Parkinson Flashcards
Which test may be performed to diagnose Parkinson disease (PD)?
Neuromuscular studies to identify reflex function
Presence of two cardinal signs which improve with levodopa
Neuroimaging to identify specific midbrain lesion
Serum creatine phosphokinase levels
The diagnosis of idiopathic PD is made based on clinical presentation and examination findings with two of three cardinal manifestations present that respond to dopaminergic therapy.
Parkinson Risks
Genetic (familial) Age Toxin exposures (especially pesticides) Certain drugs Brain injury high iron intake Anemia Obesity
PR Pathophysiology
widespread depletion of dopamine in the substantia nigra and the nigrostriatal pathway to the caudate and putamen. Depigmentation, neuronal loss, and gliosis are most significant in the substantia nigra pars compacta and the pontine locus ceruleus. This dopamine depletion ultimately results in increased inhibition of the thalamus and reduced excitatory input to the motor cortex
Parkinson Signs
Classic features:
Asysmetric or unilateral tremor, rigidity, bradykinesia, flexed posture
Increased resistance to passive movement at a joint
Shuffling gait with decrease in arm swing
The rest tremor of “pill rolling” is an early sign
PD vs Essential Tremor
Essential tremors occur with deliberate, willed movement while PD tremors occur at rest
PD Diagnosis
Imaging and labs helpful only to rule out other causes of symptoms
Exam findings of three cardinal manifestations that improve with dopaminergic therapy is critical for diagnosis
PD Differentials
Other neurodegenerative disorders Drug reactions (neroleptics) Infections Metabolic disorders Trauma Tumors Toxicity (CO poisoning) Vascual
Features that suggest PD diagnosis is not correct
Patient does not improve with levadopa Symmetric motor signs Lack of tremor Falls at early stage of disease Dysuria at early stage of disease
Selegiline
MAO Inhibitor
Does not provide functional benefit, but may delay need for levadopa therapy
High risk for dopaminergic toxicity with levadopa
5mg twice per day is max dose
Levadopa
Most effective symptom treatment, esp for rigidity and tremors
Start with small doses to reduce risk of toxicity
Usually combined with carbidopa to reduce toxicity
Levadopa becomes less effective over time (5 years)
Levadopa-induced complications
complications include motor fluctuations (wearing-off phenomenon), involuntary movements (dyskinesia), abnormal postures of the extremities and trunk (dystonia), and other complex motor fluctuations. Motor complications are more common in patients with young-onset PD (40 to 59 years at PD onset) compared with older-onset PD
Dopamine Agonists
Longer duration of action
Mis-used as a ‘levadopa sparing agent’
Orthostatic hypotension is common initial side effect but less likely to cause dyskinesias
High cardiac risk and impulse control risks
Pramipexole started at 0.125 mg twice a day and slowly increased
COMT Inhibitors
Potentiate levadopa, no effect on their own
May help with the wearing off periods of levadopa
Start at 100mg three times per day usually
Anticholinergics
Used in younger patients where tremors are the main problem
Dry mouth, blurred vision, urinary problems can occur
Most start at 0.5mg per day
Amantadine
Antiviral that has some antiparkinson uses
100-200 mg twice per day
