Interventional procedure consultation document

Deep brain stimulation for refractory chronic pain syndromes (excluding headache)

Treating persistent pain (except headache) using deep brain stimulation

Refractory chronic pain syndromes are characterised by pain that persists despite treatment and for longer than expected. Causes are varied and pain can occur anywhere in the body. Chronic pain can be debilitating and have a significant impact on a person’s quality of life. A variety of treatments can be used depending on the cause and precise symptoms. This procedure aims to treat chronic pain that does not respond to other treatments. It involves stimulating a precise area of the brain using an electrode.

The National Institute for Health and Clinical Excellence (NICE) is examining Deep brain stimulation for refractory chronic pain syndromes (excluding headache) 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 Deep brain stimulation for refractory chronic pain syndromes (excluding headache).

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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.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

NICE is committed to promoting through its guidance race and disability equality and 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 guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved. 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: 21 December 2010

Target date for publication of guidance: March 2011

1   Provisional recommendations

1.1  Current evidence on the safety of deep brain stimulation (DBS) for refractory chronic pain syndromes (excluding headache) shows that there are serious but well known side effects. There is evidence that the procedure is efficacious in some patients who are refractory to other forms of pain control. Therefore this procedure may be used provided that normal arrangements are in place for clinical governance, consent and audit.

1.2  During the consent process patients should be informed that DBS may not control their chronic pain symptoms. They should be fully informed about the possible risks associated with this procedure including the small risk of death.

1.3  DBS should only be used in patients with refractory chronic pain syndromes which other treatments have failed to control. Patient selection should be carried out by a multidisciplinary team specialising in pain management.

2   The procedure

2.1  Indications and current treatments

2.1.1  Chronic refractory pain syndromes often have a complex natural history and unclear aetiology. The pain may be nociceptive, neuropathic or deafferentation pain. In some cases, it is of uncertain origin (for example, in multiple sclerosis).

2.1.2  Treatment of chronic refractory pain usually includes physical treatments and/or medication. Neurostimulatory techniques such as spinal and peripheral nerve stimulation have been introduced as treatment options for patients whose condition is unresponsive to other forms of treatment.

2.2   Outline of the procedure

2.2.1  Deep brain stimulation involves stereotactic targeting of specific anatomical sites within the brain (such as the sensory thalamus or hypothalamus) to modulate the central processing of pain signals.

2.2.2  With the patient under local anaesthesia and/or intravenous sedation, electrodes are inserted into the brain (through small holes drilled into the skull) using magnetic resonance imaging and/or computed tomography (CT). A test stimulation (or macrostimulation) is used to check for side effects. Postoperative CT scans may be used to assess the position of the electrodes and to identify complications such as local haemorrhage.

2.2.3  Following satisfactory electrode testing, a pulse generator is implanted under the chest wall and connected by tunnelled wires to the electrodes. The generator usually remains switched ‘on’.

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/802/overview

2.3   Efficacy

2.3.1  A non-randomised comparative study of 43 patients with post-stroke pain treated by DBS or motor cortex stimulation reported pain reduction greater than 60% in 25% (3/12) and 48% (15/31) of patients respectively (measured on a visual analogue scale [not described]; follow-up not stated).

2.3.2  A case series of 112 patients with chronic intractable deafferentation pain reported that 47% (42/89) of patients were pain-free and 31% (28/89) of patients were ‘improved’ at follow-ups ranging from 6 months to 6 years. The procedure was considered to have failed in the remaining patients (21% [19/89]).

2.3.3  The Specialist Advisers listed key efficacy outcomes as a reduction in frequency and severity of pain, improvement in physical and mental function, improvement in quality of life, and reduction in medication requirements.

2.4   Safety

2.4.1  Intracranial haemorrhage was reported in 4% (5/141) of patients (timing of events not stated) in a case series of 141 patients with nociceptive or deafferentation pain; 1 patient died, and of the 4 patients who were left with neurological deficit, 2 recovered completely and 2 were left with significant deficits.

2.4.2  A case series of 122 patients reported 2 deaths: 1 was due to massive cerebral oedema and haematoma in the basal ganglia and the other was due to coronary occlusion occurring 9 weeks after ventricular haemorrhage which complicated the procedure.

2.4.3  The case series of 141 patients with nociceptive or deafferentation pain reported infection in 12% (17/141) of patients (23 cases). Of these, 12 cases occurred within 30 days of the procedure and 10 cases were reported after 30 days (1 case not described). One patient was successfully treated with antibiotics alone, 2 with antibiotics and debridement, and 11 with antibiotics and electrode removal (other 3 patients not described).

2.4.4  The case series of 122 patients reported ventriculitis in 1 patient, subgaleal infection in 4 patients and subdural empyema in 1 patient. The patient with ventriculitis and 3 of those with subgaleal infection were successfully treated with antibiotics, but the remaining 2 patients required removal of the DBS system.

2.4.5  The case series of 141 patients reported several major safety events related to the device: erosion of hardware in 7% (10/141) of patients, leakage of current into soft tissues usually from electrical insulation fractures in 9% (12/141), electrode migration resulting in failure in 10% (14/141) and other hardware failure in 4% (6/141). In the patients with hardware erosion, 5 patients had the DBS system removed and 5 had successful re-implantation without the need for antibiotics. Electrode migration only occurred with early versions of the electrodes.

2.4.6  Permanent eye movement dysfunction related to the position of the electrode tip was reported in 2% (3/122) patients in the case series of 122 patients.

2.4.7  The Specialist Advisers listed anecdotal adverse events as suspected development of a new neuropathic pain condition after migration of the lead, mood change from aberrant stimulation, stimulation-induced reversible side effects such as dysarthria and seizures. The Specialist Advisers considered theoretical adverse events to include cerebral infarction.

2.5   Other comments

2.5.1  The Committee noted that the available studies described heterogeneous treatment protocols and patient groups. In addition, most were published some years ago and techniques of DBS have evolved. These factors made interpretation of the evidence difficult.

2.5.2  The Committee noted strongly positive commentaries from patients who had been treated by DBS; some described how even partial relief of their pain had resulted in significantly improved quality of life. One patient reported that they no longer self-harmed after having this procedure.

3   Further information

This guidance requires that clinicians undertaking the procedure make special arrangements for audit. NICE has identified relevant audit criteria and is developing an audit tool (which is for use at local discretion), which will be available when the guidance is published.

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

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

November 2010

_{Personal data will not be posted on the NICE website. In accordance with the Data Protection Act names will be anonymised, other than in circumstances where explicit permission has been given.}

 _{It is the responsibility of consultees to accurately cite academic work in order that they can be validated.}