Muscle & nerve
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Comparative Study
Comparison of continuous and discontinuous FK506 administration on autograft or allograft repair of sciatic nerve resection.
An immunosuppressant drug that also possesses neuroregenerative properties, FK506 enhances the rate of axonal regeneration and improves recovery after nerve lesions. Nevertheless, prolonged immunosuppression may not be justified to assure the success of nerve regeneration. In this study, we compare the effects of continuous and discontinuous FK506 treatment on regeneration and reinnervation after sciatic nerve resection repaired with autologous or allogenic grafts in the mouse. ⋯ The number of regenerated myelinated fibers in the group was significantly lower than in autografts. Thus, continuous or discontinuous FK506 administration slightly accelerated the rate of reinnervation in autografts. In allograft repair, FK506 significantly enhanced both the rate and degree of regeneration and recovery, but its withdrawal resulted in graft rejection, a marked deterioration in function, and loss of regenerating fibers.
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Painful electrical stimulation of the fingers evokes an inhibitory response in hand muscles (cutaneous silent period, CSP). The aim of this study was to determine whether purely nociceptive thermal stimuli applied to the hand evoke a CSP. High-intensity laser pulses (205 +/- 44 mJ) were delivered to the dorsum and palm of the hand in five volunteers. ⋯ Electrical stimulation of both the dorsum and the palm evoked a CSP (latency 65 +/- 5 ms), although the reflex threshold was significantly lower after stimulation of the palm. This study confirms that the CSP is a nociceptive response specific to limbs that grasp. In humans, palm nociceptors are probably more functionally effective than dorsal nociceptors in inducing the hand-muscle inhibition that interrupts hand prehension (so that a potentially noxious source is dropped) before proximal muscles withdraw the limb.
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The development of the personal computer has simplified the process of quantitating sensory thresholds using various testing algorithms. We reviewed the technical aspects and reproducibility of different methods to determine threshold for light touch-pressure, vibration, thermal, and pain stimuli. Clinical uses and limitations of quantitative sensory testing (QST) were also reviewed. ⋯ QST has been shown to be reasonably reproducible over a period of days or weeks in normal subjects. The use of QST in research and patient care should be limited to instruments and their corresponding methodologies that have been shown to be reproducible. Literature data do not allow conclusions regarding the relative merits of individual QST instruments.
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We investigated the associations of baseline epidermal nerve fiber (ENF) densities and morphology (percent ENF swellings) and quantitative sensory testing (QST) with clinically defined human immunodeficiency virus (HIV)-associated distal polyneuropathy (DSP) and whether these measures are predictive of development of symptomatic DSP over time. Fifty-seven HIV-infected subjects with and without DSP and 19 controls participated. Mean ENF densities were lower at the distal leg and proximal thigh in asymptomatic or symptomatic DSP than in controls. ⋯ The percent ENF swellings at the distal leg correlated with the thresholds for both minimal (HP 0.5) and intermediate (HP 5.0) heat pain (HP) intensity. A higher percent ENF swellings in the distal leg [hazard ratio (HR) 1.16, 95% CI 1.02-1.31] and HP 0.5 thresholds (HR 1.03, 95% CI 1.01-1.05) were the only two measures associated with a shorter time to development of symptomatic DSP. Quantitation of ENF swellings and heat pain thresholds deserve further study as predictors of symptomatic neuropathy.
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Oxaliplatin, a platinum-based chemotherapeutic agent, is effective in the treatment of solid tumors, particularly colorectal cancer. During and immediately following oxaliplatin infusion, patients may experience cold-induced paresthesias, throat and jaw tightness, and occasionally focal weakness. We assessed nerve conduction studies and findings on needle electromyography of patients with metastatic colorectal cancer before and during treatment with oxaliplatin. ⋯ After 8-9 treatment cycles, sensory nerve action potential amplitudes declined, without conduction velocity changes or neuromyotonic discharges. The acute neurological symptoms reflect a state of peripheral nerve hyperexcitability that likely represents a transient oxaliplatin-induced channelopathy. Chronic treatment causes an axonal neuropathy similar to other platinum-based chemotherapeutic agents.