The New ACLS Guidelines
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Functional Neurosurgery and Anesthetic Considerations
Susan M Ryan, PhD, MD Associate Clinical Professor Department of Anesthesia, UCSF 2006
What is Functional Neurosurgery?
“Neurosurgery intended to improve or restore function by altering underlying physiology”
Areas of Functional Neurosurgery • • • • •
Movement disorders Seizures Pain syndromes Psychiatric disorders Peripheral nerve injuries
Areas of Expansion • Movement disorders • Seizures • Psychiatric disorders
Neurosurgical Techniques • Deep brain stimulation (DBS) • Selective ablation electrodes
• Implantation viral vectors stem cells
• Cranial nerve/ peripheral electrical stimulation
Functional Neurosurgery • Began in mid-1900’s
• Eclipsed by effective medications • Now: Non-responders Advanced cases
Neurosurgical Techniques • Deep brain stimulation Best established use:
Parkinson’s Disease
• Vagal nerve stimulation Best established use:
Seizure disorders
DBS/VNS Studies in Progress • • • • • •
Obesity Fibromyalgia Cluster headache Tourette’s Syndrome Depression Obsessive Compulsive Disorder
DBS for Parkinson’s Disease
Clinical Features • ‘Pill-rolling’ tremor • Masked faces
• ‘Cog-wheel’ rigidity • Festinating gate
• Bradykinesia
Pathologic Features • Progressive neuronal death • Dopamine neurons of substantia nigra • Non- dopamine populations in CNS and PNS • Bulbar function • Sympathetic chain • Parasympathetics of the gut
Basal Ganglia in PD
Treatment • Medications • L-dopa + periph. inhibitor (Sinamet) • Dopamine agonists • MAO inhibitors • COMT inhibitors • Amantadine
DBS Surgery • Goal: Improvement in PD symptoms
• Tremor • Rigidity • Hypokinesia • Gait • Balance
DBS Surgery • Placement of stereotactic frame prior to procedure • MRI to confirm coordinates
DBS Surgery • Stereotactic head frame attached to bed • Pt placed in sitting position
DBS Stereotactic Surgery
• Drill hole in skull to allow electrode placement for recording & stimulation
DBS Stereotactic Surgery
• Electrode passed slowly to record single cells in nucleus of interest
DBS Stereotactic Surgery
• Visual and auditory feedback of cell location and characteristics
DBS Stereotactic Surgery
• Listening for cell response during leg movement
DBS Surgery • • • •
Find best location within the nucleus Place stimulating electrode Close burr hole, remove frame Induce general anesthesia • Tunnel leads • Place generator in upper chest wall • Wait to activate stimulator in outpatient setting
Anesthesia: DBS Generator placement • General anesthesia for generator placement • No particular anesthetic Propofol or inhaled agent work well Avoid dopamine antagonists Avoid demerol Muscle relaxants OK
• Prevent or treat emergence hypertension • Not much pain in post-op setting
PD: Specific Issues • Risk of exacerbation Consider intraoperative continuation of medications
• Hemodynamics may be labile Degeneration of sympathetic ganglia Dopamine-related hypotension, hypovolemia
PD: Specific Issues • Airway or pulmonary compromise
• Upper airway obstruction • Dysarthria and history of choking • Restrictive ventilatory pattern • Aspiration risk
Patients with Existing DBS • DBS is usually on 24/7 for PD pts
• May be off at night in other conditions • Consider turning off prior to surgery
DBS: Surgical Risks
• Intracerebral hemorrhage • Venous air embolism • Emotional lability
DBS: Surgical Risks Intracerebral hemorrhage • Monitor patient for neurologic changes • Risk: 1.6% per lead • Avoid hypertension Keep SBP < 140 Consider arterial line Antihypertensives: labetalol, hydralazine
DBS: Surgical Risks Venous air embolism • Early detection
• Communicate with surgeon • Support blood pressure • Provide O2 • Airway plan
DBS: Surgical Risks Emotional Lability • Usually no treatment needed • Consider sedation PRN
DBS Outcomes Bilateral DBS of STN: • N = 49 • Assessed at 1,3, and 5 years
• Assessed on and off meds and stimulation (Krack, et al, NEJM 349, 2003)
DBS Outcomes • Stimulation alone: significant improvement • Synergy between meds and stimulation
