Muscle & nerve
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Diabetic lumbosacral radiculoplexus neuropathy (DLRPN) (also called diabetic amyotrophy) is a well-recognized subacute, painful, asymmetric lower-limb neuropathy that is associated with weight loss and type II diabetes mellitus. Nondiabetic lumbosacral radiculoplexus neuropathy (LRPN) has received less attention. Comparison of large cohorts with DLRPN and LRPN demonstrated that age at onset, course, type and distribution of symptoms and impairments, laboratory findings, and outcomes are similar. ⋯ Cutaneous nerves from patients with DLRPN and LRPN show pathological evidence of ischemic injury (multifocal fiber loss, perineurial thickening and degeneration, neovascularization, microfasciculation, and swollen axons with accumulated organelles) and microvasculitis (mural and perivascular inflammation, separation and fragmentation of mural smooth muscle layers of microvessels and hemosiderin-laden macrophages). Controlled trials with immune-modulating therapies in DLRPN are in progress, and preliminary data suggest that such therapy may be beneficial in LRPN. It is likely that DLRPN and LRPN are immune-mediated neuropathies that should be separated from chronic inflammatory demyelinating polyneuropathy and from systemic necrotizing vasculitis.
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The purpose of this study was to describe the relationship between the delay in initiation and termination of muscle contraction and clinical measures of motor impairment and physical disability in the affected upper limb of patients with hemiparesis. Electromyographic (EMG) activity of 26 long-term survivors of stroke was recorded during isometric wrist flexion and extension. Upper limb motor impairment and disability were assessed with the Fugl-Meyer motor assessment (FMA) and arm motor ability test (AMAT), respectively. ⋯ However, the delay was not significantly affected by stroke type, stroke level, side of hemiparesis, or presence of aphasia. Delay in initiation and termination of muscle contraction correlated significantly with FMA and AMAT. Abnormally delayed initiation and termination of muscle contraction may contribute to hemiparetic upper limb motor impairment and physical disability in hemiparetic patients.
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A 49-year-old woman developed acute left facial, hypoglossal, and phrenic nerve palsies, as well as dysphagia and weakness in the neck and arms. Electrophysiologic studies showed an acute motor axonal neuropathy. ⋯ Intravenous immunoglobulin treatment resulted in good clinical recovery. The present report indicates that the cranial and phrenic nerves may be affected unilaterally in Guillain-Barré syndrome, and that there is clinical variability in the axonal subtype of this syndrome.
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Clenbuterol is known to act as a neuroprotective substance in the central nervous system, and also reduces muscle atrophy after denervation. The aim of this study was to evaluate its influence on peripheral nerve regeneration. The rat sciatic nerve model was used in four groups (n = 8 per group). ⋯ Muscle weight ratios of the clenbuterol group were significantly increased after 6 weeks, and the animals showed improved function of the hindlimb. Thus, therapy with 100 microg/kg clenbuterol daily after coaptation of a sciatic nerve showed a positive influence on clinical, histological, and morphometrical parameters in the rat model. The underlying mechanism remains unclear.
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This review addresses the issue of how axotomy of peripheral nerve fibers leads to pain and hyperalgesia. The point of axotomy (the nerve injury site), the dorsal root ganglia, and the dorsal horn of the spinal cord are candidate sites for generation of the pain signal that is likely to be critical for maintaining the neuropathic pain state. This review considers neuropathic pain from a "systems" perspective, tracing concepts of neuropathic pain from the work of Henry Head to the present. ⋯ These abnormalities in the intact nociceptor, which arise in the context of Wallerian degeneration, probably play a role in creating or maintaining the abnormal pain state. These considerations probably also apply to the understanding of pain arising in other neuropathies. The findings relative to the "intact" nociceptor provide a rationale by which to understand how therapies distal to the nerve injury site may diminish pain.