Neuromodulation encompasses a variable definition in both its entity and activity. It can include various treatments that involve the stimulation of various nerves in the central nervous system, peripheral nervous system, autonomic nervous system or deep cell nuclei of the brain that leads to the “modulation” of its activity. By definition neuromodulation is a therapeutic alteration of activity either through stimulation or medication, both of which are introduced by implanted devices.
The idea and allure of neuromodulation stems from its initial direction of a reversible alteration of the nervous system. It is the idea of neural “modulation” as supposed to “ablative” or resective procedures. Treatments are reversible and have the ability to be turned off in most situations.
Implanted devices are usually neural stimulators and drug delivery devices such as pumps. The neuromodulation community is based on a multidisciplinary approach that is diverse in its delivery. It involves physicians, industry and basic science researchers. Clinicians involved in the procedures vary from neurosurgeons, anesthesiologists, pain specialists and rehab physicians. Those involved in the multidisciplinary approach can include neurologists, psychiatrists, psychologists, primary care physicians, and physical therapy.
There are two types of pain. Neuropathic pain is described as burning, or shooting shock like pain. This type of pain tends to be resistant to treatment with pain medications such as opiods. It can result from nerve damage or abnormal nerve conduction such as pain exhibited with failed back syndrome after surgery, post surgical pain, multiple back operations, and various other conditions which can be evaluated by the treating physician.
Nocioceptive pain is a dull, throbbing pain which is more amendable to treatment with pain medications. It results from irritated nerves by your skin or organs. This is seen commonly in cancer, or after a fracture.
Spinal cord stimulation is the most common form of neurostimulation and administers low voltage stimulation to the spinal cord or a targeted nerve to hinder or block the transmission of pain. The system is implanted in a space surrounding the spinal cord, called the epidural space where it stimulates pain- inhibiting nerve fibers which can mask the sensation of pain with a tingling sensation. The lead is attached to a power source which can be implanted in different locations such as the abdomen or buttocks. You will also have a hand held remote control so that you can turn the device on and off as you wish and make adjustments to the stimulation.
Spinal cord stimulation may be a treatment option for the management of chronic pain, most specifically neuropathic pain, but also ischemic pain and visceral pain. It is a reversible therapy which can be tested before permanent implantation.
Spinal cord stimulation(SCS) delivers therapeutic doses of electrical current to the spinal cord for the management of neuropathic pain. The most common indications failed back surgery syndrome(FBSS), and complex regional pain syndrome (CRPS), but may also include ischemic limb pain and angina. There are scattered reports regarding the treatment of intractable pain due to other causes including visceral/abdominal pain, cervical neuritis pain, spinal cord injury pain, post-herpetic neuralgia, and neurogenic thoracic outlet syndrome. Experience suggests that, in selected patients, SCS can produce at least 50% pain relief in 50-60% of the implanted patients. Interestingly, with the proper follow-up care, these results can be maintained over several years.
Peripheral nerve stimulation (PNS) has been coming in favor with occipital nerve stimulation for the treatment of various headaches and neuropathic pain of the neck.
Drug Delivery Devices
Pain medication has been delivered by implantable pumps. Implantable pumps are surgically implanted into the area of interest and deliver the medication directly to a desired target. It enables a lower dosage to be administered and decreases, if not eliminate the side effects seen with systemic absorption.
Intrathecal implants are used in the treatment of various pain syndromes such as that associated with nerve injury or cancer pain, as well as for the treatment of spasticity seen with stroke and spinal cord injury patients.
Benefits: The goal of neurostimulation is to reduce pain, rather than to eliminate pain. It has been shown to have a 50% improvement in pain relief, reduce the use of more medications, and also allow the pursuit of a more active lifestyle which may have been hindered by the pain.
– According to a study conducted by North et al. in 2005, 47% of patients who received Spinal Cord Stimulation (SCS) found that it relieved their pain by 50% or more; this is significantly more than the 12% who achieved the same effect through reoperation. North RB, Kidd DH, Farrokhi F, Piantadosi SA. Spinal cord stimulation versus repeated lumbosacral spine surgery for chronic pain: a randomized, controlled trial. Neurosurgery. 2005;56:98-106; discussion 106-107.
-Recent systematic reviews of many trials with thousands of patients also verify the benefits of SCS. A 2005 review of 74 studies of 3300 patients with chronic leg and back pain and FBSS found that:
62% of implanted patients achieved at least 50% pain relief.
53% needed no analgesics post-SCS.
40% returned to work.
70% were satisfied with SCS.