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?

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