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 andgical Sur Therapy. Springfield, Ill: Charles C Thomas, 1961 UC Davis Deep Brain Stimulation Program What do the basal ganglia do?
• Scale Movement H Y – amplitude and velocity P E R I D N • Focus Movement I D D R I I E R R – select specific muscles C E E T C C T – suppress antagonist T muscles
• 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
H Y P E R D I I N R D E I D C R I T E R C E T C T
Mink Prog Neurobiol 1996 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 X – STN (driving the GPi) – GPi (inhibiting the thalamus) X
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
GPi STN
normal:
PD:
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
AXIAL PLANE
Brain Orientation
Zona • incerta Accurate implantation STN
Red SNc nucleus SNr CN III CN III nerve roots – Location, location, location nerve roots
OculomotorOculomotor nucleusnucleus Medial ofof CN CN III III lemniscal – Awake, stereotactic surgery pathway 1) Indirect targeting 2) Direct targeting 3) Physiological targeting – Microelectrode recording/mapping – Test stimulation • Adjustable, reversible system
UC Davis Deep Brain Stimulation Program DBS Surgery Steps
1) Indirect targeting 2) Direct targeting 3) Physiological targeting
UC Davis Deep Brain Stimulation Program 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 12mm (lateral)
Y ‐3mm (ant/post)
Z ‐4mm (sup/inf)
UC Davis Deep Brain Stimulation Program 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
UC Davis Deep Brain Stimulation Program Direct Targeting Select 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 Localizer box Merge Patient placed in using local used for CT – with MRI comfortable position, anesthesia provides fiducials plan then sedated
UC Davis Deep Brain Stimulation Program DBS Surgery
Prepped and draped. Stereotactic head frame mER with Incision and burr hole placed. set to proper coordinates patient awake
UC Davis Deep Brain Stimulation Program 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 ‐‐ leg area is dorsal/medial ‐‐ arm area is lateral ‐‐ 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
Error Structures Side effect
Too IC: CBT Dysarthria lateral IC: CST Tonic contractions FEF fibers Contra gaze dev
Too CN3 Diplopia Zona medial Red nucleus Paresthesia, flush incerta Limbic STN Personality STN Too Med Lemnisc Parasthesia Red posterior SNc nucleus SNr CN III CN III nerve roots Too IC: CST Tonic contractions nerve roots anterior IC: CBT Dysarthria OculomotorOculomotor nucleusnucleus Hypothalam Flushing Medial ofof CN CN III III lemniscal pathway
UC Davis Deep Brain Stimulation Program Intraoperative Imaging: iCT
Standard OR, equipment, surgical technique; awake surgery with mER
UC 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 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: Unlikely to improve: Tremor •Gait instability / falls Rigidity (tightness) •Freezing of gait Bradykinesia (slowness) • Speech Dystonia • Swallow Dyskinesia* • 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