Today, she gets relief from an electronic device the size of a stopwatch that neutralizes pain signals at their source. The device, called a neurostimulator, is implanted surgically beneath the skin near her hip. It works by sending low-voltage electrical impulses directly to targeted nerves peripheral to her spinal cord.

Scientists believe these impulses activate the body's own pain-inhibiting mechanism, triggering certain nerve fibers to close a "gate" that ordinarily allows pain signals to reach the brain.

"It's like turning off the pain switch, in a very literal sense," said Dr. William O. Witt, the pain specialist who placed Underwood's implant in November 2007. Witt is director of the University of Kentucky's Interventional Pain Associates.
The stimulation of the nerves produces a tingling sensation, which Underwood describes as similar to “a foot that has fallen asleep.” The relief it provides, she says, is immediate and has remained effective for nearly a year so far.

"Anybody who has been through chronic pain knows it's all you can think about," Underwood said. "You can't do anything except deal with the pain. It becomes your whole life. With the implant, I can do pretty much anything I want. I can walk several miles at a time. I can exercise. I can sit down."
Once worried that her injury would prevent her from ever becoming a mother, Underwood and her husband now expect their first child at the end of the year.

"That's probably the best indicator of just how much this implant has changed my life for the better," she said.
Electronic nerve stimulation has been used for pain control since the mid-1970s. It has come into prominence in the last several years, Witt said, because of significant advances in product design and a better understanding by physicians of how to identify patients for whom the treatment is likely to succeed.

"One major advantage of this form of therapy is that, unlike most surgical procedures, it is possible to perform a trial prior to the implant," Witt said. "This way, the patient can experience the expected degree of pain relief before committing to the procedure."
Witt defines a successful trial as one that produces a 70-80 percent reduction in pain without the use of analgesic drugs. After a successful trial, the surgery can be performed on an outpatient basis. The procedure carries minimal risks of complications, comparable to those of other common outpatient surgeries.

Underwood's implant is one of a new generation of devices that offers patients a greater degree of control over their own pain management than was previously possible. An external controller about the size of a cell phone allows Underwood to choose from several different programs, which vary the intensity, frequency and pulse-width of the stimulation.

"That is a huge benefit," Witt said, "Being able to 'dial in' the right level of stimulation not only gives better pain relief, but it puts the patient in control, giving them more autonomy and independence."

Witt began using neurostimulators in 1986 and has performed more than 1,000 procedures to implant similar devices. He views the new-generation implants as one of several emerging treatment modalities that have the potential  to revolutionize treatment of chronic pain, by reducing the dependency of patients — and  their doctors — on dangerous drugs.

Millions of Americans suffer from chronic pain, defined as moderate to severe pain lasting longer than three months without significant remission. It is a debilitating condition that greatly diminishes quality of life. In addition to the suffering the pain inflicts directly, it often limits patients' abilities to carry out normal work and family responsibilities or to enjoy leisure activities.

Attempting to treat chronic pain with opioid painkillers is a huge mistake that happens far too often, Witt said. These drugs are not particularly effective for pain caused by nerve injuries, and they carry significant risks for dependence and abuse. Even in cases where narcotics do provide relief, the body rapidly builds up tolerance, making them generally undesirable for long-term use. There is even a body of literature demonstrating that with long-term use, these drugs are capable of actually increasing the experience of pain, a phenomenon known as opioid-induced hyperalgesia.
Pain specialists work to educate patients about the many facets of pain management, Witt said. This often includes lifestyle adjustments, such as smoking cessation, weight loss and exercise. It may also involve medication, surgery, or some combination of treatments. But the first step in treating pain is to find out where it's coming from.

"Pain is typically a sign that there's something wrong going on in the body," Witt said. "The first responsibility of any physician is to look for the underlying cause. Before we start treating ‘pain’ it is critical to rule out medically or surgically correctible disease and to establish a diagnosis. Once a diagnosis is made, we have an arsenal of tools and techniques to help patients manage their pain and, in some cases, eliminate it."

Interventional Pain Associates is located at 101 Prosperous Place, Suite 335, in Lexington. For more information, or to schedule an appointment, please call (859) 323-7246.