Can imaging findings help differentiate spinal neuropathic arthropathy from disk space infection? Initial experience

Imaging of Spondylodiscitis: A Comprehensive Updated Review-Multimodality Imaging Findings, Differential Diagnosis, and Specific Microorganisms Detection

Spondylodiscitis is defined by infectious conditions involving the vertebral column. The incidence of the disease has constantly increased over the last decades. Imaging plays a key role in each phase of the disease. Indeed, radiological tools are fundamental in (i) the initial diagnostic recognition of spondylodiscitis, (ii) the differentiation against inflammatory, degenerative, or calcific etiologies, (iii) the disease staging, as well as (iv) to provide clues to orient towards the microorganisms involved. This latter aim can be achieved with a mini-invasive procedure (e.g., CT-guided biopsy) or can be non-invasively supposed by the analysis of the CT, positron emission tomography (PET) CT, or MRI features displayed. Hence, this comprehensive review aims to summarize all the multimodality imaging features of spondylodiscitis. This, with the goal of serving as a reference for Physicians (infectious disease specialists, spine surgeons, radiologists) involved in the care of these patients. Nonetheless, this review article may offer starting points for future research articles.

Imaging of Spine Infections

The incidence of spondylodiskitis has increased over the last 20 years worldwide, especially in the immunodepressed population, and it remains a complex pathology, both in terms of diagnosis and treatment. Because clinical symptoms are often nonspecific and blood culture negative, imaging plays an essential role in the diagnostic process. Magnetic resonance imaging, in particular, is the gold standard technique because it can show essential findings such as vertebral bone marrow, disk signal alteration, a paravertebral or epidural abscess, and, in the advanced stage of disease, fusion or collapse of the vertebral elements. However, many noninfectious spine diseases can simulate spinal infection. In this article, we present imaging features of specific infectious spine diseases that help radiologists make the distinction between infectious and noninfectious processes.

Spinal disorders mimicking infection

Spinal infections are very commonly encountered by radiologists in their routine clinical practice. In case of typical MRI features, the diagnosis is relatively easy to interpret, all the more so if the clinical and laboratory findings are in agreement with the radiological findings. In many cases, the radiologist is able to make the right diagnosis, thereby avoiding a disco-vertebral biopsy, which is technically challenging and associated with a risk of negative results. However, several diseases mimic similar patterns, such as degenerative changes (Modic) and crystal-induced discopathy. Differentiation between these diagnoses relies on imaging changes in endplate contours as well as in disc signal. This review sought to illustrate the imaging pattern of spinal diseases mimicking an infection and to define characteristic MRI and CT patterns allowing to distinguish between these different disco-vertebral disorders. The contribution of advanced techniques, such as DWI and dual-energy CT (DECT) is also discussed.

[Spondylodiscitis and epidural abscesses]

CLINICAL/METHODOLOGICAL PROBLEM

Spondylodiscitis is an inflammation of the intervertebral disc, which in adults is generally associated with spondylitis of the adjacent vertebrae. It often presents clinically with nonspecific symptoms such as back or neck pain. It may be caused by various pathogens, especially bacteria. One or more vertebral segments can be affected. The infection can spread to surrounding compartments and can lead to epidural abscesses. Radiology, in particular magnetic resonance imaging (MRI), plays an important role in the diagnostic work-up and in the follow-up to monitor response to therapy. Treatment consists of conservative (antibiotics) and invasive approaches, including surgery. Interventional puncture and drainage is a promising alternative to surgery, especially in early stages of abscess formation.

STANDARD RADIOLOGICAL METHODS

Magnetic resonance imaging (MRI), computed tomography (CT), nuclear medical procedures, conventional x‑ray.

PERFORMANCE

MRI has the highest value. CT and nuclear medical procedures can be used as a supplement to MRI and in patients with contraindications for MRI.

PRACTICAL RECOMMENDATIONS

With adequate diagnosis and therapy, spondylodiscitis has a good prognosis. In addition to targeted or calculated drug therapy, invasive treatment is the main focus, especially for epidural abscesses. Interventional radiological drainage can represent a less invasive alternative to surgical treatment.

Pathophysiology and MRI Findings of Infectious Spondylitis and the Differential Diagnosis

MRI에서 추간판의 이상 신호와 위, 아래 척추체 종판의 파괴, 종판 주변의 골수부종 등은 감염성 척추염의 전형적인 소견으로 여겨지나 퇴행성 척추질환, acute Schmorl's node, 척추관절병증, synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO)/chronic recurrent multifocal osteomyelitis, 척추신경관절병증, calcium pyrophosphate dehydrate 결절침착질환 등 다양한 비감염성 척추질환에서도 나타날 수 있다. MRI에서 이러한 비감염성 척추질환과 감별되는 감염성 척추염의 영상 소견은 추간판의 고신호와 농양, 척추 연부조직의 농양, 그리고 T1 강조영상에서 저신호로 보이는 종판의 경계가 불명확해지는 점 등이다. 그러나 이러한 감별점이 항상 적용되는 것은 아니며 감염성, 비감염성 질환의 영상 소견에 유사점이 많기 때문에 정확한 진단을 위해서는 감염성 척추염뿐만 아니라 감염과 감별해야 하는 다양한 질환의 병태생리와 연관된 영상학적 특징을 아는 것이 중요하다.

