Alfonso Fasano, MD, PhD

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Abstract: Deep brain stimulation has become widely accepted as a treatment for Parkinson's disease (PD), dystonia and tremor, and as an off-label treatment for many other movement disorders. In recent years, new official indications have been approved: obsessive-compulsive disorder and focal epilepsy with secondary generalization. This field is expanding exponentially in two not mutually exclusive fields: clinical and technological. Clinically, we have achieved a deeper understanding of outcomes, thus facilitating the process of target and patient selection. In fact, we have gained a better understanding of established indications, particularly with respect to the debate on whether subthalamus or globus pallidus pars interna should be the target of choice for PD. In addition, the role of DBS for treating dystonia has been further defined in terms of patient selection and surgical outcome. Other established (e.g. essential tremor, epilepsy) and novel indications (e.g. Tourette syndrome) have been addressed as well. Finally, recent technological advantages in neuromodulation have opened new avenues towards new targets and indications.

Key Words: Deep brain stimulation, movement disorders, Parkinson's disease, tremor, dystonia.

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Deep brain stimulation (DBS) is an established neuromodulation technique made possible by the neurosurgical placement of electrodes which deliver a mild electrical current to stimulate areas in the deep brain.

DBS has become widely accepted as a treatment for Parkinson's disease (PD), dystonia and tremor, and as an off-label treatment for many other movement disorders.

We have gained a better understanding of established indications, particularly with respect to the debate on whether subthalamus or globus pallidus pars interna should be the target of choice for PD.

In recent years, new official indications have been approved: obsessive-compulsive disorder and focal epilepsy with secondary generalization.

The advance of neuromodulation technologies has provided clinicians with new tools making targeting, programming, and overall management easier.

Nevertheless, we still fail to have reliable methods predicting the surgical outcome even in established indications, such as epilepsy or dystonia. In fact, the surgical outcome always relies on patient selection, which is mainly driven by the trade off between surgical risk and expected benefits.

DBS cannot cure or change the progression of the disease but it can help relieve symptoms and improve quality of life.

In PD, DBS can help symptoms that respond to levodopa with two exceptions: speech responds to levodopa, but does not usually improve with DBS (and might get worse) whereas tremor not responding to levodopa improves with DBS.

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Daniel S Sa, MD and Robert Chen, MBBChir, MSc, FRCPC
Division of Neurology and Morton and Gloria Shulman Movement Disorders Centre, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, ON.

The treatment of Parkinson's Disease (PD) has undergone major changes over the past decade with the introduction of new drugs and the development of more advanced and reliable surgical procedures. However, the role of each of these different treatment alternatives is not yet clearly defined. Frequently raised questions include the most appropriate treatment in early PD and determining which patients with more advanced PD are suitable for surgery. In this review, we will attempt to address some of these issues.

Initial Treatment
The first decision to make is when to begin treatment. Since there is no therapeutic strategy proven to halt or slow disease progression, treatment initiation should be related to the level of disability. Therefore, drug therapy should be initiated when symptoms are interfering with social or occupational functions. This is usually due to impaired motor function but sometimes is related to embarrassment.

The next question is which treatment to offer. There is a long-standing debate regarding whether to start with levodopa or dopamine agonists. The levodopa proponents argue that it is still the most effective therapy for PD, and early treatment (before postural instability) has been proven to reduce mortality.