Dural Adhesions Research Articles

Intentional Dural Resection during en bloc Spinal Resection Could Provide a Secure Surgical Margin for Patients with Recurrent Spinal Tumors.

It is always difficult to obtain a comfortable surgical margin for patients with recurrent malignant or invasive benign spinal tumors. Tumor intraspinal invasion and dural adhesion are the essential reasons. There are always residual tumor cells maintained at the edge of dura. Dural resection is a key point to obtain a comfortable surgical margin for such cases. Whether such patients benefit from this risky surgical procedure is unknown. This study aims to understand better the oncological results, associated risks, and neurological function of this risky surgical procedure. We retrospectively reviewed clinical data from six consecutive patients who registered spinal tumors in our institute and underwent dural resection during en bloc spinal resection from June 2013 to May 2020. The demographic and perioperative data, oncological outcomes, complications, and neurological status were collected and analyzed. All six patients were followed up for 24 to 46 months (mean follow-up time: 32.8 months). Local recurrence was detected in one patient (1/6, 16.7%) at 36 months postoperatively and in five patients with no evidence of disease at the last follow up (survival rate 83.3%). Eleven complications occurred in four patients (66.7%), and the dural resection-related complications included only four cases of cerebrospinal fluid leakage (CSFL), which accounted for 36.4% (4/11) of all complications. Neurologic status evaluated by the Frankel grade showed improvement of one grade in one case and deterioration of one to two grades in five patients immediately after surgery. All deterioration cases recovered to the preoperative level 6 months after the operation. Dural resection is significant for patients with dura matter invaded by recurrent primary malignant or invasive benign spinal tumors with the purpose of clinical cure. This study demonstrated that in strictly selected cases, intentional dural resection could provide satisfying local control and long-term disease-free survival with acceptable complications and satisfying neurological function.

Perspective: Timely diagnosis and repair of intraoperative thoracic/lumbar cerebrospinal fluid (CSF) leaks.

Our review of 12 articles for this perspective showed the frequency of intraoperative thoracic and/or lumbar CSF fistulas/dural tears (DT) ranged from 2.6% - 8% for primary surgical procedures. Delayed postoperative CSF leak/DT were also diagnosed in 0.83% (17/2052 patients) to 14.3% (2/14 patients) of patients undergoing thoracic and/or lumbar procedures. Further, the rate of recurrent postoperative CSF leaks/DT varied from 13.3% (2/15 patients) to 33.3% (4/12 patients). Intraoperative, postoperative delayed, and recurrent postoperative traumatic postsurgical thorac CSF leaks/DT can be limited by performing initially sufficient operative decompressions and/or decompressions/fusions (i.e., utilizing adequate open exposures vs. inadequate minimally invasive (MI) approaches). The incidence of CSF leaks/DT can be further reduced by spine surgeons' utilization of operating microscopes, and their avoiding routine attempts at total synovial cyst excision and/or complete resection of hypertrophied/ossified yellow ligament in the presence of significant dural adhesions. Multiple CSF leak/CT repair techniques included; using interrupted, non-resorbable sutures for direct dural repairs (i.e. 7-0 Gore-Tex sutures where the suture is larger than the needle thus plugging needle holes), and adding where needed muscle patch grafts, microfibrillar collagen, the rotation of Multifidus muscle pedicle flaps, fibrin sealants (FS)/fibrin glues (FG), lumbar drains (LD), and/or lumbo-peritoneal (LP) shunts. Intraoperative, postopertive delayed, and/or recurrent postoperative thorac and/or lumbar traumatic surgical CSF leaks can be reduced by choosing to initially perform the appropriately extensive open operative decompressions and/or decompresssions/fusions. It is critical to use an operating microscope, non-resorbable interrupted sutures, and where necessary, muscle patch grafts, microfibrillar collagen, the rotation of Multifidus Muscle Pedicle Flaps, FS/FG, LD, and/or LP shunts.

