Hypokinetic movement disorders: Clinical

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Hypokinetic movement disorders: Clinical

USMLE® Step 2 questions

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USMLE® Step 2 style questions USMLE

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A 75-year-old man comes to the clinic with his son because of symptoms of psychosis noticed by his son. He states that his father has been experiencing auditory hallucinations and delusions secondary to dementia associated with his Parkinson disease. He has been on multiple medications to help with dementia and psychosis but his symptoms have worsened. Which one of the following agents would be the best choice to treat his psychosis and dementia in this situation?


The cerebrum, cerebellum, and basal ganglia all help coordinate movements, so movement disorders can be traced back to these structures.

Broadly - there are hypokinetic disorders which cause slowness of movement, and hyperkinetic disorders, which cause excessive involuntary movement. We’ll be talking about the hypokinetic disorders.

Alright, when it comes to hypokinetic disorders, the term “parkinsonism” refers to several conditions including Parkinson’s disease itself, and other syndromes called “parkinson-plus” syndromes, which cause parkinsonism plus other clinical features.

These “parkinson-plus” syndromes include Lewy body dementia, multiple system atrophy, and progressive supranuclear palsy.

Parkinsonism can also be caused by medications, including antipsychotics like haloperidol and anti-emetics like metoclopramide.

The four cardinal symptoms of parkinsonism can be remembered with the mnemonic “TRAP”.

“T” for tremor, which is classically described as a resting, pill-rolling tremor, because it looks like someone is rolling a pill between their thumb and index finger.

“R” stands for rigidity, which is often described as a cogwheel-like rigidity. This means that when attempting to passively move a limb, there are a series of stops or stalls, kind of like a cog on a wheel. There’s also lead-pipe rigidity, which is when a limb is rigid throughout the entire passive movement, kind of like trying to move a lead-pipe.


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