A comprehensive review of the treatment and management of Charcot spine

Charcot spine arthropathy (CSA), a result of reduced afferent innervation, is an occurrence of Charcot joint, a progressive, degenerative disorder in vertebral joints, related mostly to spinal cord injury. The repeated microtrauma is a result of a lack of muscle protection and destroys cartilage, ligaments, and disc spaces, leading to vertebrae destruction, joint instability, subluxation, and dislocation. Joint destruction compresses nerve roots, resulting in pain, paresthesia, sensory loss, dysautonomia, and spasticity. CSA presents with back pain, spinal deformity and instability, and audible spine noises during movement. Autonomic dysfunction includes bowel and bladder dysfunction. It is slowly progressive and usually diagnosed at a late stage, usually, on average, 20 years after the first initial insult. Diagnosis is rarely clinical related to the nature of nonspecific symptoms and requires imaging with computed tomography (CT) and magnetic resonance imaging (MRI). Conservative management focuses on the prevention of fractures and the progression of deformities. This includes bed rest, orthoses, and braces. These could be useful in elderly or frail patients who are not candidates for surgical treatment, or in minimally symptomatic patients, such as patients with spontaneous fusion leading to a stable spine. Symptomatic treatment is offered for autonomic dysfunction, such as anticholinergics for bladder control. Most patients require surgical treatment. Spinal fusion is achieved with open, minimally-open (MOA) or minimally-invasive (MIS) approaches. The gold standard is open circumferential fusion; data is lacking to determine the superiority of open or MIS approaches. Patients usually improve after surgery; however, the rarity of the condition makes it difficult to estimate outcomes. This is a review of the latest and seminal literature about the treatment and chronic management of Charcot spine. The review includes the background of the syndrome, clinical presentation, and diagnosis, and compares the different treatment options that are currently available.

Non-infectious thoracic discitis: A diagnostic and management dilemma. A report of two cases with review of the literature

Discitis/ Osteomyelitis is an inflammatory process involving an intervertebral disc and the adjacent vertebral bodies. Infection is the most common cause of discitis, which is often spontaneous and hematogenous in origin. However, many noninfectious processes affecting the spine such as pseudarthrosis in ankylosing spondylitis, amyloidosis, destructive spondyloarthropathy of hemodialysis, Modic changes type 1, neuropathic arthropathy, calcium pyrophosphate dehydrate (CPPD) spondyloarthropathy and gout can mimic infectious discitis/ osteomyelitis. To determine whether a particular patient's spinal process is due to an infectious versus non-infectious cause can be challenging. Although clinical findings and laboratory studies including erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) can be helpful in the diagnosis of bacterial discitis/osteomyelitis due to their high sensitivity; however, their specificity is low. Moreover, both the infectious and non-infectious discitis can appear quite similar on the imaging studies. We present two cases of thoracic discitis with adjacent vertebral osteomyelitis of probable non-infectious etiology. Both were managed with instrumented fusion for stabilization. We also discuss a range of noninfectious causes of discitis/spondylitis and their radiological features which can help differentiate from infectious processes.

A Rare Case of Cervical Charcot After Spinal Cord Injury: A Case Report

CASE

We present a rare case of cervical Charcot disease that was diagnosed in a paraplegic patient by loss of function caudal to the original level of spinal cord injury. Clinical imaging, diagnosis, differentials, and operative management are discussed.

CONCLUSIONS

Charcot disease of the cervical spine is rare and very difficult to diagnose in the paraplegic patient population. High clinical suspicion should be maintained in these patients who demonstrate any form of neurologic deterioration, mechanical instability, or change in spinal alignment. It is often necessary to rule out infection. Spinal decompression and surgical stabilization is the treatment of choice.

Infectious Spondylitis Mimics: Mechanisms of Disease and Imaging Findings

Infectious processes of the spine are on the rise; in this scenario recognition of entities imitating infection is very important. The discovertebral unit is regarded as one of the most important and active sites in the spine. Importantly, the vertebral bony rim and the anterior corners of the vertebral bodies have significant vascularization, they are the last regions to ossify in the developmental process and suffer mechanical forces. Early septic or aseptic discitis-osteomyelitis, properly called spondylitis, involves these anterior regions. Early degeneration is characterized by disc desiccation; however, there is preferential involvement for the corners of the vertebral bodies as well. Many entities to include degenerative changes, inflammatory spondyloarthropathies, neuropathic spine, or pseudo arthrosis, among others, affect the discovertebral unit and can imitate infection. With some exceptions, important imaging findings for the identification of an infectious mimic include the absence of soft tissue enhancement or fluid collections in the paraspinal or epidural regions, and the involvement of multiple levels or the posterior elements. We review developmental, anatomical, and pathologic concepts correlating with imaging clues. Overall, our goal is to increase awareness and to improve recognition of mimicking entities.

