Peripheral Nerve Field Stimulation

An Innovative Case Report Detailing the Successful Treatment of Post Thoracotomy Syndrome with Peripheral Nerve Field Stimulation

ABSTRACT

The detrimental effects of post-thoracotomy pain syndrome is experienced worldwide, however, an effective treatment regimen remains elusive (1).  Chronic post-thoracotomy pain syndrome is characterized by continuous burning and aching, with or without radiation, which persists along the thoracotomy incision site for at least two months following surgery, independent of the original condition requiring the thoracotomy.

The exact incidence of post-thoracotomy pain syndrome is unknown; however, a retrospective study demonstrates occurrence in more than 50% of cases (2).  The precise pathology of this chronic pain condition has been hypothesized with many possibilities and likely is caused by a multitude of mechanisms, including: direct trauma, compressive neuropathy, and stretch injuries to the intercostals nerves at the costovertebral junction.  Other proposed sources are chronic costochondritis, costochondral dislocation, intercostal neuroma, and nerve entrapment.

We report a case of post-thoracotomy pain syndrome effectively treated with peripheral nerve field stimulation (PNfS).

Key words: Post-thoracotomy pain syndrome, peripheral nerve stimulation, spinal cord stimulation, chronic pain syndrome, post-surgical pain.

CASE REPORT

We present a pleasant 61-year-old female with a long-standing history of post-laminectomy syndrome and more recent onset of post-thoracotomy syndrome.  The patient sustained a fall three years prior, which resulted in multiple rib and vertebral fractures requiring her initial lumbothoracic surgeries.  One year following, the patient developed a spontaneous vertebral compression fracture with cord compression, lower extremity weakness, and severe pain requiring a thoracic corpectomy and revision of her previous fusion.

The patient soon after developed symptoms of persistent “burning” and sharp pain in the area of surgical incision with radiation to the bilateral lower extremities.  The pain persisted and worsened until the pain became unbearable and the patient was referred to a pain specialist.

On the day of initial presentation, the patient rated her pain as VAS 10/10, burning, throbbing, and sharp, with radiation to the left lateral chest wall.  The patient’s point of maximum intensity was at and below her thoracotomy incision.  The patient was distressed about the persistent severity of the pain as well as the chronic use of oral pain medications.  After a spinal MRI was performed to rule out other causes of her pain, the option of spinal cord stimulation was discussed.  However, due to a large scar from her sacrum to her high thoracic region from her recent thoracolumbar fusion with corpectomy, and because of the patient’s previous spine fusion, the patient was deemed too risky for a standard epidural spinal cord stimulator (SCS) trial.  However, percutaneous peripheral field stimulation was thought to be a suitable and safe option.  The patient was scheduled for a peripheral nerve field  stimulator trial under fluoroscopic guidance.

On the day of her trial, the patient was taken to the procedure suite and placed in the prone position with appropriate monitoring and mild sedation.  The patient was prepped and draped in a sterile fashion.  Under fluoroscopic guidance, a large laminectomy defect from the mid-lumbar region to the mid-thoracic region was confirmed as well as fusion from L3-T9, leaving no obvious place for centrally placed spinal cord stimulator leads without risk to the patient.  Percutaneous peripheral lead placement was then initiated adjacent to her thoracotomy scar and worst pain.

After local anesthetic was injected, a 14-gauge St. Jude’s Medical Tuohy needle was advanced subcutaneously along the scar in the lateral left aspect where the patient complained of the most severe pain. An 8-contact St. Jude lead was advanced through the needle. Approximately two inches below, in parallel fashion to the initial lead placement, another 14-gauge Tuohy needle was advanced subcutaneously. An 8-contact electrode was then advanced through this needle.  The needles were removed and the leads were left in place. Both leads were turned on and the patient reported coverage over her most painful area, even more so, the pain had completely resolved.

Pressure was held over the needle entry location and steri-strips and a sterile Tegaderm was placed. The patient was then taken to the recovery room and monitored for 30 minutes prior to discharge.

