Dopamine Precursors and Agonists
This drug prevents levodopa from being converted to dopamine before it crosses the blood–brain barrier.
What is Carbidopa?
This MAO-B inhibtor increases dopamine levels in the CNS by inhibiting its breakdown.
*Don't have to name all, just one*
What is an Selegiline/Rasagiline/Safinamide?
These are the two most common DBS targets used to treat the motor symptoms of Parkinson disease.
What are the subthalamic nucleus (STN) and globus pallidus internus (GPi)?
This classic Parkinsonian symptom—shaking at rest—often responds dramatically to DBS.
What is tremor?
A PD patient has tremor, rigidity, freezing, and cognitive decline. Levodopa improves the first three symptoms except the freezing. Predict which symptoms DBS is most versus least likely to improve.
What are tremor and rigidity most likely; freezing and cognition least likely?
Dopamine precursors and agonists can cause these behavioral side effects.
What is impulse control issues (i.e., excessive gambling, shopping, eating, etc)?
This class of Parkinson disease medications prevents the peripheral breakdown of levodopa by blocking its conversion to 3-O-methyldopa.
What are COMT inhibitors?
In Parkinson disease, loss of dopamine ultimately causes excessive activity of this basal ganglia output nucleus, increasing inhibition of the thalamus.
What is the GPi?
Unlike an irreversible ablative procedure, DBS has these two major therapeutic advantages.
What are adjustability and reversibility?
A patient diagnosed with “PD” develops early falls, autonomic failure, poor levodopa response, and rapid progression. Before considering DBS, clinicians should reconsider this.
What is the diagnosis of idiopathic Parkinson disease?
Features suggesting atypical parkinsonism predict poorer DBS outcomes and should prompt diagnostic reassessment.
This is the only dopamine agonist that is available as an injectable or infusion
What is Apomorphine?
This class of drugs can be used a monotherapy or levadopa adjuncts for Parkinson's
What are MAO-B inhibitors?
In Parkinson disease, excessive output from the basal ganglia suppresses thalamocortical motor activity. Effective DBS of the STN or GPi ultimately produces this functional effect on the motor thalamus.
What is disinhibition of the thalamus, increasing thalamocortical motor activity?
DBS can reduce these involuntary, dance-like movements that commonly develop after years of levodopa therapy.
What is dyskinesia?
A 68-year-old with severe levodopa-responsive bradykinesia, rigidity, dyskinesias, and motor fluctuations has mild hypertension but intact cognition and excellent functional status. Does age 68 alone exclude DBS?
What is no?
The dopamine agonists, Pramipexole, Ropinirole, and Rotigotine, have a longer half-life relative to this dopamine-increasing drug
What is Levadopa?
This COMT inhibitor is rarely used because of its risk of severe liver toxicity.
What is Tolcapone?
With the important exception of tremor, the best predictor that a patient’s motor symptom will respond to DBS is improvement of that symptom with this medication.
What is levodopa?
These “midline” symptoms of advanced PD—including postural instability and freezing that do not respond to levodopa—generally respond poorly to DBS.
What are axial symptoms?
Patient A has disabling levodopa-responsive rigidity and motor fluctuations but intact cognition. Patient B has severe dementia, falls, and levodopa-resistant gait freezing. This patient is the better DBS candidate.
Who is Patient A?
Using alternatives to levodopa as initial Parkinson therapy may delay motor complications (i.e. dyskinesias and motor fluctuations), but comes with this major disadvantage.
What is less effective control of Parkinson's symptoms (tremor, rigidity, and bradykinesia)?
Selegiline, an MOA-inhibitor, is metabolized into this stimulant-like compound, which contributes to insomnia.
What is amphetamine?
DBS electrodes are implanted in the brain, but the electrical pulses themselves are generated by this device, usually implanted beneath the skin of the chest.
What is an implantable pulse generator (IPG)?
Hemorrhage and infection are primarily risks of this aspect of DBS, whereas dysarthria and paresthesias are more commonly risks of this other aspect.
What are surgery and stimulation, respectively?
Patient A has severe levodopa-responsive motor fluctuations and wants to reduce medication. Patient B has severe dyskinesia but needs to maintain dopaminergic medication for other symptoms. Which DBS target might be favored for each?
What are STN for Patient A and GPi for Patient B?
STN DBS often permits greater medication reduction, whereas GPi DBS provides strong direct suppression of dyskinesia without requiring medication reduction.