Use of indocyanine green angiography during endoscopic microvascular decompression for trigeminal neuralgia

BackgroundThe aim of this study was to assess the efficacy of indocyanine green (ICG) angiography during full endoscopic microvascular decompression for trigeminal neuralgia. MethodsWe extracted retrospective data of patients who received ICG videoangiography during full endoscopic microvascular decompression for trigeminal neuralgia. Preoperative neurovascular contact was evaluated by three-dimensional (3D) fusion images using image analysis software Ziostation2 (ZIOSOFT, Tokyo, Japan) and Intraoperative ICG angiography was used in pre and post ICG injection to identify and assess blood flow in the offending vessel for adequate transposition planification and assess for immediate post transposition blood flow or vasospasm respectively. Patients were assessed the next morning for early signs of brainstem infarction and at one month follow up. ResultsThere were 44 patients. All patients had ICG videoangiography done during the procedure. The mean age was 65.5 and male female ratio 3.4:1. Some anatomical variants were identified during this procedure. Five patients (11.3%) had a trigeminocerebellar artery, three patients (6.8%) had a developed superior petrosal vein and one patient (2.2%) had dural adhesions with encasement of anterior inferior cerebellar artery. Among the 44 patients enrolled, 34 had transposition done and 10 had combined transposition either with neurolysis or Teflon interposition. The main offending vessel was Superior cerebellar artery (SCA) in 23 patients (67.6%). In 5 (14.7%) of 34 patients who underwent Transposition, vasospasm was seen and no complications were observed in all patients but 93.1% had good pain control in postoperative. ConclusionICG angiography in endoscopic microvascular decompression is safe and effective in depicting the offending vessel, its branches and some perforators and contributes significantly to the determination of treatment strategy.

Dehydrated human amnion/chorion membrane use in emergent craniectomies shows minimal dural adhesions.

Decompressive craniectomies (DCs) are routinely performed neurosurgical procedures to emergently treat increased intracranial pressure secondary to multiple aetiologies, such as subdural haematoma, epidural haematoma, or malignant oedema in the setting of acute infarction. The DC procedure typically induces epidural fibrosis post-cranial resection, resulting in adherence of the dura to both the brain internally and skin flap externally. This becomes especially problematic in the setting of skull flap replacement for cranioplasty as adherences can lead to bridging vein tear, damage to the underlying brain cortex, and other postoperative complications. Dural adjuvants, which can contribute to decreased rate of adherence formation, can thereby reduce both postoperative cranioplasty complications and operative duration. Dehydrated human amnion/chorion membrane (DHACM) allografts (AMNIOFIX, MIMEDX Group Inc., US) have been shown to reduce the rate of dural scar tissue formation in re-exploration of posterior lumbar interbody fusion operations which require entry into the epidural space. The purpose of this study was to evaluate whether or not the use of DHACM in the setting of emergent craniectomies decreased the rate of dural adhesion formation and subsequent cranioplasty complications. Patients (n=7) who underwent emergent craniectomy and intraoperative placement of DHACM were evaluated during replacement of either an autologous skull cap or a custom-made implant, at which point the degree of adhesions was qualitatively assessed. Placement of DHACM below and on top of the dura resulted in negligible adhesion being found during the defect exposure, and there were no intraoperative complications during cranioplasties. Reported estimated blood loss across the seven patients averaged 64.2ml, total operative time averaged 79.2 minutes, and time dedicated to exposing defect for bone flap placement was <3 minutes.

Intraparenchymal Meningioma, A Challenging Diagnosis: Case Report

Background: Primary intraparenchymal meningiomas are extremely rare; their similarities to other intra-axial lesionsand thelack of dural adhesion make their presurgical diagnostic approach challenging. Case Description: A 27-year-old male, with no past medical history, presented to our emergency department for a first time grand mal seizure. Magnetic resonance imaging evidenced a 1,6×1,2 cm mass in the right temporo-parietal region. It was iso intense on T1WI, hyper intense on T2 WI, surrounded by large vasogenic edema and homogeneously enhanced on contrast magnetic resonance imaging with diffusion restriction. During surgery, the tumor was found to be located within the parenchyma with no dural attachment. It was removed en bloc. Histopathological examination confirmed the positive diagnosis of transitional meningioma (WHO Grade I). Conclusion: Intraparenchymal meningiomas are rarely reported in the literature. Their preoperative diagnosis is extremely difficult to make. Histopathological examination plays a key role for an accurate diagnosis.