• Allows decrease in medication doses • Improvement in L-dopa dyskinesias • Akinesia, speech, and freezing of gait all worsened (Krack, et al, NEJM 349, 2003)
DBS vs Medical Therapy • Randomized-pair trial: • DBS + optimized medical tx • Optimized medical tx • 75% of pairs favored DBS + meds Quality of life Severity of motor sxs off medication
(Deuschl et al, NEJM, 355, 2006)
DBS: other motor diseases • Essential tremor
• Dystonia • More sedation during MRI
DBS and Tourette’s • Motor/speech tics
• Up to 1% school age children • 1/3 persist into adulthood
DBS for Tourette’s (Visser-Vandewalle, J. Neurosurg 99: 2003) 45 40 35 30 # Tics Per 25 Minute 20 15 10 5 0
Pre DBS 1 wk Post Long-term
#1
#2
#3
DBS and Psychiatric Disease • Depression • Pilot in 2005 • 4/6 patients improved >50% on testing • Currently at least 3 ongoing NIH trials • 10 to 20 patients per study
Vagus Nerve Stimulation
Vagus: Mixed Sensory and Motor • 20% efferent: parasympathetic control of the heart and gut viscera • 80% afferent: extensive connections to limbic and higher cortical systems • Animal studies VNS: EEG changes and seizure cessation
Vagal Nerve Stimulation • Approved device made by Cyberonics
• Chronic, intermittent stimulation to cervical vagus • Prevents and aborts seizures
Vagal Nerve Stimulation • Typical settings:
• Automatic: 30 sec stimulation q 5 min • Additional manual: if pt feels aura, may wave wand over generator to activate stimulator
Vagal Nerve Stimulation • Results from 3 studies: • Significant decrease in seizures: 24%-35% • Controls: low-level stimulation • Seizure frequency decreased further over time • Decreased medication doses
VNS Surgery • Performed under general anesthesia • Leads wrapped around L vagus in neck • Only L, and only unilateral
• Generator placed upper left chest
Final Electrode/tether Placement Anchor Tether
Positive Electrode
Negative Electrode
VNS Surgery • Possible intraop complications with lead testing: • Arrhythmias- transient sinus arrest • Labile hemodynamics
• Airway obstruction (vocal cord stimulation)- if not intubated
VNS Surgery • Surgical complications: • Infection: 2.9% • Hoarseness or temporary vocal cord paralysis: 0.7% • Hypesthesia or lower left facial paralysis: 0.7%
VNS Surgery: Chronic Side Effects • Hoarseness • Cough • Paresthesias • Dyspepsia
• Disrupted sleep • Worsening sleep apnea
VNS: Anesthesia • Pre-op considerations: • Take usual seizure medications • CBC, electrolytes • EKG • cardiac medications?
VNS: Anesthesia • May use local, MAC, or GA • Usually GA- no restriction on agents • Endotracheal tube • Blood loss is minimal
VNS: Anesthesia • Anti-seizure medications induce hepatic enzymes-- higher anesthetic doses? • Post-op seizures are common- be prepared
• Incidence of transient vocal cord paralysis
Chronic VNS • Turn off for other surgery • Restart in recovery
VNS for Depression • Seizure pts with VNS: happier over time! • N = 60 pts • previously failed numerous treatments
• 2 weeks on meds only • 2 weeks stim adjust + meds • 8 weeks fixed stimu + meds
VNS for Depression • Open label study: • 30.5% of patients responded with significant decrease in depression rating scale • 15% full remission
• Substantial functional improvement, even in non-responders
VNS for Depression • Placebo controlled study: • • • •
N= 225 VNS-responding patients: 15% Placebo-responding patients: 10% Lower levels of stimulation
• Much to figure out, although now FDA approved
Other ongoing VNS studies • Cervical VNS: • • • •
PTSD Panic disorder OCD Rapid-cycling bipolar disorder
• Bilateral diaphragmatic VNS • Morbid obesity
Functional Neurosurgery • DBS • Targets stimulation based on neuroanatomy. Tailors stim to the disorder. • Invasive. • Requires neurosurgery
• VNS • Simultaneous stimulation of multiple tracts & nuclei. • No specific target. Same stimulation for a number of disorders. • Much less invasive. Does not require neurosurgeon. • Procedure in search of an application?
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