Authors
Dawn DeWitt, MC, MSc, MACP, FRACP
In this module
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.
- Bradykinesia + at least one other sx/sign and absence of red flags (next slide); 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.
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.