Peripheral nerve stimulation may help manage neuropathic pain in injured soldiers

Anesthesia & AnalgesiaMar 22 2012

An peripheral nerve stimulation technique may be a valuable new approach for relief of severe neuropathic (nerve-related) pain in injured soldiers, reports an article in the March issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).

Peripheral nerve stimulation provides good short-term control of neuropathic pain related to combat injuries in soldiers who aren't candidates for more definitive treatment, according to the report by Dr Michael Kent and colleagues of the Department of Anesthesiology at Walter Reed Army Medical Center, Rockville, Md.

Peripheral Nerve Stimulation Shows Success in Two Cases
Dr Kent and coauthors describe their experience with peripheral nerve stimulation in two soldiers with severe neuropathic pain of one or both legs related to recent (within five months) combat injuries. Neuropathic pain is a common and difficult-to-treat type of pain caused by nerve damage, occurring in patients with trauma, diabetes, and other conditions. Phantom limb pain after amputation is an example of neuropathic pain.

The two soldiers had severe, persistent pain despite medications and a wide range of other attempted treatments. In this situation, the next step would be spinal cord stimulation, in which a mild electrical current is applied to electrodes implanted along the spine. If successful, this "central" nerve stimulation approach produces a feeling of numbness that overcomes the sensation of pain.

However, both patients had conditions that made it unadvisable to perform surgery to implant the spinal electrodes. One had back injuries that were still healing; the other was receiving blood-thinner medications.

This led Dr Kent and his fellow pain specialists to try an alternative approach: electrical stimulation applied directly to the peripheral nerves in the leg. They performed an intervention using ultrasound to guide placement of the stimulators, including both legs in one patient. Just as in spinal cord stimulation, a mild electrical current was applied to interrupt the abnormal nerve impulses.

Once electrical stimulation was turned on, both patients had prompt relief of neuropathic pain—on a 10-point scale, pain scores decreased from 6 to 2. This allowed the patients to cut back on or eliminate the use of strong pain medications and to resume full participation in physical therapy.

The procedure also brought immediate and significant improvements in general activity, mood, and sleep. In these difficult cases, peripheral nerve stimulation was originally intended as a "bridge" until definitive spinal cord stimulation could be performed. However, after a few weeks, both patients were able to keep their pain under control without the need for permanent electrode implants or electrical stimulation.

Limb trauma remains one of the most common battlefield injuries—especially since advances in body armor have improved the chances of surviving combat trauma. Such patients are commonly left with neuropathic pain, which can be very difficult to treat. Spinal cord stimulation is a useful alternative, but may not be suitable for some patients. Peripheral nerve stimulation has been successfully used for chronic neuropathic pain, but there have been no reports of its use for short-term pain management.

The new study suggests that peripheral nerve stimulation is a valuable option for acute management of severe neuropathic pain in soldiers with combat injuries. At least in the two reported cases, it effectively reduced pain, allowing patients to increase their level of function while reducing the need for strong pain medications.

The results raise the possibility that short-term management with peripheral nerve stimulation may even avoid the need for long-term spinal cord stimulation, at least in some cases. Dr Kent and colleagues conclude, "Peripheral nerve stimulation may be an additional tool for patients who do not response to standard treatments for acute trauma-related neuropathic pain."