Muscle & nerve
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Comparative Study
Peripheral nerve size in normals and patients with polyneuropathy: an ultrasound study.
Ultrasound has been used for visualizing peripheral nerve pathology. Our goal was to use ultrasound to quantitate the sizes of upper extremity nerves along their length in control subjects and patients with neuropathy. We measured median and ulnar nerve cross-sectional areas (NCSA) in the arms of 190 subjects, including 100 with neuropathies and 90 controls. ⋯ In GBS, nerve enlargement occurred early and with minimal electrodiagnostic abnormalities in some patients. We conclude that NCSA measured by ultrasound is a quantifiable marker of nerve features that should be corrected for patient characteristics and nerve site. NCSA is generally larger in demyelinating than it is in axonal polyneuropathies.
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Ultrasound-guided near-nerve neurography is a new tool that can be used to assess nerve regeneration before reinnervation occurs. In this study, ultrasound-guided near-nerve measurements were validated against axon diameter counts in rabbits during a 15-week regeneration period after a crush lesion of their peroneal nerve. ⋯ A moderate to good positive correlation was found, which reached a maximum of 0.7 at a cut-off of 3 microm, corresponding to the minimal size of the myelinated axons. Our results suggest that, following a similar validation study in humans, ultrasound-guided near-nerve neurography may be clinically useful when early evaluation of nerve activity is needed.
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High-resolution ultrasound has become increasingly useful in the evaluation of peripheral nerves. As we have gained experience, clinically helpful ultrasonographic signs have been detected. ⋯ This sign has not been previously described. We present a case in which the ultrasonographic Tinel sign helped accurately guide a nerve biopsy in a woman with mononeuritis multiplex.