mostly constituted by the outer layer of dura and the inner layer called arachnoid membrane, which regulates diffusion of drugs into the intrathecal space. The pia matter surrounding the spinal cord is a permeable structure allowing the passage of drugs through intercellular spaces. The relationship between nerve roots, CSF, and subarachnoid catheters determines the passage of an intrathecal catheter which can cause damage to nerve roots and spinal cord. Multiple factors may be involved in the mechanisms of drug diffusion across the membranes of the spinal cord, as well as in their dilution with the CSF, which will lead to the final drug distribution and availability at nerve roots and the spinal cord.

Discovery of a new ligament of the lumbar spine: the midline interlaminar ligament.

BACKGROUND: The ligaments of the lumbar spine are integral to structural integrity and have been well-studied. However, during the routine dissection of the lumbar spine, we identified to our knowledge, a previously undescribed midline ligament near the ligamenta flava but distinctly separate. PURPOSE: The purpose of this study was to investigate the morphology of this ligament termed by us the midline interlaminar ligament. STUDY DESIGN: Cadaveric study. METHODS: Thirty-four lumbar vertebral levels from 10 fresh frozen adult cadavers were dissected. The ligamenta flava were dissected anteriorly. The junction between the right and left ligamenta flava was observed and the presence and morphometrics of the median interlaminar ligament (MIL) were recorded. Random ligaments underwent tensile strength testing. Metal wires were also placed on the ligaments and fluoroscopy performed. RESULTS: Twenty-six out of 34 (76.5%) lumbar levels were found to have a MIL traveling on the internal aspect of the most medial aspect of the laminae and positioned slightly anterior to the plane of the ligamenta flava. The mean length and width of the MIL were 9.03±4.29 mm and 4.94±1.56 mm, respectively. The mean force necessary until failure for the MIL was 12.3N. CONCLUSIONS: Based on our findings, a distinct MIL was identified in the lumbar spine at the majority of lumbar levels. CLINICAL SIGNIFICANCE: The MIL might have clinical significance and potential biomechanical importance. Further studies are now necessary to better elucidate this anatomical structure.

Electron Microscopy of Dural and Arachnoid Disruptions After Subarachnoid Block.

BACKGROUND: It has been customary to attribute postdural puncture headache (PDPH) incidence and severity to size and nature of the dural hole produced during major neuraxial blockade or diagnostic dural puncture. Needle orientation in relation to the direction of dural fibers was thought to be of importance because of the propensity for horizontal bevel placement to cause cutting rather than splitting of the dural fibers. METHODS: In vitro punctures of stringently quality-controlled human dural sac specimens were obtained with 27-gauge (27G) Whitacre needle (n = 33), with 29G Quincke used parallel to the spinal axis (n = 30), and with 29G Quincke in perpendicular approach (n = 40). The samples were studied with a scanning electron microscope, and the perimeter, appearance, and area (%) of the lesion were calculated. RESULTS: When using small 27G to 29G needles, neither needle tip characteristics nor needle orientation had a substantial bearing on the damage to dural fibers in the dural lesion. Of ultimate importance was the characteristic and size of the hole in the arachnoid. Arachnoid layer lesions produced by different types of spinal needles were not markedly different. CONCLUSIONS: Accepted theories of the etiology of PDPH need to be revised. This article marks the first time that arachnoid layer damage has been quantified. Dural fibers tend to have sufficient "memory" to close back the hole created by a spinal needle, whereas arachnoid has diminished capacity to do so. The pathogenesis of PDPH and its resolution algorithm are a far more complex process that involves many more "stages" of development than hitherto imagined.

Anatomic Basis for Brachial Plexus Block at the Costoclavicular Space: A Cadaver Anatomic Study.

