Sudomotor dysfunction is one of the earliest detectable neurophysiologic abnormalities in distal small fiber neuropathy. Traditional neurophysiologic measurements of sudomotor function include thermoregulatory sweat testing (TST), quantitative sudomotor axon reflex testing (QSART), silicone impressions, the sympathetic skin response (SSR), and the recent addition of quantitative direct and indirect axon reflex testing (QDIRT). These testing techniques, when used in combination, can detect and localized pre-and postganglionic lesions, can provide early diagnosis of sudomotor dysfunction and can monitor disease progression or disease recovery. In this article, we review the common tests available for assessment of sudomotor function, detail the testing methodology, review the limitations and provide examples of test results.
Objective: To evaluate a novel method to quantify the density of nerve fibers innervating sweat glands in healthy control and diabetic subjects, to compare the results to an unbiased stereologic technique, and to identify the relationship to standardized physical examination and patientreported symptom scores.Methods: Thirty diabetic and 64 healthy subjects had skin biopsies performed at the distal leg and distal and proximal thigh. Nerve fibers innervating sweat glands, stained with PGP 9.5, were imaged by light microscopy. Sweat gland nerve fiber density (SGNFD) was quantified by manual morphometry. As a gold standard, three additional subjects had biopsies analyzed by confocal microscopy using unbiased stereologic quantification. Severity of neuropathy was measured by standardized instruments including the Neuropathy Impairment Score in the Lower Limb (NIS-LL) while symptoms were measured by the Michigan Neuropathy Screening Instrument.Results: Manual morphometry increased with unbiased stereology (r ϭ 0.93, p Ͻ 0.01). Diabetic subjects had reduced SGNFD compared to controls at the distal leg (p Ͻ 0.001), distal thigh (p Ͻ 0.01), and proximal thigh (p Ͻ 0.05). The SGNFD at the distal leg of diabetic subjects decreased as the NIS-LL worsened (r ϭ Ϫ0.89, p Ͻ 0.001) and was concordant with symptoms of reduced sweat production (p Ͻ 0.01). Conclusions:We describe a novel method to quantify the density of nerve fibers innervating sweat glands. The technique differentiates groups of patients with mild diabetic neuropathy from healthy control subjects and correlates with both physical examination scores and symptoms relevant to sudomotor dysfunction. This method provides a reliable structural measure of sweat gland innervation that complements the investigation of small fiber neuropathies. Assessment of small myelinated and unmyelinated nerve fibers is a central component of the evaluation of peripheral nerve disease. 1,2 Most polyneuropathies prominently target small nerve fibers; the subsequent small fiber dysfunction, impaired sensory perception, and sudomotor deficits lead to a predisposition to limb ulceration, infection, and amputation.3 Small sensory fiber function is evaluated with quantitative sensory testing while skin biopsy quantification of intraepidermal nerve fiber density (IENFD) provides a structural measure of small fiber cutaneous innervation. 4 Functional measures of peripheral postganglionic autonomic sudomotor nerves include the quantitative sudomotor axon reflex test (QSART) and silicone impression
Randomized controlled trials (RCTs) are the hallmark of evidence-based medicine and form the basis for translating research data into clinical practice. This review summarizes commonly applied designs and quality indicators of RCTs to provide guidance in interpreting and critically evaluating clinical research data. It further reflects on the principle of equipoise and its practical applicability to clinical science with an emphasis on critical care and neurological research. We performed a review of educational material, review articles, methodological studies, and published clinical trials using the databases MEDLINE, PubMed, and ClinicalTrials.gov. The most relevant recommendations regarding design, conduction, and reporting of RCTs may include the following: 1) clinically relevant end points should be defined a priori, and an unbiased analysis and report of the study results should be warranted, 2) both significant and nonsignificant results should be objectively reported and published, 3) structured study design and performance as indicated in the Consolidated Standards of Reporting Trials statement should be employed as well as registration in a public trial database, 4) potential conflicts of interest and funding sources should be disclaimed in study report or publication, and 5) in the comparison of experimental treatment with standard care, preplanned interim analyses during an ongoing RCT can aid in maintaining clinical equipoise by assessing benefit, harm, or futility, thus allowing decision on continuation or termination of the trial.
Introduction-Peripheral sudomotor dysfunction is present in many peripheral neuropathies, but structural assessments of sudomotor fibers rarely occur.