504 Safety and Efficacy of Brain-Responsive Neurostimulation Treatment With Depth Leads Placed in the Neocortex

INTRODUCTION: Responsive neurostimulation (RNS) is efficacious in treating medically refractory epilepsy arising from neocortical foci. During clinical trials, most patients with neocortical seizure foci received cortical strip leads, perhaps due to intracranial monitoring with subdural grids/strips. Stereo-electroencephalography (sEEG) has become more widely utilized since the trials, resulting in increased placement of neocortical RNS depth leads. This is also an appealing approach when dural adhesions make strip lead implantation difficult. METHODS: We conducted retrospective chart review of adult patients with refractory epilepsy at seven institutions who underwent placement and connection of at least one RNS depth lead in the neocortex. RESULTS: 61 neocortical depth leads were connected to the RNS neurostimulator in 53 patients. 33 patients had additional depth leads in a non-neocortical focus, and 12 had an additional neocortical strip lead. Median follow-up was 2.2 years (range: 0.4 – 5.2 years). Median clinical seizure reduction in seizures was 63% at 1 y and 75% at last follow-up. 12 patients (23%) were seizure-free at last follow-up; a majority of these (83%) were seizure-free for &gt;6 mo, with five patients seizure-free for &gt;1 y. There were two (3.8%) scalp infections. One patient (1.9%) had each of the following: chemical meningitis, epidural hematoma, post-surgical status epilepticus (resolved with stimulation), new-onset non-epileptic seizures, and stimulation-related nausea (resolved with programming). CONCLUSIONS: Our multicenter series of 53 patients with neocortical-onset epilepsy treated with neocortical RNS depth leads demonstrated 75% median seizure reduction at 2 y of follow-up with a similar safety profile to placement of deep brain electrodes for movement disorders. Neocortical depth leads may be preferred with the RNS system following sEEG evaluation and/or if strip placement poses increased surgical risk.

Effectiveness of different epidural coverage materials for preventing postoperative scar hyperplasia and dural adhesion in spine

Objective: To analyze the effects and mechanisms of three commonly used epidural coverings, gelatin sponge, bovine Achilles tendon extract collagen and polyester urethane fiber, in preventing epidural scar adhesions after laminectomy in rats. Methods: Forty-eight adult Wistar rats were excised from L2 to L5 lamina to establish laminectomy models, and were divided into four groups with random number table according to different covering materials (12 rats in each group): blank group (group A), gelatin sponge group (absorbable, group B), polyester urethane fiber group (non-absorbable, group C) and bovine Achilles tendon extract collagen group (absorbable, group D). At 4 and 12 weeks postoperatively, the spinal tissues of the operated area were taken for gross observation (Rydell scar adhesion rating criteria) and histological observation (Nussbaum criteria); and the expression of three scar proliferation-related cytokines, basic fibroblast growth factor (bFGF), growth transforming factor β1 (TGF-β1) and vascular endothelial growth factor (VEGF), were measured in the peridural tissues. The differences between the indices in each group were analyzed and compared. Results: All 48 rats survived, and gross and histological findings at 4 and 12 weeks showed no dural adhesions in the gelatin sponge and bovine Achilles tendon extract collagen groups, adhesions in the polyester urethane fiber group, and heavy adhesions and spinal cord compression in the blank control group. There were significant differences in the Rydell grade and Nussbaum histological score between the absorbable material group and the non-absorbable group (both P<0.05). Western protein blotting at 4 and 12 weeks confirmed that the expression levels of three cytokines, including bFGF, TGF-β1, and VEGF, were lower in the absorbable material group than those in the non-absorbable group (all P<0.01). Immunofluorescence tests at 12 weeks confirmed that the expression of bFGF, TGF-β1 and VEGF were all lower in the gelatin sponge group (9.81±0.81, 12.42±2.35, 8.63±1.76) and the bovine Achilles tendon extract collagen group (12.70±2.02, 8.23±1.03, 10.19±2.67) than those in the polyester urethane fiber group (33.94±2.03, 30.29±2.76, 25.79±1.21) (all P<0.01). Conclusions: Bovine achilles tendon extract collagen and gelatin sponge can effectively reduce the hyperplasia of scar and dural adhesions after spinal surgery.

