坐骨神经切割伤MR神经成像一例

患者男,21岁.左侧大腿后上部被刺伤,左下肢麻木、运动障碍.次日上午在外院行显微手术,术中见股二头肌断裂,坐骨神经干大部分横断,分别行神经干和股二头肌吻合术.2007年5月8日,术后41 d,因"垂足和下肢时有放射性疼痛"来我院骨科就医.     

MR neurography findings of soleal sling entrapment

OBJECTIVE: The ever-increasing use of higher field strength (3 T) scanners and novel pulse sequences with improved spatial resolution and signal-to-noise ratio have rendered MR neurography (MRN) a valuable technique in the assessment of peripheral neuropathies. The aim of this study is to illustrate the imaging findings of high-resolution MRN in patients who suffer from tibial nerve entrapment due to a soleal fibromuscular sling and to correlate the imaging findings with intraoperative and clinical examination results. CONCLUSION: This article depicts the surgically confirmed imaging findings of high-resolution MRN in tibial nerve entrapment by the soleal sling.     

Peripheral nerve surgery: the role of high-resolution MR neurography

High-resolution MRN is becoming increasingly available due to recent technical advancements, including higher magnetic field strengths (eg, 3T), 3D image acquisition, evolution of novel fat-suppression methods, and improved coil design. This review describes the MRN techniques for obtaining high-quality images of the peripheral nerves and their small branches and imaging findings in normal as well as injured nerves with relevant intraoperative correlations. Various microsurgical techniques in peripheral nerves, such as neurolysis, nerve repairs by using nerve grafts, and conduits are discussed, and MRN findings of surgically treated nerves are demonstrated.     

High-resolution MR neurography of diffuse peripheral nerve lesions

High-resolution MR imaging of peripheral nerves is becoming more common and practical with the increasing availability of 3T magnets. There are multiple reports of MR imaging of peripheral nerves in compression and entrapment neuropathies. However, there is a relative paucity of literature on MRN appearance of diffuse peripheral nerve lesions. We attempted to highlight the salient imaging features of myriad diffuse peripheral nerve disorders and imaging techniques for MRN. Using clinical and pathologically proved relevant examples, we present the MRN appearance of various types of diffuse peripheral nerve lesions, such as traumatic, inflammatory, infectious, hereditary, radiation-induced, neoplastic, and tumor variants.     

Pelvic hydatid disease: CT and MRI findings causing sciatica.

Pelvic masses, especially hydatid disease, rarely present with sciatica (1, 2). We present the computed tomography (CT) and the magnetic resonance imaging (MRI) findings of a 49-year-old female patient with presacral hydatid disease, who was evaluated for her sciatica. We also want to emphasize the importance of assessing the pelvis of patients with symptoms and clinical findings that are inconsistent and that cannot be satisfactorily explained by the spinal imaging findings.     

MR imaging evaluation of suprascapular nerve entrapment

The aim of this study was to assess the significance of muscular edema, atrophy, and fatty changes in the diagnosis of suprascapular nerve entrapment (SSNE), and to confirm muscular edema as the most significant sign of neuropathy. A retrospective study of 18 patients with suprascapular nerve entrapment was performed. All patients underwent electromyographic studies and MR imaging with a 1.5-T Echo Speed system (General Electric, Milwaukee, Wis.). The diagnosis of muscle edema was reached when muscles presented a high signal on T2-weighted fast spin-echo (SE) fat-suppressed images. Muscular trophicity and fatty changes were analyzed on a sagittal oblique cut using SE T1-weighted images. Intra- and inter-observer reproducibility using kappa test, sensitivity, and specificity were analyzed, together with negative and positive predictive value of each criterion. The topographic diagnosis was correct as edema affected the infraspinatus muscle alone when the suprascapular nerve was entrapped at the spinoglenoid notch. Both the supraspinatus and infraspinatus muscles were affected when nerve was compressed at the suprascapular notch. Sensitivity and specificity of muscular edema were, respectively, 94.5 and 100%. Muscular atrophy sensitivity and specificity were 81 and 80%, respectively. Fatty changes sensitivity and specificity were 25 and 96%, respectively. Muscular edema seems to be a more sensitive sign of SSNE than muscle atrophy and fatty changes when compared with EMG results. Magnetic resonance imaging can reach a positive, topographic, and etiologic diagnosis of SSNE.     

