Parkinson’s disease versus Dementia with Lewy bodies

A patient usually comes to the movement disorder clinic with the diagnosis of Parkinson’s disease because there’s a quirky symptom that puzzles the general neurologist. Small idiosyncrasies about the presentation of illness and the onset of symptoms can mean the difference between Parkinson’s disease and Dementia with Lewy bodies, a variant diagnosis. Perhaps you think, so what? The diagnosis of an illness describes a certain course. The diagnosis gives a range of issues that typically present themselves with progression of illness, and they vary.
A patient comes to the clinic diagnosed with PD yet the first indication of illness was hallucinations. Standard patients with PD may experience hallucinations when they are sleep deprived, over-medicated or in advanced stages of illness. The patient’s symptoms are readily apparent upon physical examination; cogwheel rigidity exists in the muscles of the arms, there is slowness of movement and the hands exhibit a resting tremor. It has not been two years since diagnosis. The most astounding symptom is the loss of substantial weight in two months. PD patients lose weight over the years, not in sudden drops.

The specialist concedes the patient’s symptoms are not typical for PD. He would like the patient evaluated by a neuropsychologist who will evaluate cognition, or mental faculties and access what the deficits are. The family members who have come with the patient attest to the loss of memory, and increased reliance on others to remember, and perform basic functions such as grocery shopping.

He would like to target two issues in the clinical session- he’d like to improve sleeping and ensure the patient is eating adequately. To improve sleeping, he tells the patient to open the drapes during the day, let in the sun and try not to nap. At night, he writes a prescription of the antidepressant, Remeron or its generic, myrtazapine. The medication may take up to a month to have anti-depressant effects, but in the meanwhile, it increases appetite and makes patients sleepy. It is to be taken at night.

The essential difference between Parkinson’s disease and Dementia with Lewy bodies is the distribution of the protein masses, called Lewy bodies. While patients with PD also harbor the plaques, they begin low in the brain, eventually migrating to inhabit cells higher in the cortex as the patient becomes demented at end stage illness. In the other scenario, the mental decline evident early on occurs because Lewy bodies have invaded the cortex of the brain and impaired its normal functioning.


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