TASER Electronic Control Devices Review Of Safety Literature

uli, are inherently protective against such cardiac events along with the lack of
current penetration deep within the torso to reach the heart itself.
In general, skeletal muscle activation by electrical stimulation is elicited by excitation
of α -motor neurons which innervate such muscle fibers. This fact often
comes as a surprise, in that skeletal muscle cells are themselves excitable. Recall
that “rheobase” is defined as the minimum stimulus strength necessary (generally
occurring at long stimulus durations or pulse widths) and “chronaxie” is the
stimulus duration needed at twice the rheobase stimulus strength (as a measure
of how steeply the strength-duration relationship rises for brief stimulus durations).
Excitability of skeletal muscle, per se, is far less than that of their motor neuron
cells in that both rheobase and chronaxie values of skeletal muscle are higher
than those of the myelinated nerve axons which innervate them. Thus there is
essentially zero direct activation of skeletal muscle cells. Sensations of pain, discomfort,
sensory overload, etc. in response to electrical weapon stimuli would be
expected to result from a host of sensory nerve fiber types, to some extent dependent
upon the specific locations of electrical weapon probe attachment to the
body (as well as the specific tissues located between and near the probes in
what might be called the “capture” zone of the probes where excitable cells are
likely activated).
Electrical Stimulation of Motor and Sensory Nerves
Electrical stimulation of motor or sensory nerves can be achieved in general if an
imposed electric field near such nerves is sufficient in amplitude, timing and spatial
extent to depolarize (i.e. shift the cell’s membrane potential in a positive direction)
the cell to “threshold” (where an action potential is elicited). Rattay’s “activating
function” modeling approach to nerve excitation implies that relatively long,
straight cell processes (such as the axons of α-motor neurons which may be up
to 1 meter in length as they pass from their cell bodies out to muscles in the extremities)
are stimulated according to the shape of the E field (i.e. electric field)
imposed along their lengths where changes in the E field (which will also correlate
to changes in the current density J) bring about stimulation. 6
In this brief analysis, however, we will focus only upon a corollary to Rattay’s
theory which also states that where nerve cells start and stop (i.e. at their cell
body or at their connections to other cells such as at skeletal muscle innervation
sites or at the end receptors of sensory cells, etc.) or where such cells bend with
respect to the imposed E field then stimulation thresholds tend to correlate well to
the magnitude itself of the imposed E field (or current density J).
The largest diameter myelinated α-motor neuron axons (which innervate skeletal
muscle fibers) tend to have relatively low electrical thresholds. This is because, in
general, threshold correlates inversely with cell diameter (so larger diameter cells
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