philip hess rn university of pennsylvania. review the pathophysiology of parkinson disease (pd) ...
TRANSCRIPT
PATHOPHYSIOLOGY AND ANESTHETIC MANAGEMENT
OF PARKINSON DISEASEPhilip Hess RN
University of Pennsylvania
Objectives
Review the pathophysiology of Parkinson Disease (PD)
Discuss the perioperative management of patients who suffer from PD
Highlight the anesthetists role in Deep Brain Stimulation surgery
Upper Motor Neurons
Movement is initiated in the motor cortex Planned and sensory guided movement Descend in tracts through the
diencephalon and brainstem Separate to innervate the extrapyramidal
and cranial nerve nuclei Descend through the medulla to the
spinal cord via the lateral corticospinal tract (CST)
Pyramidal Tract
Motor fibers which have not branched off to the cranial nerve nuclei or the extrapyramidal tract descend through the pyramidal tract and corticospinal tract (and you know the rest)
Extrapyramidal Tract
Controls involuntary movement and muscle tone
Spatial feeling, muscles of expression
Includes basal ganglia, subthalamus of diencephalon, and cerebellum (among others)
Upper Motor Neurons Summed Up
Upper motor neurons are the final common pathway between cortical and subcortical structures
Basal ganglia Planning, initiating, sequencing, and
modulation of voluntary movement Cerebellum
balance, posture, coordination
So Why Do We Care?
Disruption of signaling pathways gives rise to the debilitating symptoms seen in PD and other diseases of the nervous system
Basal ganglia structures of interest to us Substantia nigra
Dopamine synthesized here Globus pallidus
Inhibitory action that balances the excitatory action of the cerebellum
Subthalamic nucleus Modulates muscle movement (smooths,
coordinates)
Parkinson Disease
Clinical syndrome that manifests as motor dysfunction and psychiatric disturbance (eventually) Rigidity Bradykinesia Tremor Postural instability Involuntary muscle movement
Causes of PD
Prevalence is 1-2 : 1000 Mostly idiopathic Can result from exposure to toxins
(manganese, pesticides, carbon disulfide) Drugs (methamphetamine, reglan,
compazine, 1st generation anti-psychotics, ect)
Repeated head trauma (Muhammed Ali) Feature of other diseases Genetic
Pathophysiology
Neurotransmission within basal ganglia is a balance between the excitatory effects of acetylcholine and the inhibitory effects of dopamine
Dopamine is synthesized by neurons of the substantia nigra
In PD, degeneration of nigral neurons leads to a loss of dopaminergic inhibition
Thus, a relative excess of cholinergic activity ensues
Manifestation
Jerky, uncoordinated movement Early: loss of arm swing when walking,
absence of head rotation when turning the body
Eventually progresses to pill rolling tremor, diaphragmatic spasm, oculogyric crisis
Mask like facies, dysarthria Dementia (often), aspiration, death
Treatment
Designed to increase dopamine concentrations in the basal ganglia or decrease the neuronal effects of acetylcholine
Sinemet (carbidopa/levodopa) most prescribed Levodopa: dopamine precursor
Crosses the blood brain barrier to be converted to dopamine
Carbidopa: decarboxylase inhibitor Does not cross the blood brain barrier Prevents the conversion of levodopa to dopamine in
the periphery; thus, leaves more in circulation to cross BBB
Side Effects of Levodopa
Dyskinesias Psychiatric disturbances Increased myocardial contraction and
heart rate Orthostatic hypotension Nausea, vomiting
Other Medications
MAOIs inhibit the catabolism of dopamine Concerns with MAOIs?