Design and Fabrication of Nanofibrous Dura Mater with Antifibrosis and Neuroprotection Effects on SH-SY5Y Cells.

The development and treatment of some diseases, such as large-area cerebral infarction, cerebral hemorrhage, brain tumor, and craniocerebral trauma, which may involve the injury of the dura mater, elicit the need to repair this membrane by dural grafts. However, common dural grafts tend to result in dural adhesions and scar tissue and have no further neuroprotective effects. In order to reduce or avoid the complications of dural repair, we used PLGA, tetramethylpyrazine, and chitosan as raw materials to prepare a nanofibrous dura mater (NDM) with excellent biocompatibility and adequate mechanical characteristics, which can play a neuroprotective role and have an antifibrotic effect. We fabricated PLGA NDM by electrospinning, and then chitosan was grafted on the nanofibrous dura mater by the EDC-NHS cross-linking method to obtain PLGA/CS NDM. Then, we also prepared PLGA/TMP/CS NDM by coaxial electrospinning. Our study shows that the PLGA/TMP/CS NDM can inhibit the excessive proliferation of fibroblasts, as well as provide a sustained protective effect on the SH-SY5Y cells treated with oxygen–glucose deprivation/reperfusion (OGD/R). In conclusion, our study may provide a new alternative to dural grafts in undesirable cases of dural injuries.

Ossified Ligamentum Flavum: Epidemiology, Treatment, and Outcomes.

Ossification of the ligamentum flavum (OLF) is an uncommon but potentially serious spinal condition which can cause progressive compression of the spinal canal with associated devastating neurologic compromise. Although debate exists regarding the exact etiology of OLF, overexpression of genes and transcription factors centered around the Notch and Wnt signaling pathways because of increased mechanical stress seems to be related. There are many clinical and radiographic presentations of OLF; however, progressive myelopathy is the most commonly encountered. Radiographic analysis may reveal isolated OLF or OLF combined with ossification of other areas of the spine, such as disk, posterior longitudinal ligament, and dura. When surgery is necessary for OLF, several surgical strategies exist including open laminectomy with excision, endoscopic decompression, Bridge Crane resection, en block resection, and combined anterior and posterior approaches. Resection may be complicated by dural adhesion or dural ossification, and postoperative neurologic deficits are not uncommon.

Resection of Lumbar Spinal Facet Joint Cysts and Cerebrospinal Fluid Leakage: Incidence, Prognostic Parameters, and Outcome in a Single-center Series.