Suprascapular nerve entrapment: evaluation with MR imaging.

Entrapment of the suprascapular nerve is frequently overlooked in the differential diagnosis of shoulder pain. The diagnosis is typically not considered until patients develop severe weakness secondary to atrophy of the spinatus (spinous) musculature that the nerve supplies. Twenty-seven masses were identified adjacent to the suprascapular nerve on magnetic resonance (MR) images of the shoulder; there were 21 ganglion cysts, two synovial sarcomas, one Ewing sarcoma, one chondrosarcoma, one metastatic renal cell carcinoma, and one hematoma associated with a fracture. Atrophy of both the supraspinatus and infraspinatus muscles was seen in association with anteriorly located masses and proximal entrapment of the nerve in 11 cases (40%); isolated atrophy of the infraspinatus muscle was seen in association with posteriorly located masses and distal entrapment of the nerve in nine cases (33%). MR imaging may facilitate the diagnosis of suprascapular nerve entrapment in patients with shoulder pain of unclear origin when perineural masses and atrophy of the spinatus musculature are present.     

Lipomatosis of the sciatic nerve: typical and atypical MRI features

Lipomatosis of nerve, also known as fibrolipomatous hamartoma, is a rare condition of nerve, usually affecting the median nerve. The MRI appearance is characteristic. We describe two cases of lipomatosis of nerve involving the sciatic nerve, an extremely unusual location for this lesion, in patients with sciatic neuropathy. These cases share the typical features previously described in the literature for other nerves, but also contain atypical features not previously highlighted, relating to the variability in distribution and extent of the fatty deposition. Recognition of the MRI appearance of this entity is important in order to avoid unnecessary attempts at surgical resection of this lesion.     

Review of the principal extra spinal pathologies causing sciatica and new MRI approaches

In this paper we illustrate the principal extraspinal pathologies causing sciatica and new approaches for the study of structures such as the lumbosacral plexus (LSP). Visualisation of the LSP in its entirety is difficult with conventional two-dimensional MRI sequences owing to its oblique orientation. In our institution, we have found that the utilisation of three-dimensional short tau inversion-recovery sampling perfection with application-optimised contrasts using different flip angle evolutions sequence is helpful, allowing multiplanar and maximum intensity projection reconstructions in the coronal oblique plane and curvilinear reformats through the plexus. Diffusion tensor imaging enables the observation of microstructural changes and can be useful in surgical planning. The normal anatomy of the LSP, its different extraspinal pathologies and differential diagnoses are thoroughly presented.     

MR properties of rat sciatic nerve following trauma.

T(1) and T(2) relaxation times, magnetization transfer (MT), and diffusion anisotropy of rat sciatic nerve were measured at different time intervals following trauma. The nerve injury was induced by either cutting (irreversible nerve degeneration) or crushing (degeneration followed by regeneration). The MR properties were measured for proximal and distal portions of the injured nerve. The portions of the nerve proximal to the induced injury exhibited MR characteristics similar to those of normal nerves, whereas the distal portions showed significant differences in all MR parameters. These differences diminished in the regenerating nerves within approximately 4 weeks post injury. In the case of irreversible nerve damage, the differences in the distal nerves were slightly larger and did not resolve even 6 weeks after induced trauma. The MR measurements were correlated with histopathology exams. Observed changes in tissue microstructure, such as demyelination, inflammation, and axonal loss, can result in a significant increase in the average T(1) and T(2) relaxation times, reduction in the MT effect, and decrease in diffusion anisotropy. MR parameters, therefore, are very good indicators of nerve damage and may be useful in monitoring therapies that assist nerve regeneration. Magn Reson Med 45:415-420, 2001.     