Management of autonomic dysreflexia associated with Charcot spinal arthropathy in a patient with complete spinal cord injury: Case report and review of the literature

Background:

Charcot spinal arthropathy (CSA) clearly represents a challenge in long-term spinal cord injury patients, one that can have extremely uncomfortable and potentially lethal outcomes if not managed properly.

Case Description:

A 66-year-old man with a history of complete C7 quadriplegia presented with new-onset autonomic dysreflexia that resulted from Charcot spinal arthropathy (CSA). Pathologic instability, in the atypical site of the mid-thoracic spine, spanning from the T8–T9 vertebral levels was appreciated on physical exam as an audible, palpable, and visible dynamic kyphosis; kyphosis was later confirmed on neuroimaging. Based on the CSA severity and sequelae, the patient underwent bilateral decompression laminectomy with lateral extracavitary arthrodesis and posterior instrumentation. Symptoms dramatically improved and at 1-year follow-up, dynamic thoracic kyphosis and most symptoms of autonomic dysreflexia had resolved.

Conclusions:

Based on our case and published reports, vigilant imaging and thorough physical examination in long-standing spinal cord injury could help early diagnosis and treatment of CSA, theoretically preventing development of cord atrophy and subsequent long-term sequelae. Surgical correction rather than bracing may be recommended in patients who have complete injury at or above T6 in patients with symptoms of autonomic dysreflexia associated with CSA confirmed on neuroimaging.

Major destructive asymptomatic lumbar Charcot lesion treated with three column resection and short segment reconstruction. Case report, treatment strategy and review of literature

Charcot's spine is a long-term complication of spinal cord injury. The lesion is often localized at the caudal end of long fusion constructs and distal to the level of paraplegia. However, cases are rare and the literature relevant to the management of Charcot's arthropathy is limited. This paper reviews the clinical features, diagnosis, and surgical management of post-traumatic spinal neuroarthropathy in the current literature. We present a rare case of adjacent level Charcot's lesion of the lumbar spine in a paraplegic patient, primarily treated for traumatic spinal cord lesion 39 years before current surgery. We have performed end-to-end apposition of bone after 3 column resection of the lesion, 3D correction of the deformity, and posterior instrumentation using a four-rod construct. Although the natural course of the disease remains unclear, surgery is always favorable and remains the primary treatment modality. Posterior long-segment spinal fusion with a four-rod construct is the mainstay of treatment to prevent further morbidity. Our technique eliminated the need for more extensive anterior surgery while preserving distal motion

Rheumatoid arthritis-associated spinal neuroarthropathy with double-level isthmic spondylolisthesis

INTRODUCTION

To the best of our knowledge, there has been no report regarding rheumatoid arthritis associated with spinal neuroarthropathy and combined double-level isthmic spondylolisthesis. Here, we report a rare case of spinal neuroarthropathy with double-level isthmic spondylolisthesis in a rheumatoid arthritis (RA) patient. A 56-year-old female patient under medical treatment for RA during the last 13 years presented aggravating radiating pain to her right lower extremity and a limping gait developed 4 months ago. The disease activity of RA had remained low for a long time. Serial radiographs during last 8-year follow-up showed progressive dislocation at L4-L5 and L5-S1 with double-level isthmic spondylolisthesis and severe destructive status at the last follow-up. The patient underwent decompression and circumferential fusion with sacropelvic fixation and acceptable reduction was obtained.

CONCLUSION

A RA patient with double-level isthmic spondylolisthesis showed a progressive destructive lesion. In addition to clinical presentations, the imaging findings were very similar to ones of spinal neuroarthropathy. The authors conclude that this Grand Round case probably had SNA secondary to RA and that this, combined with two-level isthmic spondylolisthesis, resulted in her rapidly progressing destructive lumbar lesion.

Can the pattern of vertebral marrow oedema differentiate intervertebral disc infection from degenerative changes?

AIM

To evaluate whether various patterns of bone marrow oedema could be used to discriminate between infection and degenerative change.

MATERIALS AND METHODS

Seventy patients with imaging features suspicious for discitis and available clinical follow-up were blindly reviewed for vertebral marrow oedema on sagittal short-tau inversion recovery (STIR) images according to the following patterns: I, vertebra oedema is adjacent to the intervertebral space and sharply-marginated; II, vertebral oedema is adjacent to the intervertebral space but not sharply marginated from normal marrow or involves the entire vertebral body; and III, vertebral oedema is distant from the endplate with intervening hypointense marrow signal.

RESULTS

Of 45 patients with a clinical diagnosis of discitis, pattern II was the most common oedema pattern (64%). Approximately 20% and 9% of discitis patients showed patterns I and III, respectively. In patients with degenerative changes, 44% patients showed pattern I, 32% showed pattern II, and 24% showed pattern III. Pattern II had a sensitivity, specificity, and positive predictive value of 0.64, 0.68, and 0.78 for diagnosing spine infection, respectively.

CONCLUSIONS

Although bone marrow oedema in infective discitis most often extends from the disc space and has indistinct margins, the oedema may also have sharp margins or be remote from the involved intervertebral space. Bone marrow oedema patterns of infective discitis overlap with those of degenerative disease and are not sufficiently reliable to exclude infection in cases with magnetic resonance imaging findings suggestive of discitis.

