Perceptions and electric senoidal current stimulation

Abstract

-Objective: To analyze the relationship between perceptions and electrical senoidal curre n t stimulation (ESCS). Method: The study population comprise 100 healthy volunteers. ESCS of 5 Hz and 2 kHz were applied to the left index finger at one and 1.5 sensory threshold. Following each stimulus train a list of eight words (four related to thin fiber sensations and four related to thick fiber sensations) was p resented to the subjects who were asked to choose the three words closer to the experienced sensation. Each chosen word was given a score 1; final results were obtained by the sum of the scores for the words related to thin and thick fiber systems for each situation. Results: For 5 Hz ESCS at one and 1.5 sensory threshold thin fibers had significantly higher scores than thick fibers; for 2 kHz ESCS, thick fibers had significantly higher score s . Conclusion: These results show that there is a relation between diff e rent sensations and ESCS of different frequencies.KEY WORDS: peripheral nerve, electric stimulation, senoidal currents, sensations, perceptions. Percepções e estimulações elétricas por correntes senoidaisRESUMO -Objetivo: Estudar a relação entre as sensações evocadas por estimulação elétrica por corre n t e senoidal (ESCS). Método: 100 voluntários normais foram estudados. ESCS a 5 Hz e 2 kHz foram aplicadas no dedo indicador esquerdo com uma e 1,5 vezes o limiar sensorial. Listas de oito palavras (4 re l a c i o n a d a s a fibras grossas, 4 a fibras finas) foram apresentadas após cada estimulação e foi solicitado que o sujeito escolhesse as 3 palavras que mais se aproximassem das sensações experimentadas. Às palavras escolhidas foi dado o escore 1. Os resultados finais para análise foram obtidos da soma dos escores para as palavras relacionadas aos diferentes sistemas de fibras. Resultados: Para ESCS a 5 Hz sensações relacionadas a fibras finas foram significantemente mais escolhidas, já para estimulações a 2 kHz sensações relacionadas a fibras g rossas foram significantemente mais escolhidas. Conclusão: Estes resultados mostram um relação entre diferentes percepções e diferentes freqüências de correntes elétricas senoidais.

Current perception threshold and reaction time in the assessment of sensory peripheral nerve fibers through sinusoidal electrical stimulation at different frequencies

“…Results related to sensory perception (Table 3) are similar to those found in works of Tierra-Criollo et al (2006) and Pimentel et al (2006), which suggested that sinusoidal electrical currents at 5 and 2,000 Hz evoke different sensations. According to Félix et al (2009), stimuli at 2,000 Hz would activate Aβ-fibers while stimuli at 5 Hz would activate Aβ-, Aδ-, and C-fibers.…”

“…The classification errors led to a better class separation for Arrangement 2 (1, 250, and 3,000 Hz) than Arrangement 1 (5, 250, and 2,000 Hz), the latter widely used in literature for the evaluation of peripheral nervous fibers (Hedman andSullivan, 2011, Lowenstein et al, 2008;Matsutomo et al, 2005;Nishimura et al, 2004;Pimentel et al, 2006). Additionally, it was possible to verify that classification errors occur mainly at low and medium frequencies, for both arrangements, suggesting that such stimuli can activate similar fiber groups.…”

“…• All reports having at least one word such as "prick", "pang", "twinge", and "burn" (Pimentel et al, 2006) or related, such as "heating" or "pinching" were classified as "Group X"; • All reports that showed at least a word such as "squeeze", "pressure", "movement", and "vibration" (Pimentel et al, 2006) or related, such as "tingling sensation", "contraction", "touch" or "numbness", were classified as "Group Y"; • Reports that showed words related to both groups above were classified as 'Group XY". Thus it was possible to check, through the sensory perceptions reported, whether there was any correlation between the stimulus frequency and the sensory perception reported.…”

“…Findings suggest that a 2,000 Hz stimulus would excite Aβ-fibers, a 250 Hz one, Aβ-or Aδ-fibers, and a 5 Hz one, Aβ-, Aδ-or C-fibers, according to Pimentel et al (2006) and Liu et al (1996). Therefore, we suppose that the sinusoidal current neuroselectivity may be better observed if ST and RT parameters are jointly evaluated.…”

Cortical Alpha Oscillation During 3 kHz Steady-State Sinusoidal Electric Current Stimulation

“…They were allowed to a forced choice maximum of three words from the list. Similar methodology was employed in previous studies [16,24,25]. In addition, participants were asked to mark a line indicating stimulation subjective discomfort perceived in a continuous line, whose extremities ranged from "No discomfort at all" to "Extremely uncomfortable".…”