Spinal Dura Mater Research Articles

Dural manipulation coinciding with transient asystole during lumbar spine surgery: illustrative case.

Hemodynamic disturbances during lumbar spine surgeries have proven to be exceptionally rare, with only seven published cases demonstrating instances where intraoperative dural manipulation coincided with bradycardia, hypotension, and/or asystole. The authors present the case of a 39-year-old male with a history of chronic low-back pain and leg weakness. Imaging demonstrated a disc herniation at L5-S1, resulting in impingement of the left S1 traversing nerve root. The patient agreed to surgery. The preoperative workup was unremarkable. While retracting the S1 nerve root, transient asystole occurred when the S1 nerve root was manipulated, causing the patient's heart rate to drop from 51 to 0 bpm. Manipulating the nerve root once again triggered a similar event, and upon cessation of the surgical stimulus, the patient's heart rate spontaneously returned to baseline. Other potential causes of these hemodynamic perturbations were excluded. As in other reported cases, each cardiovascular disturbance corresponded with either direct or indirect dural manipulation. Given the limited number of lumbar spinal cases reported to have undergone hemodynamic perturbances via dural manipulation, this case report provides evidence for the likelihood of a spinal-cardiac reflex between the cardiovascular system and the spinal dura mater. https://thejns.org/doi/10.3171/CASE24158.

Sensory nerve formations in the myodural bridge complex of adult humans

The myodural bridge complex (MDBC) consists of connective tissue bands connecting the spinal dura mater to the suboccipital muscles passing throughout the posterior atlanto-occipital and atlanto-axial spaces. It is a universal evolutionarily conserved anatomical structure present in most vertebrate species including humans. Its physiology is unknown, but it is thought that it may be related to cerebrospinal fluid circulation. On the other hand, there is no information about the possible innervation of MDBC in humans. In the present study, immunohistochemistry (S100 protein and neurofilament proteins) was used to study the innervation of MDBC in five specimens of adult human cadavers. In all cases, nerve profiles were observed forming isolated nerve fibers or small nerve bundles, sometimes associated with blood vessels. In one case (1/5), at the level of the junction of the MDBC with the posterior rectus capitis minor muscle, complex capsulated formations containing a variable number of sensory nerve formations were found. We consider that such formations may be related to the proprioceptor system of the suboccipital muscles, but further studies are needed to determine their frequency, density and possible function.

Microscopic observation of collagen fibers in spinal dura mater under uniaxial stretch

Microscopic observation of collagen fibers in spinal dura mater under uniaxial stretch

Artificial spinal dura mater made of gelatin microfibers and bioadhesive for preventing cerebrospinal fluid leakage.

Artificial spinal dura mater was designed by combining solution blow-spun gelatin microfibers and dopamine-capped polyurethane bioadhesive. Notably, the gelatin microfibers had a special pore structure, good water adsorption capability, and excellent burst pressure resistance. The bioadhesive layer contributed to the excellent sealing performance in the wet state. This material provides a promising alternative as an artificial spinal dura mater to prevent cerebrospinal fluid leakage.

The relationship between myodural bridge, atrophy and hyperplasia of the suboccipital musculature, and cerebrospinal fluid dynamics

The Myodural Bridge (MDB) is a physiological structure that is highly conserved in mammals and many of other tetrapods. It connects the suboccipital muscles to the cervical spinal dura mater (SDM) and transmits the tensile forces generated by the suboccipital muscles to the SDM. Consequently, the MDB has broader physiological potentials than just fixing the SDM. It has been proposed that MDB significantly contributes to the dynamics of cerebrospinal fluid (CSF) movements. Animal models of suboccipital muscle atrophy and hyperplasia were established utilizing local injection of BTX-A and ACE-031. In contrast, animal models with surgical severance of suboccipital muscles, and without any surgical operation were set as two types of negative control groups. CSF secretion and reabsorption rates were then measured for subsequent analysis. Our findings demonstrated a significant increase in CSF secretion rate in rats with the hyperplasia model, while there was a significant decrease in rats with the atrophy and severance groups. We observed an increase in CSF reabsorption rate in both the atrophy and hyperplasia groups, but no significant change was observed in the severance group. Additionally, our immunohistochemistry results revealed no significant change in the protein level of six selected choroid plexus-CSF-related proteins among all these groups. Therefore, it was indicated that alteration of MDB-transmitted tensile force resulted in changes of CSF secretion and reabsorption rates, suggesting the potential role that MDB may play during CSF circulation. This provides a unique research insight into CSF dynamics.