Case 234: Neuropathic Spondyloarthropathy

History A 70-year-old woman presented to a peripheral hospital with signs and symptoms of acute chronic obstructive pulmonary disease (COPD) exacerbation. The patient also reported acute on chronic onset of thoracolumbar back pain over a period of 24 hours. She denied any history of recent trauma or intravenous drug use. She did not have any long-term indwelling catheters. The patient's medical history was also complicated by stage 4 renal failure from long-standing type II diabetes, hypertension, iron deficiency anemia, aortic stenosis, and prior bariatric surgery. The patient was not undergoing dialysis for her renal dysfunction, nor was she receiving steroids for COPD. On clinical examination, she was afebrile and tachypneic. Although she was not amenable to a full neurologic examination, she reported subjective leg weakness. There were no localizing signs or evidence of myelopathy. Perianal sensation and rectal tone were preserved. Pulmonary examination revealed wheezes and decreased basilar air entry. The patient's white blood cell count was 6.8 × 10(9)/L. Her blood chemistry was normal, aside from an elevated blood creatinine level of 158 mmol/L. Her erythrocyte sedimentation rate was elevated at 56 mm/h, and her C-reactive protein level was normal at 4.4 mg/L (41.9 nmol/L). Chest radiographs showed mild pulmonary edema with a small right pleural effusion. The patient was transferred to our facility for evaluation of findings on thoracic spine radiographs obtained at a peripheral hospital. Unenhanced thoracic spine magnetic resonance (MR) imaging was performed first and was followed by computed tomography (CT) to further delineate the findings. The patient's renal status precluded intravenous contrast material administration.

Pyogenic spinal infections

Spinal infections are a spectrum of disease comprising spondylitis, diskitis, spondylodiskitis, pyogenic facet arthropathy, epidural infections, meningitis, polyradiculopathy, and myelitis. Inflammation can be caused by pyogenic, granulomatous, autoimmune, idiopathic, and iatrogenic conditions. In an era of immune suppression, tuberculosis, and HIV epidemic, together with worldwide socioeconomic fluctuations, spinal infections are increasing. Despite advanced diagnostic technology, diagnosis of this entity and differentiation from degenerative disease, noninfective inflammatory lesions, and spinal neoplasms are difficult. Radiological evaluations play an important role, with contrast-enhanced MR imaging the modality of choice in diagnosis, evaluation, treatment planning, interventional treatment, and treatment monitoring of spinal infections.

Charcot arthropathy of the spine in spinal cord injured individuals with sacral deafferentation and anterior root stimulator implantation

AIMS

To investigate the occurrence of Charcot spinal arthropathy (CSA) after sacral deafferentation (SDAF) and sacral anterior root stimulation (SARS) of the bladder in patients suffering from neurogenic lower urinary tract dysfunction (NLUTD) as a result of spinal cord injury (SCI).

METHODS

Retrospective evaluation of patients who had undergone SDAF/SARS at a single SCI rehabilitation centre. The occurrence rate of stimulation dysfunction was determined, and the medical records and radiological images of the included patients were examined for CSA. The diagnosis of CSA was based on radiological criteria. The occurrence rate of CSA was estimated for all SARS patients and for those with SARS dysfunction, and the odds ratios (OR) for the occurrence of CSA were calculated.

RESULTS

In 11/130 SARS patients (8%), CSA was observed a median 8 years (95% CI 5-16 years) after SDAF/SARS or a median 21 years (95% CI 9-41 years) after SCI had occurred. The median follow-up time was 14 years (range 6-25 years). The proportion of patients with CSA was significantly (P = 0.036) greater in patients with SARS dysfunction (7/41) than in patients without SARS dysfunction (4/89). The odds of CSA were four times greater (OR 4.3, 95% CI 1.0-21.5) in patients with SARS dysfunction compared to those without. Furthermore, the odds of CSA were 20 times greater (OR 20.2, 95% CI 8.4-47.0) in patients with SARS compared to those without.

CONCLUSIONS

Charcot spinal arthropathy should be considered a potential long-term complication of SDAF/SARS, and spinal instability is a possible reason for SARS dysfunction.

Do all Charcot Spine require surgery?

INTRODUCTION

Spinal neuroarthropathy (SNA), also called "Charcot spine", is very uncommon disease of unknown etiology. Kronig first reported this pathology in 1884 on a patient with Tabes dorsalis (also known as syphilitic myelopathy). As syphilis tends to disappear in developed countries, spinal cord lesion is the most frequent etiology of SNA.

OBJECTIVES

To describe clinical and radiographic results in 12 patients suffering from spinal neuroarthropathy (SNA).

METHODS

Twelve patients diagnosed with SNA were included in the study. All patients were wheelchair users. The average delay between the neurological disease and the diagnosis of SNA was 18 years. All patients were initially treated conservatively. Surgery was only indicated in persistent symptomatic or instable cases, and for infected SNA. Surgery was a circumferential arthrodesis.

