Deep Brain Stimulation (DBS) Ramin Amir. Novin, 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, Neuro. Psychologists, 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 [~5 x 4 mm], GPI, or Vim thalamus) on a computer system – Use image guidance & MER (Micro. Electrode 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 Micro. Electrode 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?
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