5.cme event 2014 -- handout - uc davis health · • basal ganglia review – physiology (rate...

Deep Brain Stimulation:Surgical Process

Kia Shahlaie, MD, PhDAssistant Professor

Bronte Endowed Chair in Epilepsy ResearchDirector of Functional Neurosurgery

Minimally Invasive NeurosurgeryDepartment of Neurological Surgery

University of California, Davis

UC Davis Deep Brain Stimulation Program

Outline

• Brief history• Basal ganglia review

– Physiology (rate model)– Parkinson’s disease

• DBS Procedure– Step 1:  direct, indirect, physiological targeting– Step 2:  pulse generator implantation

• Postop care and outcomes– Programming– Risks and benefits of DBS

UC Davis Deep Brain Stimulation Program

Irving Cooper (1922‐1985)

• Born in Atlantic City, NJ– Son of a salesman– Worked his way through school

• BA, MD, MS, PhD, NSG residency 

– Faculty at NYU, then NYMC

• Pioneer in functional neurosurgery– Anterior choroidal artery ligation…

Cooper IS: Parkinsonism: Its Medical and Surgical Therapy. Springfield, Ill: Charles C Thomas, 1961

UC Davis Deep Brain Stimulation Program

What do the basal ganglia do?

• Scale Movement – amplitude and velocity

• Focus Movement– select specific muscles – suppress antagonist muscles

• Rate Model:

DIRECT

INDIRECT

HYPERDIRECT

Direct: Facilitate “wanted” movementsIndirect: Inhibit “unwanted” movements

UC Davis Deep Brain Stimulation Program

Rate Model

STRIATUM

THALAMOCORTEX

BASAL GANGLIA GPi

UC Davis Deep Brain Stimulation Program

Rate model explains kinetic disorders

Hypokinetic disorders:Parkinson’s disease

Hyperkinetic disorders:Dystonia, hemiballism, HD

Delong, TINS 1990:13, 281‐285

UC Davis Deep Brain Stimulation Program

Focused excitation/surround inhibition model of BG function

Nambu Neurosci Res 2002Mink Prog Neurobiol 1996

DIRECT

INDIRECT

HYPERDIRECT

UC Davis Deep Brain Stimulation Program

XX

Rate model provided the rationale for basal ganglia surgery in PD

• Loss of DA input to striatum– Direct pathway is underactive– Indirect pathway is overactive– NET:  Excess inhibition of thalamocortical relay

• Nuclei that are overactive in PD– STN (driving the GPi)– GPi  (inhibiting the thalamus) 

UC Davis Deep Brain Stimulation Program

GPi and STN are overactive in PD

Loss of dopaminergic activity results in disinhibition of the STN and GPi

normal:

PD:

STNGPi

UC Davis Deep Brain Stimulation Program

DBS Surgery for PD• Indications

– Clear diagnosis of idiopathic PD– Continued good motor response to dopamine– Motor fluctuations and dyskinesias from meds– Independent ambulation in best “on” state

• Contraindications– Dementia– Age > 80years (?)– Poor function in best “on” state– Poor MD/patient relationship

• Unilateral/bilateral– Cognitive status, laterality of symptoms

UC Davis Deep Brain Stimulation Program

Goals of DBS surgery

• Primum non nocere!– “elective” operation

• Accurate implantation– Location, location, location– Awake, stereotactic surgery

1) Indirect targeting 2) Direct targeting 3) Physiological targeting 

– Microelectrode recording/mapping– Test stimulation

• Adjustable, reversible system

STN

Zona incerta

Red nucleus

Medial lemniscal pathway

AXIAL PLANE

Oculomotor nucleus of CN III

Brain Orientation

SNr SNc

CN III nerve roots

STN

Zona incerta

Red nucleus

Medial lemniscal pathway

AXIAL PLANE

Oculomotor nucleus of CN III

Brain Orientation

SNr SNc

CN III nerve roots

UC Davis Deep Brain Stimulation Program

DBS Surgery Steps

1) Indirect targeting2) Direct targeting3) Physiological targeting

UC Davis Deep Brain Stimulation Program

Indirect TargetingDevelop 3D coordinate system

Define AC, PC, and 3 midline points 3D map with MCP at 0,0,0mmUC Davis Deep Brain Stimulation Program

