Anatomy Study About The Meningovertebra Ligaments In The Posterior Cervical Epidural Space

At present, how to prevention the durallacerationiseandepiduralhematoma is still one of the difficult problem for spinal surgery. Dural lacerationise the one of the most common complications of spinal surgery, if handled incorrectly, this complication will result in Cerebrospinal Fluid Leakage, meningitis, pseudomeningocele or intracranial infection, which are horrible threat to patients’health. Epiduralhematoma is also a common complication of spinal surgery, the morbility of that would cause serious nerve disorder is 0.1%-0.24%, and the reason for 40% of these cases is not clear. But the epidural hematoma develops rapidly, and will do harm to patients health.There are many reason for dural laceration and epiduralhematoma in spine surgery, such as:synechia, hypertension,and blood coagulation disorder, etc; Liu peng hold that the common reason include hurt by surgical instruments or bone fragments,tension of the dura and nerve root Which are related to unexperience of the surgeon, unskilled or rough surgical operation and unfamiliar with the anatomical structures.According to some research 76.4 percent dural laceration located in the dorsal lateral region. Therefore, in order to reduce the occurrece of cerebrospinal fluid leakage,it is important to identify the anatomical structures. And surgeonsshould pay more attention to prevent dural laceration and its complications in spinal surgeryIn 1895, Hoffmann described some fibrous tissues connecting the dura to the spinal cord and since that time the ventrolateral connections was called "Hofmann ligments". These ligaments do prevent the dura from bridging across in the lumbar area, thus moving far away from the posterior surface of the vertebral body after wide posterior decompression.At operation, the plica mediana dorsalis is regularly seen between two adjacent arches during lumbar horizontal hemilaminectomy. Complete collapse of the dural sac after loosening its median attachments underneath of the vertebral arches. Warm India ink gelatine mixture injected into epidural spaces. Cross-section of lumbar spine. Dorsomediandural fold clearly demonstrated after somewhat of the periduralgelatine mass in the dorsolaterar compartments has been removed.Spencer find that the dural ligaments, as described, connecting the dura to the posterior longitudinal ligament and vertebral body in the anterior aspect. A new finding is the additionl attachment by a ligamentous band running from the sheath of the exteathecal nerve root to the inferior pedicle of the respective foramen. These ligments anchor dura anteriorly in the spinal canal. A disc protrusion will generat a contact force and compress nerve root even there are plenty of room.Epiduroscopy was performed on 48 autopsy subjects by Blomberg in 1986. He indicate that large amounts of connective tissue were present in the epidural space.The connective tissue was distributed both dorsally and laterally. This connection gave rise to a fixation of the dura mater to the flaval ligaments and also narrowed the epidural space in the midline so tight that the dura mater was held very close to the flaval ligaments. The existence of the dorsomedian connection might help to explain some of the unexpected events that may occur during clinical epidural anesthesia, e.g., accidental dural puncture and an uneven onset and spread of anesthesia. This research indicated that the dorsomedian connection may be of he same origin as the ventral connection, and may be congenital.Ludinghausen, Juan Sanchez, Luyendijk described a dorsomedian fold between two adjacent arches at the time of laminectomies. Complete collapse of the dural sac after loosening its median attachments underneath of the vertebral arches. Warm India ink gelatin mixture injected pefidurally. Cross-section of lumbar spine. Dorsomediandural fold clearly demonstrated after somewhat of the periduralgelatine mass in the dorsolatera] compartments has been removedGeers observed meningovertebral ligaments in lumbar vertebral segments. In the anterior epidural space, these ligaments appeared as thin connective bands that anchor the outer surface of the dura mater to the periosteum of the posterior wall of the vertebral body, to the posterior longitudinal ligament, or to the internal aspect of the pedicles. In the posterior epidural space, similar meningovertebral ligaments also extended from the outer surface of the dura mater to the vertebral laminae and to the ligamentaflava. In the lateral epidural space, similar thin fibrous structures were observed, anchoring the lateral