deep brain stimulation (dbs) ramin amirnovin, md ldr neurosurgery and associates
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Deep Brain Stimulation (DBS)
Ramin AmirNovin, MDLDR 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
FramelessFrameless
Surgical Technique
• Frameless vs Frame-based surgery:– Less bulk and discomfort for patient; proven equal efficacy
Frame-basedFrame-based
Head
Targeting Platform
MicroElectrode stand/driver
MicroElectrode
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
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