Indirect TargetingSelect target based on atlas data

Vectors STN

X (lateral)

12mm

Y (ant/post)

‐3mm

Z(sup/inf)

‐4mm

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Direct TargetingRevise based on direct visualization, internal landmarks

Along anterior edge of red nucleus on axial

3mm lateral to edge of red nucleus

2mm below superior edge of red nucleus

UC Davis Deep Brain Stimulation Program

Direct TargetingSelect entry point and trajectory

Entry‐ Avoid cortical veins‐ Enter crest of gyrus‐ Burr hole location

Trajectory‐ Avoid sulci‐ Avoid ventricle‐ Avoid subependyma‐ Avoid major 

parenchymal vessels

UC Davis Deep Brain Stimulation Program

Day of surgery…

Head frame placed using local anesthesia

Localizer box used for CT –

provides fiducials

Merge with MRI plan

Patient placed in comfortable position, 

then sedated

UC Davis Deep Brain Stimulation Program

DBS Surgery

Prepped and draped.Incision and burr hole placed.

Stereotactic head frame set to proper coordinates

mER with patient awake

UC Davis Deep Brain Stimulation Program

Physiological Targeting: mERSubthalamic nucleus (STN)

Goal:  Dorsolateral motor territory of STN

‐‐ leg area is medial‐‐ arm area is lateral

Globus pallidus internus (GPi)

Goal:  Posterior motor territory of GPi

‐‐ leg area is dorsal/medial‐‐ arm area is ventral/lateral

UC Davis Deep Brain Stimulation Program

Physiological Targeting: Test Stimulation

Subthalamic nucleus (STN) Globus pallidus internus (GPi)

UC Davis Deep Brain Stimulation Program

Interpreting STN Test Stimulation

STN

Zona incerta

Red nucleus

Medial lemniscal pathway

Oculomotor nucleus of CN III

SNr SNc

CN III nerve roots

STN

Zona incerta

Red nucleus

Medial lemniscal pathway

Oculomotor nucleus of CN III

SNr SNc

CN III nerve roots

Error Structures Side effect

Too lateral

IC: CBTIC: CSTFEF fibers

DysarthriaTonic contractionsContra gaze dev

Too medial

CN3Red nucleusLimbic STN

DiplopiaParesthesia, flushPersonality

Too posterior

Med Lemnisc Parasthesia

Too anterior

IC: CSTIC: CBTHypothalam

Tonic contractionsDysarthriaFlushing

UC Davis Deep Brain Stimulation Program

Intraoperative Imaging: iCT

Standard OR, equipment, surgical technique; awake surgery with mERUC Davis Deep Brain Stimulation Program

Post‐implantation MRI

Subthalamic nucleus (STN) Globus pallidus internus (GPi)

UC Davis Deep Brain Stimulation Program

Hospital stay:  1 night

UC Davis Deep Brain Stimulation Program

Stimulator Implantation

Outpatient surgery (same day discharge, general anesthesia)UC Davis Deep Brain Stimulation Program

Clinic follow‐up for programmingPhysician programmer

Patient programmer

Contacts/monopolar/bipolar Voltage Frequency Pulsewidth

monopolarC+/1‐

Bipolar0‐/1+

UC Davis Deep Brain Stimulation Program

Benefits of DBS for PD

~ 30% improvement in motor scores

~ 40% improvement in ADL scores

~ 50% reduction in PD medication needs

DBS is typically as effective as “best” dopamine response…Likely to improve: Tremor Rigidity (tightness) Bradykinesia (slowness) Dystonia Dyskinesia*

Unlikely to improve:• Gait instability / falls• Freezing of gait• Speech• Swallow• Cognitive deficits

UC Davis Deep Brain Stimulation Program

Risks of DBS surgery

from Starr PA and Silay C, 2008

• Infection: 5‐10%• ICH/hemorrhage: 2‐4%• Neurological deficit: <1% 

UC Davis Deep Brain Stimulation Program