The retrodural space of Okada

OBJECTIVE: The retrodural space of Okada is a potential space that can act as a conduit for the spread of inflammatory or infectious processes, connecting ipsilateral adjacent facet joints, contralateral adjacent facet joints, adjacent neural foramen, paraspinal musculature, and spinous process adventitial bursa (i.e., Baastrup disease). CONCLUSION: Awareness of these potential retrodural communications during diagnostic imaging interpretation and interventional spine injection procedures can play an important role in patient care and management.     

Spinous process fractures in osteoporotic thoracolumbar vertebral fractures

Objectives

To evaluate the incidence and pattern of spinous process fractures (SPFs) in patients with osteoporotic compression fractures (OCFs) of the thoracolumbar spine.

Methods

Spinal MRI or CT of 398 female patients (age range 50–89 years, mean age 70 years) who had OCFs in the thoracolumbar spine were retrospectively reviewed. The incidence, location and imaging results for the SPFs were evaluated.

Results

Of the 398 patients who had thoracolumbar OCFs, 14 (3.5%) had SPF. In six patients with single compression fractures, the SPF occurred at the level just above the vertebral compression fracture. In six out of seven patients with multiple continuous compression fractures, the SPF occurred just one level above the uppermost level of the compression fracture. The remaining one patient who had thoracolumbar spinal fixation at T12–L2 with continuous compression fractures in T12–L5 had a SPF in L2. In one patient who had multiple compression fractures in discontinuous levels (fractures at T10 and L1, respectively), the SPF occurred at T12. The directions of the fractures were vertical or oblique vertical (perpendicular to the long axis of the spinous process) in all cases.

Conclusion

In the presence of an OCF in the thoracolumbar spine, a SPF was found in 3.5% of cases, and most of the fractures were located just one level above the compression fracture. Therefore, in patients who have OCF, the possibility of a SPF in the level just above the compression fracture should be considered.Osteoporosis is a common disease owing to an increase in the population of older people. Osteoporosis is a disease that induces bone fragility, caused by a decrease in trabecular bone, and the resulting fracture is called an insufficiency fracture. The most common osteoporotic compression fractures occur in the spine, sacrum, pubis, femoral neck and wrist [1].Although the most common methods for imaging vertebral fractures are still spinal radiographs, benign spinal compression fractures are commonly detected by MRI or CT on osteoporotic patients with back pain. Sometimes, it is difficult to differentiate a benign spinal compression fracture from a malignant cause of the spinal compression fracture. However, in most cases, a benign spinal compression fracture shows some specific features: a low-signal-intensity band on T₁ and T₂ weighted images, spared normal bone marrow signal intensity of the vertebral body, retropulsion of a posterior bone fragment and multiple compression fractures [2]. A relationship between osteoporosis and benign spinal compression fractures, including insufficiency fractures, has been reported. A study examining the relationship between benign compression fractures of the spine and insufficiency fractures of the sacrum has also been reported [3]. However, there have been few reports of spinous process fractures in the osteoporotic spine [4]. Moreover, there have been no studies examining the relationship between spinous process fractures and benign compression fractures of the spine.We have noted index cases of spinous process fractures in certain patients with osteoporotic compression fractures. There has been no report of spinous process fractures in patients with osteoporotic compression fractures. The aim of this study was, therefore, to evaluate the relationship between osteoporotic compression fractures and spinous process fractures in patients with osteoporosis.     

Case report 688

The double spinous process sign at multiple levels is a reliable indication of fractures of multiple spinous processes. When multiple thoracic vertebrate are involved, as in the patient reported here, the AP radiograph may offer the sole clue to the extent of injury on the plain films.     