RESULTS

From 12 patients, with a median follow-up of 4 years, five patients were operated on and 7 patients were still conservatively treated. Two patients with back pain and evolutive destruction were declined for surgery. One suffered of bilateral hip ankylosis and extensive spinal surgery would have confined him to bed, and one due to an evolutive bedsore. One patient improved with a complete regression of back pain.

CONCLUSION

Nowadays, surgical treatment is recommended with an extensive and circumferential fusion, in order to prevent relapses. Good radiographic outcome is reported but functional results have not been studied. Natural evolution of SNA remains unknown but can be less disabling than surgery. This pathologic mobility can contribute to patient's autonomy and can therefore be considered as opportune. Conservative therapy can be considered for SNA.

LEVEL OF EVIDENCE

Level IV.

Pyogenic and non-pyogenic spinal infections: emphasis on diffusion-weighted imaging for the detection of abscesses and pus collections

The incidence of spinal infections has increased in the past two decades, owing to the increasing number of elderly patients, immunocompromised conditions, spinal surgery and instrumentation, vascular access and intravenous drug use. Conventional MRI is the gold standard for diagnostic imaging; however, there are still a significant number of misdiagnosed cases. Diffusion-weighted imaging (DWI) with a b-value of 1000 and apparent diffusion coefficient (ADC) maps provide early and accurate detection of abscess and pus collection. Pyogenic infections are classified into four types of extension based on MRI and DWI findings: (1) epidural/paraspinal abscess with spondylodiscitis, (2) epidural/paraspinal abscess with facet joint infection, (3) epidural/paraspinal abscess without concomitant spondylodiscitis or facet joint infection and (4) intradural abscess (subdural abscess, purulent meningitis and spinal cord abscess). DWI easily detects abscesses and demonstrates the extension, multiplicity and remote disseminated infection. DWI is often a key image in the differential diagnosis. Important differential diagnoses include epidural, subdural or subarachnoid haemorrhage, cerebrospinal fluid leak, disc herniation, synovial cyst, granulation tissue, intra- or extradural tumour and post-surgical fluid collections. DWI and the ADC values are affected by susceptibility artefacts, incomplete fat suppression and volume-averaging artefacts. Recognition of artefacts is essential when interpreting DWI of spinal and paraspinal infections. DWI is not only useful for the diagnosis but also for the treatment planning of pyogenic and non-pyogenic spinal infections.

Characteristics and surgical management of neuropathic (Charcot) spinal arthropathy after spinal cord injury

BACKGROUND CONTEXT

Neuropathic (Charcot) spinal arthropathy (CSA) is a rare but progressive and severe degenerative disease that develops in the absence of deep sensation, for example, after spinal cord injury. The diagnosis of CSA is often delayed as a result of the late onset or slow progression of the disease and the nonspecific nature of the reported clinical signs. Considering risk factors of CSA in combination with the common clinical signs may facilitate timely diagnosis and prevent severe presentation of the disease. However, there is a lack of data concerning the early signs and risk factors of CSA. Furthermore, the complications and outcomes after surgical treatment are documented insufficiently.

PURPOSE

To investigate the early signs and risk factors of CSA after spinal cord injury, as well as the complications and outcome after surgical treatment.

STUDY DESIGN

Retrospective case series from a single center.

PATIENT SAMPLE

Twenty-eight patients with 39 Charcot joints of the spine.

OUTCOME MEASURES

Clinical signs, radiological signs, risk factors, and complications.

METHODS

The case histories and radiological images of patients suffering from CSA were investigated.

RESULTS

The first clinical symptoms included spinal deformity, sitting imbalance, and localized back pain. Long-segment stabilization, laminectomy, scoliosis, and excessive loading of the spine were identified as risk factors for the development of the disease. Postoperative complications included implant loosening, wound healing disturbance, and development of additional Charcot joints. All patients were able to return to their previous levels of activities.

CONCLUSIONS

Radiological follow-up of the entire thoracic and lumbar spine should be performed in paraplegic patients. Risk factors in combination with typical symptoms should be considered to facilitate early detection. Functional restoration can be achieved with appropriate surgical techniques.

Charcot spine treated using a single staged posterolateral costotransversectomy approach in a patient with traumatic spinal cord injury

Charcot spine is a progressive and destructive process that affects the vertebral bodies, intervertebral discs, and posterior facets. It is the result from repetitive microtrauma in patients who have decreased joint protective mechanisms due to loss of deep pain and proprioceptive sensation, typically because of spinal cord injury. The objective of the study is to report an unusual case of Charcot spine, as a late complication of traumatic spinal cord injury, treated by a circumferential arthrodesis performed with a single staged posterolateral costotransversectomy approach.

[Radiological diagnostics of inflammatory spinal diseases: what is the state of the art?]

Back pain is nonspecific and allows a broad range of differential diagnoses. In the early phase of infectious or neoplastic processes conventional diagnostic radiology rarely shows groundbreaking findings. Magnetic resonance imaging (MRI) is the method of choice to detect early changes in the vertebral bodies, intervertebral discs and surrounding tissues. Fluid-sensitive, fat-suppressed sequences (STIR) and contrast media are used to distinguish infections from other diseases. Due to the typical signal intensity in T1 and T2 sequences, infections of degenerative, rheumatic, and neoplastic processes can be defined and allow the initiation of appropriate therapy.

