Deep brain stimulation for tremor and dystonia (excluding Parkinson's disease) (interventional procedures consultation document)


Interventional Procedure Consultation Document

Deep brain stimulation for tremor and dystonia (excluding Parkinson’s disease)

Essential tremor (involuntary shaking of one or both hands) and dystonia (abnormal muscle spasm) can affect movement and posture. They can be treated by stimulating a precise area of the brain using an electrode.

The National Institute for Health and Clinical Excellence is examining deep brain stimulation for tremor and dystonia (excluding 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 d eep brain stimulation for tremor and dystonia (excluding 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 recommendations
  • 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The Advisory Committee will then prepare draft guidance which will be the basis for the Institute’s guidance on the use of the procedure in the NHS in England, Wales and Scotland.

Closing date for comments: 23 May 2006

Target date for publication of guidance: August 2006

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

1 Provisional recommendations

Current evidence on the safety and efficacy of deep brain stimulation for tremor and dystonia (excluding Parkinson’s disease) appears adequate to support the use of this procedure provided that the normal arrangements are in place for consent, audit and clinical governance.


Patient selection and management should be carried out in the context of a multidisciplinary team.

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2 The procedure
2.1 Indications
2.1.1 Tremor and dystonia are symptoms arising from a number of different neurological diseases other than Parkinson’s disease, including essential tremor, multiple sclerosis and primary generalised dystonia.
2.1.2 Tremor is an involuntary rhythmic repetitive movement, most frequently affecting the upper limbs. It can occur at rest, or can be brought on (or exacerbated) by posture or intentional movement. Severe tremor can be disabling because it affects fine movement coordination.

Dystonia is the uncoordinated simultaneous contraction of opposing agonist and antagonist muscles. It may be limited to a particular group of muscles, or may be generalised.

2.1.4 Most patients with tremor benefit from rehabilitation and drug therapy, and early appropriate treatment may minimise functional disability. Anti-tremor drugs reduce tremor amplitude, but not frequency, and this does not always translate into functional improvement. Surgery, commonly involving surgical ablation of the thalamic nucleus, is usually reserved for patients with severe disabling tremor and functional disability that interferes with activities of daily living, and for tremor that is refractory to the highest tolerated doses of medication.

Dystonia can be treated conservatively or surgically. Currently available conservative management options for dystonia improve the symptoms but do not cure the underlying neurological disorder. The severity of dystonia may progress over time as part of the underlying neurological condition. Surgical options include thalamotomy and pallidotomy; however, benefits may not be maintained in the long term.

2.2 Outline of the procedure
2.2.1 Deep brain stimulation can be 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, which interact functionally with the substantia negra (nigra). These structures are all bilateral, and surgery can be performed on one or both sides. Deep brain stimulation alters the function of these brain nuclei through the application of an electrical current.

The procedure involves insertion of fine needles into the brain through small holes in the skull, to determine the exact position of the targeted nucleus, which may be different in each patient. This part of the procedure is usually carried out under local anaesthesia. One (or more) permanent electrode(s) is subsequently placed into this nucleus. Under general anaesthesia, wires are tunnelled subcutaneously to the anterior chest wall, where they are connected to a pulse generator.

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2.3 Efficacy

A case–control series found that, in up to 27 months’ follow-up, total tremor score improved in 17 patients treated with deep brain stimulation, but there was no significant improvement in most other efficacy outcomes. A case series of 52 patients with essential tremor who underwent deep brain stimulation reported a significant improvement in activities of daily living at 3 months’ follow-up, with scores improving from 17.8 points to 6.5 points (p < 0.001). Another case series of 19 patients found that deep brain stimulation produced an improvement in tremor score (Fahn–Tolosa–Marin scale) from 3.3 points at baseline to 0.8 points at 27-month follow-up (p < 0.005).

2.3.2 A case series of 22 patients with dystonia who underwent deep brain stimulation reported that the total score on the Burke–Fahn–Marsden dystonia rating scale improved significantly from a mean of 46.3 points at baseline to 24.3 points at 3-month follow-up. This improvement was maintained to 12 months’ follow-up, with a score of 21.0 points (p < 0.001 for both comparisons with baseline). Similarly, global disability score improved from 11.6 points at baseline to 7.6 points at 3-month follow-up and 6.5 points at 12-month follow-up (p < 0.001).
2.3.2 Very few data are available on the use of deep brain stimulation for tremor in multiple sclerosis. Three case series reported significant improvements in tremor secondary to multiple sclerosis at 12–22 months; however, two of these studies found that improvements in tremor did not necessarily correlate with improvements in functional ability. For more details, refer to the Sources of evidence (see appendix).

The Specialist Advisors noted that there are concerns about the long-term efficacy of the procedure, as tremor may become resistant to the stimulation.

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2.4 Safety

One case series reported that failure of the pulse generator occurred in 50% (6/12) of patients. Other device-related complications reported included displacement of the stimulating electrode, which sometimes required further surgery. Across three case series where it was reported as an outcome, displacement of the stimulating electrode occurred in 6% (1/18), 8% (1/12) and 15% (8/52) of patients. The incidence of lead fracture or failure in three studies was 4% (2/52), 5% (1/22) and 6% (1/18).

2.4.2 One case series of 22 patients who underwent deep brain stimulation for dystonia reported transient oedema of the frontal lobe, cutaneous necrosis of the scalp, localised skin infection and haematoma near the neurostimulator, in one patient each. However, none of these events had permanent sequelae. For more details, refer to the Sources of evidence (see appendix).
2.4.3 The Specialist Advisors noted that adverse events relating to this procedure include infection, haemorrhage (possibly causing hemiparesis), hardware failure, dysarthia, speech disturbance, cerebral oedema and death. They also noted that theoretical complications may include stroke, speech impairment, cognitive impairment, depression, suicide and risk of injury during magnetic resonance imaging scans.
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2.5 Other comments

There are variations in the technique of deep brain stimulation. In addition, the procedure may be used concurrently or sequentially with other surgery or drug therapies. Different rehabilitation methods may also have an effect on outcome.

2.5.2 Further information on the long-term effects of this procedure in patients undergoing surgery at a young age would be useful.
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3 Further information

The Institute has produced Interventional Procedures Guidance on deep brain stimulation for Parkinson’s disease ( and is developing a clinical guideline on Parkinson’s disease (

Bruce Campbell
Chairman, Interventional Procedures Advisory Committee
May 2006

Appendix: Sources of evidence

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

  • Interventional procedure overviewofdeep brain stimulation for tremor and dystonia (excluding Parkinson’s disease), February 2006

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