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Lewy body dementia

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Nervous system

Pathology

Central nervous system disorders
Central and peripheral nervous system disorders
Peripheral nervous system disorders
Autonomic nervous system disorders
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Lewy body dementia

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Lewy body dementia

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USMLE® Step 1 style questions USMLE

3 questions
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A 62-year-old man is brought to the clinic by his partner for evaluation of worsening confusion and changes in personality. Symptoms began three months ago. The patient has had multiple falls over this same time period, which the partner attributes to his “unsteady gait.” He has not had urinary incontinence, fevers, or hallucinations. He has smoked a pack of cigarettes daily for the past 10 years. He has never consumed alcohol. Vital signs are within normal limits. The patient demonstrates nystagmus at rest. He is unable to perform rapidly alternating pronation and supination movements with his hands. The patient scores 17/30 on the Mini-Mental State Examination (normal: ≥24). Brain biopsy from a deceased patient with the same condition is shown below:  


Image reproduced from Wikimedia Commons  

Which of the following additional physical exam findings is likely to be seen in this patient?  

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Transcript

Lewy body dementia is a type of dementia, where individuals lose their memory and have difficulty learning new information.

Lewy bodies refers to protein deposits found inside neurons, and they’re named after Frederic Lewy, the neurologist who discovered them.

Lewy body dementia is a neurodegenerative disease, meaning that it worsens over time, and it’s the disease that afflicted comedian and actor Robin Williams.

The brain is made up of billions of neurons that communicate with each other by releasing neurotransmitters.

Most neurons in the cerebral cortex are called cholinergic neurons because they produce acetylcholine.

In contrast, neurons in a section of the midbrain called the substantia nigra are in charge of initiating movement and other motor functions.

These neurons are called dopaminergic because they produce dopamine.

The underlying cause of Lewy body dementia isn’t well understood.

Normally, neurons contain a protein called alpha synuclein, and in Lewy body dementia, this protein gets misfolded within the neurons.

The misfolded alpha-synuclein aggregates to form Lewy bodies that deposit inside neurons, particularly in the cortex and the substantia nigra.

Under a microscope, Lewy bodies look like dark, eosinophilic inclusions inside the affected neurons.

Sources
  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Neuroimaging in Lewy body dementia" Journal of Neurology (2018)
  5. "Lewy body dementias" The Lancet (2015)
  6. "Dysfunctional brain dynamics and their origin in Lewy body dementia" Brain (2019)