Clinical characteristics and risk factors of intracranial hemorrhage after spinal surgery.

Intracranial hemorrhage after spinal surgery is a rare and devastating complication. To investigate the economic burden, clinical characteristics, risk factors, and mechanisms of intracranial hemorrhage after spinal surgery. A retrospective cohort study was conducted from January 1, 2015, to December 31, 2022. Patients aged ≥ 18 years, who had undergone spinal surgery were included. Intracranial hemorrhage patients were selected after spinal surgery during hospitalization. Based on the type of spinal surgery, patients with intracranial hemorrhage were randomly matched in a 1:5 ratio with control patients without intracranial hemorrhage. The patients' pre-, intra-, and post-operative data and clinical manifestations were recorded. A total of 24472 patients underwent spinal surgery. Six patients (3 males and 3 females, average age 71.3 years) developed intracranial hemorrhage after posterior spinal fusion procedures, with an incidence of 0.025% (6/24472). The prevailing type of intracranial hemorrhage was cerebellar hemorrhage. Two patients had a poor clinical outcome. Based on the type of surgery, 30 control patients were randomly matched in 1:5 ratio. The intracranial hemorrhage group showed significant differences compared with the control group with regard to age (71.33 ± 7.45 years vs 58.39 ± 8.07 years, P = 0.001), previous history of cerebrovascular disease (50% vs 6.7%, P = 0.024), spinal dura mater injury (50% vs 3.3%, P = 0.010), hospital expenses (RMB 242119.1 ± 87610.0 vs RMB 96290.7 ± 32029.9, P = 0.009), and discharge activity daily living score (40.00 ± 25.88 vs 75.40 ± 18.29, P = 0.019). The incidence of intracranial hemorrhage after spinal surgery was extremely low, with poor clinical outcomes. Patient age, previous stroke history, and dura mater damage were possible risk factors. It is suggested that spinal dura mater injury should be avoided during surgery in high-risk patients.

DURAL MECHANICAL RESPONSES TO LOAD-CONTROLLED ASYMMETRIC BIAXIAL STRETCH

This study conducted a series of biaxial stretching tests on the spinal dura mater. To investigate the specific effects of different loading patterns on mechanical responses of the dura mater, load-controlled asymmetric (longitudinal vs. circumferential loading at 1:0.5 and 0.5:1 ratios) and equi-load (longitudinal vs. circumferential at a 1:1 ratio) biaxial stretching tests were performed. The dural meninge was found to be most compliant when a circumferentially dominant loading pattern (longitudinal vs. circumferential at a 0.5:1 ratio or physiological biaxial stretch) was used. Additionally, physiological biaxial stretch resulted in the lowest strain energy density in the toe region of stress–strain curves, i.e., physiological deformation ranges, whereas mechanical loading caused abruptly stiffening of the linear region of stress–strain curves even under circumferentially dominant loading. On the other hand, stress relaxation and elastin content of the dural tissue had no effect on stored strain energy density within the range of biaxial stretch tested in this study. These results indicate that physiological biaxial stretching contributes to structural protection of the spinal cord and the spinal dura, which may be attributable to changes in the arrangement of embedded collagen fibers and concomitant mechanical interactions with surrounding tissues.

A Neglected Normal Anatomical Structure in Mammal: A Study in Bats and Tree Shrews

