Implantable Devices in Select Pain Conditions
Implantable devices are being used with increasing frequency to treat chronic pain conditions.1-3 Technology continues to evolve, permitting a greater number of patients to benefit from spinal cord stimulation, which involves use of a device consisting of a set of implanted electrodes that works to mitigate pain at the dorsal horn of the spinal cord. Indications surrounding chronic pain now enable patients who had previously been excluded from consideration to benefit from the analgesia provided by these devices. Outcome measures and sustained pain relief data now span years, making this a promising area for innovation. In well-designed prospective clinical trials, these technologies are proving more cost effective than repeated nerve blocks in patients with select pain diagnoses.4-5 Neuromodulation has also been proven efficacious and is most cost effective when used soon after the diagnosis of complex regional pain syndrome,6 a pain condition that can develop after a seemingly trivial trauma to an extremity.
We encourage patients with implantable pain therapies to become educated about diagnostic testing that may interrupt therapy. The use of magnetic resonance imaging (MRI) in the presence of implanted pain devices should be assessed on a per-case basis. Some devices permit MRI of the entire body, while others can work in the presence of imaging of select body parts. Some devices do not allow MRI at all. Some intrathecal drug pumps require reprogramming after an MRI, while others require removal of the medication reservoir around the time of imaging.
If faced with a patient who may need to undergo MRI, each manufacturer maintains a support hotline accompanied by a national patient roster staffed to answer these questions. The implanting physician can also provide guidance, and select patients may be required to visit the pain center to make adjustments to the implanted hardware around the time of obtaining advanced imaging.
An Injection or Device is Not Right for Everyone
Patient selection is perhaps the most critical factor when considering candidates for interventional pain therapies. Selection does not only include medical comorbidities but also an assessment of patient expectations, a risk-benefit analysis, and a pain diagnosis. Choosing a treatment for nociceptive pain offers little benefit to a patient with a neuropathic pain condition; this underscores the importance of obtaining an accurate diagnosis.
Coexisting psychiatric diagnoses can complicate a pain assessment. An assessment of conditions such as psychosis and suicidal thoughts is also necessary. Select medical treatments for pain carry black box warnings for suicidality, while the n-type calcium channel blocker ziconotide has been associated with increased psychotic episodes in patients with a history of psychosis. Black box warnings also exist for several commonly used antiepileptic drugs and antidepressants used as pain treatment adjuncts.
The quality of evidence in support of techniques for the treatment of chronic pain continues to develop. Payors are recognizing the cost savings attributable to the use of interventional therapies compared with medications or surgery. These savings are primarily realized by decreasing healthcare utilization and will become increasingly important as more patients join Accountable Care Organizations that provide lump sums of payments to treat discrete diagnoses or episodes of care.
With more than 100 million patients suffering from chronic pain, collaboration between an interventional pain physician and a PCP represents an opportunity to optimize care for patients presenting with acute or chronic pain conditions. Both clinicians benefit from bidirectional referrals, enabling practice growth while patients enjoy improvements in functional pain outcomes. Much the way that physicians utilize multimodal pain therapies with cumulative benefit, patients benefit from multidisciplinary teams addressing the same complaint with diverse funds of knowledge.
2. Van Buyten J-P, Al-Kaisy A, Smet I, Palmisani S, Smith T. High-frequency spinal nerve stimulation for the treatment of chronic back pain patients: results of a prospective multicenter European clinical study. Neuromod Tech Neural Interface. 2013;16(1):69-66.
3. Al-Kaisy A, Van Buyten J-P, Smet I, Palmisani S, Pang D, Smith T. Sustained effectiveness of 10 kHz high-frequency spinal cord stimulation for patients with chronic lower back pain: 24-month results of a prospective multicenter study. Pain Med. 2014;15(3):347-354.
4. Kumar K, Taylor RA, Jacques L, et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a multicentre randomised controlled trial in patients with failed back surgery syndrome. Pain. 2007;132:179-188.
5. Poree L, Krames E, Pope J, Deer TR, Levy R, Schultz L. Spinal cord stimulation as treatment for complex regional pain syndrome should be considered earlier than last resort therapy. Neuromod Tech Neural Interface. 2013;16:125-141.