Epidural fat interposition between dura mater and spinous process: a new sign for the diagnosis of spondylolysis on MR imaging of the lumbar spine

The purpose of this study was to assess the diagnostic value of epidural fat interposition between the dura mater and spinous process of L5 as an indirect sign of spondylolysis on mid-sagittal MR imaging of the lumbar spine. Mid-sagittal T1-weighted MR images of the lumbar spine of 85 patients with spondylolysis and 93 patients without pars interarticularis fractures were randomized and evaluated by a masked reader. After a training sample of five cases, the reader was asked to note the presence or absence of epidural fat interposition between the dura mater and spinous process of L5 on the randomized images. The epidural fat interposition between the dura mater and spinous process of L5 was noted in 67 out of the 85 patients with spondylolysis (78.8%) and three of the patients without pars interarticularis fracture (3.2%). The difference was statistically significant (P<0.01). This sign has a specificity of 96.7%, sensitivity of 78.8%, positive predictive value of 95.7%, negative predictive value of 83.3% and accuracy of 88.2% for diagnosis of spondylolysis. Epidural fat interposition between the dura mater and spinous process may be a helpful sign for the diagnosis of spondylolysis on mid-sagittal MR imaging of the lumbar spine.     

寰椎三维有限元模型的建立及其骨折机制

目的 建立寰椎的三维有限元模型(FEM)，并对寰椎各型骨折的可能机制予以分析。方法通过CT扫描获取寰椎的空间结构信息，利用软件建立其三维有限元模型，模拟临床的不同情况，以Ansys软件分析头颅位于屈曲位、后伸位以及头颅过度后伸时寰椎后弓与枢椎棘突接触等条件下，寰椎不同部位的应力变化情况。结果(1)在不同的边界条件下，头颅位于屈曲位或后伸位上关节面受来自头颅的纵向作用力时，应力最大点集中于前弓，次级应力集中区域为侧块及后弓。由于此时侧块上下方向的活动被限制，应力的集中是因上关节面受力后推压侧块向外侧滑移，使得前后弓受牵拉张力所致。(2)头颅过度后伸寰椎后弓与枢椎棘突接触时，后弓加载，应力明显集中于寰椎后弓的近侧块处。结论(1)无论头颅位于屈曲位、中立位或后伸位，当受纵向作用力时，首先引起的是寰椎前弓的骨折；如外力足够大或持续的时间较长，将导致Jefferson骨折产生。(2)单纯后弓骨折是由于头部后伸，在上关节面受轴向压力同时，寰椎后弓受到枕骨或枢椎棘突的作用，应力集中于寰椎后弓的薄弱点所致。     

”Spinolaminar breach”: an important sign in cervical spinous process fractures

Objective. To report the sign of ”spinolaminar breach” and its likely importance in fractures of the cervical spinous processes. Design. Six cases of spinous process fractures demonstrating disruption of the spinolaminar line or ”spinolaminar breach” were analyzed. Lateral and anteroposterior radiographs (n=6), CT scans (n=3) and MRI scans (n=1) were reviewed together by the authors, with consensus being reached as to the radiographic findings. Clinical records were also reviewed. Results. The levels of injury were C6 (n=5) and C5 (n=2). Injuries were associated with delayed anterior subluxation (n=4) and neurological deficit (n=2). Five patients were male and one was female with a mean age of 31 years (range 8–59 years). Injuries resulted from motor vehicle accidents (n=4), a motor cycle accident (n=1) and a fall (n=1). Conclusion. ”Spinolaminar breach”, or disruption of the spinolaminar line, indicates a complex spinous process fracture with extension into the lamina and spinal canal. Spinous process fractures with spinolaminar breach may have associated posterior ligamentous injury with potential for delayed instability and neurological deficit. It is important that radiologists and physicians caring for the trauma patient be aware of this sign in order to avoid misdiagnosis as a ”clay shoveler’s fracture”, which can lead to adverse outcome. Received: 20 July 1999 Revision requested: 14 September 1999 Revision received: 13 October 1999 Accepted: 26 October 1999     

Extraosseous Gaucher cell deposition without adjacent bone involvement

Extraosseous Gaucher cell deposits are a rare complication of Gaucher disease that can mimic malignancy. We describe a case of Gaucher cell deposition in the subcutaneous soft tissues overlying the lower thoracic spine in an 18-year-old woman with known type III Gaucher disease. This case is unique in the literature because this subcutaneous Gaucher mass was not associated with extension from underlying bone involvement or clear lymph node origin. It demonstrated no discernible continuity with the adjacent thoracic spinous processes, the cortices of which appeared intact. Although patients with Gaucher disease are at increased risk of malignancy, Gaucher cell deposition should remain a differential consideration for soft tissue masses with or without adjacent bone involvement in patients with known Gaucher disease.     

