Deep brain stimulation (DBS)/Brain pacemaker has evolved as an important and established treatment modality for variety of advanced movement disorders and also for some psychiatry disorders.1Chronic DBS stimulation provides a non destructive and reversible means of disturbing the abnormal function of basal ganglia circuit. It can be adjusted as disease progresses or adverse event occur. Bilateral stimulation can be performed without a significant increase inadverse effects.Adverse events related to unintended stimulation of adjacent structures are readily reversible by altering the stimulus parameters.

1. Overview of Brain pacemaker

2. a p o l l o m e d i c i n e 1 0 ( 2 0 1 3 ) 2 2 0 e2 2 2
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/apme
Review Article
Overview of Brain pacemaker
Sanjay Bhaumik
Senior Consultant Neurologist, Apollo-Gleneagles Hospitals, 58 Canal Circular Road, Kolkata 700 054,
West Bengal, India
article info
abstract
Article history:
Deep brain stimulation (DBS)/Brain pacemaker has evolved as an important and estab-
Received 7 August 2013
lished treatment modality for variety of advanced movement disorders and also for some
Accepted 8 August 2013
psychiatry disorders.1
Available online 6 September 2013
Chronic DBS stimulation provides a non destructive and reversible means of disturbing
the abnormal function of basal ganglia circuit. It can be adjusted as disease progresses or
Keywords:
Pacing brain movement disorder
adverse event occur.
Bilateral stimulation can be performed without a significant increase in adverse effects.
Deep brain stimulation (DBS)
Adverse events related to unintended stimulation of adjacent structures are readily
Parkinson’s disease
reversible by altering the stimulus parameters.
Copyright ª 2013, Indraprastha Medical Corporation Ltd. All rights reserved.
1.
Introduction
Deep brain stimulation (DBS)/Brain pacemaker has evolved as
an important and established treatment modality for variety
of advanced movement disorders and also for some psychiatry disorders.1
Chronic DBS stimulation provides a non destructive and
reversible means of disturbing the abnormal function of basal
ganglia circuit. It can be adjusted as disease progresses or
adverse event occur. Bilateral stimulation can be performed
without a significant increase in adverse effects. Adverse events
related to unintended stimulation of adjacent structures are
readily reversible by altering the stimulus parameters.
2.
What is a DBS device?
It is an implantable device, made up of three main components:
1. Quadripolar brain electrodes
2. Pulse generator and
3. Extension wires
The quadripolar leads are implanted into the region of
brain involved with the disease process, using stereotactic
neurosurgical technique. Current refinement of the knowledge of basal ganglia circuitry and pathophysiology of the
diseases has narrowed the focus of movement disorder surgery to three key gray mater structures:
1. The thalamus
2. The globus pallidum and
3. The sub thalamic nucleus
The lead implantation is usually performed in awake stage
under local anesthesia to optimize the recoding of physiological data during the mapping procedures, as well as to elicit
the patient’s repot of stimulus induced side effects.
Pulse generator/Neuro stimulator is a small box shaped
device that generates the electrical signals that are sent to the
E-mail address: drsanjay_jogesh@hotmail.com.
0976-0016/$ e see front matter Copyright ª 2013, Indraprastha Medical Corporation Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.apme.2013.08.014