BACKGROUND AND OBJECTIVES: The costoclavicular space (CCS), which is located deep and posterior to the midpoint of the clavicle, may be a better site for infraclavicular brachial plexus block than the traditional lateral paracoracoid site. However, currently, there is paucity of data on the anatomy of the brachial plexus at the CCS. We undertook this cadaver anatomic study to define the anatomy of the cords of the brachial plexus at the CCS and thereby establish the anatomic basis for ultrasound-guided infraclavicular brachial plexus block at this proximal site. METHODS: The anatomy and topography of the cords of the brachial plexus at the CCS was evaluated in 8 unembalmed (cryopreserved), thawed, fresh adult human cadavers using anatomic dissection, and transverse anatomic and histological sections, of the CCS. RESULTS: The cords of the brachial plexus were located lateral and parallel to the axillary artery at the CCS. The topography of the cords, relative to the axillary artery and to one another, in the transverse (axial) plane was also consistent at the CCS. The lateral cord was the most superficial of the 3 cords and it was always anterior to both the medial and posterior cords. The medial cord was directly posterior to the lateral cord but medial to the posterior cord. The posterior cord was the lateral most of the 3 cords at the CCS and it was immediately lateral to the medial cord but posterolateral to the lateral cord. CONCLUSIONS: The cords of the brachial plexus are clustered together lateral to the axillary artery, and share a consistent relation relative to one another and to the axillary artery, at the CCS.

Threshold selection criteria for quantification of lumbosacral cerebrospinal fluid and root volumes from MRI.

BACKGROUND AND PURPOSE: The high variability of CSF volumes partly explains the inconsistency of anesthetic effects, but may also be due to image analysis itself. In this study, criteria for threshold selection are anatomically defined. METHODS: T2 MR images (n = 7 cases) were analyzed using 3-dimentional software. Maximal-minimal thresholds were selected in standardized blocks of 50 slices of the dural sac ending caudally at the L5-S1 intervertebral space (caudal blocks) and middle L3 (rostral blocks). Maximal CSF thresholds: threshold value was increased until at least one voxel in a CSF area appeared unlabeled and decreased until that voxel was labeled again: this final threshold was selected. Minimal root thresholds: thresholds values that selected cauda equina root area but not adjacent gray voxels in the CSF-root interface were chosen. RESULTS: Significant differences were found between caudal and rostral thresholds. No significant differences were found between expert and nonexpert observers. Average max/min thresholds were around 1.30 but max/min CSF volumes were around 1.15. Great interindividual CSF volume variability was detected (max/min volumes 1.6-2.7). CONCLUSIONS: The estimation of a close range of CSF volumes which probably contains the real CSF volume value can be standardized and calculated prior to certain intrathecal procedures.

Loss of Nm23 is associated with a more favorable tumor microenvironment in patients with breast cancer.

AIM: Nm23 is a metastasis suppressor gene whose downregulation triggers metastatic progression. The aim of this study was to investigate the expression of Nm23 in breast carcinomas and its relationship with tumor microenvironment markers. METHODS: A retrospective study was done (128 breast cancer patients from 2007 to 2010). Nm23, LPA1, SMA, CD34, CD8, and CD68 protein expressions were evaluated using immunohistochemistry. Image analysis was used to determine the immunostaining percentage area of Nm23, LPA1, and SMA; the number of the total vessel fraction CD34 positive; and the number of CD8+ and CD68+ cells. The mean ± SE was calculated. The differences among groups were evaluated using Student t-test for parametric data and Mann Whitney U test for nonparametric data. RESULTS: Cases were divided into two groups: Nm23+ and Nm23-. LPA1 immunostaining was significantly increased in Nm23- group. Immunostaining percentage area of SMA was not significantly higher when Nm23 was negative. CD34 immunopositive blood vessels, number of T CD8+ cells, and the number of macrophage CD68+ cells were increased when Nm23 was absent. CONCLUSION: Our results suggest that the absence of Nm23 causes an increase in LPA1, CD8+ and CD68+ inflammatory cells, and angiogenesis marker. Therefore, Nm23 loss could be associated with a more favorable environment for the development and dissemination of breast cancer. However, more studies are needed to determine this association.