Multidetector computed tomography of cervical spine fractures in ankylosing spondylitis

PURPOSE: To analyze multidetector computed tomography (MDCT) cervical spine findings in trauma patients with advanced ankylosing spondylitis (AS). MATERIAL AND METHODS: Using PACS, 2282 cervical spine MDCT examinations requested by emergency room physicians were found during a period of 3 years. Of these patients, 18 (16 M, aged 41-87, mean 57 years) had advanced AS. Primary imaging included radiography in 12 and MRI in 11 patients. RESULTS: MDCT detected one facet joint subluxation and 31 fractures in 17 patients: 14 transverse fractures, 8 spinous process fractures, 2 Jefferson's fractures, 1 type I and 2 type II odontoid process fractures, and 1 each: atlanto-occipital joint fracture and C2 laminar fracture plus isolated transverse process and facet joint fractures. Radiographs detected 48% and MRI 60% of the fractures. MRI detected all transverse and odontoid fractures, demonstrating spinal cord abnormalities in 72%. CONCLUSION: MDCT is superior to plain radiographs or MRI, showing significantly more injuries and yielding more information on fracture morphology. MRI is valuable, however, in evaluating the spinal cord and soft-tissue injuries. Fractures in advanced AS often show an abnormal orientation and are frequently associated with spinal cord injuries. In these patients, for any suspected cervical spine injuries, MDCT is therefore the imaging modality of choice.     

Magnetic resonance imaging of para-acetabular insufficiency fractures in patients with malignancy

AIM: To describe the characteristic magnetic resonance imaging (MRI) findings of para-acetabular insufficiency fractures in patients with malignancy, and compare the MRI appearance of these fractures with that of metastatic bone disease. MATERIALS AND METHODS: MRI examinations were reviewed in 16 patients with a known malignant tumour and severe hip pain that raised the possibility of local recurrence or metastatic disease. Six patients had received pelvic irradiation, and three patients were receiving steroid medication. RESULTS: The total number of fractures detected was 21: a solitary fracture was present in 11 patients and five patients had bilateral para-acetabular fractures. Two patients had associated sacral insufficiency fractures, and one of them had stress fractures involving both acetabular columns. Conventional radiography allowed the diagnosis of 14 (67%) fractures; six (28%) radiographic examinations were negative; and one (5%) examination was equivocal for fracture. Available scintigraphic and computed tomography (CT) studies revealed typical findings of fracture. Using MRI, insufficiency fractures appeared as linear regions of low signal intensity on T1- and T2-weighted images. Marked marrow oedema was evident in all cases. Fractures characteristically were parallel to the superior acetabulum in a curvilinear fashion in 18 (86%) instances, and were oblique in three (14%) instances. The fractures demonstrated considerable enhancement after intravenous gadolinium administration. No associated soft tissue masses were documented. CONCLUSION: Para-acetabular insufficiency fractures are a cause of hip pain, which may mimic skeletal metastasis in the patient with malignancy and pelvic irradiation. Recognition of the characteristic MRI findings of these fractures can preclude misdiagnosis and unnecessary bone biopsy.     

Degenerative diseases of the vertebral column

Several distinct degenerative processes affect the articulations of the vertebral column; each is associated with characteristic radiographic and pathologic abnormalities, and many are accompanied by significant clinical manifestations. A discussion of these processes is best accomplished according to the type of joint that is involved. With regard to cartilaginous articulations, of which the intervertebral disk is most important, intervertebral (osteo)chondrosis, spondylosis deformans, and, in the cervical spine, uncovertebral arthrosis are the major degenerative disorders. Osteoarthritis (osteoarthrosis) affects any of the synovium-lined joints of the vertebral column, including the apophyseal, costovertebral, transitional lumbosacral, median atlantoaxial, and sacroiliac articulations. Fibrous articulations, ligaments, or entheses (sites of tendon or ligament attachment to bone) are involved in diffuse idiopathic skeletal hyperostosis, ossification of the posterior spinal ligaments, and Baastrup disease. Of the many complications of these degenerative processes, alignment abnormalities (including segmental instability, degenerative spondylolisthesis, senile kyphosis, and degenerative scoliosis), intervertebral disk displacement, calcification or ossification, and spinal stenosis are the most important.     

