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ANALGESIA

Neuromodulation in Patients Deployed to War Zones

Anthony Dragovich, MD^*, Thomas Weber, DO^*, Daniel Wenzell, MD, Michael H. Verdolin, MD, and Steven P. Cohen, MD^||

From the *Department of Surgery, Womack Army Medical Center Ft. Bragg, North Carolina; Department of Surgery, Madigan Army Medical Center, Tacoma, Washington; Department of Anesthesiology, Naval Medical Center San Diego, San Diego, California; Departments of Anesthesiology and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland; and ||Department of Surgery, Walter Reed Army Medical Center, Washington, DC.

Address correspondence and reprint requests to Anthony Dragovich, MD, 25 Bay Point, Sanford, NC 27332. Address e-mail to dragov3{at}mac.com.

Abstract

Four active duty military personnel and two retired soldiers/military contractors were treated with spinal or peripheral nerve stimulators. All six personnel were able to deploy after the stimulators were placed. Five patients had no incidents during their deployments. One patient completed four deployments but had mechanical complications that necessitated eventual revisions.

Considering the risks and limitations of reoperation, nerve blocks, and pharmacotherapy in a forward-deployed area, spinal cord stimulation provides an appealing alternative in soldiers who desire to remain deployable on active duty.

Spinal cord stimulation (SCS) has been used to treat chronic pain syndromes for more than 40 yr. Since the first description by Shealy et al.1 in 1967, numerous clinical and technologic improvements have been made. Most studies published in the 1970s and 1980s reported success rates of approximately 40%.2 These high failure rates could generally be attributed to a combination of factors, including mechanical failures, surgical complications, and poor patient selection. However, improvement in all of these areas has dramatically increased success rates. In a systematic review of patients with complex regional pain syndrome and failed back surgery syndrome, Taylor et al.3 reported that 62% of patients experienced a significant reduction in pain, 40% returned to work, 53% discontinued analgesics, and 70% were satisfied with treatment.

Notwithstanding these advances, SCS is still considered by many to be a last resort for patients who have failed all other treatment modalities. There are no reports of any patients returning to physically strenuous occupations after SCS implantation. In fact, many physicians consider SCS a relative contraindication to vigorous physical activity. This is one reason many patients opt for repeat spinal surgery rather than SCS despite evidence demonstrating SCS may be superior to reoperation.4 The reluctance to implant physically active patients is not unreasonable considering that the complication rate from technical problems, such as lead failure, migration, or fracture, ranges between 8.3% to 42.8%, with many attributed to falls or excessive activity.5,6

The current operations in Iraq and Afghanistan have produced unique medical challenges in pain medicine. Soldiers are surviving more severe injuries that leave them with residual pain and disability. Due to advances in medical science and the physical and mental fortitude of our soldiers, many previously career-ending and life-altering disabilities have been overcome. Many soldiers desire to remain in military service, but unremitting pain is often the last standing hurdle.

There are several treatment options in patients with chronic nonmalignant pain, but few are conducive to the physically and mentally demanding lifestyle of service personnel. In this article, we report five cases from our treatment records in which service personnel or contractors deployed or were preparing to deploy to a combat zone with a SCS, and one case whereby a marine was treated with occipital nerve stimulation for headaches sustained after an improvised explosive device injury and subsequently redeployed to Afghanistan. These are the only known cases of neuromodulation use in deployed personnel. This case series has been approved for publication by the Womack Army Medical Center IRB (Table 1).

CASE HISTORIES

Case 1
A 37-yr-old male soldier left active duty to join the army reserve in 2002. In the 18 mo before exiting active duty, he underwent an L5-S1 discectomy for radiculopathy and subsequent spinal fusion after his pain failed to resolve. After his surgeries, he was maintained on gabapentin and oxycodone as needed, with moderate relief. While in the reserves, he continued to work full-time as a supervisor in a supermarket. In 2003, his pain began to worsen. His pain was predominantly in his left leg, with associated tingling but no weakness. He sought help from a civilian pain specialist who, in 2004, placed a single lead SCS after multiple failed trials with adjuvants and nerve blocks.

In 2006, the soldier’s military police unit deployed to Afghanistan. At the time, he was taking venlafaxine and hydrocodone once or twice a month as needed, and using the SCS for up to 2 h several times per week. After consultation with his civilian and military physicians, he elected to accompany his unit. He completed a 12-mo deployment with only one visit to a battalion surgeon for back pain, which was treated with a nonsteroidal antiinflammatory drug.

