Anatomy of mamillo-accessory foramen and prevalence of ossified mamillo-accessory ligament in lumbar vertebrae related to age

PURPOSE

Ossification of the mamillo-accessory ligament (MAL) results in the formation of a mamillo-accessory foramen (MAF), which is associated with aging. The MAL tethers the medial branches of the lumbar dorsal rami to the lumbar vertebrae. A MAL ossified at the lumbar vertebrae can cause low back pain by compressing the medial branch of a dorsal ramus. Age ranges related to ossification of the MAL have not been reported in previous studies. The objective of the present study was to determine the prevalence of ossification of the MAL in the lumbar column and its relationship to aging, and to measure the newly formed MAF at each level of the lumbar vertebrae.

METHODS

This study examined 935 dried lumbar vertebrae from 187 donors at Khon Kaen University, Thailand, consisting of 93 females and 94 males. The research focused on ossification patterns of the MAL, categorizing them into three patterns.

RESULTS

We found that over 50% of ossified MAL occurred in the 30-45-year-old range and the frequency increased with age. The prevalence of ossified lumbar MAL was 72.73%, especially in L5 on the left side in females (76.92%). The width of the MAF did not differ significantly between the sexes, but it was greater on the left side (2.46 ± 1.08; n = 76) than the right (2.05 ± 0.95; n = 72) (p = 0.016).

CONCLUSION

Ossification of the MAL into the MAF progresses with age, leading to low back pain from nerve compression. Physicians should be aware of the MAF during anesthesia block to treat low back pain.

Minimum effective concentration of ropivacaine for ultrasound-guided transmuscular quadratus lumborum block in total hip arthroplasty: a randomized clinical trial

OBJECTIVE

This trial aimed to identify the Minimum Effective Concentration (MEC90, defined as the concentration which can provide successful block in 90% of patients) of 30 mL ropivacaine for single-shot ultrasound-guided transmuscular Quadratus Lumborum Block (QLB) in patients undergoing Total Hip Arthroplasty (THA).

METHODS

A double-blind, randomized dose-finding study using the biased coin design up-and-down sequential method, where the concentration of local anesthetic administered to each patient depended on the response from the previous one. Block success was defined as a Numeric Rating Scale (NRS) score during motion ≤ 3 at 6 hours after arrival in the ward. If the block was successful, the next subject received either a 0.025% smaller dose (probability of 0.11) or the same dose (probability of 0.89); otherwise, the next subject received a 0.025% higher ropivacaine concentration. MEC90, MEC95 and MEC99 were estimated by isotonic regression, and the corresponding 95% Confidence Intervals (95% CIs) were calculated by the bootstrapping method.

RESULTS

Based on the analysis of 52 patients, MEC90, MEC95, and MEC99 of ropivacaine for QLB were estimated to be 0.352% (95% CI 0.334-0.372%), 0.363% (95% CI 0.351-0.383%), and 0.373% (95% CI 0.363-0.386%). The concentration of ropivacaine at 0.352% in a volume of 30 ml can provide a successful block in 90% of patients.

CONCLUSIONS

For ultrasound-guided transmuscular QLB in patients undergoing THA, 0.352% ropivacaine in a volume of 30 ml can provide a successful block in 90% of patients. Further dose-finding studies and large sample size are required to verify the concentration.

Laparoscopic versus Ultrasound-Guided Transversus Abdominis Plane Block for Postoperative Analgesia Management after Radical Prostatectomy: Results from a Single Center Study