The myodural bridge is a dense connective tissue connecting muscles and ligaments to the spinal dura mater in the atlanto-occipital interspace. Some researchers believe that the myodural bridge may play a vital physiological role. It is possible, for instance, that the prevention of spinal dura mater infoldings might be involved in regulated cerebrospinal fluid circulation. For instance, it is possible to prevent spinal dura mater infoldings, regulating cerebrospinal circulation. Bats are nocturnal and the only mammals that can perform a genuine and sustained flight, whereas tree shrews are arboreal mammals that often climb to a high altitude of about 10,000 feet. Both animals have lifestyles that are different from other previously studied mammals. The study of these two animals will shed further light on the existence of the myodural bridge in mammals. Gross anatomical dissection was used to observe the connections between the deep muscles of the neck and the dura mater at the level of the atlanto-occipital interspace. The existing structures were analyzed using conventional and special histological staining techniques. The suboccipital regions in bats and tree shrews contained the rectus capitis dorsal major (RCDma), rectus capitis dorsal minor (RCDmi), oblique capitis anterior (OCA), and oblique capitis posterior (OCP). Dense connective tissue connects the RCDmi to the posterior atlanto-occipital membrane (PAOM) and the latter to the spinal dura mater. The myodural bridge in these mammals shares a similar structure to the myodural bridge in humans. Histological analyses confirmed that the connective fibers of the myodural bridge were primarily type I collagen fibers. In this study, it is supplemented by the existence of the myodural bridge in mammals. This further demonstrates that myodural bridge widely exists in the normal anatomy of mammals. This provides morphological support for a comparative anatomical study of the physiological function of the myodural bridge.

Radiation disrupts the protective function of the spinal dura mater in a mouse model of tumor-induced spinal cord compression

Radiation disrupts the protective function of the spinal dura mater in a mouse model of tumor-induced spinal cord compression

Collagen-Based Grafts and Autologous Dura Replacement in Patients with Dura Abnormalities: A Retrospective Comparative Evaluation

Introduction: Accidental spinal anomalies of the spinal dura mater are the source of cerebrospinal fluid (CSF) leakage. Typically, dura abnormalities are identified in 3 percent of endoscopic lumbar discectomy cases. Objective: The purpose of the current research was to evaluate the results of autologous dura replacement versus collagen-based grafts in individuals with dura deformities. Methods: The Institute of Neurosurgery at Liaquat National Hospital Karachi undertook this randomized evaluation to identify the most effective therapy for dura mater defects. Employing non-probability random selection, 82 cases among both sexes were selected. Participants were divided randomly into two subgroups i.e. Group 1A received an autologous graft for dura restoration, whereas Group 2B received a semi-synthetic dura replacement. A skilled surgeon led a medical team of six people who completed the entire process. Results: The operation duration for semi-synthetic collagen was significantly reduced. There was a 40 minute variation in total time spent by the two groups. Autologous grafts showed ideal tightness and better flexibility and fair workability on the other hand semi-synthetic collagen showed better tightness and workability and ideal flexibility. Postoperative hospital stays were seen to be 26 + 2.5 hours in Group 1A whereas they were 23 + 2.5 hours for Group B. Conclusion: According to the aforementioned findings, an accessible, secure, and efficient substitution for an autologous graft for dura restoration in dura abnormalities is the use of a semi-synthetic collagen substitute. Keywords: semi-synthetic collagen substitute, cerebrospinal fluid, dura abnormalities, autologous graft.

A case of idiopathic hypertrophic pachymeningitis presented with seizures

Idiopathic hypertrophic pachymeningitis (IHP) is a rare disease involving localized inflammatory thickening of the intracranial or spinal dura mater without an identified cause. Seizure is a very unusual presentation of IHP. We present a 58-year-old-female patient with seizures caused by IHP. This case indicates that although IHP is rare, it has the potential to cause seizures.

The relationship between myodural bridges, hyperplasia of the suboccipital musculature, and intracranial pressure.

During mammalian evolution, the Myodural Bridges (MDB) have been shown to be highly conserved anatomical structures. However, the putative physiological function of these structures remains unclear. The MDB functionally connects the suboccipital musculature to the cervical spinal dura mater, while passing through the posterior atlanto-occipital and atlanto-axial interspaces. MDB transmits the tensile forces generated by the suboccipital muscles to the cervical dura mater. Moreover, head movements have been shown to be an important contributor to human CSF circulation. In the present study, a 16-week administration of a Myostatin-specific inhibitor, ACE-031, was injected into the suboccipital musculature of rats to establish an experimental animal model of hyperplasia of the suboccipital musculature. Using an optic fiber pressure measurement instrument, the present authors observed a significant increase in intracranial pressure (ICP) while utilizing the hyperplasia model. In contrast, surgically severing the MDB connections resulted in a significant decrease in intracranial pressure. Thus, these results indicated that muscular activation of the MDB may affect CSF circulation, suggesting a potential functional role of the MDB, and providing a new research perspective on CSF dynamics.