Selegiline is an MAOI that is not associated with adverse side effects
Some others: Bromocriptine mesylate and pergolide mesylate
Dopamine receptor agonists Benztropine mesylate
Anticholinergic Amantadine
Antiviral – may be useful at initial diagnosis
Deep Brain Stimulation
Surgical electrodes inserted into basal ganglia Ventral intermediate nucleus (VIM)
Cerebellar afferent receiving zone of thalamus Reduces tremor
Subthalamic nucleus (STN) Most common target for DBS
Reduces tremor but reduces bradykinesia, rigidity, and improves gait
Internal segment of globus pallidus (GPi) 2nd most common target for DBS (result similar to
STN) Considered the main output for limb movements
Surgical Procedure
The case begins with the patient under MAC anesthesia Stereotactic frame is placed (held in place with
pins or screws) Patient is taken to MRI for brain mapping Patient is returned to OR
The case continues with the patient under deep MAC sedation (I know, a contradiction in terms..) Patient’s head is placed in Mayfield pins and
image guided navigation system is attached to stereotactic frame
Procedure Cont’d
The scalp is localized and 14 mm burr holes are drilled in the skull (bilateral)
A probe is passed into the deep brain tissue No pain here as the brain tissue has no pain
efferents MAC is discontinued
The patient is allowed to wake up in order to communicate with the surgical team as the electrodes are placed.
Computer guided placement of the electrodes ensues
Procedure Cont’d
The patient performs tasks and answers questions during electrode placement
Tremors are elicited and proper electrode placement is confirmed when they are ablated.
Once the permanent electrode placement takes place, the stereotactic frame is removed and general anesthesia is induced.
Electrode leads are tunneled and the stimulus generator is implanted in the chest.
Anesthetic Considerations
To manage the anesthetic , you must understand the treatment of PD (Stoelting, 2012 )
Elimination 1/2t of Sinemet Requires frequent dosing, so give 20 minutes before
surgery and redose via OGT or NGT Hypertension and dysrhythmias
Treat with butyrophenones (droperidol, haloperidol) Antagonize the effects of dopamine in basal ganglia
Acute dystonia with Alfentanil Ketamine controversial due to SNS response
Has been used successfully
Management Cont’d
Patients told to withhold meds prior to DBS Difficult IV placement due to tremor At electrode placement, GABA agonists
(propofol, benzos) may interfere with electrode recordings
opioids and dexmedetomidine are ok Avoid excessive sedation to prevent
airway compromise Remember.. The head frame is in place..the
bed is turned 90 degrees away.. Uh oh.. What if your patient goes apneic?
More Trouble…
Risk of air embolism HOB is usually at 15 degrees
Risk of hypertension with pinning and airway instrumentation
Risk of seizures Stoelting ( 2012 ) says seizures normally
abate; but if they don’t, push propofol or benzos despite delaying the case
Change in LOC Rarely see with electrode placement but may be
due to hemorrhage
Even More Trouble
Upper airway dysfunction is common in PD PD causes chest wall rigidity Often see chronic obstructive disease
Medications used to treat PD cause increased cardiac irritability Blunt autonomic regulatory response
Aspiration prophylaxis H2 blocker or sodium citrate is ok
Never give Reglan Antidopaminergic and will precipitate EPS
Induction Agents
Succinylcholine is ok but RSI needed only in advanced disease
Avoid Ketamine Sympathomimetic responses may exacerbate
PD symptoms All inhalationals ok except halothane
Sensitizes the myocardium to the effects of catecholamines (instability with PD meds)
Treat hypotension with phenylephrine or epinephrine (direct acting) Why not ephedrine?
Emergence
Opioids ok for pain control but.. May cause chest wall rigidity and..
Alfentanil can cause dystonias (so don’t go there)
NSAIDS are ok, as are local anesthetics Use glycopyrrolate for reversal
Doesn’t cross BBB Anticholinergic effect may prevent dystonia
Extubate normally Watch for hypokinetic chest wall activity PD interferes with all muscles of respiration
Post Op
Give anti- Parkinson meds as soon as possible
Neurological assessment Scopolamine may confound
Increased PONV Ondansetron is good Reglan is bad
Medications to avoid Metroclopramide, droperidol, haldoperidol,
promethazine, compazine, ketamine, alfentanil, meperidine, and halothane
Questions?
References
Doyle, S.R. & Kremer, M.J. (2003). Parkinson disease: Update for nurse anesthetists. AANA Journal. 71, (3).
McPhee, S.J. & Hammer, G.D. (2010). Pathophysiology of disease: An introduction to clinical medicine. Chicago, IL. McGraw-Hill
Macksey, L.F. (2012). Surgical procedures and anesthetic implications. Sudbury, MA. Jones and Bartlett.
Perlmutter, J.S. (2006). Deep brain stimulation. Annual Review of Neuroscience. 29, 229-57.