(1) Background: Regional anesthesia, achieved through nerve blocks, has gained widespread acceptance as an effective pain management approach. This research aimed to evaluate the efficacy of laparoscopic (LAP) transversus abdominis plane (TAP) block in patients undergoing laparoscopic radical prostatectomy. (2) Methods: From January 2023 to July 2023, 60 consecutive patients undergoing minimally invasive radical prostatectomy were selected. Patients were split into two groups receiving ultrasound-guided (US) or laparoscopic-guided TAP block. The primary outcome was a pain score expressed by a 0-10 visual analog scale (VAS) during the first 72 h after surgery. (3) Results: Both LAP-TAP and US-TAP block groups were associated with lower pain scores postoperatively. No statistically significant differences were observed between the two groups in surgery time, blood loss, time to ambulation, length of stay, and pain after surgery (all p > 0.2). In the LAP-TAP block group, the overall operating room time was significantly shorter than in the US-TAP block group (140 vs. 152 min, p = 0.04). (4) Conclusions: The laparoscopic approach, compared to the US-TAP block, was equally safe and not inferior in reducing analgesic drug use postoperatively. Moreover, the intraoperative LAP-TAP block seems to be a time-sparing procedure that could be recommended when patient-controlled analgesia cannot be delivered.

Case report: Paralysis after epidural analgesia due to a hemorrhage of pure epidural venous hemangioma

Purpose

To report a case of sudden paralysis after epidural analgesia to raise awareness of the condition and the importance of early identification and appropriate treatment of extradural venous angiomas.

Clinical features

A 28-year-old man with myofascial pain syndrome experienced paraplegia after receiving an epidural block for pain relief, which was later discovered to be caused by hemorrhage from extradural venous angiomas. Decompression surgery was performed immediately and successfully. A follow-up examination was performed 5 months after surgery. The patient reported improvement in urinary retention. The muscle strength in both his lower extremities had recovered to 4 out of 5 but still exhibited considerable residual spasticity.

Conclusions

Before administering epidural analgesia to relieve undetermined pain, it is prudent to carefully weigh potential benefits against potential risks to patient health to minimize the likelihood of complications.

Filum Terminale: A Comprehensive Review with Anatomical, Pathological, and Surgical Considerations

The conus medullaris is the distal tapering end of the spinal cord, and the filum terminale (FT) is regarded as a bundle of non-functional fibrous tissue; therefore, some scholars call it the spinal ligament, while others describe the human FT as "remnants of the spinal cord." It was later found that in the human spinal cord, the FT is composed of an intradural segment and an epidural segment, and the end of the FT is connected to the coccyx periosteum. Because some nerve tissue is also found in the FT, as research progresses, FT may have the potential for transplantation. A lack of exhaustive overviews on the FT in the present literature prompted us to conduct this review. Considering that a current comprehensive review seemed to be the need of the hour, herein, we attempted to summarize previous research and theories on the FT, elucidate its anatomy, and understand its pathological involvement in various diseases.

Impact of the pericapsular nerve group (PENG) block on postoperative analgesia and functional recovery following total hip arthroplasty: a randomised, observer-masked, controlled trial

The pericapsular nerve group (PENG) block is a novel regional anaesthesia technique that aims to provide hip analgesia with preservation of motor function, although evidence is currently lacking. In this single-centre, observer-masked, randomised controlled trial, patients undergoing total hip arthroplasty received pericapsular nerve group block or no block (control group). Primary outcome measure was maximum pain scores (0-10 numeric rating scale) measured in the first 48 h after surgery. Secondary outcomes included postoperative opioid consumption; patient mobilisation assessments; and length of hospital stay. Sixty patients were randomly allocated equally between groups. The maximum pain score of patients receiving the pericapsular nerve group block was significantly lower than in the control group at all time-points, with a median (IQR [range]) of 2.5 (2.0-3.7 [0-7]) vs. 5.5 (5.0-7.0 [2-8]) at 12 h; 3 (2.0-4.0 [0-7]) vs. 6 (5.0-6.0 [2-8]) at 24 h; and 2.0 (2.0-4.0 [0-5]) vs. 3.0 (2.0-4.7 [0-6]) at 48 h; all p < 0.001. Moreover, the pericapsular nerve group showed a significant reduction in opioid consumption, better range of hip motion and shorter time to ambulation. Although no significant difference in hospital length of stay was detected, our results suggest improved postoperative functional recovery following total hip arthroplasty in patients who received pericapsular nerve group block.

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.

