What is neuromodulation?
Dr. Armando Villarreal is a Pain Management Physician at Rehabilitation Medicine Center of New York. He completed his residency at Temple University and his fellowship at Thomas Jefferson University Hospital. His area of interest is neuropathic pain and the use of neuromodulation techniques. Dr. Villarreal is the former... more
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Neuromodulation is the application of an electrical or chemical stimulus to the spinal nerves with the purpose of modulating its transmission of painful stimuli to the brain.
There are different types of neuromodulation systems: Intrathecal pumps, for example, are devices that deliver medications directly into the spinal cord, bypassing the process of absorption either through the gut or the skin. The advantage of these systems is that dosages are very small, and the risk for side effects is reduced significantly. One of the most common drugs used in these systems is Morphine, however, baclofen (an antispastic medication), has also gotten FDA approval for use intraspinally. Patients with spasticity due to spinal cord injury, multiple sclerosis, strokes, and other conditions benefit greatly for intraspinal use of baclofen because it reduces the risk of side effects and has a more potent effect than the oral form.
Another form of neuromodulation is spinal cord stimulation or SCS. In this case, an electrical current is transmitted by very small electrodes into the spinal cord, causing a retrograde release of substances called neurotransmitters that modulate the transmission of pain into the brain. It is as if you were having a bad connection while talking on your cell phone. The brain, in this case, cannot process well the transmission of pain, because the electrical stimulation is interfering with the signal coming from the spinal cord.
SCS has been in use since the ’60s, and over the years, it has evolved to the point where we now have wireless systems that can easily be implanted in a patient and all they need to do is use a remote control to activate it.
There are two types of stimulation, one called tonic, in which patients feel a sensation of “tingling” in the area where they would normally perceive pain, and another called low threshold stimulation, where the stimulation is transmitted at such a high frequency that the body is unable to perceive it. In essence, the patient does not feel anything, and the pain is gone or significantly reduced.
Spinal cord stimulation systems are indicated for pain in the upper or lower back and/or limbs caused by nerve damage. This can be the result of a back operation, trauma, or neurological diseases such as post-herpetic neuralgia, causalgia, reflex sympathetic dystrophy (RSD), or metabolic conditions such as diabetes.
There are two types of systems: surgical and percutaneous. The surgical systems, as the name implies are implanted by a surgeon in the operating room. The percutaneous systems are implanted by a pain management physician using a spinal needle, and they can easily be removed.
Usually, a patient that is considered a candidate for this therapy has what we called “a trial”, in which a temporary stimulator is placed percutaneously for a few days to determine if, in fact, it provides the patient with at least 50% improvement of symptoms. If it does, then an implanted system, in which the stimulator is placed under the skin is discussed with the patient. In this case, he/she will be taken to the operating room, and the electrodes will be tunneled under the skin and connected to an internal generator (battery) placed in the abdomen or the gluteal region. Currently, these batteries can be non-rechargeable or rechargeable, and they could last between 3 to 10 years based on the type used. At the end of that time, they will need to be replaced if the patient still needs to use the stimulator.
The field of neuromodulation is expanding. There are at least half a dozen companies selling these systems. Each has its own peculiarities, and patients can decide which system they want to use.
More recently, new companies that use peripheral nerve stimulation have come to the market. The advantage of these systems is that they are less invasive than the SCS, however, not every patient qualifies for these systems. It depends on their clinical picture, as well as other more mundane issues such as insurance coverage.
Any patient that has had pain for a long time, and had tried multiple treatments without relief of symptoms is welcome to come to our clinic and see if they will qualify for a neuromodulation procedure, either an intrathecal pump or a spinal cord stimulator.
