Interventional procedure overview of neurostimulation of lumbar muscles for refractory non-specific chronic low back pain

Indications and current treatment

Non-specific chronic low back pain (NSCLBP) can present in various ways including as neuropathic pain (associated with damage to nervous system) or nociceptive pain (associated with physical damage to joints, muscles, and ligaments). It can be exacerbated by movements. In some people the pain can resolve spontaneously. NSCLBP is a common condition with several recognisable contributing or causative factors. These include functional instability of the spine caused by dysfunction of the lumbar multifidus (large muscles that support the lower back) and arthrogenic muscle inhibition. 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). Patients 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).

What the procedure involves

The procedure is done under general anaesthesia, or local anaesthesia with sedation. A pulse generator (neurostimulator) is implanted in a subcutaneous pocket created in the lower back. Under fluoroscopic guidance either through a lateral or a midline approach, 2 stimulating leads are inserted. The distal ends of each lead have 4 stimulating 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 secured in place. The leads are tunnelled internally, then the proximal ends are connected to the pulse generator and the position is checked radiographically.

Fourteen 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 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.