Single-center series. Intraspinal facet joint cysts can lead to nerve root compression symptoms with severe discomfort and disability. Permanent improvement can be achieved by surgical resection of the cyst. However, cerebrospinal fluid (CSF) leakage is a common problem in resection of facet joint cyst.The aim of the study was to investigate the frequency of CSF leak after resection of a joint cyst and to determine predictive factors. A total of 176 consecutive patients underwent surgery for lumbar spinal facet joint cyst in our institution between 1997 and 2018. Patients with a CSF leak were compared with patients without a CSF leak (control group). CSF leakage occurred in 14 patients (8.0%) In 2 of the cases (14.3%), the CSF leak was recognized only postoperatively, in 12 cases (85.7%), the CSF leak was detected intraoperatively. Despite intraoperative dura repair, 4 of these 12 patients (33.3%) presented with CSF leakage postoperatively. Altogether 6 patients had postoperative CSF leakage. Compared with patients without CSF leak, there were no differences in preoperative symptoms, surgical technique, complications, or postoperative findings. Adhesion of the cyst to the dura mater was present in all 14 patients with CSF leakage (100%), but only 61.7% of the control group ( P <0.005). All patients in the CSF leak group showed an improvement of their preoperative symptoms. The rate of CSF leakage in resection of spinal facet joint cyst was 8% in the present study. The occurrence of a CSF leakage was independent of clinical factors, level, or side of the cyst, but significantly correlated to dural adhesion of the cyst.Since neither clinical recovery nor recurrence rates do depend on complete removal of the cyst, aggressive resection of dural adherend parts of the cyst wall should be avoided to prevent CSF leakage.

Congenital sphenoid wing defect with lateral angular dermoid presenting with CSF leak after orbital surgery

Lateral angular dermoid may have associated bony defects which must be recognized before surgery. High-resolution 3-D CT scans and MRIs define these lesions very clearly. Total excision with attention to the bony defect is usually curative. CSF leak from the operative wound at the surgery or in the post-operative period signifies the intracranial connection or dural adhesion unnoticed by the Ophthalmologist before surgery.

Characteristics and Short-Term Surgical Outcomes of Patients with Recurrent Lumbar Disc Herniation after Percutaneous Laser Disc Decompression.

Background and Objectives: Although percutaneous laser disc decompression (PLDD) is one of the common treatment methods for patients with lumbar disc herniation (LDH), the recurrence of LDH after PLDD is estimated at 4–5%. This study compares the preoperative clinical data and clinical outcomes of patients who underwent primary microendoscopic discectomy (MED) or MED following PLDD. Materials and Methods: We retrospectively analyzed 2678 patients who underwent MED for LDH. The PLDD group included patients with previous PLDD history at the same level of LDH, and a matched control group was created using propensity score matching for age, sex, and body mass index. Preoperative data, preoperative radiographic findings, and surgical data of the groups were compared. To compare postoperative changes in clinical scores between the groups, a mixed-effect model was used. Results: As a result, 42 patients (1.6%) had previously undergone PLDD, and a control group with 42 patients were created. The disc degeneration severity was not significantly different between the groups. However, Modic changes were more frequent in the PLDD group than in the matched control group (p = 0.028). There were no significant differences in dural adhesion rate or surgery-related complications including dural injury, length of stay, and recurrence rate of LDH after surgery. In addition, the improvement of clinical scores did not significantly differ between the two groups (p = 0.112, 0.913, respectively). Conclusions: We concluded that patients with recurrent LDH after PLDD have advanced endplate degeneration, which may reflect endplate injury from a previous PLDD. However, a previous history of PLDD does not have a negative impact on the clinical result of MED.

Sterile Gelatin Film Reduces Cortical Injury Associated With Brain Tumor Re-Resection.

BACKGROUNDRecurrent intracranial tumors frequently require re-resection. Dural adhesions to the cortex increase the morbidity and duration of these revision craniotomies.OBJECTIVETo describe the use of commercially available sterile gelatin film to prevent meningocerebral adhesions and decrease the rate of surgically induced ischemia from revision craniotomy.METHODSThis retrospective cohort study examined patients with recurrent glioma, meningioma, and metastasis who underwent re-resection at least 30 d following their initial tumor resection. Cortical surface tissue ischemia after re-resection on diffusion-weighted magnetic resonance imaging was compared for patients with (gelatin film group) and without (nongelatin film group) a history of gelatin film placement at the conclusion of their initial tumor resection.RESULTSA total of 84 patients in the gelatin film group were compared to 86 patients in the nongelatin film group. Patient age, sex, tumor pathology, tumor volume, tumor eloquence, laterality of surgical approach, history of radiotherapy, and time interval between resections did not differ between groups. Radiographic evidence of cortical ischemia following reoperation was less prevalent in the gelatin film group (13.1% vs 32.6%; P < .01). In multivariate logistic regression analysis, no gelatin film (P < .01) and larger tumor size (P = .02) predicted cortical surface ischemia following revision craniotomy. Postoperative complications in the gelatin film and nongelatin film group otherwise did not differ.CONCLUSIONRoutine placement of commercially available sterile gelatin film on the cortex prior to dural closure is associated with decreased surgically induced tissue ischemia at the time of revision tumor craniotomy.