MR neurography with multiplanar reconstruction of 3D MRI datasets: an anatomical study and clinical applications

Introduction Extracranial MR neurography has so far mainly been used with 2D datasets. We investigated the use of 3D datasets for peripheral neurography of the sciatic nerve. Methods A total of 40 thighs (20 healthy volunteers) were examined with a coronally oriented magnetization-prepared rapid acquisition gradient echo sequence with isotropic voxels of 1 × 1 × 1 mm and a field of view of 500 mm. Anatomical landmarks were palpated and marked with MRI markers. After MR scanning, the sciatic nerve was identified by two readers independently in the resulting 3D dataset. Results In every volunteer, the sciatic nerve could be identified bilaterally over the whole length of the thigh, even in areas of close contact to isointense muscles. The landmark of the greater trochanter was falsely palpated by 2.2 cm, and the knee joint by 1 cm. The mean distance between the bifurcation of the sciatic nerve and the knee-joint gap was 6 cm (±1.8 cm). The mean results of the two readers differed by 1–6%. Conclusion With the described method of MR neurography, the sciatic nerve was depicted reliably and objectively in great anatomical detail over the whole length of the thigh. Important anatomical information can be obtained. The clinical applications of MR neurography for the brachial plexus and lumbosacral plexus/sciatic nerve are discussed. The experiments were conducted in accordance with German regulations and laws and after a positive decision of our local ethics committee.     

采用MR扩散张量成像评估正中神经:正常和病理扩散值

摘要目的确定正中神经在不同年龄段健康男性和女性不同解剖部位的正常扩散值,并与腕管综合征病人比较。材料与方法本研究经伦理审查委员会批准并均签署知情同意书,共包括健康志愿者45例(女30例,男15例)和病人15例(女10例,男5例),     

MRI demonstration of intra-articular median nerve entrapment after elbow dislocation

We report a case of median nerve entrapment in the elbow joint diagnosed with MRI 14 months after closed reduction of a dislocated elbow joint.     

MR neurography: past, present, and future

OBJECTIVE: MR neurography (MRN) has increasingly been used in clinical practice for the evaluation of peripheral nerve disease. This article reviews the historic perspective of MRN, the current imaging trends of this modality, and the future directions and applications that have shown potential for improved imaging and diagnostic capabilities. CONCLUSION: MRN has come a long way in the past 2 decades. Excellent depiction of 3D nerve anatomy and pathology is currently possible. Further technical developments in diffusion-based nerve and muscle imaging, whole-body MRN, and nerve-specific MR contrast agents will likely play a major role in advancing this novel field and understanding peripheral neuromuscular diseases in the years to come.     

Diagnostic accuracy of clinical tests for sciatic nerve entrapment in the gluteal region

Purpose

The purpose of this study was to determine the diagnostic accuracy of the straight leg raise (SLR), active piriformis, and seated piriformis stretch tests in identifying individuals with sciatic nerve entrapment.

Methods

Thirty-three individuals (female = 25 and male = 8) with a mean age of 43 years (range 15–64; SD ± 11 years) were included in the study. Twenty-three subjects had endoscopic findings of sciatic nerve entrapment. Ten subjects without entrapment during endoscopic assessment were used as a control group. The results of the SLR, active piriformis, and seated piriformis stretch tests were retrospectively reviewed for each subject and compared between both groups. The accuracy of these tests for the endoscopic finding of sciatic nerve entrapment was determined by calculating the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio.

Results

The SLR had sensitivity of 0.15, specificity of 0.95, positive likelihood ratio of 3.20, negative likelihood ratio of 0.90, and diagnostic odds ratio of 3.59. The active piriformis test had sensitivity of 0.78, specificity of 0.80, positive likelihood ratio of 3.90, negative likelihood ratio of 0.27, and diagnostic odds ratio of 14.40. The seated piriformis stretch test had sensitivity of 0.52, specificity of 0.90, positive likelihood ratio of 5.22, negative likelihood ratio of 0.53, and diagnostic odds ratio of 9.82. The most accurate findings were obtained when the results of the active piriformis test and seated piriformis stretch test were combined, with sensitivity of 0.91, specificity of 0.80, positive likelihood ratio of 4.57, negative likelihood ratio of 0.11, and diagnostic odds ratio of 42.00.

Conclusions

The active piriformis and seated piriformis stretch tests can be used to help identify patients with and without sciatic nerve entrapment in the deep gluteal region.

Level of evidence

II.