Deep Brain Stimulation:
Surgical Process
Kia Shahlaie, MD, PhD
Assistant Professor
Bronte Endowed Chair in Epilepsy Research
Director of Functional Neurosurgery
Minimally Invasive Neurosurgery
Department 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
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• Rate Model:
Direct: Facilitate “wanted” movements
Indirect: Inhibit “unwanted” movements
UC Davis Deep Brain Stimulation Program
Rate Model
THALAMOCORTEX
STRIATUM
BASAL GANGLIA
GPi
UC Davis Deep Brain Stimulation Program
Rate model explains kinetic disorders
Hypokinetic disorders:
Hyperkinetic disorders:
Parkinson’s disease
Dystonia, hemiballism, HD
Delong, TINS 1990:13, 281‐285
UC Davis Deep Brain Stimulation Program
Focused excitation/surround inhibition model of BG function
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Mink Prog Neurobiol 1996
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Nambu Neurosci Res 2002
UC Davis Deep Brain Stimulation Program
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) X
X
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GPi and STN are overactive in PD
Loss of dopaminergic activity results in disinhibition of the STN and GPi
STN
GPi
normal:
PD:
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DBS Surgery for PD
• Indications
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Clear diagnosis of idiopathic PD
Continued good motor response to dopamine
Motor fluctuations and dyskinesias from meds
Independent ambulation in best “on” state
• Contraindications
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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
AXIAL PLANE
Brain
Brain Orientation
Orientation
• Accurate implantation
Zona
incerta
STN
– Location, location, location
– Awake, stereotactic surgery
1)
2)
3)
SNc
SNr
Medial
lemniscal
pathway
Red
nucleus
CN III
CN III
nerve roots
nerve roots
Oculomotor
Oculomotor
nucleus
nucleus
CNIIIIII
ofofCN
Indirect targeting Direct targeting Physiological targeting – Microelectrode recording/mapping
– Test stimulation
• Adjustable, reversible system
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DBS Surgery Steps
1) Indirect targeting
2) Direct targeting
3) Physiological targeting
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Indirect Targeting
Develop 3D coordinate system
Define AC, PC, and 3 midline points  3D map with MCP at 0,0,0mm
UC Davis Deep Brain Stimulation Program
Indirect Targeting
Select target based on atlas data
Vectors
STN
X (lateral)
12mm
Y (ant/post)
‐3mm
Z
(sup/inf)
‐4mm
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Direct Targeting
Revise 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
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Direct Targeting
Select entry point and trajectory
Entry
‐ Avoid cortical veins
‐ Enter crest of gyrus
‐ Burr hole location
Trajectory
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‐
Avoid sulci
Avoid ventricle
Avoid subependyma
Avoid major parenchymal vessels
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Day of surgery…
Merge Head frame placed Localizer box with MRI using local used for CT –
plan
anesthesia
provides fiducials
Patient placed in comfortable position, then sedated
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DBS Surgery
Prepped and draped.
Incision and burr hole placed.
Stereotactic head frame set to proper coordinates
mER with patient awake
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Physiological Targeting: mER
Subthalamic nucleus (STN)
Globus pallidus internus (GPi)
Goal: Dorsolateral motor territory of STN
Goal: Posterior motor territory of GPi
‐‐ leg area is medial
‐‐ arm area is lateral
‐‐ leg area is dorsal/medial
‐‐ arm area is ventral/lateral
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Physiological Targeting: Test Stimulation
Subthalamic nucleus (STN)
Globus pallidus internus (GPi)
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Interpreting STN Test Stimulation
Error
Structures
Side effect
Too lateral
IC: CBT
IC: CST
Dysarthria
Tonic contractions
FEF fibers
Contra gaze dev
CN3
Red nucleus
Diplopia
Paresthesia, flush
Limbic STN
Personality
Too medial
Too posterior
Too anterior
Zona
incerta
STN
Med Lemnisc Parasthesia
SNc
SNr
IC: CST
IC: CBT
Tonic contractions
Dysarthria
Hypothalam
Flushing
Medial
lemniscal
pathway
Red
nucleus
CN III
CN III
nerve roots
nerve roots
Oculomotor
Oculomotor
nucleus
nucleus
ofofCN
CNIIIIII
UC Davis Deep Brain Stimulation Program
Intraoperative Imaging: iCT
Standard OR, equipment, surgical technique; awake surgery with mER
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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)
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Clinic follow‐up for programming
Physician programmer
monopolar
C+/1‐
Bipolar
0‐/1+




Patient programmer
Contacts/monopolar/bipolar
Voltage
Frequency
Pulsewidth
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
• Infection: 5‐10%
• ICH/hemorrhage: 2‐4%
• Neurological deficit: <1% from Starr PA and Silay C, 2008
UC Davis Deep Brain Stimulation Program