The relationship between compensatory hyperplasia of the myodural bridge complex and reduced compliance of the various structures within the cranio-cervical junction.

The myodural bridge complex (MDBC) is described as a functional anatomic structure that involves the dense connective tissue fibers, muscles, and ligaments in the suboccipital region. It has recently been proposed that the MDBC can influence cerebrospinal fluid (CSF) circulation. In the present study, bleomycin (BLM), a type of antibiotic that is poisonous to cells, was injected into the posterior atlanto-occipital interspace (PAOiS) of rats to induce fibrous hyperplasia of structures in PAOiS. Sagittal sections of tissues obtained from the posterior-occipital region of the rats were stained utilizing the Masson Trichrome staining method. Semiquantitative analysis evidenced that the collagen volume fraction of collagen fibers of the MDBC, as well as the sum of the area of the spinal dura mater and the posterior atlanto-occipital membrane in the BLM group were significantly increased (p < .05) compared to that of the other groups. This finding illustrates that the MDBC fibers as well as other tissues in the PAOiS of rats in the BLM group developed fibrotic changes which reduced compliance of the spinal dura mater. Indeed, the sectional area of the rectus capitis dorsal minor muscle in the BLM group was measured to be increased. These changes may further restrict CSF flow. The present research provides support for the recent hypothesis proposed by Labuda et al. concerning the pathophysiology observed in symptomatic adult Chiari malformation Type I patients, that there exists a relationship between the altered compliance of the anatomic structures within the craniocervical region and the resultant compensatory hyperplasia of the MDBC.

Development, maturation, and growth of the myodural bridge within the posterior atlanto‐axial interspace in the rat

The myodural bridge (MDB) complex are fibrous bridges that functionally connect the spinal dura mater to the suboccipital musculature. Previously, we described the maturational sequence of the MDBwithin the posterior atlanto-occipital interspace of the rat. The present paper describes the morphology and developmental maturation of the MDB within the posterior atlanto-axial interspace of the rat. In the present study, E18 embryonic rats, newborn rats, and adult rats were selected to evaluate the development and growth of the MDB. Within the posterior atlanto-axial interspace of the rat, the fibers of the MDB and its associated muscles, in the embryonic rat, were observed to be scarce and lightly stained. In contrast, these same structures observed in the postnatal rat were quite apparent and robustly stained. After birth, it was observed that MDB originated from the rectus capitis dorsal major muscle, extended forward and downward, and finally merged with the posterior atlanto-axial membrane. As the rats developed and matured, the observed MDB fibers passing through the posterior atlanto-axial interspace appeared denser and more organized. This study evidenced that the MDB fibers within the posterior atlanto-axial interspace were primarily composed of type I collagen fibers in the postnatal rat. By observing the suboccipital region, we are able to hypothesize that the MDB complex plays a key role in maintaining the subdural space located within the upper cervical segment during growth and development. This study provides a morphological basis for future research on the function of the MDB complex.

Dural sac shrinkage signs on spinal magnetic resonance imaging indicate overdrainage after lumboperitoneal shunt for idiopathic normal pressure hydrocephalus.

Background: We previously found the usefulness of dural sac shrinkage signs (DSSSs), which are the anterior shift of the spinal cord and dura mater behind the cord, detected by magnetic resonance imaging (MRI) at the thoracic level for the diagnosis of spontaneous intracranial hypotension (IH). This is a retrospective survey on the usefulness of DSSSs for the early detection of iatrogenic IH caused by overdrainage through a lumboperitoneal shunt (LPS) for patients with idiopathic normal pressure hydrocephalus (INPH).Methods: Forty-five INPH patients had an LPS using a pressure programmable valve equipped with an anti-siphon device.Results: Nine patients complained of orthostatic headache after the LPS, indicating IH due to overdrainage, which persisted for more than a week in three patients and 2–7days in six patients. The headache was transient/ nonorthostatic in ten patients and absent in 26 patients. The DSSSs and accompanying enlargement of the venous plexus were observed in all three patients with prolonged orthostatic headaches. Only the anterior shift of the dura mater was observed in 1 (4%) among 25 patients who had short-term orthostatic headache, transient/ nonorthostatic headache, or absent headache, and underwent spinal MRI. A patient with prolonged severe orthostatic headache with both DSSSs eventually developed intracranial subdural effusion and underwent tandem valve surgery, which provided a quick improvement of symptoms. The DSSSs on thoracic MRI also disappeared promptly.Conclusion: DSSSs may serve as objective signs for the diagnosis of IH due to overdrainage through an LPS for INPH.

