Restorative Neurostimulation

Restorative neurostimulation is an emerging therapy aimed at reducing pain and disability from chronic mechanical low back pain (LBP) by improving the function of muscles that stabilize the lumbar spine.

Chronic mechanical LBP is often associated with impaired control and degeneration of the multifidus muscles. Atrophy of the multifidi is associated with the infiltration of fatty deposits and is brought on by an inhibition of neuromuscular reflexes. In those patients where physical therapy alone is unable to adequately strengthen the multifidi in the lumbar spine, restorative neurostimulation can be utilized to elicit isolated muscle contractions, thus providing targeted rehabilitation. The aim of the therapy is to restore the functional stability of the spine and consequently reduce mechanically induced pain by overriding underlying multifidus muscle inhibition through selective stimulation of the L2 medial branch of the dorsal primary ramus.

Similar to other neurostimulation platforms, the system consists of an implantable pulse generator (IPG), two stimulation leads, a radiofrequency telemetry programmer and a patient-controlled therapy-session activator. Implantation of the system is usually an outpatient procedure in which the leads are placed at each side of the spine over the junction of the transverse process and the superior articular process of the L3 vertebrae with the electrodes positioned next to the L2 medial branch of the dorsal primary ramus. Correct position is verified during the procedure with fluoroscopic imaging and by the ability to elicit a muscle twitch via an intraoperative electrical stimulus. A small subcutaneous pocket, usually in the upper outer quadrant of the buttock, is made to implant the IPG. As with other implantable neurostimulation systems, the leads are then tunneled under the skin to the pock-et and attached to the IPG, which is then placed within the pocket. In the current iteration of the therapy, two 30-minute patient-controlled stimulation sessions are performed each day. During each 30-minute session, twice per minute, the system delivers 10-second trains of electrical stimulation.

In the pivotal trial leading to FDA approval of the therapy, the average age of participants was 47±9 years of age, with a history of back pain for 14±11 years. At baseline, the subjects had an average low back pain Visual Analog Scale score of 7.3±0.7 cm, an Oswestry Disability Index score of 39.1±10.3 points, and an EQ-5D quality-of-life score of 0.585±0.174 (1). The clinical evaluation demonstrated clinical benefits, progressively improving over time, and all pre-defined outcome measures showed clinically substantial improvements by one year follow-up. Mean low back pain scores had improved by 59% with mean scores dropping from “severe” to “mild”; mean disability scores improved by 51% from borderline “severe” to “minimal”; and 28% of participants who were taking opioids at baseline had eliminated them. Compared to baseline, 64% of participants had a 50% or greater improvement in pain; 52% reported low back pain resolution; 73% of participants improved more than 50% in pain scores and/or disability scores and 50% of participants improved in both pain and disability scores.

Reference:

1. Gilligan, Christopher; Volschenk, Willem; Russo, Marc; Green, Matthew; Gilmore, Christopher; Mehta, Vivek; Deckers, Kristiaan; De Smedt, Kris; Latif, Usman; Georgius, Peter; Gentile, Jonathan; Mitchell, Bruce; Langhorst, Meredith; Huygen, Frank; Baranidharan, Ganesan; Patel, Vikas; Mironer, Eugene; Ross, Edgar; Carayannopou-los, Alexios; Hayek, Salim; Gulve, Ashish; Van Buyten, Jean-Pierre; Tohmeh, Antoine; Fischgrund, Jeffrey; Lad, Shivanand; Ahadian, Farshad; Deer, Timothy; Klemme, William; Rauck, Richard; Rathmell, James; Levy, Robert; Heemels, Jan Pieter; Eldabe, Sam for the ReActiv8-B investigators An implantable restorative-neurostimulator for refractory mechanical chronic low back pain, PAIN: March 09, 2021 - Volume Articles in Press - Issue - doi: 10.1097/j.pain.0000000000002258


Reviewed Aug. 2, 2021
Christopher Gilligan, MD
Member, International Neuromodulation Society
Chief, Division of Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA