The National Institute for Clinical Excellence is examining subthalamotomy for Parkinson's disease and will publish guidance on its safety and efficacy to the NHS in England, Wales and Scotland. 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 subthalamotomy for Parkinson's disease.

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 preliminary recommendation
• the identification of factual inaccuracies
• additional relevant evidence.

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• The Advisory Committee will then prepare draft guidance which will be the basis for the Institute's guidance on the use of the procedure in the NHS in England, Wales and Scotland.

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: 24 February 2004

Target date for publication of guidance: May 2004

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 subthalamotomy for Parkinson's disease does not appear adequate to support the use of this procedure without special arrangements for consent and for audit or research.

Clinicians wishing to undertake subthalamotomy for Parkinson's disease should take the following action.

• 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. Use of the Institute's Information for the Public is recommended.
• Audit and review clinical outcomes of all patients having subthalamotomy for Parkinson's disease. Publication of safety and efficacy outcomes will be useful in reducing the current uncertainty. The Institute may review the procedure upon publication of further evidence.

The clinical and cost effectiveness of subthalamotomy for Parkinson's disease is being evaluated in the PD Surg trial, which is expected to complete randomisation in 2005/6. The results of this trial are likely to provide evidence on the most appropriate use of the procedure and clinicians are encouraged to consider randomising patients in the trial (www.pdsurg.bham.ac.uk).

It is recommended that patient selection should be made with the involvement of a multidisciplinary team, and that patients should be offered the procedure only when their disease has become refractory to best medical treatment.

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 affects 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. Subthalamotomy is one form of surgery for Parkinson's disease.

Subthalamotomy involves inserting very fine needles into the brain through small holes made in the skull to destroy a part of the subthalamic nucleus using heat or radiofrequency. The exact points of needle insertion may be different in each patient. The procedure is usually carried out under local anaesthetic. Patients remain awake during the procedure so that the effects on movements can be monitored.

The evidence was limited to small case series, of which only one case study of 11 patients reported on efficacy. The data suggested an improvement in motor skills as measured by the Unified Parkinson Disease Rating Scale (UPDRS) at 12 months' follow-up. For more details, refer to the Sources of evidence (see Appendix).

The Specialist Advisors commented that there were not enough data to assess the long-term benefits of subthalamotomy for Parkinson's disease, and that subthalamic electrical stimulation had become the preferred intervention.

Reported complications included persistent dyskinesia, deterioration in learning and retrieval, and deterioration in spatial working memory. In one study of 66 patients, cerebellar signs persisted in 41% (27/66) of patients 2 weeks after surgery. For more details, refer to the Sources of evidence (see Appendix).

The Specialist Advisors listed the potential complications as risk of stroke; hemiballismus; and disturbance of speech, swallowing or gait. One Advisor was concerned about the irreversible nature of subthalamotomy and the potential need for repeated surgery.

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

The Institute has produced guidance on deep brain stimulation for Parkinson's disease, www.nice.org.ukipg019. The Institute is also in the process of producing a clinical guideline on Parkinson's disease, which is due to be published in 2005.

The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making its provisional recommendations.

• Interventional Procedure Overview of subthalamotomy for Parkinson's disease, December 2002

Available from: www.nice.org.uk/ip090overview