MR Imaging in the Differential Diagnosis of Neurogenic Foot Drop (original) (raw)
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Muscle & Nerve, 2012
Introduction: Muscle magnetic resonance imaging (MRI) is an innovative tool for exploring focal neuropathies. However, its usefulness in mild, proximal, or chronic lesions, when electromyography (EMG), the current ' 'gold standard' ' sensitivity is inadequate, has yet to be studied. Methods: Clinical, MRI, and EMG examinations were performed in 113 muscles of 17 consecutive patients with clinically diagnosed lower limb focal neuropathies. The sensitivity and specificity of MRI and EMG were evaluated in relation to disease duration, severity, and anatomical location. Results: Muscle MRI was highly sensitive for the detection of denervated muscle, and, unlike EMG, its sensitivity did not decrease regardless of the anatomical location, duration, or severity of the neuropathy. Five MRI false positives were noted, including three in the thigh muscles. Conclusions: Muscle MRI is an alternative tool to EMG in proximal, mild, or chronic clinical diagnoses of lower limb focal neuropathies. However, it also seems prone to false-positive results, particularly in proximal muscles.
Usefulness of muscle denervation as an MRI sign of peripheral nerve pathology
Australasian Radiology, 2007
Peripheral nerve disorders may be classified into compressive or entrapment neuropathies and non-compressive neuropathies. Muscle denervation recognized on MRI may be a useful sign in the diagnosis of peripheral nerve disorders. Acute or subacute denervation results in prolonged T2 relaxation time, producing increased signal in skeletal muscle on short tau inversion-recovery and fat-suppressed T2-weighted images. Chronic denervation produces fatty atrophy of skeletal muscles, resulting in increased muscle signal on T1-weighted images. This review will outline and illustrate the various ways that muscle denervation as seen on MRI may assist in the diagnosis and localization of peripheral nerve disorders.
Sequential MR imaging of denervated muscle: experimental study
AJNR. American journal of neuroradiology, 2002
MR changes in denervated muscles have been reported to occur within days up to several weeks after peripheral nerve damage. The purpose of this experimental study was to investigate the longitudinal changes in denervated muscles by using MR imaging. In 12 Lewis rats, the left sciatic nerve was transected at the level of the proximal thigh. MR imaging of both legs was performed before and 1 hour, 24 hours, 48 hours, 7 days, 14 days, 28 days, and 2 months after the procedure. The MR protocol included T1-weighted spin-echo, T2-weighted double turbo spin-echo, and turbo inversion recovery magnitude (TIRM) sequences obtained in the axial plane. Signal intensities (T2-weighted double turbo spin-echo and TIRM sequences) and the T2 TR (T2-weighted double turbo spin-echo sequence) were recorded for the soleus, peroneal, and gracilis muscles of both sides. Moreover, the circumferences of both lower legs were determined on the basis of T1-weighted images. Twenty-four hours after denervation, a...
European Radiology, 2007
Role of magnetic resonance imaging in entrapment and compressive neuropathywhat, where, and how to see the peripheral nerves on the musculoskeletal magnetic resonance image: part 1. Overview and lower extremity Abstract The diagnosis of nerve entrapment and compressive neuropathy has been traditionally based on the clinical and electrodiagnostic examinations. As a result of improvements in the magnetic resonance (MR) imaging modality, it plays not only a fundamental role in the detection of space-occupying lesions but also a compensatory role in clinically and electrodiagnostically inconclusive cases. Although ultrasound has undergone further development in the past decades and shows high resolution capabilities, it has inherent limitations due to its operator depen-dency. We review the general concepts that should be known to evaluate the entrapment and compressive neuropathy in MR imaging. We also review the course of normal peripheral nerves, as well as various clinical demonstrations and pathological features of compressed and entrapped nerves in the lower extremities on MR imaging, according to the nerves involved. The common sites of nerve entrapment of the lower extremity are as follows: sciatic nerve around the piriformis muscle; tibial nerve at the popliteal fossa and tarsal tunnel, common peroneal nerve around the fibular neck, and digital nerve near the metatarsal head. Although MR imaging can depict the peripheral nerves in the extremities effectively, radiologists should be familiar with nerve pathways, common sites of nerve compression, and common spaceoccupying lesions resulting in nerve compression in MR imaging.
Muscle CT, biopsy and EMG in diagnosis of neuromuscular diseases
Italian Journal of Neurological Sciences, 1987
The diagnostic value of EMG and muscle biopsy has been compared with muscle CT in 53patients with neuromuscular diseases. CTconcordance with clinical diagnosis was found in 62% of myopathies and was highest in Duchenne PMD and scapulo-peroneal myopathy and very low in metabolic and inflammatory myopathies. In neurogenic diseases muscle CT agreed with clinical diagnosis in 63% of patients: the highest concordance was found in acquired polyneuropathies.
MR neurography: diagnostic utility in the surgical treatment of peripheral nerve disorders
Neuroimaging clinics of North America, 2004
Advances in MR imaging have improved the visualization of normal and pathologic peripheral nerve structures in various clinical settings. Peripheral nerve imaging has the potential to dramatically change the diagnosis and treatment of peripheral nerve pathology and lead to an improved understanding of peripheral nerve pathophysiology. Currently, MR imaging serves as a problem-solving tool when additional anatomic information is needed to clarify ambiguous electrodiagnostic and clinical examinations. The next major advance in MR imaging of peripheral nerves will likely be the transition from anatomic to physiologic imaging with higher resolution as better phased-array surface coils and higher-field-strength magnets become available. Finally, MR neurography should remain complementary to the clinical examination and electrodiagnostic studies in the evaluation of peripheral nerve disorders.
MR Imaging of Entrapment Neuropathies of the Lower Extremity
RadioGraphics, 2010
Entrapment neuropathies of the knee, leg, ankle, and foot are often underdiagnosed, as the results of clinical examination and electrophysiologic evaluation are not always reliable. The causes of most entrapment neuropathies in the lower extremity may be divided into two major categories: (a) mechanical causes, which occur at fibrous or fibro-osseous tunnels, and (b) dynamic causes related to nerve injury during specific limb positioning. Magnetic resonance (MR) imaging, including highresolution MR neurography, allows detailed evaluation of the course and morphology of peripheral nerves, as well as accurate delineation of surrounding soft-tissue and osseous structures that may contribute to nerve entrapment. Familiarity with the normal MR imaging anatomy of the nerves in the knee, leg, ankle, and foot is essential for accurate assessment of the presence of peripheral entrapment syndromes. Common entrapment neuropathies in the knee, leg, ankle, and foot include those of the common peroneal nerve, deep peroneal nerve, superficial peroneal nerve, tibial nerve and its branches, and sural nerve. ©