Case 2
A 26-yr-old woman sailor sustained a sports injury to her left ulnar nerve at the elbow. The patient was treated with an ulnar nerve repair and transposition that was complicated by the development of complex regional pain syndrome II. Subsequent treatment with stellate ganglion blocks, multiple neuropathic and opioid pain medications, and physical therapy, failed to provide her with significant relief.

Two months after her surgery, a cervical SCS was implanted, which reduced her pain from 8/10 to 2/10 and enabled her to discontinue opioid therapy. Eight weeks later she was sent on an overseas assignment to Japan. One-year postimplant she was pain-free and in the process of applying to dive school.

Case 3
A 32-yr-old Marine sustained a fragmentation injury secondary to an improvised explosive device. The fragments traveled through his neck to the base of his brain, lodging next to the right vertebral artery. The patient suffered from severe headaches, but was deemed to be a poor surgical candidate because of the location of fragments in the circle of Willis. Medical management with opioids, nonsteroidal antiinflammatory drugs, and adjuvants was unsuccessful. An atlanto-axial joint injection resulted in 2 wk of pain relief, with contrast injection outlining the fragment and vertebral artery. The injection was not repeated due to distorted anatomy and transient benefit. Occipital nerve blocks and subsequent occipital nerve radiofrequency ablation also provided only short-term relief. An occipital stimulator trial conducted with ultrasound guidance to map the occipital nerve and vessels resulted in excellent pain relief. He was implanted with two octopolar leads. Activation of the stimulator alleviated the headaches. He redeployed to Iraq with his unit 8 mo postimplant, fulfilling his tour of duty without incident.

Case 4
A 33-yr-old man with a long history of radicular back pain was status post failed L5-S1 discectomy. Subsequent treatment with epidural steroids, lumbar facet radiofrequency denervation, and opioid and non-opioid pharmacotherapy failed to alleviate his symptoms. In 2004, he was boarded out of the army.

Shortly after discharge from the army, he underwent SCS implantation and was able to be weaned from all opioid and non-opioid medications. Within a year, he deployed to Iraq as a civilian contractor. In Iraq, he fell out of a transport truck and experienced a recurrence of his axial and lower extremity symptoms requiring evacuation to the United States. During a pain clinic consultation, his SCS was reprogrammed, and he was restarted on low-dose opioids.

He subsequently deployed for 4–6 mo on 3 more occasions. After his fourth deployment he was again seen in the pain clinic with increased pain. The generator was found to be nonfunctional upon interrogation. He underwent two surgical revisions but eventually had the entire system replaced with a dual octrode arrangement and a rechargeable generator. At his last interrogation, he was found to be using the stimulator 87% of the time. He continues to have severe pain despite high dose-opioid use. He was subsequently diagnosed with posttraumatic stress disorder and spent 9 wk in an inpatient facility last year.

Case 5
A 48-yr-old male military contactor with low back pain, status post laminectomy had spinal fusion 7 yr earlier that was complicated by cauda equina syndrome. His initial symptoms included a marked decrease in sensation in the perineum and bilateral lower extremities, along with urinary hesitancy. Over time he regained some sensation but continued to experience a constant dull, throbbing pain bilaterally in his low lumbar region, perineum and lower legs, rated between 5 and 8 of 10. The urinary hesitancy did not improve. Gabapentin and hydrocodone provided him with some relief, but he had difficulty performing his job secondary to medication-induced cognitive dysfunction. Tramadol, duloxetine, nortriptyline, and nonsteroidal antiinflammatory drugs provided no relief.

In an attempt to improve his pain control and decrease his medication usage, he underwent a SCS trial that successfully reduced his back pain by 50% and his leg pain by 90%. A permanent SCS was implanted in October 2007. By December 2007, he was able to be weaned from all pain medications and reported a 60% reduction in pain. He deployed to Iraq in February of 2008 and successfully completed an uneventful 6-mo tour of duty that included "multiple combat related missions and sleeping on rocks." He currently takes tramadol as needed for groin pain but his back and leg symptoms are well-controlled with the SCS.

Case 6
A 29-yr-old active duty man in a special forces unit suffered a severely sprained right ankle while training for a marathon. He was treated with standard conservative therapy but failed to improve. Four months postinjury he developed progressively increasing allodynia enveloping his right foot and lower leg without sudomotor or vasomotor changes. Further studies, including a triple-phase bone scan, computed tomography scan, and eletromyogram, failed to reveal an etiology. A diagnostic lumbar sympathetic block relieved his symptoms for 2 wk. A second lumbar sympathetic block was performed but provided only 1 wk of relief. Multiple medication trials either failed to relieve his pain or were discontinued secondary to side effects. After a successful trial, a SCS was implanted in December 2006. This relieved his pain by 50%.

