Stimulus waveform determines the characteristics of sensory nerve action potentials

Antidromic vs orthodromic sensory median nerve conduction studies

“…We used constant-current stimulation, which implies taking into account the capacitive properties of the tissue under the stimulating electrodes to reach a given intensity. Because of that, the actual stimulus intensity is lower at the onset of the stimulus than at the end of it, as the current has to overcome the absorption of charges by the human tissues (Pereira et al, 2016). Activation of axons occurs according to the strength–duration properties, when the charge of the stimulus overcomes resistance.…”

“…The second peak appears to be generated under the anode (anAP, to distinguish it from the caAP, the potential generated by depolarization under the cathode; see Aprile et al, 2003, Aprile et al, 2007, Therimadasamy et al, 2015; Leote et al, 2016). The mechanism of its generation is anode-break excitation at the switching off of the stimulus (Therimadasamy et al, 2015; Pereira et al, 2016). Even though this action potential has received some attention in recent years, not everything in its physiological mechanisms is completely understood yet.…”

“…The increase in intensity makes it disappear because of antidromic blocking from inputs generated under the cathode. The anAP is present only with constant current stimuli that have a sharp switch off (Pereira et al, 2016). Unfortunately, the design of the stimulator differs in the various machines available in the market.…”

“…The anAP is an interesting phenomenon that is largely influenced by various technical aspects. In spite of that, though, it may have some clinical applicability as a measure of excitability of sensory axons (Leote et al, 2016, Pereira et al, 2016). Although the first hypothesis that the anAP was generated in nerve terminals and intradermal nerve endings or even skin receptors at the fingertip (Aprile et al, 2003, Aprile et al, 2007) has proven to be wrong (Therimadasamy et al, 2015), it is still possible that the decreased nerve excitability characteristic of peripheral neuropathies can be indirectly demonstrated with such a simple technique (Joa and Kim, 2013; Leote et al, 2016).…”

Estado del Arte en Neurotecnologías para la Asistencia y la Rehabilitación en España: Tecnologías Auxiliares, Trasferencia Tecnológica y Aplicación Clínica

“…Sus líneas de investigación giran en torno a la fisiología del movimiento y de la percepción sensorial mediante movimientos voluntarios (Guzmán-López et al, 2015) e involuntarios (Pereira et al, 2016). También el Grupo en Electromiografía y Fisiología muscular de la Universidad Pública de Navarra ha centrado su investigación en el sistema neuromuscular mediante técnicas para el análisis, modelado, simulación y clasificación automática de señales iEMG y de superficie (Latasa et al, 2016).…”