Eliciting paresthesia or nerve stimulation are commonly used methods
for localizing nerves prior to the injection of local anesthetic.
Paresthesia is thought to result from mechanical stimulation of the nerve,
resulting in a sensory feeling described as “an electric current” or
“shock” in the sensory distribution of the nerve that is being touched. As
such, paresthesia can indicate that the needle is in close proximity to the
nerve and may be a warning sign of impending mechanical injury, should the
needle be further advanced. In contrast, nerve stimulation techniques rely
on the use of electric current to elicit motor stimulation of nerves and
confirm the proximity of the needle to the nerve.
Electrical nerve stimulation is currently the most common technique for
localizing nerves prior to the injection of local anesthetic. Depolarizing
the nerve membrane results in contraction of the effector muscles (motor
fibers) or in paresthesias (sensory fibers) in the distribution of the
nerve. These responses can be used to confirm the proximity of a needle or
catheter to the nerve. This localization technique for nerve blocks was
first described by von Perthes in 1912; however, it has only gained wider
acceptance in regional anesthesia over the last two
decades.1 Subsequently, a number of researchers have
further improved and developed this technique. Pearson introduced the
concept of using an insulated needle for the localization of
nerves;2 however, Montgomery and colleagues later
demonstrated that ordinary uninsulated needles could also be used to
localize nerves, albeit with a higher current.3 The use of
a portable transistorized nerve stimulator with a variable current output
was first introduced by Greenblatt and Denson.4 Ford and
associates further emphasized the important characteristics of electrical
nerve stimulators and the differences between insulated and uninsulated
needles.5,6 In recent years, the same electrical
stimulation principles have been applied for new uses such as percutaneous
electrode guidance (PEG),7–10 confirmation of epidural
catheter placement,11–13 and peripheral catheter
placement for continuous regional anesthesia.14 The
clinical relevance of the duration of the stimulating current and optimal
placement of the return (skin) electrode have also been
In order to use nerve stimulation effectively a basic knowledge of the
electrophysiologic principles is necessary. The following discussion is
based on the commonly accepted theoretical and practical concepts of nerve
stimulation. However, our understanding of the mechanisms of nerve
stimulation is still incomplete. Thus, the reader should remain cognizant of
the fact that current literature still has conflicting concepts and
recommendations regarding several aspects of nerve
Uncomfortable motor response to nerve stimulation can be avoided by
using a low-intensity stimulating current with a short pulse width.
However, when a higher current is used, preferential stimulation of the
motor nerve may be lost
Therefore, the best method to avoid discomfort on nerve stimulation is to limit the energy (E) or current intensity
(I) during ...
Log In to View More
If you don't have a subscription, please view our individual subscription options below to find out how you can gain access to this content.
Want remote access to your institution's subscription?
Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.
If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
AccessAnesthesiology Full Site: One-Year Subscription
Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more
Pay Per View: Timed Access to all of AccessAnesthesiology
24 Hour Subscription $34.95
48 Hour Subscription $54.95
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.