A new concept of the fiber composition of cervical spinal dura mater: an investigation utilizing the P45 sheet plastination technique

PurposeFew reports have been published regarding the microanatomy of the dura mater located at the craniovertebral junction (CVJ). In clinic, the precise microanatomy of the CVJ dura mater would be taken into account, for reducing surgical complications and ineffective surgical outcomes. The main objective of the present investigation was to further elucidate the fiber composition and sources of the cervical spinal dura mater.MethodsThe formalin-fixed adult head and neck specimens (n = 21) were obtained and P45 plastinated section method was utilized for the present study. The fibers of the upper cervical spinal dura mater (SDM) were examined in the P45 sagittal sections in the CVJ area. All photographic documentation was performed via a Canon EOS 7D Mark camera.ResultsThe posterior wall of the SDM sac at CVJ was found to be composed of stratified fibers, which are derived from three sources: the cerebral dura mater, the occipital periosteum, and the myodural bridge (MDB). The proper layer of the cerebral dura mater passes over the brim of the foramen magnum and enters the vertebral canal to form the inner layer of the SDM, and the fibers originating from the periosteum of the brim of the foramen magnum form the middle layer. The fibers of the MDB are inserted into the SDM and form its outer layer. It was found that the total number of fibers from each origin varied in humans.ConclusionAt the CVJ, the posterior wall of the SDM is a multi-layered structure composed of three different originated fibers. The cerebral dura mater, the periosteum located at the brim of the foramen magnum, and MDB contribute to the formation of the SDM. The present study would be beneficial to the choice of surgical approach at the CVJ and the protection of the SDB.

Congenital Atlanto-Occipital Fusion and its Effect on the Myodural Bridge: A Case Report Utilizing the P45 Plastination Technique

The atlanto-occipital joint is composed of the superior fossa of the lateral masses of the atlas (C1) and the occipital condyles. Congenital Atlanto-occipital fusion (AOF) involves the osseous union of the base of the occiput (C0) and the atlas (C1). AOF or atlas occipitalization/assimilation represents a craniovertebral junction malformation (CVJM) which can be accompanied by other cranial or spinal malformations. AOF may be asymptomatic or patients may experience symptoms from neural compression as well as limited neck movement. The myodural bridge (MDB) complex is a dense fibrous structure that connects the suboccipital muscular and its related facia to the cervical spinal dura mater, passing through both the posterior atlanto-occipital and atlanto-axial interspaces. It is not known if atlas occipitilization can induce structural changes in the MDB complex and its associated suboccipital musculature. The suboccipital region of a cadaveric head and neck specimen from an 87-year-old Chinese male having a congenital AOF malformation with resultant changes to the MDB complex was observed. After being treated with the P45 plastination method, multiple slices obtained from the cadaveric head and neck specimen were examined with special attention paid to the suboccipital region and the CVJM. Congenital atlanto-occipital fusion malformations are defined as partial or complete fusion of the base of the occiput (C0) with the atlas (C1). In the present case of CVJM, unilateral fusion of the left occipital condyle with the left lateral mass of C1 was observed, as well as posterior central fusion of the posterior margin of the foramen magnum with the posterior arch of C1. Also noted was a unilateral variation of the course of the vertebral artery due to the narrowed posterior atlanto-occipital interspace. Surprisingly, complete agenesis of the rectus capitis posterior minor (RCPmi) and the obliques capitis superior (OCS) muscles was also observed in the plastinated slices. Interestingly, the MDB, which normally originates in part from the RCPmi muscle, was observed to originate from a superior bifurcation within an aspect of the nuchal ligament. Therefore, the observed changes involving the MDB complex appear to be an effective compensation to the suboccipital malformations.