Experimental evaluation of a self-propelling bio-inspired needle in single- and multi-layered phantoms

In percutaneous interventions, reaching targets located deep inside the body with minimal tissue damage and patient pain requires the use of long and thin needles. However, when pushed through a solid substrate, a structure with a high aspect ratio is prone to buckle. We developed a series of multi-element needles with a diameter smaller than 1 mm and a length larger than 200 mm, and we experimentally evaluated the performance of a bio-inspired insertion mechanism that prevents needle buckling of such slender structures. The needles consisted of Nitinol wires and advance into a substrate by pushing the wires forward one after the other, followed by pulling all the wires simultaneously backward. The resulting net push force is low, allowing the needles to self-propel through the substrate. We investigated the effect of the needle design parameters (number of wires and their diameter) and substrate characteristics (stiffness and number of layers) on the needle motion. Three needle prototypes (consisting of six 0.25-mm wires, six 0.125-mm wires, and three 0.25-mm wires, respectively) were inserted into single- and multi-layered tissue-mimicking phantoms. The prototypes were able to move forward in all phantoms without buckling. The amount of needle slip with respect to the phantom was used to assess the performance of the prototypes. The six-wire 0.25-mm prototype exhibited the least slip among the three prototypes. Summarizing, we showed that a bio-inspired motion mechanism prevents buckling in very thin (diameter <1 mm), long (length >200 mm) needles, allowing deep insertion into tissue-mimicking phantoms.

Anatomical and Biomechanical Study of the Lumbar Interspinous Ligament

Objective

The lumbar interspinous ligaments (ISLs) are thin and short fibers connecting adjacent spinous processes. However, their morphology is variably described and their biomechanics are not well understood. Therefore, the purpose of this study was to assess the anatomy and biomechanics of the lumbar ISL.

Materials and Methods

Five fresh frozen cadaveric specimens were dissected posteriorly to reveal and study the lumbar ISL. Measurements of the ligaments included the anterior vertical height (length A), the posterior vertical height (length P), and the length (length H) at each lumbar level. Next, 17 lumbar vertebral levels from 6 cadaveric specimens were used for tensile strength testing. The ISLs were subjected to vertically controlled increasing manual tension. The force necessary to disrupt the ISL was recorded.

Results

All the ISLs ran horizontally in an anterior-posterior direction with a slight curve. The average of length A, length P, and length H on the right sides was 9.82, 9.57, and 20.12 mm, respectively. The average of length A, length P, and length H on the left sides was 11.56, 12.01, and 21.42 mm, respectively. The mean tensile strength of the ISL was 162.33 (N) at L1/2, 85.67 (N) at L2/3, and 79 (N) at L3/4. There was a significant difference in the tensile force between L1/2 and L2/3 and L1/2 and L3/4 (P < 0.05). The ligaments became weaker with a descent along the lumbar levels.

Conclusion

The results of this study might help surgeons understand pathology/trauma of the lumbar vertebral region.

Intramuscular Nerve Distribution of the Inferior Oblique Muscle

Purpose: The intramuscular nerve distribution in the extraocular muscles is important for understanding their function. This study aimed to determine the intramuscular nerve distribution of the oculomotor nerve within the inferior oblique muscle (IO) using Sihler's staining.Method: Seventy-two IOs from 50 formalin-embalmed cadavers were investigated. The IO including its branch of the oculomotor nerve was finely dissected from its origin to its insertion point into the sclera. The total length of the muscle and its width were measured. The intramuscular nerve course was investigated after performing Sihler's staining, which is a whole-mount nerve-staining technique that stains the nerves while rendering other soft tissues either translucent or transparent.Results: The total length of the muscle and muscle width were 30.0 ± 2.8 mm (mean±standard deviation), 8.8 ± 1.2 mm, respectively. The oculomotor nerve enters the IO around the middle of the muscle and then divides into multiple smaller branches without distinct subdivisions. The intramuscular nerve distribution within the IO has a root-like arborization and supplies the entire width of the muscle. The Sihler's stained intramuscular nerve course (covering a length of 7.6 ± 1.2 mm) finishes around the distal one-third of the IO in gross observations.Conclusion: Sihler's staining is a useful technique for visualizing the gross nerve distribution of the IO. This new information about the nerve distribution and morphological features will improve the understanding of the biomechanics of the IO.

