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

Frameless Surgical Technique Frameless vs Frame-based surgery: –Less bulk and discomfort for patient; proven equal efficacy Frame-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

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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