Download Neuro Nursing - HarvardNeurosurgeon.com

Deep Brain Stimulation
(DBS)
Ramin AmirNovin, MD
LDR Neurosurgery and Associates
Intro to Parkinson’s Disease (PD)
• Degenerative Disease in which the cells of the
substantia nigra (part of the brainstem) die & stop
making dopamine for an unknown reason.
• The loss of dopamine unleashes a cascade of events
which causes resting tremor, stiffness, slowed
movements, and walking problems
• As the disease progresses it can cause a decrease in
cognition and create confusion.
• 1% of people above 65 yo have PD (1.5:1
male:female)
• ~0.5% have PD but are not diagnosed.
• 25% misdiagnosis by non-PD neurologists
• 8% misdiagnosis by PD neurologists
Intro to Parkinson’s Disease
• Dopamine replacement (in the form Sinemet) is the
first-line therpay for PD.
• Dopamine pills help reverse much of the tremor,
stiffness, and walking problems.
• The pills only last a short time and at times require as
much as five to six times a day dosing.
• There is no cure for PD at this time.
• PD is progressive in nature and most patients require
increased doses of Dopamine w/ time.
• Eventually, most patients are refractory to
medications and have a very poor quality of life.
Intro to DBS
• Deep brain stimulation (DBS)
is the most promising surgical
therapy for PD.
• It involves putting an electrode
on each side of the brain and
stimulating the brain using a
battery which sits underneath
the clavicle.
• It's like a pacemaker for the
brain.
Intro to DBS
• Exact mechanism of action is still unclear
• Proposed mechanisms for DBS therapy:
– Inhibits the STN within the indirect pathway and
hence dis-inhibits the patient’s movements.
– Promotes the release of Dopamine in the brain
through stimulation of the dopamine fibers tracking
dorsal to the STN
PD DBS Patient Selection
• Patient selection is done by a multi-disciplinary
committee (include Neurologists, NeuroPsychologists,
Neurosurgeon, and sometimes a Psychiatrist)
• PD DBS inclusion criterion:
– Previous response to Dopamine therapy
– Reduction of motor UPDRS score by 30% in the
‘medication-on’ state
– Severe motor tremor and dyskinesias despite optimized
medical therapy
– Less than 75 years old
• PD DBS exclusion criterion:
– Dementia, hallucinations or depression
– Severe medical problems
Surgical Technique
• Overview of surgical technique:
– Apply frame/frameless adapter to awake patient
– Obtain fine-cut MRI and CT of the Brain with the
frameless fiducials (or frame) in place
– Choose surgical target (STN [~5x4 mm], GPI, or Vim
thalamus) on a computer system
– Use image guidance & MER (MicroElectrode
Recordings) to aim for the target
– Remove micro-electrode(s) & place macroelectrode
into the best path through the target
– Test stimulate the patient to rule-out side-effects
– Bring patient back for battery placement in 6 weeks
Surgical Technique
• Frameless vs Frame-based surgery:
– Less bulk and discomfort for patient; proven equal efficacy
Frame-based
MicroElectrode
MicroElectrode
stand/driver
Targeting
Platform
Frameless
Head
Surgical Technique: MER
• MER:
– Different
parts of brain
have different
firing patterns
– Used to
refine MRI
targeting
technique in
the OR
– Shown to
have better
outcomes
compared to
MRI-targeting
alone
Surgical Technique: MER
• Example:
Surgical Technique
• Special considerations for awake PD patient:
– More TLC needed for these patients
– All needed instrumentation should be ready as to
decrease waiting times in the OR and decrease
surgical time for awake patient.
– Less talking among staff (includes surgeons)
– Conversation between staff should be kept
professional even when there are problems
– Avoid anxiety inducing words (e.g., ‘knife’ is ‘#10’,
‘Stitch’ is ‘3-0 vicryl’)
– Any music should be calming in nature (patient
may request their own music)
Surgical Technique
• DBS lead stimulated to test for side effects
and confirm location:
Expected
Too Lateral
Too Medial
DBS Outcomes
• Outcomes:
– 60-80% decrease in
tremor and walking
difficulties
– 50-80% decrease in
meds
– good long-term stability
of motor improvements
over a 10 yr follow up
– No change in cognitive
deterioration.
DBS Outcomes
DBS Outcomes
• Major problems:
– Transient confusion in 10% of patients (more
common in older patients and bilateral cases)
– Need for battery changes
– Infections (rare but require full removal)
– Stimulation dependent problems (e.g., buzzing
in the head, mood changes, tingling, etc)
Other Uses for DBS
• Well studied uses for DBS:
– PD
– Dystonia
– Tremor
– Chronic Pain
• Future directions for DBS:
– OCD
– Intractable Depression – 80% response in studies
– Tourette’s
Questions?
a
• b