An Unusual Intraoperative Lumbar Disc Herniation Migrating into the Posterior Epidural Space

Background: The migration of a herniated fragment of the intervertebral disc towards posterior epidural space remains an exceptional phenomenon and Its clinical presentation is not unequivocal. Its diagnosis in modern imaging can cause confusion with other lesions of the posterior epidural space. We report an unusual migration of a herniated disc fragment into the posterior epidural. Method: we describe a case of an unusual migration of disc fragment into the posterior epidural space admitted in Neurosurgery department of University Teaching Hospital of Cotonou in 2019. Result: A 33-year-old man was admitted for progressive bilateral radiculopathy, gait disturbances and constipation. The clinical examination noted a moderate perineum and right buttock hypoesthesia, a flaccid paraparesis, bilatéral straight leg raising limitation (45°). The right patellar and achilean reflexes were depressed. MRI of the lumbar spine showed a right L4L5 herniated disc and its migration into the anterolateral epidural space. Surgery was performed with posterior approach. After an L4 and L5 laminectony, we discovered a very compressive large fragment of L4L5 intervertebral disc. The fragment was delicately dissociated from its dural adhesions. Histological examination confirmed the fibrocartilaginous nature of the sample. The post-operative period was uneventful. Three months post-operatively, he had regained his autonomy with a strength score of 5/5 in both pelvic limbs. Conclusion: Migration of intervertebral disc fragment into the posterior epidural space is a rare phenomenon. Diagnosis errors are possible. In case of posterior migration with cauda equina syndrom, we recommend laminectomy with removal of herniated disk fragment. This approach remains a simple and secure.

Evaluation of preoperative findings suggesting dural adhesion in microendoscopic over the top laminoplasty for lumbar canal stenosis

Evaluation of preoperative findings suggesting dural adhesion in microendoscopic over the top laminoplasty for lumbar canal stenosis

Dural adhesion as a cause of late clip slippage from the medial cerebral artery aneurysm.

A properly placed clip may slip off the aneurysm during the postoperative period. Many factors have been attributed to this complication, although clip adherence to the dural stitch has not been reported. Following the single occurrence of such unusual complication, 64 similar medial cerebral artery (MCA) aneurysms were retrospectively investigated at a single institution. Clip adherence to the dura demonstrated in early postoperative computed tomography (CT) was a presumed factor of a late clip migration in this study. In the series, there were 4 (6.3%) aneurysm remnants and 1 slipped clip that firmly adhered to the dura. In this particular case, the revision surgery revealed the spring coil firmly adhering to the dura in the previous suture line. Neither the occurrence of an aneurysm neck remnant nor clip slippage were related to the clip's adherence to the dura in the analysis of the entire group (p > 0.05). On the contrary, application of a fenestrated clip did contribute to that finding in multivariate analysis (p < 0.01). Unlike the rest, two surgeons unintentionally tended to position the clip close to the dura (p < 0.01). The clip-to-dura distance measured in the follow-up CT angiography 1 year after the surgery differed from that in the postoperative CT in 83.8% of the cases and decreased by an average of 0.5 mm. Clip-to-dura adherence should be regarded as a normal finding in the postoperative CT following MCA aneurysm clipping. Surgeons should consider the possibility of clip head protrusion into the dural stitch line.

