Seminars in musculoskeletal radiology
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Semin Musculoskelet Radiol · Nov 2010
ReviewUltrasound and magnetic resonance imaging of the peripheral nerves: current techniques, promising directions, and open issues.
High-resolution ultrasound (US) and magnetic resonance (MR) imaging are the two imaging methods of choice for the study of peripheral nerves. The many advances that have been made in recent years, either by US or MR imaging, including diffusion tensor imaging and tractography, offer new perspectives for the assessment of many pathological processes affecting peripheral nerves such as entrapment syndromes, tumors and tumor-like lesions, and traumatic disorders. ⋯ US and MR imaging are complementary, each having advantages and disadvantages. Tractography is still emerging in the musculoskeletal field, particularly for the analysis of peripheral nerves, but this technique seems promising.
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Semin Musculoskelet Radiol · Nov 2010
ReviewTraumatic neuropathies: spectrum of imaging findings and postoperative assessment.
Traumatic injury to peripheral nerves is a significant cause of morbidity and disability. Until reinnervation occurs, electrodiagnostic studies cannot differentiate severe axonotmetic lesions (Sunderland class 4) from complete nerve transection or neurotmesis (Sunderland class 5). This limitation is relevant clinically because in cases of neurotmesis an improved outcome may be achieved with an early surgical repair (within 1 week after trauma). ⋯ The role of diagnostic imaging in stretching injuries, contusion trauma, penetrating wounds, and after surgery is discussed. A multimodality diagnostic approach including physical examination, electrophysiology, and US and MR imaging allows an accurate evaluation of most peripheral nerves. Imaging assessment of peripheral nerves trauma is useful for the diagnosis, follow-up, and postoperative evaluation.
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The diagnosis of a peripheral nerve tumor can often be suggested on imaging. Direct continuity with a neural structure or location along a typical nerve distribution, shape, and intrinsic magnetic resonance (MR) signal characteristics represent the most important signs in this regard. ⋯ This article reviews the MR imaging appearance, clinical and pathological features of schwannoma, localized neurofibroma, plexiform neurofibroma, intraneural perineurioma, fibrolipomatous hamartoma, nerve sheath ganglion, traumatic neuroma, malignant peripheral nerve sheath tumor, and secondary malignant neoplasms of peripheral nerves. Typical findings are illustrated on the basis of histologically confirmed cases.
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Ultrasound (US) and MR imaging have been shown able to detect in-depth features of brachial plexus anatomy and to localize pathological lesions in disorders where electrophysiology and physical findings are nonspecific or nonlocalizing. High-end gradient technology, phased array coils, and selection of an appropriate protocol of pulse sequences are the main requirements to evaluate the brachial plexus nerves with MR imaging and to distinguish between intrinsic and extrinsic pathological changes. A careful scanning technique based on anatomical landmarks is required to image the brachial plexus nerves with US. ⋯ In the thoracic outlet syndrome, imaging performed in association with postural maneuvers can help diagnose dynamic compressions. MR imaging and US are also effective to recognize neuropathies about the shoulder girdle involving the suprascapular, axillary, long thoracic, and spinal accessory nerves that may mimic brachial plexopathy. In this article, the clinical entities just listed are discussed independently, providing an overview of the current status of knowledge regarding imaging assessment.
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Clinicians frequently encounter compressive neuropathies of the lower extremity. The clinical history and physical examination, along with electrodiagnostic testing and imaging studies, lead to the correct diagnosis. ⋯ We provide a detailed review of compression neuropathies of the lower extremity with an emphasis on magnetic resonance (MR) imaging characteristics. We discuss the clinical presentation, etiology, anatomical location, and MR imaging appearance of these neuropathies, including the piriformis syndrome, iliacus syndrome, saphenous neuropathy, obturator neuropathy, lateral femoral cutaneous neuropathy (meralgia paresthetica), proximal tibial neuropathy, common peroneal neuropathy, deep peroneal neuropathy, superficial peroneal neuropathy, tarsal tunnel syndrome, Baxter's neuropathy, jogger's foot, sural neuropathy, and Morton's neuroma.