MRI of cervical spine injuries complicating ankylosing spondylitis

OBJECTIVE: The objective was to study characteristic MRI findings in cervical spine fractures complicating ankylosing spondylitis (AS). Technical issues related to MRI are also addressed. MATERIALS AND METHODS: A review of 6,774 consecutive cervical spine multidetector CT (MDCT) scans obtained during 6.2 years revealed 33 ankylosed spines studied for suspected acute cervical spine injury complicating AS. Of these, 20 patients also underwent MRI. RESULTS: On MRI, of these 20 patients, 19 had a total of 29 cervical and upper thoracic spine fractures. Of 20 transverse fractures traversing both anterior and posterior columns, 7 were transdiskal and exhibited less bone marrow edema than did those traversing vertebral bodies. One Jefferson's, 1 atlas posterior arch (Jefferson's on MDCT), 2 odontoid process, and 5 non-contiguous spinous process fractures were detectable. MRI showed 2 fractures that were undetected by MDCT, and conversely, MDCT detected 6 fractures not seen on MRI; 16 patients had spinal cord findings ranging from impingement and contusion to complete transection. CONCLUSION: Magnetic resonance imaging can visualize unstable fractures of the cervical and upper thoracic spine. Paravertebral hemorrhages and any ligamentous injuries should alert radiologists to seek transverse fractures. Multiple fractures are common and often complicated by spinal cord injuries. Diagnostic images can be obtained with a flexible multipurpose coil if the use of standard spine array coil is impossible due to a rigid collar or excessive kyphosis.     

Toward a better knowledge of the lateral x-ray picture of the cervical spinous process

The authors describe various alterations to the cervical spinous processes and stress the importance of examining the cortical bone.     

Pelvic insufficiency fractures associated with radiation atrophy: clinical recognition and diagnostic evaluation

 Pelvic bone injuries are infrequent complications of radiotherapy. However, insufficiency fractures in irradiated pelvic bones may be underdetected, particularly in postmenopausal women. We describe the clinical presentation, radiologic evaluation, and course of disease in three patients with postradiation pelvic insufficiency fractures. Differential diagnosis included metastatic disease, tumor recurrence, and second malignancy. Recognition of radiographic features may prevent unnecessary, possibly morbid treatments.     

Imaging features of cervical spondylolysis--with emphasis on MR appearances

AIM: To describe the imaging features of cervical spondylolysis, with emphasis on magnetic resonance imaging (MRI) appearances. MATERIALS AND METHODS: The clinical and imaging features (plain radiographic, CT and MRI) of three patients with cervical spondylolysis were reviewed. RESULTS AND CONCLUSIONS: Three cases of C6 cervical spondylolysis have been described and the world literature reviewed. The plain radiographic features in two cases with bilateral defects showed spondylolisthesis and abnormalities of the pars and adjacent facet joints. CT demonstrated well corticated defects and associated spina bifida occulta in all cases. The defects were seen in only one case on MRI but in all cases, absence of the spinous process of C6 was noted on sagittal sequences due to the spina bifida occulta. Cervical spondylolysis is an uncommon condition that must be distinguished from an acute fracture and diagnosed radiologically to prevent mismanagement. Although the defect may be difficult to identify on MRI, absence of the spinous process on sagittal sequences should raise the suspicion of the abnormality.     

Missed pathological femoral neck fracture undergoes spontaneous healing

Pathologic fractures are common complications of metastatic bone disease in patients with breast cancer. Fractures involving the proximal femur generally cause significant pain that is exacerbated by ambulation. Due to excessive stress on the weight-bearing hip joint, these fractures present a significant burden on the quality of life among patients. Here we describe a case of a 38-year-old female patient who was found to have a pathologic fracture of the proximal femur missed on imaging studies that underwent spontaneous union. Pathologic fractures rarely heal on their own, since a tumor at the fracture site interferes with bone healing and most fractures have to be managed with surgical intervention. Fractures can be missed on imaging studies in the setting of extensive metastatic disease. Physicians should be cognizant of this fact and maintain a high level of suspicion to recognize fractures with unusual presentations where patients may not present with the typical findings of acute onset of pain and inability to ambulate or bear weight.     