Five days following the trial implantation, the patient returned to the office reporting 50-60% pain relief, VAS of 3-4/10, and stated, “I am very pleased with the results and am excited about the permanent stimulator.”   Of interest the patient only received relief from the more inferior lead and could not feel adequate stimulation or coverage from the lead placed at the level of her scar.

Two months later the patient was approved for and taken to the OR for permanent placement of the PNfS device.  The permanent placement involved two 8-contact electrodes, with one being placed two inches below the patient’s thoracotomy scar as previously done and one lead placed two inches inferior and parallel to the first lead.  The IPG was placed over the patient’s left buttock in standard position.  Upon follow-up the patient has reported even better coverage over her painful areas and admits to 80% and higher reductions in her painful symptoms.

DISCUSSION

Post-thoracotomy pain syndrome occurs in approximately 50% of patients after thoracotomy, with 5% of the afflicted patients describing it as severe and disabling (3).  In addition to the aforementioned pain, further physical detriments (pulmonary function and postoperative mobility) as well as psychological distress can lead to an increased morbidity to the patient (4).

The precise pathological lesion remains unclear, but synonymous data suggests that it is a combination of neuropathic (intercostal) and myofascial causes (5).  The majorities of patients report a mild to moderate pain level and can be most appropriately treated with conservative management.  However, it is the lesser segment of the population who develop a debilitating condition that requires further intervention.

Peripheral nerve field stimulation (PNfS) involves the subcutaneous placement of electrical leads over the patient’s area of pain.  An advantage of PNfS over SCS is the ability to place the lead directly adjacent to the affected nerve or painful area, improving the likelihood of sufficient nociceptive blockade.  This mechanism is exciting the pain medicine community because it offers the possibility of successful pain relief in a multitude of conditions that have typically been refractory to conservative medical management (6).  In theory, this is an excellent treatment option for patients suffering from post-thoracotomy syndrome who may not be candidates for spinal cord stimulation.

PNfS is a relatively new treatment. As a result, little evidence-based medicine supports its long-term efficacy. Nevertheless, it has relatively few contraindications and the majority of patients who undergo PNfS report a significant decrease in pain and the use of pain medication at 12 months following implantation. Therefore, PNfS may be considered an effective means to relieving pain and decreasing the use of pain medication, particularly opiates, in patients with post-thoracotomy syndrome.

CONCLUSION

Despite intraoperative methods that are implemented to reduce the risk of developing post-thoracotomy syndrome, post-thoracotomy syndrome can develop without reason, leaving a subset of patients refractory to conservative pain management and debilitated.

Although the data is limited, in the aforesaid case report, post-thoracotomy syndrome was effectively treated with the use of peripheral nerve stimulation.  This resulted in a significant pain perception reduction, increased quality of life and mobility, as well as decreased usage of oral pain medications.

In the future there will be a wider acceptance of the use of PNfS after further evaluation with large prospective studies because it is minimally-invasive, can be tested, is reversible in effect, and has adjustable settings.  These unique qualities may eventually make PNfS the preferred treatment modality for otherwise intractable conditions, such as post-thoracotomy syndrome.

References

  1. Bruno M. Strebel, MD; Steffen Ross, MD. Chronic post-thoracotomy pain syndrome. CMAJ. 2007 October 23; 177(9): 1027, 1029.
  2. Pluijms WA, Steegers MAH, Verhagen AFTM, et al. Chronic post-thoracotomy pain: a retrospective study. Acta Anaesthesiol Scand 200 6;50:804-8.
  3. Rogers ML, Duffy JP. Surgical aspects of chronic post-thoracotomy pain. Eur J Cardiothorac Surg 2000;18:711-6.
  4. Koehler RP, Keenan RJ. Management of postthoracotomy pain: acute and chronic. Thorac Surg Clin. 2006 Aug;16(3):287-97
  5. Karmakar MK, Ho AM. Postthoracotomy pain syndrome. Thorac Surg Clin. 2004 Aug;14(3):345-52.Paicius et al. Peripheral Nerve Field Stimulation in Chronic Abdominal Pain. Pain Physician. 3006;9:261-266