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Regulation of Sympathetic Nerve Activity in Humans: New Concepts Regarding Autonomic Adjustments to Exercise and Neurohumoral Excitation in Heart Failure
Published in Irving H. Zucker, Joseph P. Gilmore, Reflex Control of the Circulation, 2020
David W. Ferguson, Allyn L. Mark
Over 1300 microneurographic experiments have been performed at the University of Iowa since 1984, without major or permanent complications. In a systematic survey, we have found that less than 10% of subjects have any symptoms after microneurography and all of these symptoms have been transient and mild (Anderson et al., 1989).
Evaluation of Autonomic Failure
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
A) The recording of sympathetic nerve activity through an electrode placed in a peripheral nerve is known as microneurography (Delius et al., 1972b). This technique allows recordings of action potentials from sympathetic fibers in awake, unanesthetized subjects. The autonomic features of peripheral sympathetic nerves, with each fascicle encapsulated by connective tissue of high impedance, allows recording selectively from that fascicle, without confounding activity from neighboring fascicles. With microneurographic recordings it is possible to evaluate two types of sympathetic fibers: skin and muscle sympathetics (Delius et al., 1972a, 1972b; Vallbo et al., 1979; Wallin and Sundlof, 1982; Mark et al., 1985; Fagius and Wallin, 1980).
Sensory testing and clinical neurophysiology
Published in Harald Breivik, William I Campbell, Michael K Nicholas, Clinical Pain Management, 2008
Ellen Jørum, Lars Arendt-Nielsen
Microneurography is an invasive technique that was developed by Swedish neurophysiologists Hagbarth and Vallbo to make single-fiber recordings from nerve fibers in subjects who are awake. Erik Torebjörk was the first to record from single afferent C-fibers in humans in 1974.40 Since then, he has described the human nociceptive system, both mapping the different classes of C-nociceptors1 and describing the pathophysiology of C-nociceptors in peripheral injury.2,9 Few reports have been published on this technique in patients, but recently some studies have been performed showing sensitization of mechano-insensitive fibers and spontaneous activity41 as well as catecholamine-induced activation of nociceptors.42
Effects of arm cranking exercise on muscle oxygenation between active and inactive muscles in people with spinal cord injury
Published in The Journal of Spinal Cord Medicine, 2021
Several limitations should be considered. First, we could not measure sympathetic nerve activity directly using microneurography due to device and technical limitations. Also, this study included SCI with only low thoracic and lumbar motor complete SCI, not cervical or upper thoracic SCI. Recruitment of these participants locally was difficult, and IRB approval could not be obtained for these populations. Further, we could not completely rule out the effects of skin43 and adipose tissue thickness30,56 on NIRS signals. However, HHb as an index of muscle O2 extraction was not strongly affected by skin blood flow. We also performed physiological calibrations, and used two detectors to minimize the effects of skin and adipose tissue thickness on the NIRS signals.31 A recent study debated the validity of NIRS signals in people with SCI, due to several methodological and physiological limitations (e.g. muscle atrophy, intramuscular fat, and movement artifact).57 We must acknowledge the potential limitations of the device, and therefore, future studies are required.
Clinical diagnosis and management of small fiber neuropathy: an update on best practice
Published in Expert Review of Neurotherapeutics, 2020
Grazia Devigili, Daniele Cazzato, Giuseppe Lauria
Microneurography is a valuable neurophysiological technique developed to record the activity of single C-nociceptors, thermoceptors, mechanoreceptors, and sympathetic fibers from peripheral nerves in awake subjects. This technique provided data regarding the physiological activity of C fiber and elucidated the pathophysiological correlates of clinical phenomena in painful syndromes such as spontaneous activity, sensitization, and hyperexcitability [94]. In SFN and other conditions characterized by peripheral neuropathic pain, microneurography could detect abnormal C-nociceptor activity [20]. Furthermore, it allowed investigating the effect of drugs on blocking the abnormal on-going activity of C-nociceptors [95]. Its application in clinical practice, however, remains partly limited by complex technical requirements, time to perform the exam, and collaboration of the patient.
Subjective sensitivity data: Considerations to treat heteroscedasticity
Published in Cogent Medicine, 2019
Daniel Schmidt, Andresa M.C. Germano, Thomas L. Milani
Skin is the largest organ in the human body and enables various external stimuli, such as touch or vibration, to be detected. This is achieved by mechanoreceptors located in the skin. For example, plantar mechanoreceptors are known to contribute to human balance regulation (Horak, Nashner, & Diener, 1990; Kavounoudias, Roll, & Roll, 1998; Peterka, 2018). Plantar sensitivity, however, depends on various factors like age (Gescheider, Bolanowski, Hall, Hoffman, & Verrillo, 1994) or skin temperature (Germano, Schmidt, & Milani, 2016; Schmidt, Germano, & Milani, 2017). Furthermore, the ability of balance regulation is impaired in various groups, such as patients with peripheral neuropathy, in which plantar sensitivity deteriorates (Inglis, Horak, Shupert, & Jones-Rycewicz, 1994). This highlights the clinical importance of skin sensitivity in order to detect certain diseases. Of course, the interpretation of the outcomes of skin sensitivity measurements must be correct in order to meet clinical requirements. Skin sensitivity may be assessed invasively inserting microelectrodes into afferent nerve fibers (microneurography). Other, more common approaches are known as subjective methods, such as determining vibration sensitivity (vibration perception thresholds, VPTs).