Imaging of spine infection

This article reviews the imaging and relevant clinical details of infection of the extradural spine. Spine infections are increasing in incidence and in frequency of diagnosis. They are clinically important despite their relative rarity, because they may be life-threatening, and because early diagnosis leads to improved outcomes. The focus is on pyogenic spondylodiscitis. The also typically pyogenic conditions of epidural and subdural abscess, facet joint infection, and pyomyositis are discussed. Nonpyogenic, granulomatous infections are also addressed. Magnetic resonance imaging is emphasized. The radiologist's role in performing minimally invasive sampling procedures is highlighted.

Treatment of infections of the spine

Spinal infection may involve the vertebrae, the intervertebral discs, and the adjacent intraspinal and paraspinal soft tissues. It often starts with subtle and insidious clinical signs and symptoms and may development to a debilitating and even life threatening disease. Spinal infections occur with increasing incidence and are nowadays a disease of everyday's practice for physicians treating spinal disorders. Traditionally, conservative treatment consisting of antibiosis and immobilisation is considered the first tier therapy. However, due to a considerably high rate of vertebral column instability or neurological impairment caused by the infected tissue, comprehensive experience with surgical measures have been acquired over the last decades. Thanks to tremendous improvements of surgical implants and techniques, surgical treatment has already begun to challenge conservative treatment to eventually become the first tier therapy for spinal infections in the future. This review seeks to give an overview of epidemiology, pathogenesis, diagnostic evaluation, and current nonsurgical and surgical therapy of spinal infections on the basis of the existing literature, which consists largely of retrospectively acquired data of single-centre experience with sample sizes of less than 100 patients treated with individually defined indications and treatment algorithms, and followed with various outcome parameters.

MR imaging assessment of the spine: infection or an imitation?

Magnetic resonance (MR) imaging is a powerful diagnostic tool that can be used to help evaluate spinal infection and to help distinguish between an infection and other clinical conditions. In most cases of spinal infection, MR images show typical findings such as vertebral endplate destruction, bone marrow and disk signal abnormalities, and paravertebral or epidural abscesses. However, it is not always easy to diagnose a spinal infection, particularly when some of the classic MR imaging features are absent or when there are unusual patterns of infectious spondylitis. Furthermore, noninfectious inflammatory diseases and degenerative disease may simulate spinal infection. It is necessary to be familiar with atypical MR imaging findings of spinal infection and features that may mimic spinal infection to avoid misdiagnosis and inappropriate treatment.

Vertebral endplate signal changes (Modic change): a systematic literature review of prevalence and association with non-specific low back pain

The prevalence of "vertebral endplate signal changes" (VESC) and its association with low back pain (LBP) varies greatly between studies. This wide range in reported prevalence rates and associations with LBP could be explained by differences in the definitions of VESC, LBP, or study sample. The objectives of this systematic critical review were to investigate the current literature in relation to the prevalence of VESC (including Modic changes) and the association with non-specific low back pain (LBP). The MEDLINE, EMBASE, and SveMED databases were searched for the period 1984 to November 2007. Included were the articles that reported the prevalence of VESC in non-LBP, general, working, and clinical populations. Included were also articles that investigated the association between VESC and LBP. Articles on specific LBP conditions were excluded. A checklist including items related to the research questions and overall quality of the articles was used for data collection and quality assessment. The reported prevalence rates were studied in relation to mean age, gender, study sample, year of publication, country of study, and quality score. To estimate the association between VESC and LBP, 2 x 2 tables were created to calculate the exact odds ratio (OR) with 95% confidence intervals. Eighty-two study samples from 77 original articles were identified and included in the analysis. The median of the reported prevalence rates for any type of VESC was 43% in patients with non-specific LBP and/or sciatica and 6% in non-clinical populations. The prevalence was positively associated with age and was negatively associated with the overall quality of the studies. A positive association between VESC and non-specific LBP was found in seven of ten studies from the general, working, and clinical populations with ORs from 2.0 to 19.9. This systematic review shows that VESC is a common MRI-finding in patients with non-specific LBP and is associated with pain. However, it should be noted that VESC may be present in individuals without LBP.

Scintigraphic imaging of vertebral osteomyelitis with 111in-biotin

STUDY DESIGN

Early diagnosis of vertebral infection (hematogenous or postsurgical) is necessary to choose a correct therapy and to minimize dramatic complications. All patients suspected to have vertebral infection underwent radiologic imaging and In-Biotin scintigraphy.

OBJECTIVE

Biotin is a growth factor used by many bacteria. The aim of our study is to use In-Biotin to diagnose vertebral infections.

