Parkinson Disease: The Daily PANCE Blueprint
A 68-year-old man is brought in by his wife, who says he has slowed down over the past two years. He takes longer to dress, his handwriting has become small and cramped, and his voice is softer. He has fallen twice. On examination he has a resting tremor of the right hand that disappears when he reaches for a cup, cogwheel rigidity at the right wrist, and reduced arm swing on the right when he walks. His gait is shuffling with short steps and he turns en bloc. His face is expressionless and he blinks infrequently. Cognition is intact, extraocular movements are full, and orthostatic vitals are normal. He takes no antipsychotics or antiemetics. Which of the following is the most likely diagnosis?
A. Essential tremor
B. Progressive supranuclear palsy
C. Drug-induced parkinsonism
D. Parkinson disease
E. Normal pressure hydrocephalus
Answer and topic summary
The answer is D. Parkinson disease
An asymmetric resting tremor with bradykinesia and cogwheel rigidity in an older adult is Parkinson disease. The pathology is degeneration of dopaminergic neurons in the substantia nigra pars compacta, with intracytoplasmic Lewy bodies made of α-synuclein; symptoms appear only after roughly 60% to 80% of those neurons are already gone, which is why the disease is well established by the time anyone walks into your office. The cardinal features are worth committing to memory as TRAP: Tremor at rest, Rigidity, Akinesia or bradykinesia, and Postural instability. Two qualities of that tremor do most of the diagnostic work. It is a resting tremor — classically a 4 to 6 Hz pill-rolling movement that improves when the patient reaches for something and worsens with distraction or walking — and it is asymmetric at onset. Every small detail in this stem is the same disease seen from a different angle: the cramped handwriting is micrographia, the blank face is hypomimia, the soft voice is hypophonia, and the reduced arm swing is bradykinesia showing up in gait. Diagnosis is clinical; imaging is used to exclude alternatives rather than to confirm, and a strong response to levodopa supports it. Treatment is symptomatic, since nothing yet slows the neurodegeneration. Carbidopa-levodopa is the most effective drug and is favored in older or more functionally impaired patients; the carbidopa blocks peripheral decarboxylation so more levodopa reaches the brain and there is less nausea. Younger patients are often started on a dopamine agonist such as pramipexole or ropinirole to defer levodopa-related dyskinesias — but counsel them about somnolence and impulse-control disorders like gambling and compulsive shopping, which patients rarely volunteer unless asked. MAO-B inhibitors, amantadine for dyskinesia, and deep brain stimulation of the subthalamic nucleus for refractory motor fluctuations round out the toolkit, and physical therapy genuinely helps gait and falls. Separating the look-alikes: essential tremor is bilateral and symmetric, appears with action such as holding a cup or writing rather than at rest, often involves the head and voice, frequently improves with alcohol, and responds to propranolol or primidone; progressive supranuclear palsy announces itself with early falls and a vertical gaze palsy, and his extraocular movements are full; drug-induced parkinsonism from antipsychotics or metoclopramide is typically symmetric and he takes neither; and normal pressure hydrocephalus is the triad of a magnetic shuffling gait, urinary incontinence, and dementia — wet, wacky, and wobbly — with ventriculomegaly on imaging and no resting tremor, whereas his cognition is intact.
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