The soldier deployed to Iraq in early 2007 with a self-modified uniform that allowed him to easily change stimulator programs (Fig. 1). He completed a physically demanding 6-mo deployment without complications or need of medical resources. Since his return, he continues to perform all his duties, which include long road marches with heavy ruck sacks, running, scuba diving, and rock climbing.

View larger version (108K): [in this window] [in a new window]   Figure 1. Antenna pouch mounted to trousers with antenna in (top) and out (bottom) to demonstrate position. The antenna is held inside the pouch by hook and loop fasteners on the inner sides of the pouch.

DISCUSSION

A major dilemma faced by medical officers is how to control chronic pain in a motivated soldier who might otherwise be an asset to his unit. SCS has been successfully used to treat war injuries,7 but in the military community it is widely acknowledged that neuromodulation renders a serviceman nondeployable. Yet, the convergence of several factors, such as technological advances in equipment, more refined selection criteria (Table 2), forward-deployed medical assets, and the unique value of veteran soldiers with combat experience, have led some specialists to reexamine this premise.

In this series, we present six cases that demonstrate SCS can be a viable option for motivated patients in a physically and mentally challenging environment. The use of SCS becomes even more conceptually appealing when one considers the limitations of alternative therapies. The use of nerve blocks in theaters of operation is limited by the lack of trained personnel outside of combat support hospitals and the need for repeated treatments. Pharmacotherapy has similar downsides in that all neuropathic pain medications have the potential to cause lethargy and cognitive dysfunction, which can endanger lives in combat situations.

The use of opioids can pose particularly daunting challenges in austere environments. By their depressant effects on the central nervous system and hypothalamic-pituitary-adrenal axis, opioids can cause depression, lethargy, cognitive impairment, impaired wound healing, immunosuppression, and loss of muscle mass, all of which may place soldiers at increased risk of injury.8,9 If opioids are lost, stolen or unable to be refilled, withdrawal can occur in a hostile environment. Even under the best of circumstances, less than half of patients with noncancer pain treated with opioids will obtain long-term benefit, and 25% will experience significant adverse effects.9 All of these factors make opioids and high doses of adjuvants poor choices in soldiers preparing for deployment.

In view of the risks and limitations associated with more conventional pain treatment, SCS seems to be an attractive choice for motivated soldiers who wish to remain deployable. In a 22-yr retrospective review in 410 patients with chronic pain treated with SCS, Kumar et al.10 found significant improvements in mood, sleep, and energy levels sustained throughout the mean 97-mo follow-up period. After weighing the risk: benefit ratio of SCS to other therapies in soldiers with chronic pain wishing to stay on active duty, we believe the scales tilt in favor of SCS in carefully selected patients.

Although the average follow-up was only 24 mo in our series, the potential for SCS to enable soldiers and other patients in physically demanding occupations to meet their occupational goals should be strongly considered in patients who fail other treatments. Five of the six patients did not have any mechanical complications during the deployment. None of these patients could have deployed before placement of the SCS, and all five successfully completed their tour of duty with minimal need for medical resources. Case 4 illustrates that this treatment is not without potential complications. Patient selection is of paramount importance in selecting SCS candidates, and a 6-mo trial period whereby a soldier with a stimulator engages in training that simulates his deployment duties might reduce the risk of pain recurrence or mechanical malfunction necessitating medical evacuation. The failed deployment of patient 4 underscores the inherent risk of reinjury any time a person is engaged in a physically demanding environment.

In conclusion, this small series suggests that SCS should be considered in motivated patients who suffer from chronic pain and wish to return to physically strenuous occupations. Both the patient and treating physicians should be aware of the limitations and potential complications of dorsal column and peripheral nerve stimulators. However, with appropriate selection criteria, SCS can be a life-altering therapy that enables soldiers and other patients to achieve their professional goals.

Footnotes

Accepted for publication January 7, 2009.

Anthony Dragovich is currently at TF 10, Ibn Sina Hospital, Baghdad, Iraq, APO AE 09348, until June 2009.

REFERENCES

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Google Scholar Articles by Dragovich, A. Articles by Cohen, S. P. PubMed PubMed Citation Articles by Dragovich, A. Articles by Cohen, S. P. Related Collections Pain Medicine Pain Technology