Efficacy and safety of cervicothoracic epidural blood patch for patients with spontaneous intracranial hypotension

Epidural blood patch (EBP) is a generally effective treatment for spontaneous intracranial hypotension (SIH) caused by cerebrospinal fluid (CSF) leakage through the spinal dura mater. It is still unclear; however, whether application near the leakage site (targeted EBP) is more effective than distal application (untargeted EBP). Further, EBP targeted to high thoracic or cervical spine levels is infrequent due to greater technical requirements and potential complications. Here, we examined the safety and efficacy of EBP applied to high thoracic or cervical spine levels. We retrospectively reviewed the clinical and outcome data of 13 patients receiving cervical or high thoracic EBP for SIH. All patients were referred by neurologists following poor response to conservative treatment and presented with persistent headache aggravated by orthostatic changes. Neuroimaging confirmed CSF leakage and targeted EBP resulted in immediate pain improvement. Repeated injections provided additional improvement for patients with recurrent headache. No serious adverse events were documented during follow-up. Based on recent studies and our clinical experience, we conclude that EBP targeted to the high thoracic and cervical spine is safe and effective for early-stage SIH.

Effect of Anatomical Sites on the Mechanical Properties of Spinal Dura Subjected to Biaxial Stretching

Abstract The spinal cord is encased by spinal meninges called the pia, arachnoid, and dura maters. Among these membranes, the dura mater is the thick and outermost layer and is the toughest and strongest. Thus, mechanical failure of the dura mater can lead to spontaneous cerebrospinal fluid leaks or hypovolemia, resulting in a complication or exacerbation of unfavorable symptoms involved in a mild traumatic brain injury. To develop protective equipment that can help prevent such injuries, accurate characterization of the spinal dura mater is required, especially regarding the mechanical properties at different anatomical sites. In this study, we used an equiload biaxial tensile tester to investigate the mechanical properties of porcine meningeal dura mater along the whole length of the spine. The resultant strain of the dorsal side was greater than that of the ventral side (P &amp;lt; 0.01), while the circumferential direction was significantly stiffer than the longitudinal direction (P &amp;lt; 0.01) at lower strains regardless of the spinal level. We also found that the material stiffness progressively increased from the cervical level to the thoracolumbar level at lower strains, which implies that the dura mater inherently possesses structurally preferred features or functions because the neck requires sufficient flexibility for daily activities. Further, Young's modulus was significantly less on the dorsal side than on the ventral side at higher strains (P &amp;lt; 0.05), suggesting that the dorsal side is readily elongated by spinal flexion even within the range of physiological motion.

Comparison of numerical methods for cerebrospinal fluid representation and fluid-structure interaction during transverse impact of a finite element spinal cord model.

Spinal cord impacts can have devastating consequences. Computational models can investigate such impacts but require biofidelic numerical representations of the neural tissues and fluid-structure interaction with cerebrospinal fluid. Achieving this biofidelity is challenging, particularly for efficient implementation of the cerebrospinal fluid in full computational human body models. The goal of this study was to assess the biofidelity and computational efficiency of fluid-structure interaction methods representing the cerebrospinal fluid interacting with the spinal cord, dura, and pia mater using experimental pellet impact test data from bovine spinal cords. Building on an existing finite element model of the spinal cord and pia mater, an orthotropic hyperelastic constitutive model was proposed for the dura mater and fit to literature data. The dura mater and cerebrospinal fluid were integrated with the existing finite element model to assess four fluid-structure interaction methods under transverse impact: Lagrange, pressurized volume, smoothed particle hydrodynamics, and arbitrary Lagrangian-Eulerian. The Lagrange method resulted in an overly stiff mechanical response, whereas the pressurized volume method over-predicted compression of the neural tissues. Both the smoothed particle hydrodynamics and arbitrary Lagrangian-Eulerian methods were able to effectively model the impact response of the pellet on the dura mater, outflow of the cerebrospinal fluid, and compression of the spinal cord; however, the arbitrary Lagrangian-Eulerian compute time was approximately five times higher than smoothed particle hydrodynamics. Crucial to implementation in human body models, the smoothed particle hydrodynamics method provided a computationally efficient and representative approach to model spinal cord fluid-structure interaction during transverse impact.