Expanding the Horizon for Chronic Pain Patients: Advanced Spinal Cord Stimulator Technology Offers New Hope

Founded in 1993, Advanced Bionics Corporation, a Boston Scientific Company, has gained recognition as the manufacturer of the cochlear implant, which uses a sophisticated technology that delivers electrical stimulation to the auditory nerve to restore hearing. Five years ago, Advanced Bionics began exploring the feasibility of applying this technology platform to spinal cord stimulators. The company saw the possibility of creating a much more effective stimulator than conventional models, which use a less dynamic technology.

Since then, Advanced Bionics has developed the Precision™ spinal cord stimulator, for which it received FDA approval in April 2004. In the following article, physicians and patients discuss their experience with the new technology.

Physicians cite benefits of new technology

A solo practitioner, Louis Raso, MD, operates a full-service pain management clinic that provides both inpatient and outpatient invasive therapy for many acute and chronic pain syndromes. Raso believes that the Precision device provides a significant advance in stimulator technology.

Raso has implanted the unit with a wide variety of patients, from individuals who have undergone multiple back surgeries to those with Parkinson’s disease. “I have seen very positive outcomes with the Precision device,” he says. As an example, Raso cites the case of a 30-year-old patient with fractures and fusions in both ankles who had been confined to a wheelchair and became ambulatory after the implant. Raso also notes that many of his chronic pain patients have greatly reduced their use of medications after the implant, an outcome that not only benefits the patients’ health but also helps lower care costs.

Over the past 10 years, Daniel Bennett, MD, DABPM, has witnessed the evolution of spinal cord stimulation from both a research and clinical perspective. In addition to conducting research in neuromodulation, he operates a private practice at the Integrative Treatment Center in Denver, a multidisciplinary spine/pain center.

Bennett has used the Precision technology to treat multiple forms of neuropathic pain, including complex regional pain syndrome (CRPS), diabetic neuropathy, dorsal nerve root injuries and failed back surgery syndrome.

To illustrate the benefits of the Precision system, Bennett describes its use with patients suffering from CRPS. “Typically, these patients have one or two extremities that are swollen and burning like fire,” he says. “Consider the situation of a patient who can’t lay his arm on the table because it hurts so much. With the previous technology, we would need to thread in the leads and install an antenna; you can imagine how painful this would be for such a patient. By contrast, the Precision mechanism does not require an antenna but instead uses a remote control to make adjustments. In addition, we have observed that the Precision system covers the patient’s pain 25 to 30 percent better. And, this technology provides coverage of both upper and lower extremities with one device. ”

Bennett also notes that the simplicity of the device helps alleviate the concerns of older patients who tend to be uncomfortable with technology. “I was discussing the Precision system with a 67-year-old patient who has CRPS,” Bennett explains. “She was very nervous about the fact that she would need to program the device. We arranged for her to talk with another CRPS patient who was programming her own Precision system.

As the current user described the experience step-by-step, the new patient realized, ‘This is easy, it’s just a matter of pushing a couple of buttons,’ and her fears were put to rest.”

Benchmark study focuses on relief of low back pain

With the features provided in the Precision system, Advanced Bionics has identified the opportunity to address one the most thorny areas of pain management: lower back pain. “Historically, it has been very difficult to achieve significant relief for these patients with a stimulator,” says study coordinator Jim Thacker.

In December 2004, Advanced Bionics launched a benchmark study to determine the efficacy of their device in relieving primary or secondary low back pain. “We hope to prove that the Precision unit is effective both in locating the exact ‘hot spot’ of the pain as well as in providing long-term relief,” says Thacker.

The two-year study is being conducted at 28 sites across the continental United States. Two hundred patients will be enrolled, comprising 180 recipients of permanent implants and an observation group of 20 patients without stimulators. Participants will be assessed for 12 months after receiving the permanent implant. Proof of efficacy requires demonstrating a trial-to-implant ratio of greater than 50 percent. Currently, the study is on target to achieve a ratio of 70 percent or greater.

Both Raso and Bennett, who head up clinics engaged in the study, are hopeful about the potential of the Precision device to relieve low back pain. Raso notes the case of a 29-year-old policeman with lumbar radiculopathy and intractable lower back pain. For nine months, the patient had been unable to work, even at a desk job. He was strongly opposed to having fusion because it would result in such decreased mobility that he would not be able to return to work as an officer. “He had a young family,” Raso relates. “He wanted to get back to his job, to be able to support them. After receiving the Precision implant, he received such relief that he’s now back on the street force full-time.”