SUMMARY OF BACKGROUND DATA

Magnetic resonance imaging, even if endowed with fairly good sensitivity and specificity, shows some limitations in the study of the onset of pathology and in postsurgical conditions. Conventional scintigraphic imaging, like bone scintigraphy with Tc-MDP, Ga-citrate scintigraphy, or Positron Emission Tomography with [F]FDG, are limited by relatively low specificity; the use of Streptavidin/In-Biotin scintigraphy, based on aspecific uptake of tracer in the site of infection, shows good results in term of sensibility and specificity but the use of heterologous protein might engender immunogenic reactions.

METHODS

All patients (pts) (n = 110) of the study underwent In-biotin scintigraphy 2 hours after intravenous injection of the tracer, 71 pts were suspected to have hematogenous vertebral infection (Group I) and 39 pts were suspected to have postsurgical infection (Group II). The reference for final diagnosis was either bacterial cultures, histopathologic analysis, and/or clinical/imaging follow-up for at least 1 year.

RESULTS

In-biotin scintigraphy showed a sensitivity of 84% and specificity of 98% in Group I and a sensitivity of 100% and specificity of 84% in Group II.

CONCLUSION

Our results showed that In-Biotin scintigraphy possess high diagnostic accuracy. This technique is easy to perform and requires short imaging time-point after intravenous tracer injection. Moreover if In-Biotin uptake is due only to high proliferation rate of bacteria presents in site of infection, it will be further investigated to discriminate definitely bacterial from sterile inflammation.

Charcot spine

Identification of a destructive spinal process in the acute setting most commonly is related to infection or neoplasm. In the appropriate clinical setting, Charcot spine, also known as neuropathic spinal arthropathy or spinal neuroarthropathy, should be considered. We present a case of spinal destruction due to spinal neuroarthropathy in a 51-year-old man who had been paraplegic for 13 years, and review the characteristic and potentially differentiating imaging findings of this uncommon process.

Nuclear medicine imaging of bone infections

The inflammation and infection of bone include a wide range of processes that can result in a reduction of function or in the complete inability of patients. Apart from the inflammation, infection is sustained by pyogenic microorganisms and results mostly in massive destruction of bones and joints. The treatment of osteomyelitis requires long and expensive medical therapies and, sometimes, surgical resection for debridement of necrotic bone or to consolidate or substitute the compromised bones and joints. Radiographs and bone cultures are the mainstays for the diagnosis but often are useless in the diagnosis of activity or relapse of infection in the lengthy management of these patients. Imaging with radiopharmaceuticals, computed tomography and magnetic resonance are also used to study secondary and chronic infections and their diffusion to soft or deep tissues. The diagnosis is quite easy in acute osteomyelitis of long bones when the structure of bone is still intact. But most cases of osteomyelitis are subacute or chronic at the onset or become chronic during their evolution because of the frequent resistance to antibiotics. In chronic osteomyelitis the structure of bones is altered by fractures, surgical interventions and as a result of bone reabsorption produced by the infection. Metallic implants and prostheses produce artefacts both in computed tomography and magnetic resonance images, and radionuclide studies should be essential in these cases. Vertebral osteomyelitis is a specific entity that can be correctly diagnosed by computed tomography or magnetic resonance imaging at the onset of symptoms but only with radionuclide imaging is it possible to assess the activity of the disease after surgical stabilization or medical therapy. The lack of comparative studies showing the accuracy of each radiopharmaceutical for the study of bone infection does not allow the best nuclear medicine techniques to be chosen in an evidence-based manner. To this end we performed a meta-analysis of peer reviewed articles published between 1984 and 2004 describing the use of nuclear medicine imaging for the study of the most frequent causes of bone infections, including prosthetic joint, peripheric post-traumatic bone infections, vertebral and sternal infections. Guidelines for the choice of the optimal radiopharmaceuticals to be used in each clinical condition and for different aims is provided.

Imaging of infectious spinal disorders in children and adults

The aim of this review article is to outline the imaging of infectious disorders of the spine in adults and children. The clinical presentation, potential routes of infection and the pathogens commonly identified are discussed. The value of different imaging modalities in the diagnosis of spinal infection is presented including radiographic, CT, MR imaging and Nuclear Medicine including PET. The use of image guided techniques for diagnosis and subsequent treatment is briefly covered. The major differential diagnoses of infectious disorders of the spine are identified and contrasted with the typical findings in infection. The use of follow up imaging is evaluated.

Infectious spondylitis

Infection of the spine is a rare but serious cause of back pain. Conventional radiographs remain the initial screening procedure. Typically two adjacent vertebral bodies and the intervening disk space are affected. Early in the course of the disease, radiographs may be normal or nondiagnostic. Magnetic resonance imaging or radionuclide bone scan will establish pathology centered in the vertebral body. Because of the ability to image soft tissues, magnetic resonance imaging is particularly helpful in detecting paravertebral and extradural abscesses. Four other conditions may mimic infectious spondylitis: degenerative disk disease associated with Modic type 1 changes, pseudoarthrosis in ankylosing spondylitis, dialysis spondyloarthropathy, and neuropathic spondyloarthropathy. Advanced imaging studies in combination with radiographs and clinical information are essential in determining the correct diagnosis.

Charcot's disease of the spine: diagnosis and treatment

STUDY DESIGN

Retrospective study.