Preserving ligamentum flavum for preventing dural adhesions after lumbar surgery in model rabbits

Preserving ligamentum flavum for preventing dural adhesions after lumbar surgery in model rabbits

Effects of silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model.

The authors investigated the effects of a silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model. They found that it significantly reduced postlaminectomy dural adhesion formation and inflammation. Dural adhesion formation, thought to be an inevitable consequence of laminectomy, is one of the most common complications following spinal surgery, and the authors' results indicate that the silk solution might be a potential novel therapeutic agent for dural adhesion formation.

A less invasive suboccipital decompression-cranioplasty for Chiari type I malformation: Is it beneficial?

Abstract This was a retrospective study of 10 Chiari Malformation type I patients who were treated by the author since 2010–2016. This study aims to elucidate the benefit of modified foramen magnum decompression by preserving the bone as propose upside down-inside out (UDIO). The principle of handling is posterior fossa decompression (suboccipital decompression), as an established procedure, and ensures craniocaudal cerebrospinal fluid flow. Many complications such as cerebrospinal fluid leak, pseudomeningocele, dural adhesion, herniation of cerebellar tissue and cerebellar sag after foramen magnum decompression and duraplasty have been reported. The author wanted to know if the suboccipital decompression with additional cranioplasty, by reinstalling the suboccipital bone upside down-inside out (UDIO), is beneficial in this malformation treatment? There were 10 patients in this report, consisting of 7 females and 3 males. All patients were decompressed using the UDIO technique and duraplasty. All patients improved and, 1 patient needed a syringosubarachnoid shunt. There was no clinical deterioration, nor acute surgical complication and none suffered of pseudomeningocele and cerebellar sag, in an at least 12-months period of observation (range 12 months to 67 months). This small study suggests that the UDIO technique is safe, less invasive, beneficial and may be used as an option for Chiari type I malformation.

Clinical relation among dural adhesion, dural ossification, and dural laceration in the removal of ossification of the ligamentum flavum

Background ContextDural laceration frequently occurs during surgery in patients with ossification of the ligamentum flavum (OLF), mainly because of dural adhesion (DA) and dural ossification (DO) between the ligamentum flavum and the dura mater. However, the radiological predictive factors of DA in OLF have rarely been reported. PurposeThe objective of this study was to determine the preoperative radiological signs for predicting intraoperative DA in OLF by using preoperative magnetic resonance imaging (MRI) and computed tomography (CT). Study DesignThis is a retrospective study. Patient SampleThis study included 182 patients who underwent decompressive laminectomy and OLF removal from 2005 to 2014. Outcome MeasureDemographic data, preoperative neurologic status, surgical procedure and results, and intraoperative and postoperative complications were analyzed. Clinical outcome was assessed with the Japanese Orthopaedic Association score. Materials and MethodsDepending on the morphologic appearance of OLF in preoperative radiographs, we aimed to investigate the prevalence of intraoperative DA and DO. We used the following factors of representative classifications: (1) surface appearance, (2) “double-layer” or “tram-track” sign, (3) cross-sectional area of the stenosed level, (4) Sato classification as axial classification, (5) Kuh classification as sagittal classification, and (6) high–signal-intensity change on T2-weighted MRI. ResultsIntraoperative evidence of DA was observed in 52 patients (29%), and DO was observed in 23 patients (13%). Twenty-seven patients (15%) had dural laceration during surgery. Statistically, DA was closely associated with the non-uniform type of surface appearance (odds ratio 5.396, p=.001) and with the presence of either a double-layer sign or a tram-track sign (odds ratio 11.525, p<.001). In the preoperative CT and MRI, 21 out of 23 patients with DO showed a “double-layer sign” or a “tram-track sign.” ConclusionsThis study identified two predictive factors of DA in OLF, which were the non-uniform surface appearance and the presence of a double-layer sign or a tram-track sign. The presence of DO in OLF was closely associated with a double-layer sign or a tram-track sign in the preoperative radiological images.