Study uses BHI™ 2 test series to effectively measure outcomes

In selecting measurement tools for the benchmark study, Bennett strongly supported the use of the BHI 2 (Battery of Health Improvement 2) test and the shorter version of this assessment, the BBHI™ 2 (Brief Battery of Health Improvement 2) test. These instruments evaluate physical, psychological and social factors commonly associated with pain patients.

“I had become very familiar with these tools in both clinical and research settings,” says Bennett. “I felt that they would be well-suited to this study because, unlike other instruments used to assess pain, these tools are normed on injury and pain patients.”

“The BHI 2 test series makes the study possible,” says Thacker. “Our goal is to measure the efficacy of the therapy and we can’t do that without reliable measurement tools. These assessments provide well-validated, proven instruments and, most important, there are no other tests on the market that cover Biopsychosocial as thoroughly.”

The study also uses a prototype of the Momentary Pain Scale, which is currently in development. Whereas the BHI 2 and BBHI 2 tests employ a 0-to-10 pain scale that evaluates the patient’s pain over the course of a month, this latest addition to the BHI 2 test series includes a 0-to-10 scale that measures pain on an immediate basis.

Bennett emphasizes the value of the BHI 2 and BBHI 2 tests’ brevity. “When you are conducting research with a pain population, you don’t have the luxury of administering four or five hours of testing to find out everything you need to know,” he says. “These patients typically have a very limited ability to concentrate and to sit for a long period of time. The BHI 2 test series enables us to gather a broad range of information quickly.”

The BBHI 2 test is used initially to qualify candidates for inclusion in the study. Once the patient is admitted into the study group, the BHI 2 instrument is administered to set a baseline. Three months after the permanent implant, the patient is given the BBHI 2 test to measure progress. At six and 12 months, the patient retakes the BHI 2 test and results are compared to the baseline to measure progress over time.

Study participants take the assessments using the PAD, a hand-held electronic device. “The touch screen and large-type format of the PAD make test-taking much easier for pain patients, especially those who are unable to hold a pen,” says Bennett. The PAD works particularly well for study purposes, Raso notes, because the information input by the patients feeds directly into the central research data bank.

BHI™ 2 test series useful in a variety of applications

Raso administers the BHI 2 test to many of his chronic pain patients, not only those involved with the study. He finds the test beneficial in demonstrating therapy efficacy for insurers, many of which require a psychological assessment prior to any kind of implantable pain therapy. “The BHI 2 test is an especially effective tool for demonstrating efficacy because it assesses pain in specific areas of the body,” he notes.

Raso also considers the BHI 2 test’s 0-to-10 pain scale to be helpful in determining appropriate candidates for therapy. “For example, if a patient reports that they are experiencing a pain level of 10 in multiple areas of the body, there is probably no therapy that is going to satisfy this individual,” he says. “Or, if a patient reports that their lowest tolerable pain level is a 2, it’s unlikely that any device is going to benefit them.”

In addition, Raso likes the fact that the BHI 2 instrument compares patients to other individuals with similar injuries. And, he has discovered that the test’s anxiety and depression scales often help uncover the root source of the problem. “Sometimes, if you simply treat the patient’s anxiety or depression you have addressed the real issue, without needing to do anything anatomically.”

Like Raso, Bennett uses the BHI 2 test series regularly in his clinical practice to identify underlying issues. “We physicians tend to look at

patients in the context of pathology,” he says. “She’s a ‘gall bladder,’ he’s a ‘failed back.’ We sometimes forget that there’s a person inside there living with the pathology—and if you don’t treat the whole person, you’ve missed the boat. The BHI 2 and BBHI™ 2 tests are very effective in helping us understand the person behind the pathology.”

Technology to help restore lives

As practitioners who work daily with chronic pain patients, both Bennett and Raso are excited about the outcomes they have witnessed with the use of the Precision device. “I treat people who have lost the ability to walk, to work, to participate in family activities,” says Raso. “With the availability of this technology, I am now able to say to my patients: ‘I will give you your life back.’”

For more information, go to www.advancedbionics.com.

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