OBJECTIVE

To report nine cases of Charcot's joint of the spine, to clarify the difficulty in diagnosis and treatment, and to analyze the literature.

SUMMARY OF BACKGROUND

Charcot's joint of the spine, also known as spinal neuropathic or neurogenic arthropathy, is a destructive condition that affects the intervertebral disc and the adjacent vertebral bodies. It is the result of a loss of joint protection mechanisms, generally secondary to a spinal cord lesion. We report a series of nine patients treated surgically.

METHODS

Eight men and one woman suffering from paraplegia or tetraplegia were reviewed. The time interval between the neurologic disorder and the diagnosis of neuropathic spinal arthropathy was 10 to 36 years. The most frequent presenting symptom was an evolutive thoracolumbar kyphosis, sometimes associated with back pain or increased spasticity in the lower limbs. The neuropathic arthropathy involved the thoracic spine in four patients and the lumbar spine in four other patients. The remaining patient presented two arthropathies, one thoracic and one lumbosacral. A percutaneous vertebral biopsy was performed in five patients suspected to have an infection or a tumor. Treatment was always surgical. In eight cases, a circumferential fusion was performed in the area of the dislocated vertebral levels. The postoperative follow-up was from 3 years to 10 years.

RESULTS

A solid and stable circumferential fusion of the spine was obtained in all patients. The functional status improved in all patients. Pain and sagittal imbalance were successfully treated. The increased spasticity observed at the initial examination improved in all patients who returned to the neurological deficit initially present before the onset of Charcot's arthropathy.

CONCLUSIONS

The diagnosis of Charcot's arthropathy of the spine must be considered in paraplegic and tetraplegic patients with spinal deformity with bone destruction and vertebral dislocation in the absence of an infection or neoplastic disease. The treatment of a Charcot's spine is circumferential fusion and osteosynthesis. Monitoring by clinical and imaging examination must be continued, because multifocal vertebral lesions can occur in cases of extensive proprioceptive deficit.

Clinical feasibility of two-step streptavidin/111In-biotin scintigraphy in patients with suspected vertebral osteomyelitis

PURPOSE

Streptavidin accumulates at sites of inflammation and infection as a result of increased capillary permeability. In addition to being utilised by bacteria for their own growth, biotin forms a stable, high-affinity non-covalent complex with avidin. The objective of this investigation was to determine the diagnostic performance of two-step streptavidin/111In-biotin imaging for evaluating patients with suspected vertebral osteomyelitis.

METHODS

We evaluated 55 consecutive patients with suspected vertebral osteomyelitis (34 women and 21 men aged 27-86 years), within 2 weeks after the onset of clinical symptoms. Thirty-two of the patients underwent magnetic resonance imaging (MRI) and 24, computed tomography (CT). DTPA-conjugated biotin was radiolabelled by incubating 500 microg of DTPA-biotin with 111 MBq of 111In-chloride. Two-step scintigraphy was performed by first infusing 3 mg streptavidin intravenously, followed 4 h later by 111In-biotin. Imaging was begun 60 min later.

RESULTS

Streptavidin/111In-biotin scintigraphy was positive in 32/34 patients with spinal infection (94.12% sensitivity). The study was negative in 19/21 patients without infection (95.24% specificity). The corresponding results for MRI and CT were 54.17% and 35.29% (sensitivity), and 75% and 57.14% (specificity), respectively. All statistical parameters of diagnostic performance (Youden's J index, kappa measure of agreement with correct classification, accuracy, sensitivity, specificity, positive likelihood and negative likelihood) were clearly better for streptavidin/111In-biotin scintigraphy than for either MRI or CT.

CONCLUSION

Streptavidin/111In-biotin scintigraphy is highly sensitive and specific for detecting vertebral osteomyelitis in the first 2 weeks after the onset of clinical symptoms, and is potentially very useful for guiding clinical decisions on instituting appropriate therapy.

Forefoot pain involving the metatarsal region: differential diagnosis with MR imaging

Many disorders produce discomfort in the metatarsal region of the forefoot. These disorders include traumatic lesions of the soft tissues and bones (eg, turf toe, plantar plate disruption, sesamoiditis, stress fracture, stress response), Freiberg infraction, infection, arthritis, tendon disorders (eg, tendinosis, tenosynovitis, tendon rupture), nonneoplastic soft-tissue masses (eg, ganglia, bursitis, granuloma, Morton neuroma), and, less frequently, soft-tissue and bone neoplasms. Prior to the advent of magnetic resonance (MR) imaging, many of these disorders were not diagnosed noninvasively, and radiologic involvement in the evaluation of affected patients was limited. However, MR imaging has proved useful in detecting the numerous soft-tissue and early bone and joint processes that occur in this portion of the foot but are not depicted or as well characterized with other imaging modalities. Frequently, MR imaging allows a specific diagnosis based on the location, signal intensity characteristics, and morphologic features of the abnormality. Consequently, MR imaging is increasingly being used to evaluate patients with forefoot complaints. Radiologists should be familiar with the differential diagnosis and MR imaging features of disorders that can produce discomfort in this region.