Info on Neurostimulation
If you or someone you care about has been living with chronic intractable
pain, neurostimulation may provide new hope. Neurostimulation is a medical treatment for people suffering from chronic pain.
Thousands of people have been treated successfully with neurostimulation.
Neurostimulation is actually one of a number of emerging medical
technologies called neuromodulation. Neuromodulation therapies are used to attain pain relief or symptom relief for certain types of chronic pain and neurological
Neuromodulation: Getting at the Source of the Pain
uses an implanted device an implanted drug pump or a neurostimulator (spinal cord stimulator) to deliver small doses
of drugs or low-levels of electricity directly to nerve fibers. This direct approach to treating neurological problems at
their source can be very effective in modulating, or lessening, symptoms of pain or motor dysfunction.
A Treatment with Real Advantages
Neuromodulation has two significant
advantages. First, it can be very effective for certain conditions. Second, the implanted device can be easily removed. If
you dont achieve the desired level of pain or symptom relief, you can decide to have the implant removed.
What Is It?
Neurostimulation, also called electrostimulation, is a form of neuromodulation. It has been approved by the United States Food and Drug Administration
(FDA) as a treatment for certain types of chronic pain associated with the trunk and/or limbs. The therapy involves applying
very small amounts of electricity directly to selected nerves or anatomic structures. The electricity triggers a neurological
response that interferes with the transmission of unwanted pain or motor dysfunction signals to the brain.
Types of Neurostimulation
Medical professionals divide neurostimulation
into subcategories based upon the type of nerve that is being stimulated. Nerves within the brain or spinal cord make up the
central nervous system. One type of central nervous system neurostimulators is spinal cord stimulation.
- Spinal cord stimulation (SCS) involves the stimulation of nerves in the spinal cord by placing
electrodes in the space above the spinal cord (epidural space). Spinal cord stimulation is sometimes referred to by its older
name dorsal column stimulation. Spinal cord stimulation is indicated for the treatment of chronic pain of the trunk and/or
Nerves outside of the central nervous system make up the peripheral
nervous system. Peripheral nerves can also be stimulated. For example, sacral nerve stimulation (SNS) involves the stimulation
of nerves in the sacral (pelvic) area.
- Peripheral nerve stimulation (PNS) involves stimulation of nerves of the peripheral nervous system
which are outside of the central nervous system (spinal cord and brain).
The type of neurostimulation that might be appropriate for your
condition depends upon many factors, including the cause of your pain or neurologic disorder, as well as its type and location.
Some indications are approved by the FDA and other regulatory bodies, and others are not. See the indications section of this site for more information on approved indications.
Spinal Cord Stimulation (SCS) for Chronic Pain Relief
cord stimulation (SCS) is a type of neurostimulation that has been used for decades to treat chronic pain of the trunk and/or
limbs. Spinal cord stimulation can be effective in relieving persistent or severe neuropathic pain.
Spinal cord stimulators typically consist of three components designed
to work together as a system: two implanted components (a power source and leads); and an external controller. The power source
generates electrical pulses, which are carried by the lead to electrodes at the end of the lead. The external controller allows
the doctor to program the power source to generate pulses customized for the individual receiving the therapy.
A relatively short noninvasive surgical procedure is required to
place the electrodes in the space above of the spinal column (epidural space). When the power source is turned on, the electrodes
will stimulate the nerve fibers that are associated with the areas of the body affected by pain. For many people, this stimulation
of the targeted nerves effectively changes pain messages and some patients describe the feeling that replaces the pain as
a tingling or massaging sensation called paresthesia. For many patients, paresthesia is much more pleasant than the pain in
this case, spinal cord stimulation is a good option. However, for some patients paresthesia is not a pleasant sensation. A
trial procedure is normally performed to determine a patients response to spinal cord
Peripheral Nerve Stimulation (PNS): Applying Proven Technology to
Challenging Pain Problems
Peripheral nerve stimulation (PNS) is similar to spinal cord stimulation. The difference is that
PNS electrodes stimulate nerves outside the central nervous system, whereas spinal cord stimulation target nerves in the central
nervous system. The treatments are believed to work similarly. They trigger a neurological response that interferes with the
transmission of unwanted pain or motor dysfunction signals.
Who Can It Help?
Neurostimulation is not for everyone.
First, you may be able to obtain relief from more conservative,
less invasive or less expensive treatment options. Many doctors believe that other pain therapies including analgesics, NSAIDs,
and sometimes even surgery should be tried and fail before offering patients the opportunity to try neurostimulation.
