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Neurosci Res. 2017 Aug;121:43-48. doi: 10.1016/j.neures.2017.03.007. Epub 2017 Mar 18.

Pain-related evoked potentials after intraepidermal electrical stimulation to Aδ and C fibers in patients with neuropathic pain.

Author information

1
Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan; Medical Corporation Jinseikai, Chiba, Japan.
2
Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan; Department of Neurology, National Hospital Organization Chiba-East Hospital, Chiba, Japan. Electronic address: sagiri-i@par.odn.ne.jp.
3
Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.

Abstract

Neuropathic pain can result from neuronal hyperexcitability and complex interactions of the nociceptive pathways. Intraepidermal electrical stimulation (IES) is a novel technique that can selectively activate Aδ and C fibers. To investigate patterns of changes in Aδ- and C-mediated brain responses in patients with neuropathic pain using IES, we recorded pain-related evoked potential (PREP) after IES of Aδ and C fibers in 20 patients with neuropathic pain and 15 age-matched healthy volunteers. We evaluated PREP latencies, amplitudes, and amplitude ratios of PREPs after C/Aδ-fiber stimulation. PREP amplitudes after Aδ-fiber stimulation tended to be smaller in the patient group, whereas there were no significant differences in amplitudes after C-fiber stimulation between the patient and normal control groups. PREP amplitude ratios after C/Aδ-fiber stimulation were significantly greater in the patient group than in the control group, and the higher ratio tended to be associated with a greater visual analog scale score. Patients with neuropathic pain had a tendency towards decreased Aδ amplitudes and significantly increased C/Aδ PREP amplitude ratios and this ratio appeared to be associated with the intensity of pain. Our findings suggest that decreased inhibition of the Aδ to C nociceptive systems is associated with generation of neuropathic pain.

KEYWORDS:

Aδ-fiber; C-fiber; Intraepidermal electrical stimulation; Neuropathic pain; Pain-related evoked potentials; Small fiber

PMID:
28322984
DOI:
10.1016/j.neures.2017.03.007
[Indexed for MEDLINE]

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