Imaging manifestations of spinal fractures in ankylosing spondylitis

BACKGROUND AND PURPOSE: Spinal fractures in ankylosing spondylitis (AS) were difficult to diagnose before CT and MR imaging were available. The purpose of our investigation was to characterize spinal fractures and determine the value of different imaging modalities in AS. METHODS: Twelve successive cases of spinal fractures were identified in MR imaging files of AS patients. Conventional radiographs were available for 12, CT scans for 7, and 3D-CT scans for 4. We carefully reviewed clinical histories and imaging presentations. RESULTS: Fractures were found in the cervical spine in 3 patients and in the thoracolumbar spine in 9. The 3 columns of the spine were involved in 11 patients. A routine 4-mm axial CT was not enough to demonstrate all fractures and ligament tears. The sensitivities of 3D-CT scans for demonstration of the following problems were similar to that of MR imaging and were better than that of conventional radiographs: tearing of the posterior longitudinal ligament, the thoracic spinous process fracture, and the facet fracture. MR imaging depicted these following findings that usually were not shown on conventional radiographs or 3D-CT scans: cord deformity, soft tissue disruption, and ligament tears in the posterior column. MR imaging also showed avascular necrosis and occult fractures better than conventional radiographs or CT scans. CONCLUSIONS: MR imaging shows abnormalities in AS that may not be clear or even detectable by using other imaging methods. With the capability to show lesions in the posterior column, MR imaging can serve to evaluate AS patients with spinal fracture for the possibility of 3-column involvement.     

Solitary 18F-fluorodeoxyglucose avid spinous process cholangiocarcinoma metastasis proven on CT guided percutaneous needle bone biopsy.

A 65-year-old female with newly diagnosed cholangiocarcinoma was referred for a FDG PET/CT for initial staging. There was a region of moderate FDG avidity localizing to the hepatic hilum representing the primary site of malignancy. An unexpected moderately FDG avid focus was demonstrated in the spinous process of the T11 vertebra with no corresponding mass lesion seen on low dose CT and no evidence of distant metastatic disease elsewhere. A percutaneous CT guided needle bone biopsy was performed which confirmed a solitary T11 spinous process metastasis on histopathology.     

Age-related alterations in the vertebral spinous processes and intervening soft tissues: radiologic-pathologic correlation

A radiologic-pathologic correlative investigation of the normal age-related alterations in the spinous processes and intervening soft tissues was performed using cadaveric spines and both ancient and modern macerated vertebral specimens. Extreme lordosis in the cervical or lumbar spine results in spinous process apposition, formation of interspinous bursae, eburnation with osteophytosis, and creation of synovial articulations. A concomitant degenerative enthesopathy involves the supraspinous or interspinous ligamentous attachments in any spinal segment. The differential diagnosis of this phenomenon, the clinical significance of which in a given patient is controversial, includes rheumatoid and other inflammatory arthritides as well as crystal deposition disease.     

Multiple superficial femoral artery pseudoanurysms following sub intimal application of paclitaxel coated technology

Drug coated balloons (DCB) are a commonly used endovascular option for treating patients presenting with symptomatic peripheral vascular disease. DCB have illustrated to increase primary patency and thus have been a popular choice in addressing restenosis caused by neointimal hyperplasia. Pseudoaneurysms (PSA) are a common vascular pathology, the causes of which include iatrogenic, trauma, stent fractures and angioplasty balloon overuse. Herein, we describe the case where a patient developed multiple superficial femoral artery (SFA) PSA potentially secondary to the subintimal application of paclitaxel.     

Baastrup’s disease (kissing spine) demonstrated by FDG PET/CT

18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) is a widely used imaging modality in cancer patients. However, there are many potential non-neoplastic causes of FDG uptake. We report a case of FDG uptake between the spinous processes, secondary to Baastrup’s disease. Knowledge of this pattern of uptake is helpful in diagnosing Baastrup’s disease and avoiding false-positive diagnoses.