The National Institute for Clinical Excellence is examining deep brain stimulation for Parkinson's Disease and will publish guidance on its safety and efficacy to the NHS in England and Wales. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisors, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about deep brain stimulation for Parkinson's Disease.

This document has been prepared for public consultation. It summarises the procedure and sets out the provisional recommendation made by the Advisory Committee.

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

The process that the Institute 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 the Final Interventional Procedures Document (FIPD) and submit it to the Institute.
• The FIPD may be used as the basis for the Institute's guidance on the use of the procedure in the NHS in England and Wales.

For further details, see the Interim Guide to the Interventional Procedures Programme, which is available from the Institute's website (www.nice.org.uk/ip).

Closing date for comments: 22 July 2003

Target date for publication of guidance: 26 November 2003

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.

Current evidence on the safety and efficacy of deep brain stimulation for Parkinson's Disease appears adequate to support the use of the procedure, provided that normal arrangements are in place for consent, audit and clinical governance.

The Interventional Procedures Advisory Committee recommended that patient selection should be made with the involvement of a multi-disciplinary team, and that patients should be offered the procedure only when their disease has become refractory to best medical treatment.

Deep brain stimulation for Parkinson's disease is the subject of the multi-centre PDSurg trial. The Advisory Committee will review the results from this trial and revise their recommendations if necessary.

Parkinson's disease is a chronic disease of the brain characterised by gradually worsening tremor, muscle rigidity and difficulties with starting and stopping movements. The condition is usually treated with drugs. Surgery may be considered in people who have responded poorly to drugs, who have severe side effects from medication, or who have severe fluctuations in response to drugs (on-off syndrome).

Parkinson's disease is common, affecting about 0.5% of people aged 65 to 74 years and 1-2% of people aged 75 years and older. Experts believe that 1-10% of people with Parkinson's disease might be suitable for brain surgery.

Surgery for Parkinson's disease is carried out on structures within the brain that are responsible for the modification of movements, such as the thalamus, the globus pallidus and the subthalamic nucleus. Each of these structures consists of two parts: one on the left hand side of the brain and one on the right. Surgery may be carried out on one or both sides.

Surgical treatment aims to correct the imbalance created by diminished function of the substantia nigra, the underlying abnormality in Parkinson's disease. Surgery alters, through either destruction or electrical stimulation, the function of brain nuclei, such as the thalamus, globus pallidus or subthalamus that interact functionally with the substantia nigra. Deep brain stimulation is one form of surgery for Parkinson's disease.

The procedure is generally performed in two separate steps. The first step of the procedure is carried out under local anaesthetic and involves the placement of electrodes at the target site. The patient is then fully anaesthetised and a pulse generator is implanted under the skin. The pulse generator produces a high - frequency electrical current that is sent along the electrode to the target area. The stimulus parameters can be adjusted to provide the best response and minimise adverse reactions.

The evidence suggested that subthalamic nucleus stimulation results in improved motor skills, function and movement in patients with Parkinson's disease. For more details refer to the overview (see below).

The Specialist Advisors considered the procedure to be established practice within specialised units. They did not question short-term efficacy, but commented that long-term efficacy was unknown. One Specialist Advisor commented that careful selection of patients was crucial to maximise the chances of success of the procedure.

The complications associated with deep brain stimulation include risk of stroke, confusion, speech disorders and visual problems. In the two largest studies, involving 102 and 111 patients, the incidence of stroke was approximately 3%. For more details refer to the overview (see below).

The Specialist Advisors noted that all procedures involving deep brain stimulation carried similar risks. They considered the procedure to be safe if performed by a multidisciplinary team in a neuroscience unit; the team should include a neurologist and a neurosurgeon; and the unit should have facilities for psychological assessment and, ideally, neurophysiology.

The Advisory Committee noted that current evidence relates to relatively young patients.

The following source of evidence was considered by the Interventional Procedures Advisory Committee.

• Interventional Procedure Overview of Deep Brain Stimulation for Parkinson's Disease, April 2003