Successful Treatment of Chronic Neuropathic Pain With Subcutaneous Peripheral Nerve Stimulation: Four Case Reports
Mazin Al Tamimi, MD, FIPP* † · Heather Rachel Davids, MD ‡ · Matthew M. Langston, MD ‡ · Jason Krutsch, MD † · Alexander Yakovlev, MD § · Giancarlo Barolat, MD
*Colorado Spine and Pain Management, Littleton, CO, USA; † University of Colorado School of Medicine—Anesthesiology, Aurora, CO, USA; ‡ UCHSC—Pain Medicine, Aurora, CO, USA; § Comprehensive Pain Management of the Fox Valley, Appleton, WI, USA; and ¶ The Barolat Institute, Lone Tree, CO, USA
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ABSTRACT
Introduction. Chronic pain is a prevalent medical condition in the general population and is one of the most common reasons patients visit their primary care doctors. When the pain is resistant to the common treatment modalities, it presents a challenge for the physician and may have profound consequences for the quality of life of the patient. Methods. We present four case reports in which subcutaneous peripheral nerve stimulation was successfully used to treat chronic neuropathic pain after all other treatment efforts had failed. Results. In all cases, the patients underwent a trial of peripheral nerve stimulation with good results. The patients reported decreased use of pain medications, increased quality of life, and high satisfaction with the procedure results. Conclusion. The use of subcutaneous peripheral nerve stimulation as a viable treatment alternative in certain cases of chronic neuropathic pain should continue to be rigorously evaluated.
KEY WORDS: Interscapular pain, neuropathic pain, peripheral nerve stimulation, post-herpetic neuralgia, post-thoractomy pain.
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Introduction
Chronic pain is a prevalent problem in the general population (1) and is one of the most common reasons that prompts patients to visit their doctors (2). The pain that is resistant to typical treatment modalities presents a challenge for the physician and may have profound consequences for the quality of life of the patient. Once the patient fails initial conservative treatment, such as medical management, physical therapy, and a transcutaneous electrical nerve stimulator (TENS) unit trial, the treatment plan may progress to interventional options such as epidural injections or nerve blocks. In the event that these options fail, if appropriate, the pain specialist may opt to treat with spinal cord stimulation (SCS); however, in many cases, the location of the pain is not conducive to treatment with SCS. Anatomically, placement may bedifficult or it may be impossible to cover the full area of pain (3). Or, the treatment will simply fail. In some cases, subcutaneous peripheral nerve stimulation (PNS) may be a viable treatment option that should be considered when other treatments fail or as an alternative to other treatments such as SCS.
We present four case reports of various presentations of patients with chronic neuropathic pain who were successfully treated in the University of Colorado Health Sciences Interventional Pain Clinic with subcutaneous PNS after all other treatment efforts failed. The cases we report cover a variety of scenarios: one case of interscapular neuropathic pain, two cases of post-thoracotomy pain, and one case of post-herpetic neuralgia (PHN). In each of these cases, the pain was persistent and refractory to all other treatment methods initiated. After appropriate evaluation, each patient underwent a subcutaneous PNS trial of a short duration with follow-up of permanent placement. Reports in the literature discussing using subcutaneous PNS for similar cases range from scant (interscapular pain, PHN) to unavailable (post-thoracotomy pain). In each case reported in this article, treatment with subcutaneous PNS proved to be an effective option.
Case Reports
Case 1
A 47-year-old woman with a diagnosis of interscapular neuropathic pain had failed all efforts at conservative treatment including medical management, an intercostal nerve block, trigger point injections, a facet block, and a TENS unit trial. A botulinum toxin injection was denied by insurance. After evaluation by a pain psychologist, the patient underwent a subcutaneous PNS trial in which two Precision octopolar nerve stimulator leads (Advanced Bionics, Valencia, CA, USA) were placed in the subcutaneous tissues targeting the epicenter of the patient’s pain corresponding with the dermatomal distribution of T3, T4, and T5. The leads were placed percutaneously via 14 g Touhy needle. During the ten-day trial, she reported a pain level of 0–1 on a visual analog scale (VAS; pain level before the trial was 6/10). We then pursued permanent implantation of the two Precision nerve stimulator leads. When taken back to the operating room, the pain fields were mapped and were found to be very close to the area that was previously covered with the trial stimulator leads. A 2-cm incision was carried down into the subcutaneous and subdermal fat layer through an area of local anesthetic infiltration in the tissue inferior to the right medial scapular border. Next, a 14-gauge Tuohy procedure needle was advanced through the subcutaneous tissue in a cephalad direction until the tip was in the superior most margin of the pain field. An Advanced Bionics (Valencia, CA) 50-cm, eight-contact lead was advanced through the procedure needle. This process was repeated in an identical fashion along a parallel trajectory approximately 2 cm lateral to the previous lead. Both procedure needles were withdrawn so as to avoid dislodging the leads. Each lead was connected to an intraoperative stimulator cable and stimulator testing confirmed good coverage of the area of pain. Using 0 silk ties, each lead was anchored in two places to the underlying fascia. Using a 14-gauge procedure needle, a subcutaneous tunnel was developed from the medial incision to the lateral incision. A pocket was developed above the gluteal area for implantation of an implantable pulse generator (IPG). A tunneling device was used to connect the lateral incision to the IPG site. The leads were passed through the subcutaneous tissue so that they exited the IPG site wound. The leads were cleaned and connected to the IPG. Continuity was tested and the wounds were copiously irrigated with bacitracin solution and then closed in multiple layers. Using a VAS, the patient reported an improvement from 7/10 before the procedure to 0–1/10 of her pain level afterward. Since the permanent subcutaneous PNS placement, we have been able to discontinue all narcotic and sleep aid medications. One year after the permanent placement, the patient continues to report improved functionality and high satisfaction with the results. Figure 1 shows the lead placement.
