Medications are effective in about 70% of patients with essential tremor and work well for most with Parkinson’s disease (PD). Many patients with essential tremor, however, are unable to complete activities of daily living with ease even with the use of medications. In people with PD, symptoms worsen over time despite medication. For these patients, successful symptom treatment may be found in deep brain stimulation (DBS).
Approved by the FDA in 1998 to treat essential tremor and again in 2002 for PD, DBS involves implanting electrodes in the deep part of the brain. The electrodes are connected to a wire tunneled under the skin to a battery that is implanted just under the skin in the chest. It essentially acts like a pacemaker for the brain. While it’s unclear exactly how DBS works, it appears that electrical stimulation overrides abnormal signals in the brains of patients with PD and essential tremor.
Identifying Ideal Candidates for DBS
For many individuals with PD, medications may only suppress symptoms for a short time, forcing patients to take their medication more frequently as they wait for the next dose to kick in. In these cases, physicians should consider DBS. Other beneficiaries of DBS include those with PD for whom medications are completely ineffective for reducing tremor. Research shows that only 50% to 70% of patients with essential tremor respond well to medication. Those who don’t respond typically suffer from a poor quality of life and should be considered candidates for DBS. Contraindications to DBS include significant cognitive problems and uncontrolled depression.
Getting the Word Out About DBS
Despite a decade’s worth of experience, DBS is still underutilized in PD and tremor sufferers. A recent study estimates that about 3,000 (10%) patients with PD in Michigan qualify for DBS, but only about 500 have undergone the procedure. Many clinicians have either never heard of it or are uncomfortable offering it to their patients because of the fears that any person would have when considering brain surgery. While there are risks involved with DBS, studies suggest that only 3% of patients experience adverse events like stroke, bleeding in the brain, or infection. It’s important to get the word out to physicians and patients about the dramatic improvements that can be achieved with DBS.
“It’s important to get the word out to physicians and patients about the dramatic improvements that can be achieved with DBS.”
The good news is that the technology for using DBS to treat PD and tremor is continuing to improve. MRI technology now allows surgeons to visualize the structures and plan better for surgery. Electrodes on opposite sides of the brain can now be connected to the same battery, whereas before they were connected to separate batteries. The battery sizes have also become smaller, adding a new aspect to patient preferences. In addition, companies are striving to make DBS batteries last longer and to develop rechargeable batteries.
A Multidisciplinary Approach in DBS
Patients with PD and tremor should be informed by their providers that the best outcomes with DBS are achieved when a multidisciplinary team approach is utilized. Good surgeon technique is a must for DBS, but so too is involving a specialist at programming the stimulator. Other important team members include a neurologist, neuropsychologist, social worker, speech therapist, and physical therapist. Patients should also be informed that they won’t see results immediately after the surgery is completed, but significant improvements will follow in time.
Readings & Resources (click to view)
Mirabella G, Iaconelli S, Romanelli P, et al. Deep brain stimulation of subthalamic nuclei affects arm response inhibition in Parkinson’s patients. Cereb Cortex. 2011, Aug 1 [Epub ahead of print]. Available at http://cercor.oxfordjournals.org/content/early/2011/08/01/cercor.bhr187.short?rss=1.
Serranová T, Jech R, Dušek P, et al. Subthalamic nucleus stimulation affects incentive salience attribution in Parkinson’s disease. Mov Disord. 2011. Jul 20. [Epub ahead of print]. Available at http://dx.doi.org/10.1002/mds.23880.
Azmi H, Machado A, Deogaonkar M, Rezai A. Intracranial air correlates with preoperative cerebral atrophy and stereotactic error during bilateral STN DBS surgery for Parkinson’s disease. Stereotact Funct Neurosurg. 2011;89:246-252.
Montgomery E, Huang H, Walker H, et al. High-frequency deep brain stimulation of the putamen improves bradykinesia in Parkinson’s disease. Mov Disord. 2011. Jun 28. [Epub ahead of print]. Available at http://dx.doi.org/10.1002/mds.23842.
Adam J, van Houdt H, Scholtissen B, et al. Executive control in Parkinson’s disease: Effects of dopaminergic medication and deep brain stimulation on anti-cue keypress performance. Neurosci Lett. 2011;500:113-117.
Blomstedt P, Sandvik, Hariz M, et al. Influence of age, gender and severity of tremor on outcome after thalamic and subthalamic DBS for essential tremor. Parkinsonism Relat Disord. 2011. Jun 13. [Epub ahead or print]. Available at www.sciencedirect.com/science/article/pii/S1353802011001465.
Louis E, Gillman A. Factors associated with receptivity to deep brain stimulation surgery among essential tremor cases. Parkinsonism Relat Disord. 2011;17:482-485.