Percutaneous Electrical Nerve Stimulator for Treatment of Chronic Spinal Pain

Percutaneous Electrical Nerve Stimulator for Treatment of Chronic Spinal Pain

Background:

Chronic neck and back pain are common and severe problems. Chronic low back pain is the leading cause of disability, and chronic neck pain is the fourth leading cause of disability in the United States. Beyond basic medication, physical therapy, and steroid injections, treatment options are very limited.

The NSS-2 percutaneous electrical nerve stimulator (PENS) is a relatively new device for the treatment of chronic pain. This programmable electroacupuncture device is worn for a recommended 10 to 12 days on the external ear, stimulating the auricular vagus nerve. It is postulated to release endorphins and relieve pain. There is minimal literature on the use of PENS for the treatment of patients with medically refractory chronic spinal pain.

Purpose/Objectives:

The objective of this study is to determine if the NSS-2 device could serve as an effective alternative modality for the treatment of chronic refractory spinal pain. This question has not been addressed in the published literature. Our goal was to study a series of patients who had failed medications, physical therapy, and injections. Our purpose was to see if patients responded to the device, and if so, how long the results lasted.

Method:

Patients who had the PENS placed for chronic refractory spinal pain were included in the study. Participants were recruited from a single-site neurosurgical practice. Inclusion criteria included chronic ( > 3 months) neck and/or lower back pain. All patients failed medication, physical therapy, and epidural steroid injections. Exclusion criteria included pregnancy, hemophilia, heart monitor, deep brain stimulator, permanent spinal cord stimulator, and pacemaker. 

One hundred forty-four (n = 144) consecutive patients received the PENS between March 2021 and May 2022. Twenty (20) patients who removed the device prior to the 12-day period due to irritation or excessive sweating were excluded from the study. Baseline Oswestry Disability Index (ODI), Neck Disability Index (NDI), and Numeric Pain Rating Scale (NRS) were collected retrospectively for one hundred twenty-four patients through chart reviews. Follow-up ODI, NDI, and NRS were collected through telephone conversation with patients in June and July 2022.

Results:

The mean patient follow-up was 37.0 weeks. 68 patients (54.8%) experienced pain relief after treatment with the PENS. In patients with neck pain, mean NDI scores decreased from 43.8% to 25.4%, and mean NRS decreased from 7.9 to 3.9. In patients with low back pain, mean ODI scores decreased from 47.2% to 37.1%, and mean NRS scores decreased from 7.9 to 5.2.  The rate of improvement in patients with neck pain (70.6%) was significantly greater (p-value< 0.02) than in patients with back pain (51.4%). Interestingly, 30.0% of patients who responded to treatment remained improved at one year follow-up.

Conclusions: Our study shows that a significant number of patients experienced reduced pain and disability as a result of treatment with the PENS. Patients with neck pain responded better than patients with low back pain. Many patients in this difficult patient population experienced durable relief, lasting over one year. Our study suggests that the PENS may be a useful adjunct in the management of patients with chronic spinal pain. Additional research, including a prospective randomized control trial, may be warranted to further study use of the PENS device in this difficult patient population.

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