outer surface of the dural sac to the contours of the intervertebral foramina. Histologic examination of the fetal and adult spinal levels showed that the meningovertebral ligaments are mainly composed of dense connective tissue, mixed with elastic fibers, and surrounded by fat lobules, and some ligment go with vessles. Specific immunohistochemistry demonstrated that their major component consisted of collagen type I fibrils. These ligaments were in continuity with the most external fibre elastic layers of the dura mater at one of their extremities and with the osteofibrous walls of the spinal canal, on their other end. Laterally, they were connected with the medial aspect of the epineurium of the spinal nerves. Hamid indicated that the structures of the epidural space are already formed in the fetus of 13 weeks, but they differentiate progressively within the connective tissue. There were many more similarities between the adult and the 39-week fetus.IhsanSolaroglu,etc. have described a new ligament, the ATA, between the dural sac and the ligamentumflavum at the L5 level. The ATA is an important structure that creates a potential risk for inadvertent dural lacerations during flavectomy. Dissecting the ATA before the flavectomy may be an important step in reducing postoperative cerebrospinal fluid leaks, which may result in significant benefits for patients and health care organizations.Shi Benchao indicate that he dorsal meningovertebral ligaments in lumbosacral region connected the dura ligament flavum as well as lamina. Inadvertent management of these ligaments potential risk for inducing dural lacerations andepiduralhemorrahage.Dissecting the meningovertebral ligaments before the discectomy may reduce postoperative cerebrospinal fluid leakage.Shinomiya find that abundant posterior epidural ligaments were observed between the posterior dura mater and the ligamentumflavum. Posterior epidural ligaments in the cervical spine have not been reported previously. The anterior displacement of the dura mater may be attributed to a lack of and/or insufficiency of the posterior epidural ligaments. In 1996, he perform another experiment with animals, and reach the conclusions that:the role of the posterior cervical epidural ligaments is to anchor the posterior dura mater to the ligamentumflavum. Loss of the ligaments allows anterior displacement of the posterior dura mater in flexion. Abnormal distribution of or lack of the cervical posterior epidural ligaments may lead to flexion myelopathy.At the same time kimmel find the similar structure and indicate that these are very important ligments, dissecting these ligaments before the discectomy can prevent cerebrospinal fluid leakage.Several reports were found about the meningovertebral ligaments in lumbosacral region. But there was no reference systematicly describe dorsal connective tissue or ligaments in the epidural space in cervical region. To solve this problem, we performed a study to learn more about these ligaments between dura and ligmentflavum or lamina. We are aimed to find out thire morphological character and regularities of distribution, reveal their real physiological function and clinical significance in the lumbar spine surgery. Provide more detailed anatomical information to surgeon in order to reduce related complications.This study divide into two parts as follws:Chapter 1 Anatomical study of the dorsal meningovertebra ligaments in the cervical epidural space based on endoscopicObjective:To observe of the dorsal meningovertebra ligaments in the cervical epidural space with endoscopic,keep the vertebral canal undestroyed in order to reveal its real morphology character.Methods:A total of 20 healthy adult cervical spine specimen that were fixed in 10% formalin were used (10 male and 10 female; age range,45-63 years; mean age, 53 years). The spine was transected at the level of the intervertebral disc between C7 and T1. Remove the paraspinal muscle carefully. Put the endoscopic into the epidural space from caudal to cranial. All findings were documented with photography.Results:The epidural space is fill with fat and connection tissue and venous plexus also can be found. The meningovertebral ligaments can be find in all of these 20 cervical specimens, they locate between the dura and the ligamentaflava or lamina. According to their morphology character on endoscopy, the can be divided into four types:strip-type (54.8%), cord-type (10.3%), grid type (8.9%), and thin slice type (26.0%). The orientation of the ligaments mostly is craniocaudalfromdura to the ligmentflavum or laminate.And the meningovertebral ligaments sometimes connect with venous plexus,someligments are crossed by blood vessels (mostly venous plexuses). Meningovertebral ligaments become strain when push the dura by endoscopic。