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What is DBS?
A surgically implanted medical device called a brain pacemaker.
Sends electrical impulses to the brain.
Traditionally used to treat movement disorders such as chronic pain, Parkinson’s disease, tremor, and dystonia.
Three Major ComponentsThree Major Components
Implanted pulse generator (IPG) battery-powered neurostimulator
encased in a titanium housing, which sends electrical pulses to the brain to interfere with neural activity at the target site
Lead coiled wire insulated in
polyurethane with four platinum iridium electrodes and is placed in one of three areas of the brain
Extension insulated wire that runs from the
head, down the side of the neck, behind the ear to the IPG, which is placed subcutaneously below the clavicle or in some cases, the abdomen
Components
How DBS affects the Brain
DBS directly changes brain activity in a controlled manner
It’s effects are reversible
Often kicks in only after a number of weeks for psychiatric disorders
This phenomenon cannot be wholly explained by a directly inhibiting mechanism
Not yet fully understood
Procedure
All three components are surgically implanted into the body
A hole about 14mm is drilled in the skull and the electrode inserted under local anesthesia
IPG and lead installed under general anesthesia
Lead is placed in one of three areas of the brain depending on patient condition
Cost and Recovery Time
Costs about $30,000 plus physician and MRI feesTypically covered by insurance with doctor’s
recommendation Patients typically go home the next day after the
lead implantation surgeryAfter surgery, swelling of the brain tissue, mild
disorientation and sleepiness are normalAfter 2–4 weeks, there is a follow-up to remove
sutures, turn on the neurostimulator and program it
The batteries in the pulse generator must be replaced every three to five years done with a small incision as an outpatient procedure
Relation to Psychiatric Disorders
Psychiatric adverse effects were observed in DBS-treated Parkinson’s disease patients.
Modern knowledge of psychiatric disease, due to modern brain imaging procedures, allows for identification of potential stimulation sites for DBS.
Being studies for treatment of Tourette’s, OCD, and depressive disorders
Psychiatric Disorders
Tourette’s Syndrome chronic but often fluctuating occurrence of vocal (throat
clearing, coughing, coprolalia) and motor (blinking, grimacing, jumping) tics
Obsessive-Compulsive Disorder mental disorder characterized by intrusive thoughts that
produce anxiety, by repetitive behaviors aimed at reducing anxiety, or by combinations of such thoughts (obsessions) and behaviors (compulsions)
Major Depression Disorder mental disorder characterized by an all-encompassing low
mood accompanied by low self-esteem, and loss of interest or pleasure in normally enjoyable activities
Statistics of Psychiatric Disorders
Tourette’s, OCD, and depressive disorders affect about 17 million people in the US alone (7.7% of population)
Depressive disorder is the leading cause of disability in the US for ages 15-44 (14.8 million affected in US)
Tourette’s Syndrome Study
In 2007, the Neurosurgical Division of Istituto Galeazzi IRCCS in Italy performed a study on 18 patients
The greatest experience in the DBS treatment has been assembled in the thalamus—the internal ventro-oral nucleus, centromedian nucleus, and parafascicular nucleus
The average improvement rate for tic symptoms was around 70%, as measured using the most frequently employed scale, the Yale Global Tic Severity Scale (YGTSS)
The 24-month results of 15 of the 18 patients, documented continued amelioration of the symptoms
Obsessive-Compulsive Disorder Study
In 2006, a study in Korea performed a study on 17 patients
Patients underwent stereotactic bilateral anterior cingulotomies and were followed for 24 months surgical procedure is the severing of the supracallosal
fibres of the cingulum bundle
The mean improvement rate of the Y-BOCS score achieved from the baseline was 48%
Study allowed for identification of possible DBS sites
Depressive Disorder Study
In 2008, a study in Ontario, Canada was performed on 6 patients
The subgenual cingulum was the target area for DBS
In four of six patients with otherwise refractory depression DBS achieved clear relief of symptoms after 6 months
There was an average 71% reduction in score on the Hamilton Rating Scale for Depression (HAM-D)
Side Effects of DBS
possibility of Apathy Hallucinations Compulsive gambling Hypersexuality Cognitive dysfunction Depression
These are temporary and related to correct placement and calibration of the stimulator and so are potentially reversible
Because the brain can shift slightly during surgery, there is the possibility that the electrodes can become displaced or dislodged May cause more profound
complications such as personality changes
Electrode misplacement is relatively easy to identify using CT or MRI
Complications of surgery include bleeding within the brain
Conclusion
The results of DBS for psychiatric disorders that have been published to date are encouraging
They open up a new perspective in the treatment of otherwise intractable disorders.
The efficacy, mechanism of action, and adverse effects of DBS for this indication still need to be further studied