Complications Associated With Electromyography: A Systematic Review

OBJECTIVES

The aims of the study were to systematically review the available literature concerning complications due to electromyography and to review those associated with nerve conduction studies.

DESIGN

A systematic review was undertaken of Medline and Cochrane Central Register of Controlled Trials. Any complication related to clinical electromyography written in English was included, and all bibliographies were scanned for missed articles.

RESULTS

A total of 27 articles fit the inclusion criteria, with two observational studies, and the rest case series or case studies; 42 patients were reported. Of these, 28 patients required hospitalization and 22 required surgery or a procedure, with zero deaths reported. Needle-related complications were the most prevalent (18 patients reported), with 17 related to pneumothoraces. Disorders of hemostasis were identified in 13 patients (many were asymptomatic) and cutaneous disorders were identified in 11 patients. Only one complication was identified in the narrative review related to nerve conduction studies.

CONCLUSIONS

This systematic review identified a variety of complications related to electromyography. Although the incidence of these occurrences cannot be elucidated from the case series and case study-predominant literature, adverse events seem to be rare but can cause significant morbidity. Electromyographers should be aware of all reported complications; this review outlines all reported occurrences that fit the inclusion criteria.

Ossification of the mamillo-accessory ligament: a review of the literature and clinical considerations

Ossification of the mamillo-accessory ligament (MAL) is a misunderstood phenomenon; however, many have posited that it can result in nerve entrapment of the medial branch of the dorsal ramus causing zygapophyseal joint related low back pain. The MAL has been studied anatomically by few, yet the data indicate possible associations between ossification of this ligament and spondylosis. It has been proposed that mechanical stress upon the lumbar spine may also lead to progressive ossification of the MAL into a bony foramen.

Case report: difficulty in diagnosis of delayed spinal epidural hematoma in puerperal women after combined spinal epidural anaesthesia

Background

Spinal epidural hematoma is a rare but serious complication of epidural anaesthesia and neurological impairment. Epidural hematoma usually becomes evident within a few hours of the procedure. Delayed clinical presentation of spinal epidural hematoma is even rarer and insidious.

Case presentation

We reported a case of a 44-year-old woman who underwent a caesarean section for a twin pregnancy during which a delayed dorsal spinal epidural hematoma occurred. Symptoms were reported 5 days after surgery and 72 h after removal of the epidural catheter. An MRI scan showed a dorsal epidural hematoma. The patient was moved to the Neurosurgical Department and underwent decompression surgery.

Conclusion

The possibility of the delayed onset of a spinal epidural hematoma in a pregnant woman who undergoes epidural anaesthesia in labour must always be taken into consideration. In order to achieve the best clinical result, we stress the importance of a timely diagnosis and prompt surgical treatment.

Jaw pain and myocardial ischemia: A review of potential neuroanatomical pathways

Cardiac pain is usually manifested as a crushing, squeezing, or sensation of pressure in the center of the chest. The pain can be referred to the left shoulder, neck, jaw, and epigastric region as well as the temporomandibular region, paranasal sinuses, and head in general. Although not well understood, during myocardial ischemia, the process of cardiac referred pain to craniofacial structures can be explained by the convergence of visceral and somatic relays at the trigeminal nucleus in the brain stem. The goal of this article is to review the possible pathways for referred jaw pain due to myocardial ischemia. Clin. Anat. 32:476-479, 2019. © 2019 Wiley Periodicals, Inc.

Intramuscular Nerve Distribution in the Medial Rectus Muscle and Its Clinical Implications

PURPOSE

The intramuscular nerve distribution in the extraocular muscles may be crucial for understanding their physiological and pathological responses. This study aimed to determine the oculomotor nerve distribution in the medial rectus muscle (MR) using Sihler's staining.

METHOD

Thirty-seven MRs from 23 cadavers were investigated. The MR including the oculomotor nerve was finely dissected from its origin to its insertion point into the sclera. The total length of the muscle-belly, tendon length and maximum width of the muscle were measured. We evaluated the pattern of distribution and the length of the intramuscular nerve distribution by gross observation after performing Sihler's staining, which is a method for visualizing the distribution of nerve fibers without alteration of the nerve.

