JAHDIEL FRANCO BME 482 Deep Brain Stimulation for Psychiatric Disorders.

JAHDIEL FRANCOBME 482

Deep Brain Stimulation for Psychiatric Disorders

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

Other Tourette’s Syndrome Studies

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

Other OCD Studies

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)

Other Depressive Disorder Studies

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