Conclusion:The meningovertebral ligaments locate between the dura and the ligamentaflava or lamina, they can attached dura to the posterior spinal canal wall. If these ligments handled incorrectly, it will lead to dural laceration and epidural hematoma or some other server complication.Chaper 2 The study of the dorsal meningovertebral ligaments in the cervical epidural space by naked eye and surgical microscopeObjective:Open the spinal canal,to observe themorphological characteristics of the dorsal meningovertebral ligaments in the cervical epidural space and reveal their physiology and pathology significant.Methods:A total of 20 healthy adult cervical spine specimen that were fixed in 10% formalin were used (10 male and 10 female; age range,45-63 years; mean age, 53 years). The spine was transected at the level of the intervertebral disc between C7 and T1.. Remove the paraspinal muscle carefully.Afterepiduroscopy, the vertebral bodies from C1 to C7 were carefully removed to expose the duralsac,and keep the attachments between the dural sac and the laminae or ligamentumflavum intact. Remove the fat in posterior epidural space to observe ligments between dura and ligmentflavnm or lamina,record their distribution, morphology, number, orientation and sites of origin and insertion. The length, width or diameter and thickness of the ligaments were measured using vernier calipers (accurate to 0.01 mm) under the surgical microscope. Analysis the measurements using SPSS 13.0 (SPSS Inc., Chicago, IL, USA). The easurement data were expressed in the form of " x±S (min-max)", and the qualitativedata were tested with the chi-squared test.Results:The dorsal meningovertebral ligaments were observed in each of the22 adult cervical vertebral segments in the posterior epi-duralspace, They were located between the posterior dural sac and the ligamentumflavum or laminae, and most of them were distributed in the cervi-cal segment above the level of C5-C6。 The meningovertebral ligaments were closely connected to the dura mater. The larger posterior epidural ligaments originated from strips of the posterior dural sac itself. Therefore, those points of attachments might become thin and were more vulnerable to rupture. The meningovertebral ligaments were very closely connected to the ligamentaflava, and difficult to separate. Nevertheless, the connections between the meningovertebral ligaments and the vertebral laminae were not so solid.The data showed that the dorsal meningovertebral ligaments are located moreon the ligamentaflava than the laminae (χ2=42.088, P=0.000),and the occurrence rate of dorsal meningovertebral ligaments at C2/C2 and C4/C5 was 100%. No such ligament was found at the level of C7 laminae. The dorsal meningovertebral ligaments were located in the median, paramedian areas of the posterior epidural space, and the orientation of the ligaments was mostly craniocaudal from the dorsal surface of the dural sac to the vertebral laminae or ligamentumflavum. At a single segment level, there was often only one ligament; or two ligaments, However, in some specimen there ligment also can be found.According to the morphology character observed the dorsal meningovertebralligaments in the cervical region can be divided into four types:strip type(54.8%), cord type (10.3%), grid type (26.0%), and thin slice type (8.9%). The dorsal meningovertebral ligaments became increasingly developed in a cephalad direction from the last cervical vertebrae and were thickest at the level of the C1-C2 vertebrae, in which part, the dorsomedian connections were found to be exceptionally strong,Histologic examination of the meningovertebral ligaments revealed fibrous connective tissue. Collagen fibers stain green, and elastic fibers stain red with Masson’s trichrome. The meningovertebral ligaments was composed of a many collagen fibers and comparatively lesser elastic fibersConclusion:The ligaments connect between the dura and ligament flavum or lamina in cervical epidural space. Inadvertent management of these ligaments increase the risk for dural lacerations and epidural hemorrahage. Dissecting the meningovertebra ligaments before cervical flavectomy or laminectomy may be an important step in reducing postoperative cerebrospinal fluid leaks and epidural hematoma, which may result in significant benefits for patients and health care organizations.The anterior displacement of the dura mater may be attributed to a lack of and/or insufficiency of the posterior epidural ligaments.