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Deep Brain Stimulation in Patients with Parkinson’s Disease

Published: November 1st, 2016

Category: UAD Student Blog

By: Kiersten Lenas & Kara Watford

Deep Brain Stimulation (DBS) is a therapeutic surgical procedure that is used to treat symptoms of Parkinson’s disease (PD), essential tremor, and other movement disorders involving the basal ganglia circuit. These movement disorders are caused by abnormal electrophysiologic activity within the basal ganglia circuit, and deep brain stimulation uses electrical impulses to adjust and correct communication between the affected structures.

dbs

There are three components of Deep Brain Stimulation: neurostimulator, DBS lead, and extension. These are all placed internally with surgery. The neurostimulator can be described as a device similar to a pacemaker and is also referred to as the Implantable Programmable Generator or battery. It is implanted under the skin of the chest and serves to send electrical impulses that regulate rhythms in the brain. The DBS lead is an insulated wire that contains electrodes inserted into the brain. An insulated wire referred to as the extension connects the DBS lead and the neurostimulator.

The criteria for choosing candidates for Deep Brain Stimulation can vary with different disorders and symptoms. In Parkinson’s Disease, the ideal recipient of DBS responds to medications, is younger than 69 (though exceptions can be made), has relatively intact cognitive functioning, and lacks any comorbidities that may reduce the benefits of surgery. These patients must also have idiopathic PD and display at least a 30% improvement in response to medication. A DBS candidate with PD should exhibit issues such as medication wearing off before the next dose, increased motor fluctuations (on-off states), or abnormal movements (dyskinesia). Along with these criteria, a patient and his or her family need to completely understand what a DBS surgery entails. This surgery does not generate success in every patient, and there are several, significant risk factors to consider.

It is also important for patients with PD who are considering Deep Brain Stimulation to understand the implications of the surgery. The University of Florida Center for Movement Disorders and Neurorestoration (UF CMDNR) provides mnemonic that gives patients an idea of what to expect from DBS – DBS IN PD.

Does not cure.

Bilateral procedures may be needed for walking and balance problems.

Smooths out on/off fluctuations.

Improves tremor, stiffness (rigidity), bradykinesia (slowness), and dyskinesia in most cases, but does not necessarily make them go totally away.

Never improves symptoms that don’t responds to your best “on”. For example, if gait or balance do not improve with best medication response, it will not improve with surgery.

Programming visits many times during the first 6 months, then visits very 6 months thereafter.

Decreases medication only some of the time.

(http://movementdisorders.ufhealth.org/for-patients/deep-brain-stimulation-information/why-everyone-is-not-a-candidate/ )

 

While DBS in patients with Parkinson’s may improve motor symptoms such as tremor, rigidity, bradykinesia, and dyskinesia, improvements do not seem to carry over into speech, and may actually have a negative impact in regards to speech. These outcomes, however, are highly variable between patients. Speech in patients with PD usually presents as a hypokinetic dysarthria and is characterized by breathiness, hoarseness, reduced loudness, monoloudness, monopitch, short rushes of speech, and imprecise articulation.

According to different research studies, DBS may lead to functional decline of certain speech functions such as decreased jaw velocity, reduced articulatory precision, laryngeal hyperfunction, and reduced intelligibility. Some studies of DBS in patients with PD have also shown improvement for some speech functions, such as strengthening of the upper and lower lip and tongue, as well as increases in pitch variability and sound pressure level. Lead implantation also influences the outcome of speech function. Where in the subthalamic nucleus (STN) the lead is placed during implantation can have various implications on speech, with medial and/or posterior placement being associated with reduced intelligibility, and left STN placement associated with a greater negative impact on prosody, articulation, and intelligibility.

FDA has recently approved the St. Jude Medical Infinity DBS System, a deep brain stimulation therapy system that uses directional lead technology. Directional lead technology reduces side effects by increasing the precision when directing the electrical current to the desired target structure and reducing spread to surrounding areas. This new technology has been shown to personalize therapy and optimize outcomes in patients with Parkinson’s Disease and essential tremor. The differences between the Infinity DBS System and previous models include the use of segmented electrodes. These electrodes have the capability to be turned on and off, improving the precision of direction, shape and length of stimulation. It includes the smallest IPG, which has the ability to be upgraded without another surgery. The Infinity DBS system also includes the first iOS software platform for personalized, wireless use.

 

References

Hegland, K. (2016). Hypokinetic Dysarthria [PowerPoint slides]

 

National Parkinson Foundation. (N.D.) Deep Brain Stimulation. Retrieved from

http://www.parkinson.org/understanding-parkinsons/treatment/surgery-treatment-options/Deep-Brain-Stimulation

 
Okun, M.S., Fernandez, H. H., Foote, K. D. (N.D.) Deep Brain Stimulation Information: Why

Everyone is Not a Candidate? Retrieved from http://movementdisorders.ufhealth.org/for-patients/deep-brain-stimulation-information/why-everyone-is-not-a-candidate/

 

Okun, M.S., Fernandez, H. H., Foote, K. D. (N.D.) Deep Brain Stimulation Information: Who is a

Candidate? Retrieved from http://movementdisorders.ufhealth.org/surgery/deep-brain-stimulation-surgery/ http://movementdisorders.ufhealth.org/for-patients/deep-brain-stimulation-information/who-is-a-candidate-for-dbs/

 

St. Jude Medical. (2016, September 26). DBS Therapy Options. Retrieved from

https://www.sjm.com/en/patients/movement-disorders/dbs-therapy-options

 

St. Jude Medical. (2016, October 6). St. Jude Medical Announces U.S. Launch and First Implant

of New Deep Brain Stimulation System and Directional Lead for Patients Suffering from Movement Disorders. Retrieved from http://media.sjm.com/newsroom/news-releases/news-releases-details/2016/St-Jude-Medical-Announces-US-Launch-and-First-Implant-of-New-Deep-Brain-Stimulation-System-and-Directional-Lead-for-Patients-Suffering-from-Movement-Disorders/default.aspx

 

University of Pittsburgh. (N.D.) Deep Brain Stimulation for Movement Disorders. Retrieved from

http://www.neurosurgery.pitt.edu/centers-excellence/epilepsy-and-movement-disorders-program/deep-brain-stimulation-movement-disorders