Authors
Dawn DeWitt, MD
In this module
- Optional activity
Watch the movie Awakenings.
Characterize as hypokinetic vs. hyperkinetic
- Speed, amplitude, and frequency of movement; fatigability, suppressibility; randomness, directionality.
- Detailed assessment of motor function and gait.
- Assess muscle tone for rigidity—increase in resistance to passive movement.
- Gait: Base, pace, stride, foot clearance, postural stability, arm swing.
Hypokinetic disorders: Parkinson disease
- Loss of dopamine neurons in substantia nigra.
- Aggregation of ɑ-synuclein protein and formation of Lewy bodies.
- Genetic, age, pesticides.
- Slowly progressive with cardinal symptoms signs.
- Resting tremor: Usually one-sided; 30% do not have at presentation.
- Bradykinesia: Slow to move and slow to change movements.
- Rigidity: Usually at presentation, cog-wheeling.
- Gait/balance issues: Narrow-based, turning problematic.
- Diagnosis
- Bradykinesia + at least one other sx/sign and absence of red flags; head CT to rule out vascular dz or hydrocephalus.
- Trial of levodopa is often helpful.
- "Dopamine transporter scans" or PET-CT are not necessary unless significant dx uncertainty.
- Other sx include autonomic issues (constipation, sweating, bladder, etc.)
- May have slow processing, micrographia, sleep problems, depression, anxiety, emotional incontinence (pseudobulbar affect).
Think Parkinson Variant If...
- Early dementia (first year of dx): Dementia with Lewy bodies (DLB).
- Visual hallucinations: DLB; note PD meds may precipitate hallucinations.
- Supranuclear gaze palsy, slow vertical saccades: Progressive supranuclear palsy.
How to spot ocular abnormalities in progressive supra nuclear palsy? A practical review
- Postural instability and falls (early): Multiple System Atrophy (MSA)* or PSP.
- Gait ataxia (+ dysmetria and nystagmus): MSA.
- Rapid/sudden onset and step-wise deterioration: Vascular parkinsonism.
- Dysautonomia (postural hypotension), incontinence, sweating inappropriate, impotence: MSA.
- Unresponsive to levodopa: Any of the above (MSA, PSP, VP or CBD (corticobasaldegeneration)).
MSA formerly known as Shy-Drager syndrome.
- Treatment
Starting medications
- Patients with a clear dx (>65 y.o.): Levodopa/carbidopa combination medication is first-line therapy.
- Levodopa (dopamine precursor).
- Most effective: Use controlled-release for night-time, rapid for on-off sx.
- Complications: Loss of effect (wearing off) and dyskinesia (invol mvts) affect 50%.
- Carbidopa, peripheral decarboxylase inhibitor, blocks adverse systemic effects.
- Levodopa (dopamine precursor).
- Other meds are used to control side-effects:
- Dyskinesia, tremor, fatigue → add amantadine (Glutamate NBMA antagonist).
- Tremor/dystonia → add anticholinergic (e.g., benztropine); constipation, urinary retention, etc are limiting side-effects.
Less frequently used
- Mild cases: Consider Monoamine oxidase B (MAOB) inhibitors (e.g., selegiline).
- In younger patients (<65 yo), 1st-line is dopamine agonists: Pramipexole, ropinerole, or cabergoline (decrease levodopa exposure and SE).
- If neurogenic orthostatic hypotension (Parkinson +), can use droxidopa (norepinephrine precursor) with carbidopa.
- Also salt, fludrocortisone, or midodrine.
- Deep brain stimulation (DBS) to subthalamic nucleus and globus pallidus interna → if responding to levodopa but have severe fluctuations or severe tremor.
- Medication psychosis → reduce levodopa if possible.
- Pimavanserin (PD-specific) or quetiapine.
"The Woman Who Could Smell Parkinson’s," by Scott Sayare, June 14, 2024.
She first noticed the scent on her husband. Now her abilities are helping unlock new research in early disease detection.