Interventional procedure consultation document

Peripheral nerve-field stimulation for chronic low back pain

Treating chronic low back pain by nerve stimulation

Chronic low back pain is tension, soreness and/or stiffness, often worsened by movement, in the lower back lasting more than 6 weeks. Low back pain is common. It affects around one-third of the UK adult population each year. Peripheral nerve-field stimulation (PNFS) involves implanting electrodes in the back, and connecting them to a neurostimulator (a battery-powered device that delivers electrical stimulation to the nerves) under the skin. The patient uses a remote control to deliver low-voltage electrical stimulation to the tissue layers under the skin of the lower back. The stimulation causes a tingling sensation (paraesthesia). The aim is to mask and ease the discomfort.

The National Institute for Health and Clinical Excellence (NICE) is examining peripheral nerve-field stimulation for chronic low back pain and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. NICE’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about peripheral nerve-field stimulation for chronic low back pain.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

• comments on the provisional recommendations
• the identification of factual inaccuracies
• additional relevant evidence, with bibliographic references where possible.

Note that this document is not NICE’s formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that NICE will follow after the consultation period ends is as follows.

The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.

The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the NICE website (www.nice.org.uk/ipprogrammemanual).

Through its guidance NICE is committed to promoting race and disability equality, equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our interventional procedures guidance. In particular, we aim to encourage people and organisations from groups who might not normally comment on our guidance to do so.

In order to help us promote equality through our guidance, we should be grateful if you would consider the following question:

Are there any issues that require special attention in light of NICE’s duties to have due regard to the need to eliminate unlawful discrimination and promote equality and foster good relations between people with a characteristic protected by the equalities legislation and others?

Please note that NICE reserves the right to summarise and edit comments received during consultations or not to publish them at all where in the reasonable opinion of NICE, the comments are voluminous, publication would be unlawful or publication would otherwise be inappropriate.

Closing date for comments: 17 December 2012

Target date for publication of guidance: March 2013

1                      Provisional recommendations

1.1                  Current evidence on the efficacy of peripheral nerve-field stimulation (PNFS) for chronic low back pain is very limited, in both quantity and quality. Evidence on safety is also limited and there is a risk of complications from any implanted device. Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit or research.

1.2                  Clinicians wishing to undertake PNFS for chronic low back pain should take the following actions.

• Inform the clinical governance leads in their Trusts.
• Ensure that patients understand the uncertainty about the procedure’s safety and efficacy and provide them with clear written information. In addition, the use of NICE’s information for the public is recommended. [[URL to be added at publication]]

1.3                  Selection of patientsfor treatment using PNFS for chronic low back pain should be done by a multidisciplinary team, including specialists in pain management and functional neurosurgery.   

1.4                  Clinicians should enter details about all patients undergoing PNFS for chronic low back pain onto the UK Neuromodulation Register [web link] once access to that database is available. They should audit and review clinical outcomeslocally and should document and consider their relationship to patient characteristics.

1.5                  NICE encourages collaborative data collection and publication of comparative studies into PNFS for chronic low back pain. Outcomes should include measures of pain, function and quality of life, particularly in the long term. Full details of any complications and adjunctive or subsequent treatments should be recorded.

2                      The procedure

2.1                  Indications and current treatments

2.1.1              Chronic low back pain is a common condition with a number of contributing and/or causative factors.  In some individuals the pain can resolve spontaneously.

2.1.2              Conservative treatments include advice and education, posture and exercise training, manual therapies, analgesics, non-steroidal anti-inflammatory drugs and acupuncture. For patients with severe chronic low back pain that is refractory to conservative interventions, surgery such as spinal fusion procedures or insertion of prosthetic intervertebral discs may be done.

2.2                  Outline of the procedure

2.2.1              PNFS for chronic low back pain is usually done in 2 stages. First, electrodes are implanted and connected to a neurostimulator. If this produces benefit over a trial of several days then the patient receives a fully-implanted system, at a second operation.

2.2.2              The procedure is done using local anaesthesia. One or more lead(s) are introduced percutaneously into the subcutaneous tissues of the lower back. Depending on the patient’s pain pattern, coverage needs and anticipated changes in the patient’s condition, it may be appropriate to implant several leads. Implanting several leads may provide greater flexibility for covering the patient’s pain pattern with paraesthesia. Intra-operative stimulation is used to verify that the electrodes have been correctly placed. The lead(s) are tunnelled under the skin to a distant exit site and connected by an external extension lead to a hand-held neurostimulator. The patient is able to change the stimulation settings within limits set by the clinician.

2.2.3              The second stage is carried out if the trial is successful. Local anaesthesia is used (sometimes with sedation). A subcutaneous pouch is formed for the implantable neurostimulator, which is connected to the already implanted trial electrodes. The patient has a hand-held remote control that permits stimulation within set parameters. The system can be removed if desired.

Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/guidance/IP/1067/overview

2.3                  Efficacy

2.3.1              A case series of 18 patients reported that all patients had greater than 50% reduction in pain (measured by visual analogue scale [VAS]; 0–10 from best to worse) at 12 months, from a baseline pain score of 7.4.

2.3.2              A case series of 13 patients reported a reduction in pain (measured by VAS; 0–10 from best to worse) from a mean score of 7.4 (standard deviation [SD] 1.2) before PNFS to a mean score of 3.9 (SD 1.7) at a mean follow-up of 7 months (p<0.05). Pain relief was rated by the patients as excellent (improvement of 75% or more) in 15% (2/13) of patients, good (improvement 50–74%) in 38% (5/13), fair (improvement 25–49%) in 38% (5/13), and poor (improvement less than 24%) in 8% (1/13) of patients.

2.3.3              The case series of 18 patients reported that 89% (16/18) of patients had reduced or stopped opioid analgesic use at 12-month follow-up. The case series of 13 patients reported that 54% (7/13) of patients reported a reduction in analgesic use (exact timing of reporting unclear).

2.3.4              The case series of 13 patients reported that 69% (9/13) of patients were ‘satisfied’ or ‘very satisfied’ with treatment (exact timing of reporting unclear).

2.3.5              The Specialist Advisers listed key efficacy outcomes as pain reduction measured on a visual analogue scale; improvement in function as measured by the Oswestry Disability Index; improvement in quality of life as measured on the EQ-5D; reduction in concomitant medication for pain relief including neuropathic agents, opioids and non-steroidal anti-inflammatory drugs; and early mobilisation and rehabilitation.

2.4                  Safety

2.4.1              Postoperative infection requiring removal of the stimulation system was reported in 1 patient in the case series of 18 patients (timing unclear). The stimulation system was later re-implanted.

2.4.2              Device reprogramming was needed in 67% (12/18) of patients within the first 6 weeks (no further details provided) and additional education about device recharging was needed in 17% (3/18) of patients in the case series of 18 patients.

2.4.3              In addition to the above, the Specialist Advisers listed lead migration, lead fracture and postoperative bleeding as anecdotal adverse events. They listed theoretical adverse events as skin erosion, visceral damage (very rare, but not impossible, particularly in very thin patients) and haematoma.

2.5                  Other comments

2.5.1              The Committee recognised that patients being considered for PNFS for chronic low back pain commonly have very distressing and chronic symptoms, which other methods of treatment may have failed to control effectively, and who might otherwise need spinal cord stimulation.

2.5.2              The Committee recognised research in this area is difficult because of the complex and heterogeneous nature of chronic low back pain. Currently there are not enough good-quality comparative studies to be able to confidently evaluate the procedure’s efficacy. This underpins the recommendations in section 1.

3                      Further information

3.1                  For related NICE guidance see www.nice.org.uk

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

November 2012