RESULTS

The total length of the muscle-belly, tendon length, and muscle width were 37.6 ± 4.6 mm, 4.4 ± 1.9 mm, and 10 ± 1.8 mm, respectively. The oculomotor nerve enters the MR at a mean of two-fifths along the muscle (24 ± 2.0 mm posterior to the insertion point) and then typically divides into a few branches (mean of 2.1). The intramuscular nerve distribution showed a Y-shaped ramification, forming the terminal nerve plexus, and its course typically finished at around 17 ± 1.5 mm posterior to the muscle insertion point by gross observation. The nerve plexus in the upper part generally coursed more distally than the lower part.

CONCLUSION

This new information regarding the nerve distribution pattern of MR will be helpful for understanding MR function and the diverse pathophysiology of strabismus.

Mechanical relationship of filum terminale externum and filum terminale internum: is it possible to detether the spinal cord extradurally?

INTRODUCTION

Intradural transection of the filum terminale (FTI) is often used to treat tethered cord syndrome. Recently, some have proposed that the extradural part of the filum terminale (FTE) can be sectioned with equal results but with fewer complications. Therefore, the present cadaveric study aimed to evaluate the anatomical foundation of such procedures.

METHODS

A posterior lumbosacral approach was performed on five fresh-frozen cadaveric specimens to expose both the FTI and FTE. Tension was then applied to the FTE and observations and measurements made of any movement of the FTI. Other morphological measurements (e.g., length, diameter) of the FTI and FTE were also made.

RESULTS

Although very minimal movement of the FTI was seen in the majority of specimens following tension on the FTE, no specimen was found to have more cranial movement of the conus medullaris or cauda equina. The mean length and diameter of the FTI was 52.2 and 0.38 mm, respectively. The mean length and diameter of the FTE was 77 and 0.60 mm, respectively. The force necessary to move the FTI with tension applied to the FTE had a mean of 0.03 N. The average distance that the FTI moved with distal FTE tension was 1.33 mm. All specimens had a thecal sac that terminated at the S2 vertebral level. And no specimen had a low-lying conus medullaris, cutaneous stigmata of occult spinal dysraphism, or grossly visible adipose tissue in either the FTI or FTE.

CONCLUSIONS

Based on our studies, tension placed on the FTE has very little effect on the FTI and no obvious effect on the conus medullaris or cauda equina. Therefore, isolated transection of the FTE for a patient with tethered cord syndrome is unlikely to have significant effect. To our knowledge, this is the first study to quantitate the distal forces needed on the FTE to move the FTI.

Ovipositor-inspired steerable needle: design and preliminary experimental evaluation

Flexible steerable needles have the potential to allow surgeons to reach deep targets inside the human body with higher accuracy than rigid needles do. Furthermore, by maneuvering around critical anatomical structures, steerable needles could limit the risk of tissue damage. However, the design of a thin needle (e.g. diameter under 2 mm) with a multi-direction steering mechanism is challenging. The goal of this paper is to outline the design and experimental evaluation of a biologically inspired needle with a diameter under 2 mm that advances through straight and curved trajectories in a soft substrate without being pushed, without buckling, and without the need of axial rotation. The needle design, inspired by the ovipositor of parasitoid wasps, consisted of seven nickel titanium wires and had a total diameter of 1.2 mm. The motion of the needle was tested in gelatin phantoms. Forward motion of the needle was evaluated based on the lag between the actual and the desired insertion depth of the needle. Steering was evaluated based on the radius of curvature of a circle fitted to the needle centerline and on the ratio of the needle deflection from the straight path to the insertion depth. The needle moved forward inside the gelatin with a lag of 0.21 (single wire actuation) and 0.34 (double wire actuation) and achieved a maximum curvature of 0.0184 cm^-1and a deflection-to-insertion ratio of 0.0778. The proposed biologically inspired needle design is a relevant step towards the development of thin needles for percutaneous interventions.