Percutaneous Electrical Nerve Stimulation (PENS)

Sciatica due to a herniated nucleus pulposus is a common cause of pain and constitutes an important socioeconomic problem in our society .

Its lifetime prevalence is estimated to be 40%. While analgesic medications can provide temporary pain relief, both opioid and non-opioid analgesics are associated with well-known side effects.

Although epidural steroid injections offer short-term improvement in the leg pain associated with a herniated disc, they do not offer significant functional benefits and do not reduce the need for surgery.

The demand for alternative medical practices, including non-pharmacologic treatments like transcutaneous electrical nerve stimulation (TENS) and electroacupuncture, is increasing among patients.

Percutaneous electrical nerve stimulation (PENS) offers a novel approach that combines the benefits of TENS and electroacupuncture. By using acupuncture-like needle probes, PENS stimulates peripheral sensory nerves at specific dermatomal levels.

The latest research findings demonstrate that PENS excels in effectively addressing chronic low back pain compared to both TENS and exercise therapy.

Conservative medical management, including bed rest, anti-inflammatory analgesic drugs, and epidural steroids, has shown success in treating many patients with sciatica.. While this approach effectively reduces radicular pain, demonstrating improvement in functionality has proven more challenging.

However, it has been reported that if the sciatica pain is adequately controlled, the majority of patients experience spontaneous regression of the herniated nucleus pulposus.

Previous research reported by literature has indicated the benefits of peripheral electrical stimulation using TENS units for relieving pain in conditions like sciatica.

However, compared to TENS therapy, PENS therapy has been found to be significantly more effective in providing short-term pain relief and improving functionality for patients with sciatica caused by lumbar disc herniation.

This aligns with earlier studies that showed the superior efficacy of PENS over TENS for low back pain due to osteoarthritis and degenerative disc disease. The lower effectiveness of TENS can be attributed to the discomfort caused by higher amplitudes of electrical stimulation and the skin’s resistance to transmitting impulses.

While some patients preferred TENS for its non-invasive nature, the tapping sensation produced by PENS was generally well-tolerated.

Acupuncture stimulation has shown success in treating sciatic neuralgia. While many studies discussing the effectiveness of acupuncture or electroacupuncture lack a placebo treatment group, a study reported by literature conducted a double-blind, placebo-controlled study on acupuncture for acute sciatica.

Their findings revealed statistically significant improvement in the Lasegue sign and a decrease in the use of oral analgesics with acupuncture stimulation. Similarly, PENS therapy demonstrated high effectiveness in treating patients with acute sciatica.

To establish the effectiveness of PENS in the extended management of sciatica, it is essential to conduct longitudinal studies. Nonetheless, the results of this study, which employed a sham-controlled approach, indicate that PENS yields significant acute pain relief, and the pain-alleviating effects appear to accumulate throughout the three-week treatment period.

These findings suggest that employing this non-pharmacologic analgesic technique over a longer duration has the potential to generate long-term benefits for individuals with sciatica. A more extended period of PENS therapy, coupled with careful follow-up at 3, 6, and 12-month intervals, would be required to examine this hypothesis.

This sham-controlled study reported by literature was unable to employ a double-blind approach due to the unique tapping sensation associated with PENS therapy. To minimize bias, assessments were conducted by an independent evaluator, and the sham treatment was described as acupuncture-like.

It is important to note that the placement of sham-PENS needles differed from traditional acupuncture, so it would be incorrect to conclude that classical Chinese acupuncture or electroacupuncture has no potential benefit for sciatica patients.

To explore the relative effectiveness of different frequencies and durations of electrical stimulation in patients receiving PENS therapy, further studies are needed. The study’s use of a low stimulus frequency (4 Hz) for 30-minute intervals in both PENS and TENS treatments may face criticism.

However, previous research and recent studies have shown comparable analgesic responses to high and low frequency stimulation. The selection of a 30-minute stimulation period was aimed at avoiding tolerance development.

Previous experiences with PENS in various patient populations suggest that using higher or mixed frequencies of electrical stimulation in subsequent treatment sessions can result in improved analgesic responses.

The choice of needle montage in this study was based on clinical experience, but alternative montages may be more effective depending on the specific pain symptoms and manifestations.

The psychological (SF-36) assessment results further validate the clinical findings, confirming that PENS is superior to TENS and sham therapies. PENS significantly improves both the physical and mental health of patients with sciatica, reducing limitations in self-care, alleviating body pain, reducing psychological stress, and decreasing disability related to emotional problems.

In order to determine the cost-benefit of using PENS therapy as part of a multi-modal rehabilitation program, long-term outcome studies should be designed.

These studies should carefully evaluate pertinent costs, such as the stimulating device, disposables, and personnel requirements, as well as consider the treatment outcomes in monetary terms, including patient satisfaction, quality of life, and resumption of normal activities.

By examining the cost-effectiveness of PENS therapy within a comprehensive rehabilitation approach that incorporates anti-inflammatory drugs and specific low back exercises, the potential economic advantages can be better understood.

To conclude, the findings of this study support the superiority of PENS over TENS in improving short-term outcomes for individuals with sciatica. PENS therapy effectively enhances physical activity, promotes better sleep quality, and reduces reliance on oral non-opioid analgesics.