CT/MR spectrum of far lateral and anterior lumbosacral disk herniations

Forty-eight patients had 50 extraforaminal disk herniations (EFDHs) demonstrated on CT and/or MR by (1) presence of disk density or disk signal material lateral to the neural foramen, (2) displacement or obliteration of paravertebral fat, and (3) nerve root or ganglion compression or displacement. Forty-one of 50 EFDHs had a coexisting intraforaminal component; nine of 50 had an isolated far lateral herniated nucleus pulposus. EFDHs typically occurred in the absence of a coexisting intraspinal disk herniation. Migratory fragments were seen in 50% of all cases and were at or cephalad to the interspace of origin in all cases. Forty-six percent of EFDHs were at L2-L3 or L3-L4, although the most commonly affected level was L4-L5 (38%). EFDHs, which were often overlooked (15/50 scans reviewed), are an important preventable cause of failed intraspinal diskectomy. EFDHs can be readily identified on both CT and MR if appropriate scans are obtained from L2 through S1 and if the neural foramina and paravertebral spaces are carefully examined.     

Thoracic disk herniation: MR imaging

The authors undertook a retrospective study to assess the role of magnetic resonance (MR) imaging in thoracic disk herniation. The initial MR images were interpreted independently of other findings. These interpretations were compared with the findings of plain and computed tomography (CT) myelography and surgery, when available. Sixteen thoracic disk herniations were confirmed with plain and CT myelography and/or surgery. Plain myelography was performed on 14 patients and showed focal ventral filling defects in nine. Results of CT myelography were equivalent to those of MR imaging with three pulse sequences (sagittal T1 and T2 weighted, axial T1 weighted) in the identification of all the abnormal levels. In two patients, the signal from the herniated disk was so low on all sequences that thoracic disk herniation had to be inferred from the mass effect on the spinal cord. Precise location of the abnormal level with body coil MR images was achieved in six of 13 patients.     

Magnetic resonance imaging of the lumbar spine with CT correlation

The results of magnetic resonance (MR) imaging and computed tomography (CT) in 18 patients with known degenerative disk disease of the lumbar spine were compared. In 60 intervertebral disk levels studied, there were 17 disks with degeneration and disk bulge, and 15 herniated disks. Final diagnoses were based on several factors, with surgical confirmation in five patients. There was good correlation between the two methods at 51 of the 60 levels studied. However, there were major discrepancies in interpretation at nine intervertebral disk levels. These included three false-positive MR imaging interpretations of a herniated disk and one false-negative herniated disk on MR imaging. MR imaging detected one case of disk herniation that was missed prospectively on CT. There were also four presumed degenerated disks seen on MR scans that appeared normal on CT. The conus medullaris was imaged in 16 of 18 patients. The sagittal view proved best for demonstrating both disk abnormality and the conus medullaris. The transaxial view was sometimes helpful in localizing a disk herniation, but partial-volume averaging in the 7-mm slice thickness limited its usefulness. There were five disk herniations that could not be accurately localized on the MR scan. MR imaging proved more sensitive than CT in detecting early disk disease, which appeared as decreased signal intensity within the disk. In three postoperative cases, MR imaging was better able to distinguish between recurrent disk herniation and postoperative scar formation. CT, on the other hand, was more specific in distinguishing herniated disk from disk bulge and proved far superior to MR imaging in localizing disk herniation.(ABSTRACT TRUNCATED AT 250 WORDS)     