FIGURE 1. Two octopolar nerve stimulator leads were placed in the subcutaneous tissues targeting the epicenter of the patient’s pain as seen on the x-ray.
We used the following programmed parameters:
Lead 1: Frequency 40 Hz, pulse width 740 msec, amplitude 2.4 mA
Lead 2: Frequency 40 Hz, pulse width 790 msec, amplitude 2.4 mA
Electrode polarities were set as follows:
First and second electrodes: 0(+) 1(-) 2(0) 3(-) 4(0) 5(-) 6(0) 7(-)
Case 2
A 65-year-old woman presented to Pain Clinic with complaints of chest wall pain status after a thoracotomy to perform a diaphragmatic placation. The patient’s pain was located in the anteriolateral chest and abdominal wall region. This patient failed treatment with medications, a TENS unit trial, and intercostal nerve blocks. After evaluation by a pain psychologist, she underwent an eight-day PNS trial, during which she reported significant pain relief (VAS 0/10) and dramatically improved sleep, mood, and activity level. Permanent placement with one Octrode lead and two Quattrode leads (Advanced Neuromodulation Systems, Plano, TX, USA) was then performed. The electrodes were placed subcutaneously over the area covering the epicenter of her pain. An ANS Eon IPG was placed in the left lower abdominal quadrant. The patient continued to report a greatly improved pain level after the permanent subcutaneous PNS placement. She rated her pain 0/10 on a VAS four weeks after the procedure. One and a half years after the procedure, the patient no longer requires treatment with narcotics and her use of antiepileptics has decreased significantly. The patient also reports increased quality of life and improved daily function. Figures 2 and 3 show the leads in place.
FIGURE 2. Image showing octopolar lead during permanent implant in the subcutaneous tissues on the anterior chest wall (anteroposterior).
We used the following programmed parameters:
Frequency 30 Hz, pulse width 150 msec, amplitude 3 mA
Electrode polarities were set as follows:
First electrode: 0(+) 1(-) 2(-) 3(-) 4(-) 5(-) 6(-) 7(-)
Second and third electrodes: 0(+) 1(-) 2(-) 3(-)
Case 3
A 40-year-old woman presented with PHN and complaints of right upper abdomen pain overlying the area corresponding to the intercostal nerves T7, T8, and T9. The pain was described as burning, throbbing, and was associated with allodynia. The patient failed conservative management including medications, a TENS unit trial, and intercostal nerve blocks which provided good but transient pain
relief. After appropriate evaluation by a pain psychologist, we proceeded with a peripheral nerve stimulator trial. Three Quattrode leads (Advanced Neuromodulation Systems) were placed in the subcutaneous plane overlying the dermatomal region of T7, T8, and T9 intercostal nerves. At the first follow-up visit, the patient reported that she was having irritation at the site of the T9 lead. We removed the lead which resolved the localized issue. At a ten-day follow-up visit, the patient reported significant pain relief (approximately VAS 2/10 post-procedure from 8/10 pre-procedure). She subsequently underwent permanent implantation of two Octrode leads overlying T7, T9, and rechargeable Eon IPG. At her last postoperative follow-up visit, six months after her implantation, she continued to report significant pain relief with a VAS of 4/10. She also reported improved sleep, function, and reduced need for pain medications. Figure 4 shows the trial leads in place. As mentioned previously, the lead placed in the T9 distribution was subsequently removed secondary to localized irritation.
FIGURE 3. Image showing Quattrode lead during permanent implant (lateral).
We used the following programmed parameters:
Frequency 25 Hz, pulse width 140 msec, amplitude 2 mA
Electrode polarities were set as follows:
First electrode: 0(+) 1(-) 2(-) 3(-) 4(-) 5(-) 6(-) 7(+)
Second electrode: 0(+) 1(-) 2(-) 3(-) 4(-) 5(-) 6(-) 7(-)
FIGURE 4. Three Quattrode leads during the trial overlying the area corresponding to the intercostal nerves T7, T8, and T9 as seen on the x-ray.
