Non-specific severe long-term chronic refractory low back pain can present in various ways, including as neuropathic pain (associated with damage to the nervous system) or nociceptive pain (associated with physical damage to joints, muscles and ligaments). In some people, it is associated with dysfunction of the lumbar multifidus (large muscles that support the lower back) and arthrogenic muscle inhibition. This treatment is not intended for neuropathic pain.
Treatments for low back pain are described in NICE's guideline on low back pain and sciatica in over 16s: assessment and management. Conservative pain management includes pharmacological treatments (such as oral non-steroidal anti-inflammatory drugs, and weak opioids with or without paracetamol) and non-interventional treatments (such as self-management advice and education, exercise, manual therapies, and combined physical and psychological therapy). People with severe chronic low back pain that is refractory to conservative treatments may be offered interventional procedures (such as radiofrequency denervation and epidural injections) or surgery (such as spinal fusion procedures).
The procedure is done under general anaesthesia, or local anaesthesia with sedation. A pulse generator (neurostimulator) is implanted in a pocket created under the skin of the upper buttock or lower back. Under fluoroscopic guidance through a midline approach, 2 stimulating leads are inserted. The distal end of each lead has stimulation electrodes. They are positioned next to the spinal column, near the medial branch of the L2 motor nerve supply (dorsal ramus nerve) to the multifidus muscles, and fixed using flexible tines. The leads are tunnelled internally, then the proximal ends are connected to the pulse generator and the position is checked radiographically.
Approximately 14 days after the implantation procedure, the patient can start to use the device to manage their pain. While lying prone, they use a handheld wireless remote control to deliver stimulation to the nerve supply of the lumbar multifidus muscles, which causes them to contract. This is usually done twice a day for about 30 minutes each time. The pulse generator can be programmed to deliver stimulation between any pair of electrodes on each lead if needed.
The aim of neurostimulation is to help the body regain multifidus neuromuscular control by 'activating' the lumbar muscles and stabilising the spinal column, reducing chronic pain. The procedure is reversible.