MR imaging of epidural hematoma in the lumbar spine

OBJECTIVE: To bring attention to the MR imaging appearance of epidural hematoma (EDH) in the lumbar spine as a small mass often associated with disk herniation or an acute event. This paper will show our experience with this entity and describe criteria for its MR imaging appearance. DESIGN AND PATIENTS: Thirteen cases of prospectively diagnosed EDH of the lumbar spine were compared with 12 cases of prospectively diagnosed prominent epidural extrusion. Our criteria were retrospectively evaluated by the two authors for their presence or absence in each case. The chi-square test for nominal data was applied. MR imaging criteria utilized to distinguish EDH from disk herniation at our institution include: (1) signal different from disk, (2) high signal on T1-weighted images, either centrally or peripherally, (3) teardrop- or egg-shaped mass, in the sagittal plane, (4) size greater than half the vertebral body height in a craniocaudal dimension, (5) primarily retrosomatic epidural location, (6) plasticity - the mass is seen to conform closely to the contours of bone (e.g., in the lateral recess), (7) little or no disk space narrowing unless associated with disc herniation. RESULTS: Chi-square analysis demonstrated each criterion to significantly differentiate between EDH and extrusion. Only six of 13 EDH cases went to surgery in spite of their relatively large size. Two of six patients were diagnosed as having epidural clot consistent with hematoma at the time of surgery. The four patients who were not diagnosed at surgery revealed only small disk herniations or fragments of disk. CONCLUSIONS: The occurrence of EDH is more frequent than previously suspected. Spontaneous EDH is frequently associated with disk herniation and acute events such as sneezing or coughing. Most cases of spontaneous EDH will resolve prior to surgery with only the minority becoming chronic in order to be seen at surgery as an encapsulated mass. MR imaging can reliably identify EDH and distinguish between EDH and large disk extrusions.     

Extraforaminal lumbar disc herniations: CT demonstration of Sharpey's fibers avulsion

Summary Forty-seven extraforaminal lumbar disc herniations (EFLDH) accounting for 7% of all lumbar disc herniations encountered during the same period of time were reviewed. L3–L4 or L4–L5 disc was involved in 89% of the cases giving rise to a L3 or L4 nerve root compression. An abnormal motion of lateral bending with rotation of the trunk was found retrospectively in 60% of the patients. In 53% of all EFLDH a bony avulsion of the vertebral endplante facing the herniation was demonstrated at the site of attachment of Sharpey's fibers. This study suggests that this previously undescribed bony change witnesses a special injury of the spine responsible for most EFLDH.     

MR imaging of the pars interarticularis

MR imaging of the lumbar spine has become a useful method for the noninvasive evaluation of low back pain. However, bone abnormalities are more difficult to detect than soft-tissue lesions, such as herniated disk. We reviewed 14 MR images of the lumbar spine in adults with spondylolisthesis. These were correlated with CT scans and plain films in all cases. From the CT scans and plain films we found that seven patients had spondylolysis and that seven had other causes for their spondylolisthesis. It was our opinion that the MR images suggested an abnormality of the pars interarticularis in all seven of the cases confirmed to have spondylolysis and in six of the seven patients that did not have spondylolysis. We also studied four cadaver lumbar spine, obtained as blocks of tissue, and scanned in the coronal, sagittal, and axial planes with MR and in the sagittal and axial planes with CT. The tissue blocks were then sectioned in the sagittal plane. Spondylolysis is suggested on sagittal MR images when there is an inability to resolve the marrow signal in the pars as uninterrupted from the superior to the inferior facet. This is caused by a dark signal on all pulsing sequences in the pars resulting from marginal sclerosis at the site of the break. If there is also a gap at the site of the break then there will also be an increased signal in the gap resulting from the presence of soft tissue. We found four situations in which the pars can simulate spondylolysis on sagittal MR images: (1) sclerosis of the neck of the pars: (2) partial volume imaging of the degenerative spur of the superior facet slightly lateral to the pars; (3) partial facetectomy; and (4) osteoblastic metastatic replacement of the marrow of the pars.     

Lumbar root compression in the lateral recess: MR imaging,conventional myelography,and CT myelography comparison with surgical confirmation

BACKGROUND AND PURPOSE: Previous authors have shown that conventional myelography is superior to plain CT in the assessment of root compression in the lateral recess, but this question has never been evaluated with respect to MR imaging of the lumbar level. Our purpose was to assess the accuracy of MR imaging, conventional myelography, and postmyelography CT (CT myelography) of the lumbar level in identifying degenerative lateral recess root compression with surgical confirmation. METHODS: MR imaging, conventional myelography, and CT myelography of the lumbar level were assessed in the imaging of 58 lateral recesses at 38 lumbar levels in 26 patients who underwent surgery for radiculopathy with degenerative lateral recess abnormality. Each lateral recess was graded as normal, small without root compression, small with root compression, or severe root compression. RESULTS: MR imaging underestimated root compression in 28% to 29% of the cases in which root impingement was surgically confirmed. Conventional myelography underestimated root compression in only 5% to 7% of the cases and correctly predicted impingement in 93% to 95%. CT myelography underestimated root compression in 38% of the surgically confirmed cases. CONCLUSION: MR imaging significantly underestimated root compression caused by degenerative changes in the lateral recess. Although MR imaging is a superb study when used in the search for degenerative disk disease and disk protrusion, conventional myelography is a crucial supplemental study that is necessary to confirm degenerative root impingement in the lateral recess as the cause of radiculopathy.     

Recurrent postoperative sciatica: evaluation with MR imaging and enhanced CT

Magnetic resonance (MR) imaging and computed tomography enhanced with intravenous iodine injection (ECT) were prospectively compared in 80 patients in the diagnosis of recurrent postoperative sciatica. Diagnostic accuracy was determined with surgical verification. Isolated fibrosis was considered a contraindication to surgery. A decision to operate was made in 56 of the 80 patients on the basis of MR imaging findings; in 21 of the 56, the decision was also made on the basis of ECT findings. Of the 80 patients, 45 underwent surgery, In all but one of these patients, the diagnosis made on the basis of MR imaging findings was confirmed with surgical analysis. The only surgical finding that did not agree with MR imaging findings was a calcification of the common posterior ligament. The 21 diagnoses of disk herniation based on ECT findings were confirmed surgically, but among the 24 diagnoses of fibrosis made with the help of ECT, there were actually 19 recurrent herniations, four herniations with fibrosis, and one herniation at the level above the previously resected disk. MR imaging seems to be the investigation of choice in diagnosing the cause of recurrent postoperative sciatica.     

Differentiation between Symptomatic and Asymptomatic Extraforaminal Stenosis in Lumbosacral Transitional Vertebra: Role of Three-Dimensional Magnetic Resonance Lumbosacral Radiculography

Objective

To investigate the role of lumbosacral radiculography using 3-dimentional (3D) magnetic resonance (MR) rendering for diagnostic information of symptomatic extraforaminal stenosis in lumbosacral transitional vertebra.

Materials and Methods

The study population consisted of 18 patients with symptomatic (n = 10) and asymptomatic extraforaminal stenosis (n = 8) in lumbosacral transitional vertebra. Each patient underwent 3D coronal fast-field echo sequences with selective water excitation using the principles of the selective excitation technique (Proset imaging). Morphologic changes of the L5 nerve roots at the symptomatic and asymptomatic extraforaminal stenosis were evaluated on 3D MR rendered images of the lumbosacral spine.

Results

Ten cases with symptomatic extraforaminal stenosis showed hyperplasia and degenerative osteophytes of the sacral ala and/or osteophytes at the lateral margin of the L5 body. On 3D MR lumbosacral radiculography, indentation of the L5 nerve roots was found in two cases, while swelling of the nerve roots was seen in eight cases at the exiting nerve root. Eight cases with asymptomatic extraforaminal stenosis showed hyperplasia and degenerative osteophytes of the sacral ala and/or osteophytes at the lateral margin of the L5 body. Based on 3D MR lumbosacral radiculography, indentation or swelling of the L5 nerve roots was not found in any cases with asymptomatic extraforaminal stenosis.

Conclusion

Results from 3D MR lumbosacral radiculography Indicate the indentation or swelling of the L5 nerve root in symptomatic extraforaminal stenosis. Based on these findings, 3D MR radiculography may be helpful in the diagnosis of the symptomatic extraforaminal stenosis with lumbosacral transitional vertebra.     

The value of MR in differentiating subligamentous from supraligamentous lumbar disk herniations.