Second, you may have a type of pain that does not respond well to
neurostimulation. Neurostimulation in particular, spinal cord stimulation (dorsal column stimulation) works best for neuropathic
pain. Neurostimulation is generally considered to be ineffective in treating nociceptive pain.
That said, if you have tried other therapies and are not satisfied
with the results, then it might be time for you to consider other options, such as neurostimulation. The best way to determine
whether or not neurostimulation might help you is to try it through a trial stimulation.
How It Works
To understand how neurostimulation works, it is helpful to understand
the components of a neurostimulation system. Specific parts may vary according to the type of stimulator and the application,
but a neurostimulator system generally has three main components:
- The lead(s), are very thin cables consisting of metal electrodes
at one end connected by wires to an electrical connector at the other. The leads are surgically placed in the space above
the spinal cord (epidural space) or near the nerve to be stimulated, and then tunneled through the soft tissue and connected
to the power supply. In some cases, it is necessary to use a fourth component, an extension, to extend the cable back to the
power supply. The connector on the lead will be plugged into the power supply or into an extension.
The number of leads placed, the number of electrodes placed, and
the placement of the electrodes depends upon the type of stimulator and the condition being treated.
For example, a complex back pain condition might require two leads
with 16 electrodes to be placed in the epidural space of the spine.
- A power supply, which can be implanted under the skin or worn outside
of your body, to supply the energy to generate stimulation therapy.
- A programmer, which is used to program the power supply. The program(s)
are the various electrical settings of the stimulation pulses (amplitude, frequency, pulse width and polarity) that are transmitted
to each electrode on the lead. The stimulation pulses that are generated ultimately change the signals that are sent to the
brain. Instead of feeling pain, it is reported that you generally feel a different kind of sensation in the affected areas.
Most people describe this sensation as a tingling or a pleasant massaging effect. The technical name for this sensation is
Leads and Extensions
Leads are very thin cables, which consist of metal electrodes at
one end. The electrodes are connected by thin wires to an electrical connector at the other end of the lead. Manufacturers
offer a variety of leads to meet the neurostimulation needs of patients and doctors. Variations include:
- Lead type: percutaneous or surgical
- Number of electrodes: 4, 8, 16
- Electrode shape, configuration and spacing
- Lead length
Types of Leads
Percutaneous leads are leads that can be implanted
through a needle without the need for a surgical incision. The advantages of percutaneous leads are that they are faster and
easier to place, and less traumatic to the patient. Their disadvantages are that they are more prone to move (migrate) as
compared to surgical leads, and their cylindrical electrode shape makes them less energy efficient.
Surgical leads, also called paddle leads, are larger leads that
require a small surgical incision. Their advantages are that they are less prone to move (migrate) as compared to percutaneous
leads, and their flat electrode shape makes them more energy efficient. The disadvantage is that they do require a surgical
procedure to place (implant).
Percutaneous leads are almost always used for trial stimulation, whereas either percutaneous or surgical leads can be used for permanent
Number of Electrodes
Each lead has at least four electrodes, but
a lead can contain as many as 16 electrodes. The number of electrodes used depends upon the condition being treated, as well
as the doctors preference. For example, more complex pain patterns, such as those involving multiple sites (multi-focal) and
multi-extremities involve more nerve structures. Additional electrodes are often required to stimulate all of these structures.
Implanting fewer electrodes than you need can result in less pain relief.
Many doctors believe that it is best to implant extra electrodes,
just in case the pain pattern changes or the leads move (migrate). If a change or migration occurs and extra electrodes are
available, it is often possible for your doctor to reestablish pain relief by electronically repositioning the electrodes.
This is accomplished by reprogramming the power supply, which requires an office visit to see your doctor.
However, if the leads migrate and extra electrodes are not available,
then you may have to undergo another surgical procedure to surgically reposition the leads. Thus, placing extra electrodes
is like buying insurance, providing you and your doctor with some protection against possible future problems.
Electrode Size, Shape and Configuration
The size, shape and configuration
of the electrode(s) affect the path that the electricity takes as it travels through the nerve structures and the surrounding
tissue. Cylindrical electrodes, such as those found on percutaneous leads, allow electricity to flow in all directions. Flat
electrodes, on the other hand, such as those found on surgical or paddle leads, allow electricity to be directed in just one
With percutaneous leads, some of the electricity is wasted with
cylindrical electrodes because some of the electricity is directed away from the targeted nerve tissues. In addition, nerve
tissues that were not targeted can be inadvertently activated, which may interfere with the quality and comfort of the stimulation.