BackgroundSeveral clinical studies have indicated that selective serotonin reuptake inhibitors (SSRIs) administered in patients after acute ischemic stroke can improve clinical recovery independently of depression. Due to small sample sizes and heterogeneous study designs interpretability was limited in these studies. The mechanisms of action whereby SSRI might improve recovery from acute ischemic stroke are not fully elucidated.MethodsWe searched MEDLINE using the PubMed interface to identify evidence of SSRI mediated improvement of recovery from acute ischemic stroke and reviewed the literature on the potential underlying mechanisms of action.ResultsAmong identified clinical studies, a well‐designed randomized, double‐blind, and placebo‐controlled study (FLAME ‐ fluoxetine for motor recovery after acute ischemic stroke) demonstrated improved recovery of motor function in stroke patients receiving fluoxetine. The positive effects of SSRIs on stroke recovery were further supported by a meta‐analysis of 52 trials in a total of 4060 participants published by the Cochrane collaboration. Based on animal models, the mechanisms whereby SSRIs might ameliorate functional and structural ischemic‐brain damage were suggested to include stimulation of neurogenesis with migration of newly generated cells toward ischemic‐brain regions, anti‐inflammatory neuroprotection, improved regulation of cerebral blood flow, and modulation of the adrenergic neurohormonal system. However, to date, it remains speculative if and to what degree these mechanisms convert into humans and randomized controlled trials in large populations of stroke patients comparing different SSRIs are still lacking.ConclusionIn addition to the need of comprehensive‐clinical evidence, further elucidation of the beneficial mechanisms whereby SSRIs may improve structural and functional recovery from ischemic‐brain damage is needed to form a basis for translation into clinical practice.
The human skin is a highly specialized organ for receiving sensory information but also to preserve the body's homeostasis. These functions are mediated by cutaneous small nerve fibers which display a complex anatomical architecture and are commonly classified into cutaneous A-beta, A-delta and C-fibers based on their diameter, myelinization, and velocity of conduction of action potentials. Knowledge on structure and function of these nerve fibers is relevant as they are selectively targeted by various autonomic neuropathies such as diabetic neuropathy or Parkinson's disease. Functional integrity of autonomic skin nerve fibers can be assessed by quantitative analysis of cutaneous responses to local pharmacological induction of axon reflex responses which result in dilation of cutaneous vessels, sweating, or piloerection depending on the agent used to stimulate this neurogenic response. Sensory fibers can be assessed using quantitative sensory test. Complementing these functional assessments, immunohistochemical staining of superficial skin biopsies allow analysis of structural integrity of cutaneous nerve fibers, a technique which has gained attention due to its capacity of detecting pathogenic depositions of alpha-synuclein in patients with Parkinson's disease. Here, we reviewed the current literature on the anatomy and functional pathways of the cutaneous autonomic nervous system as well as diagnostic techniques to assess its functional and structural integrity.
Cell-based therapy continues to be a promising avenue for the treatment of Duchenne muscular dystrophy (DMD), an X-linked skeletal muscle-wasting disease. Recently, we demonstrated that freshly isolated myogenic progenitors contained within the adult skeletal muscle side population (SP) can engraft into dystrophic fibers of nonirradiated mdx(5cv) mice after intravenous transplantation. Engraftment rates, however, have not been therapeutically significant, achieving at most 1% of skeletal muscle myofibers expressing protein from donor-derived nuclei. To enhance the engraftment of transplanted myogenic progenitors, an intraarterial delivery method was adapted from a previously described procedure. Cultured, lentivirus-transduced skeletal muscle SP cells, derived from mdx(5cv) mice, were transplanted into the femoral artery of noninjured mdx(5cv) mice. Based on the expression of microdystrophin or green fluorescent protein (GFP) transgenes in host muscle, sections of the recipient muscles exhibited 5%-8% of skeletal muscle fibers expressing donor-derived transgenes. Further, donor muscle SP cells, which did not express any myogenic markers prior to transplant, expressed the satellite cell transcription factor, Pax7, and the muscle-specific intermediate filament, desmin, after extravasation into host muscle. The expression of these muscle-specific markers indicates that progenitors within the side population can differentiate along the myogenic lineage after intraarterial transplantation and extravasation into host muscle. Given that femoral artery catheterization is a common, safe clinical procedure and that the transplantation of cultured adult muscle progenitor cells has proven to be safe in mice, our data may represent a step toward the improvement of cell-based therapies for DMD and other myogenic disorders.
Objective-To develop a novel assessment of sudomotor function.Background-Post-ganglionic sudomotor function is currently evaluated using quantitative sudomotor axon reflex testing (QSART) or silicone impressions. We hypothesize that highresolution digital photography has advanced sufficiently to allow quantitative direct and indirect testing of sudomotor function (QDIRT) with spatial and temporal resolution comparable to these techniques.
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