PURPOSETo determine the value of MR criteria in differentiating subligamentous from supraligamentous lumbar disk herniations.METHODSA retrospective review of surgical reports and MR images of 50 patients undergoing first-time lumbar surgery was performed. Three MR imaging criteria were assessed: the presence and integrity of a low-signal-intensity line posterior to the disk herniation, the size of the disk herniation in comparison with the size of the spinal canal, and the presence of disk fragments. Correlation was made with surgical findings to determine the value of these MR criteria in differentiating subligamentous from supraligamentous disk herniations.RESULTSFor determining subligamentous disk herniations: the presence of a continuous low-signal-intensity line posterior to the disk herniation was 29% sensitive, 65% specific, and 42% accurate; disk herniation size less than 50% of the size of the spinal canal was 64% sensitive, 47% specific, and 58% accurate; and the absence of disk fragments was 88% sensitive, 12% specific, and 62% accurate. Combinations of individual MR criteria did not improve diagnostic accuracy.CONCLUSIONSFor differentiating subligamentous from supraligamentous lumbar disk herniations, none of the MR imaging criteria assessed was reliable.     

The usefulness of magnetic resonance imaging for sequestered lumbar disc herniation treated with endoscopic surgery

Forty two patients with sequestered lumbar intervertebral disc herniation were treated by endoscopic surgery with the mobile Endospine system. The herniations and migration were confirmed on magnetic resonance imaging (MRI). The interlamina fenestration and pars interarticularis fenestration approaches were used for intracanal herniations and far lateral lumbar disc herniations (FLLDH) according to the degree of migration as observed on MRI. Sequestered herniations were exposed and removed completely with the mobile endoscopic system for all patients without neurologic complications or dural tears. Intraoperative findings were compared with preoperative MRI results. Of 24 caudal intracanal herniations, 15 had sequestered nuclei located ventrally beneath the dural theca and the transverse nerve root; 5 were between the transverse nerve root and dural theca (axillary); 4 were dorsally located on the nerve root and dural theca. However, preoperative MRI did not clearly display the sequestered nuclei between the transverse nerve root and dural theca (axillary), or the dorsally migrated disc on the nerve root and dural theca. Of 6 cranial intracanal herniations, 5 had free fragments located beneath the dural theca, and 1 dorsal to the dural sac. Of the 2 dorsal herniations, the migrated nucleus adhered to the dural sac was not found on preoperative MRI; in the other case, dorsal migration of nucleus, annulus and endplate around the dural sac was also not observed on preoperative MRI. Among the 10 FLLDH, preoperative MRI showed cranial migration and foraminal obstruction in all patients, with sequestered disc material at the ventral and medial sides of the exiting nerve root, displacing the exiting nerve root and ganglion cranially and dorsally. During the 12 to 48 month postoperative follow-up period, 26 patients had excellent clinical results and 15 patients had good results (Macnab scale). In conclusion, MRI is important for evaluating sequestered lumbar disc herniation, although it has its limitations. Sequestered herniations can be exposed and removed completely with the mobile endoscopic system.     

Sequestered disc herniation mimicking psoas abscess: A rare case report

Intervertebral disc herniation is common condition, with majority occurring in lumbar and cervical spine. Most lumbar disk herniations occur within the spinal canal, with approximately 7%-10% identified within the foramen or extraforaminal location. Extraforaminal disc herniation in extreme lateral, retroperitoneal or anterior terms are used when disc material is seen towards anterolateral or anterior to the spine. Disc herniation in these locations is easily mistaken for an abscess or a neoplasm especially when it is not connected to the parent disc (sequestered disc). We describe a case of 60-year male who initially was misdiagnosed as psoas abscess and subjected to invasive investigation which later turned out to be histologically confirmed disc sequestration in the retroperitoneum. Thus, knowledge of this condition is essential in avoiding unnecessary workup and treatment.     