Experienced neurostimulation practitioners understand these and other issues associated with electrode size, shape and configuration,
and consider these issues in selecting the appropriate type of lead(s) for each individual patient.
Lead length refers to the length of wire between
the electrodes and the electrical connector. Doctors select lead lengths based upon the electrode implantation site, the physical
size of the neurostimulation patient, the distance between the stimulation site and the power source implantation site, as
well as their personal preferences. Some doctors choose to use shorter leads because they find them to be easier to maneuver
into position than longer leads, or because they want to anchor the lead in several locations to reduce the chance of migration.
Other doctors prefer to use longer leads to avoid the use of extensions (extensions are discussed below).
Extensions are thin cables consisting of connectors at both ends
connected by very thin wires. They are used whenever the lead is not long enough to reach the power supply. In that sense,
extensions are used just like you would use an extension cord around the house. Some neurostimulation systems can be implanted
without using any extensions. In most cases, doctors prefer to use as few extensions as possible because the connectors are
usually larger than the cable, and some patients find these connector lumps to be uncomfortable. Another consideration is
that each extension creates another electrical connection which has the potential to become disconnected.
Power Source IPG and RF Systems
All neurostimulators require a power source. There are two types
of power sources: implantable pulse generator (IPG) and radio frequency (RF). The systems are similar in that they both require
at least one implanted lead and an external programmer. They are distinguished from each other by, among other things, the
location of the battery.
- Implantable pulse generator, or IPG. With an IPG,
the power source consists of a battery and related electronics that are contained in a single metal container. The IPG is
completely implanted under the skin. The leads (or extensions) are plugged into the IPG.
- Radio frequency, or RF, power sources have two components:
a receiver that is implanted under the skin, and a transmitter that is worn externally, much like a cell phone or pager. The
receiver contains a metal antenna and related electronics that are contained in a small container but NO battery. The receiver
is completely implanted under the skin. The leads (or extensions) are plugged into the receiver. The transmitter contains
an antenna and related electronics, including the battery. Electrical energy is transmitted by radio waves from the transmitter
through the skin and into the receiver.
There are advantages and disadvantages to each type of system. If
you are being considered for a neurostimulator, you and your doctor will decide which system is most appropriate for your
situation. The decision is based on the pattern and complexity of your condition, your lifestyle, as well as how much electrical
energy is required to provide adequate pain relief.
IPGs Better Suited for Low-Power Applications
Like Simple Pain
Simple pain is defined as pain in a single region or a single extremity,
which is not expected to migrate, change, or worsen. If only a single extremity is involved, it is called unilateral pain.
Simple, unilateral pain can often be managed with a minimal number of electrodes, relatively low power output levels and a
single stimulation program. In other words, these are ideal applications for a fully implantable spinal cord stimulation system
the implantable pulse generator (IPG).
A major advantage of the IPG is that it is totally implanted. Thus,
it is more discreet, and it is possible to bathe, shower, or swim while receiving stimulation. Some people find this more
convenient and cosmetically acceptable.
The key disadvantage of the IPG is that it has a fixed battery life.
When the battery runs out, the IPG needs to be replaced. Replacing the battery means another trip to the operating room, and
the discomfort, cost and inconvenience of IPG replacement surgery. Another disadvantage of the IPG is that the battery adds
to the size and weight of the device. This can be an issue in smaller or more slender people, by limiting appropriate implantation
sites available to your doctor.
The primary issue in determining if the IPG is the best option for
you is not strictly your pain pattern or diagnosis, but rather how long the battery will last given the electrical energy
required to attain adequate pain relief.
The battery life of an IPG varies from patient to patient. It depends
on your pain pattern, how often you use the stimulator, the amount of electrical energy that your spinal cord stimulation
prescription requires, and how and if your pain pattern changes over time.
The battery in an IPG can last up to five years, but it is more
common to expect a life of two to three years. However, it is not unheard of for an IPG to require replacement in less than
nine months because of battery depletion. If you are being considered for spinal cord stimulation with an IPG, talk to your
doctor about estimating the battery life of your device given your stimulation requirements as determined in your stimulation trial. This will help you both to decide if an IPG is a good treatment option