3. a p o l l o m e d i c i n e 1 0 ( 2 0 1 3 ) 2 2 0 e2 2 2
electrodes. It is usually implanted under skin over subclavicular region.
Extension wires are tunneled under the skin and connect
the lead and pulse generator.
After days or weeks of device implantation stimulation
parameters are programmed.
3.
How it works?
Still there is no clearly described mechanism of action, though
there are several likely possibilities.2
High frequency of stimulation may create a global hyperpolarisation of the cell membrane resulting loss of excitability.
Stimulus may jam signal flow out of the abnormal functional areas.
Although the mechanism of DBS is not yet worked out,
doctors have enough experiences in using DBS to feel confident of its safety and effectiveness.
4.
Where to consider DBS?
There are currently three major movement disorders for
which DBS is indicated:
* Idiopathic Parkinson’s disease
* Essential tremor and
* Dystonia
Many have touted the potential benefit of DBS in selected
brain regions for variety of other disorders i.e. chronic pain,
Tourette syndrome, depression and obsessive compulsive
disorders. Still major indication remains for patient with
Idiopathic Parkinson’s disease with significant disability
inspite of optimizing medical therapy.3
5.
When to consider DBS?
The role of DBS is now viewed as a means of maintaining
motor function before significant disability ensues-rather
than being a last resort intervention for end stage Parkinson’s disease patient with no other treatment option. The goal
is to be intervene, if possible when the patient reaches a stage
where the daily burden motor symptomatology (motor fluctuation and dyskinesia) just begins to cause significant interference with daily function and occupational activities. Some
surgical research protocols require that patient experiences a
minimum amount (e.g. three to 4 h) of cumulative off and or
dyskinesia time each day to justify DBS implant surgery.
A number of factors need to be assessed in a systemic
manner to determine each patient’s suitability for DBS
treatment.4
Expectation of patient and relative should have realistic
expectation regarding outcome after surgery. It is not a cure
for PD. It improves the quality of life. It reduces tremor, rigidity, reduces motor fluctuation, increases on time and reduces dyskinesia. DBS will not have much effect on speech
221
difficulty, micrographia; sever postural instability, on time
freezing of gait, dysautonomia and cognitive dysfunction.
This treatment is effective only in idiopathic PD, not in
other Parkinsonian syndromes.
Needs proper identification of motor symptoms and signs
which are most disabling and troublesome for the patient
whether these are likely to improve by DBS.
Needs proper optimization of pharmacological treatment.
The degree to which a patient is responding to levodopa
generally predicts the response after DBS. The mostly used
scale to assess motor signs in patient with PD is the motor
subscale (part III) of the UPDRS (Unified Parkinson’s disease
rating scale). Many clinicians desire at least a 30% improvement of UPDRS score with Levodopa challenge.
A clear understanding of patient’s cognitive function is
important before DBS. Significant associated dementia suggests a widespread brain area involvement, a contraindication for DBS. Patient with significant dementia also will have
difficulty in observing and articulating their symptoms,
making adjustment of DBS parameters and medication
difficult. To screen for dementia, a mini mental status examination (MMSE) and Mattis dementia rating scale (MDRS)
can be performed. In general MMSE score of <¼24 and MDRS
total score <¼130 is contraindication for DBS procedure.5 But
there is no age limit to exclude if there are no signs of dementia or major psychiatric problem and are in good general
health.
6.
What are the risks and prognosis?
The surgery required to implant a DBS device is expensive and
potentially risky procedure, only recommended for selected
patient. DBS is not a cure for PD. The patient must have
realistic expectation regarding outcome of procedure. After
DBS the requirement of medication reduces by 40e50% and
quality of life improves by 60e70%.6 In India procedure costs
between 7.5 to 9lac. Normally battery needs replacement after
five years. Although DBS is generally recognized as a very safe
procedure, any brain surgery carries some risks. Few common
side effects are hemorrhage, infection, malfunctioning of
electrodes, side effects of electric stimulation and at times
mood changes. Fortunately all these side effects are usually
temporary and can be managed easily.
Conflicts of interest
The author has none to declare.
references
1. Tierney TS, Sankar T, Lozano AM. Deep brain stimulation
emerging indications. Prog Brain Res. 2011;194:83e95.
2. Mcintyre CC, Savasta M, Kerkerian-Le Goff L, Vitek JL.
Uncovering the mechanism(s) of action of deep brain
stimulation: activation, inhibition, or both. Clin Neurophysiol.
Jun 2004;115(6):239e248.

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3. Weaver F, Follett K, Hur K, Ippolito D, Stern M. Deep brain
stimulation in Parkinson disease; a metaanalysis of patient
outcome. J Neurosurg. 2005;103:956e967.
4. Defer GL, Widner H, Marie RM, Remy P, Levivier M. Core
assessment program for surgical interventional therapies in
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5. Saint-Cyr JA, Trepanier LL. Neuropsychologic assessment of
patients for movement disorder surgery. Mov Disord.
2000;15:771e783.
6. Lang AE, Widner H. Deep brain stimulation for Parkinson’s
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2002;17(suppl 3):S94eS101.

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