Recurrent postdiskectomy low back pain: MR-surgical correlation

The preoperative MR findings in 11 patients, all of whom had developed recurrent low back pain after surgery for herniated lumbar intervertebral disk, were correlated with the surgical findings to determine possible criteria for distinguishing recurrent disk herniation from postoperative scar (extradural fibrosis). The preoperative MR findings agreed with the surgical findings in seven of eight patients with recurrent disk herniation and in six of nine individuals with extradural fibrosis. The most important parameters in differentiating recurrent herniated disk from extradural scar were the configuration and margination of the extradural mass rather than its signal characteristics. The most reliable MR sign for recurrent herniated disk was the presence of a sharply marginated focal polypoid disk protrusion beyond the posterior margins of the adjacent vertebral bodies shown to best advantage on sagittal T1- and T2-weighted and axial T1-weighted spin-echo MR images. Disk herniations usually maintained isointensity with the intervertebral disk of origin, while extradural fibrosis exhibited variable signal intensity. The preoperative diagnosis of extradural fibrosis on MR was based primarily on its irregular configuration and extension. This study suggests that preoperative differentiation between scar and recurrent herniated disk is possible with MR when morphology and topography are considered in addition to signal intensity.     

Lumbar disk herniation: MR imaging assessment of natural history in patients treated without surgery.

The aim of this study was to evaluate the evolution of lumbar disk herniation in patients treated without surgery. Sixty-nine patients with a lumbar disk herniation proved at magnetic resonance (MR) imaging underwent a follow-up MR imaging study. The disk herniations evaluated during both MR imaging examinations were measured and classified into four categories according to the change in size that occurred. The patients were also divided into three clinical classes on the basis of the clinical outcome. Sixty-three percent of the patients showed a reduction of disk herniation of more than 30% (48% had a reduction of more than 70%), while only 8% demonstrated worsening of the clinical picture. These findings suggest that lumbar disk herniation may be primarily a medical (nonsurgical) disease and that MR imaging could play an important role in management of and research into the disorder.     

Multilevel thoracic disk herniations: CT and MR studies

Thoracic disk herniation is a disorder that can present clinically perplexing problems for physicians. The true incidence of thoracic disk herniation is difficult to assess with various authors reporting an incidence ranging between 0.15 and 1.8% of all disk herniations. Multiple thoracic disk herniations are rare and, to the best of our knowledge, have received little attention in the orthopedic, neurosurgical, and radiological literature. A retrospective review of 680 myelograms performed at our institution was carried out and only three cases of multilevel thoracic disk herniations were found. We analyze these cases, discuss the relative value of the imaging modalities used in their diagnosis, and review the literature dealing with this interesting disorder.     

Cervical spine disk herniation: comparison of CT and 3DFT gradient echo MR scans.

The purpose of this study was to compare CT and MR for the detection of cervical disk herniations. Nineteen patients suspected of harboring degenerative disk disease of the cervical spine underwent thin contiguous section CT myelography (CTM) and thin contiguous section three-dimensional Fourier transform (3DFT) gradient echo MR at 67 disk levels. Blinded readings of a high intensity CSF MR technique for the presence or absence of disk herniation were performed by three neuroradiologists. The intraobserver CT-MR concordances ranged from 84 to 89%. Using CTM as the paragon test, MR demonstrated a sensitivity of 79-91% and a specificity of 82-88% for disk herniation. Mean MR-CT concordance (86%) was nearly equivalent to that of CT-CT intraobserver concordance (88%). When consensus readings were considered, the MR-CT concordance (91%) was slightly higher than that of CT-CT intraobserver concordance (88%). We conclude that thin section 3DFT gradient echo MR with high intensity CSF is a reliable method to screen for degenerative disk disease in the cervical spine, since the agreement between MR and CTM is comparable with the intraobserver agreement of CTM.     