Case 4
A 35-year-old woman with a history of recurrent bilateral spontaneous pneumothoraces was treated by pleurodesis and with resultant post-thoracotomy pain bilaterally. She failed numerous conservative treatments which included medication management and local injections. However, she had excellent but transient relief from an intercostal nerve block. Similar results followed repeated intercostal nerve blocks. The insurance company denied pulsed radiofrequency treatment. We then offered the patient a subcutaneous peripheral nerve stimulator trial. Following psychological clearance, three quadripolar percutaneous leads (Quattrode, Advanced Neuromodulation Systems) were placed in the subcutaneous plane overlying the dermatomal regions of the pain (two on the right side and one on the left side). The ten-day trial provided the patient with significant relief with the VAS pain scale being reduced from 7–8/10 to 1–2/10. Permanent subcutaneous PNS placement was then carried out. Two leads were placed. One year after the permanent implant, she continued to have significant relief with a VAS pain score of 1–2/10 and no requirement for regular pain medications. Figure 5 shows left-sided leads in place.
FIGURE 5. Image showing two quadripolar percutaneous leads were placed in the subcutaneous plane overlying the dermatomal regions of the pain during permanent implant.
We used the following programmed parameters:
Frequency 15 Hz, pulse width 150 msec, amplitude 3 mA
Electrode polarities were set as follows:
First, second, and third electrodes: 0(+) 1(-) 2(-) 3(-)
Discussion
Chronic pain that is intractable to typical modes of treatment is a prevalent issue and has the potential to use large amounts of resources and money when there is no resolve. Once patients fail conservative modes of treatment, there should be consideration of various interventional methods including subcutaneous PNS. The cases reported here demonstrate that subcutaneous PNS can be a viable option in a variety of situations in which all other methods of treatment have been attempted.
In the first case scenario presented, subcutaneous PNS is used to treat interscapular neuropathic pain, a method rarely reported in the literature (4). In this case, the patient had very good results beginning during the trial period. Reduction of the pain leads to other benefits such as decreased dependence on opioids and sleep medications. In the second and fourth cases, we address postthoracotomy pain. Pain incidence after thoracic surgery is a common problem which often becomes chronic (5). The literature indicates that more than 50% of patients report post-thoracotomy pain that persists greater than one year (6,7). Although SCS has been used to treat postthoracotomy pain (8), there are no literature reports of which we are aware that discuss successful treatment with
subcutaneous PNS. In the event that SCS cannot cover the pain adequately (3), subcutaneous PNS holds promise for an effective alternative in these debilitating cases. In the third scenario addressing PHN, there are, once again, numerous literature reports documenting use of SCS (9,10), but there are few literature reports using subcutaneous PNS (11). PHN is notoriously challenging to treat. In this case, the effectiveness of various treatments may depend on the location of the pain. It is well described that coverage of chest and abdominal wall pain is sometimes difficult to obtain with SCS. In these instances, subcutaneous PNS may not only be an alternative, it may, in appropriate instances, be considered before SCS.
Because of the multifactorial nature of chronic pain, many of the patients who present with chronic pain complaints have endured extensive workups, taken numerous medications and dealt with inevitable side-effects, and undergone invasive procedures and/or surgery. Additionally, psychological and sleep issues become a part of the tapestry of complaints that must be addressed if the chronic pain is to be effectively treated. Not unlike the typical evaluation that is initiated before placing a SCS, an appropriate evaluation of patients with the assistance of a behavioral psychologist before considering making the recommendation of subcutaneous PNS placement is highly recommended. In an ideal situation, resolve of the chronic pain using subcutaneous PNS will also alleviate the need for antidepressants and/or sleep aids.
In all cases, we choose to use percutaneous leads vs. paddles because it is less invasive and can cover a wider area of pain coverage. In cases that the patient may need revision of percutaneous permanent leads because of reduced effectiveness, it may be more appropriate to utilize paddle leads.
From our experience over the last four years of placing peripheral nerve stimulators for intercostal neuralgia or chest wall pain, we have not had any lead migration. We usually use strain relief loops and anchors when securing the leads in all the cases.
We have found that there has been excellent efficacy with the use of subcutaneous PNS for chronic neuropathic pain regardless of whether it is bilateral, multiple, or single intercostal nerve involvement but with moderate efficacy for PHN cases.
In some cases, it may be appropriate to not relegate subcutaneous PNS to a last resort treatment. Instead, it may be advisable to consider subcutaneous PNS before SCS in cases where paresthesia coverage is notoriously difficult to achieve with intraspinal leads. More research with a greater number of patients and long-term follow-up needs to be done to determine long-term efficacy of the subcutaneous PNS as well as optimal treatment conditions.
Conflict of Interest Statement
Authors have declared no conflicts of interest.
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