Compound action potentials
recorded in the human spinal cord during neurostimulation for pain
Authors: Parker JL, Karantonis DM, Single PS, Obradovic M, Cousins MJ.
Source: Pain. 2011 Dec 19.
Parker et al. from Australia report compound action potentials in the human spinal cord during neurostimulation for pain relief.
The authors state
"Electrical stimulation of the spinal cord provides effective pain
relief to hundreds of thousands of chronic neuropathic pain sufferers.
The therapy involves implantation of an electrode array into the
epidural space of the subject and then stimulation of the dorsal column
with electrical pulses. The stimulation depolarises axons and generates
propagating action potentials that interfere with the perception of
pain. Despite the long-term clinical experience with spinal cord
stimulation, the mechanism of action is not understood, and no direct
evidence of the properties of neurons being stimulated has been
The authors report novel measurements
of evoked compound action potentials from the spinal cords of patients
undergoing stimulation for pain relief. The minimally invasive
recording technique they have developed provides data previously
obtained only through microelectrode techniques in spinal cords of
The authors state
The results reveal that Aß sensory nerve fibres are recruited at
therapeutic stimulation levels and the Aß potential amplitude
correlates with the degree of coverage of the painful area. Aß-evoked
responses are not measurable below a threshold stimulation level, and
their amplitude increases with increasing stimulation current. At high
currents, additional late responses are observed. Our results
contribute towards efforts to define the mechanism of spinal cord
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