螺旋CT多平面重建对极外侧型腰椎间盘突出症的诊断

目的 探讨极外侧型腰椎间盘突出症(ELLDH)在螺旋CT多平面重建(MPR)的特征表现，提高对该病的诊断率。方法 对25例ELLDH进行常规CT扫描 薄层螺旋扫描和冠状面、矢状面的MPR；25例中男18例，女7例，均经手术证实。结果 25例ELLDH MPR显示椎间盘突出部位及压迫同位节段脊神经根情况与手术所见基本相符，其中椎间孔内突出15例，椎间孔外侧突出4例，椎间孔内外突出3例，椎间孔内并同节段椎管内后外侧突出3例。其MPR特征为突入椎间孔内和椎间孔外的软组织块影，压迫同位节段脊神经根，形态多呈丘状、圆形或三角形。25例ELLDH中有7例常规CT扫描未发现ELLDH，病人再行MPR均发现ELLDH；8例常规CT扫描显示ELLDH可疑，通过MPR得到明确诊断；10例常规CT扫描虽发现ELLDH，但不能清楚显示神经根受压情况；25例ELLDH通过MPR均直接显示了神经根受压情况。结论 MPR在ELLDH的诊断中具有重要价值，能准确地提供椎间盘突出的部位、形态、大小以及与神经根的关系等解剖学信息，有助于临床医师选择手术方式。     

Lumbosacral nerve root enhancement with disk herniation on contrast-enhanced MR.

PURPOSETo evaluate the clinical importance of nerve root enhancement associated with lumbar disk herniation.METHODSThirty-two patients with lumbar disk herniation were examined with unenhanced and contrast-enhanced MR imaging. We investigated the relationship between nerve root enhancement and location of herniated disk in the epidural space, onset pattern of symptoms, subsequent treatment, and surgical findings.RESULTSTen of the 32 patients had nerve root enhancement, and all belonged to the group with abrupt and severe nerve root compression with no residual space for the root between the herniated disk and the pedicle in the lateral recess. Tight compression of the root without mobility was seen in the four patients with nerve root enhancement who were treated surgically.CONCLUSIONNerve root enhancement may indicate the existence of abrupt and severe compression of the nerve root as well as the presence of severe adhesion of the herniated disk and the nerve root. This finding does not necessarily determine the type of subsequent treatment.     

Spontaneous resolution of lumbar disk herniation: predictive signs for prognostic evaluation

Spontaneous regression of lumbar disk herniation in patients who did not undergo surgery nor interventional therapy is reported in up to 70% of cases; however, no perspective study has clarified the possible predictive signs of a positive evolution. Aim of our study was to search for plan and contrast enhancement MRI signs able to define disk-herniation resolution. We enrolled 64 patients, affected by 72 lumbar disk herniations as per the classification proposed by the American Society of Neuroradiology (Nomenclature and Classification of Lumbar Disk Pathology 2001). MRI examinations were performed by 1.5-T magnet, using T1w SE sequences on sagittal and axial planes, before and after contrast, and T2w FSE ones on the same planes. The following parameters were considered: age, sex, level and size of disk herniation, its relationship to the spinal canal, clinical onset interval, type of disk herniation, herniated-material signal intensity on T2w sequences and its pattern of contrast enhancement. All the patients, conservatively treated, underwent clinical and MRI follow-up examination after 6 months. At MRI follow-up exams spontaneous regression of disk herniation was observed in 34.72% of cases. Among these, free fragments regressed in 100% of cases, herniations with high signal intensity on T2w sequences in 85.18%, herniations with peripheral contrast-enhancement in 83% of cases. Disk-herniation evolution did not show any relationship with location, size and level. Our study demonstrates that MRI, in addition to its high diagnostic value, offers predictive information about disk-herniation evolution.     

Lumbar herniated disks

Patients with low back and leg pain require careful evaluation and it is essential that there is correlation between the symptoms and signs of sciatica and the imaging demonstration of nerve root compression or displacement by a disk herniation before invasive therapy is undertaken. The natural history of herniations of the nucleus pulposus is complex and the relationship between the appearances on imaging and low back and radicular pain still has to be completely resolved. Considerable experimental work has been undertaken on the relationship between nerve compression, inflammation, and pain and recent studies on cytokines may lead to more precise pharmacologic therapies. The prime value of MR imaging may be in monitoring disk and nerve root changes in longitudinal studies of patients randomized to different therapeutic programs.