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Neuromodulation. 2014 Apr;17(3):226-34; discussion 234-5. doi: 10.1111/ner.12161. Epub 2014 Feb 25.

Efficacy of kilohertz-frequency and conventional spinal cord stimulation in rat models of different pain conditions.

Author information

1
Department of Clinical Neuroscience, Section of Neurosurgery, Karolinska Institutet, Stockholm, Sweden.

Abstract

OBJECTIVES:

The aim was to compare the effects of high-frequency spinal cord stimulation (HF-SCS) at subparesthetic intensity with conventional SCS in rat models of different types of pain. In addition, microrecordings of afferent activity in the dorsal columns during both types of SCS were performed to elucidate their mode of action.

MATERIALS AND METHODS:

Miniature SCS electrodes were implanted in all rats. One group was submitted to the spared nerve injury procedure (SNI) and another to inflammatory pain after carrageenan injection into a hind paw. All animals were tested for hypersensitivity to normally innocuous tactile and thermal stimuli. One group of normal healthy rats was submitted to acute nociceptive (pinch, heat) pain. Microrecording of afferent activity in the gracile nucleus (GN) was performed in a group of nerve-lesioned rats responding to conventional SCS.

RESULTS:

HF-SCS at 500, 1,000, or 10,000 Hz at subparesthetic amplitudes produced similar reductions in hypersensitivity due to nerve lesion as did conventional SCS at 50 Hz. HF-SCS showed no effect on thermal pain. A trial to rescue non-responders to conventional SCS using HF-SCS was not successful. There were no effects either of conventional or of HF-SCS on acute or inflammatory pain. Conventional SCS produced massive activation in the GN but no activation during HF-SCS, though normal peripherally evoked afferent activity remained.

CONCLUSIONS:

Conventional SCS proved equally effective to HF-SCS in various pain models. As no activity is conveyed rostrally in subparesthetic HF-SCS, we hypothesize that its mechanisms of action are primarily segmental.

KEYWORDS:

Acute nociceptive pain; dorsal column nuclei; inflammatory pain; kilohertz frequencies; neuropathic pain; rat models; spinal cord stimulation

PMID:
24612269
DOI:
10.1111/ner.12161
[Indexed for MEDLINE]

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