Lewy Body Diseases
Lewy body dementia is a clinicopathological syndrome that may
account for up to 20% of all cases of dementia in older patients,
typically in their seventh and eighth decades. Diseases with Lewy
bodies should also be considered in the differential diagnosis of a wide
range of clinical presentations including episodic disturbances of
consciousness, syncope, sleep disorders, and unexplained delirium.
(Brown, 1999)
There are three major syndromes associated with the appearance of
Lewy bodies. These are: the movement disorder known as Parkinson
disease, autonomic nervous system failure, and dementia.
Parkinsonism, the most common syndrome with Lewy bodies, is a
disease developing in middle age. In older persons, a mixture of
cognitive, autonomic, and motor dysfunction is more common. Some
older persons with dementia who are thought to have Alzheimer
disease may actually have diffuse Lewy body disease, and some of
those persons may have a movement disorder resembling Parkinson
disease. Conversely, some patients initially presenting with Parkinson
disease may develop manifestations of Lewy body dementia. (Brown,
1999) (Kosaka, 2000)
The clinical presentation of Lewy body disease varies according to the
site of Lewy body formation and associated neuronal loss. In Parkinson
disease, the Lewy bodies are found in the substantia nigra of the
midbrain, coupled with the loss of pigmented neurons. In persons with
the dementia of diffuse Lewy body disease, there are Lewy bodies in
the neocortex. Some persons have the Lewy bodies in both locations.
The basal ganglia and diencephalon may also be involved in some
cases. (Kalra et al, 1996) (Kosaka, 2000)
Lewy bodies are spherical, intraneuronal, cytoplasmic, eosinophilic
inclusions comprising abnormally truncated and phosphorylated
intermediate neurofilament proteins, alpha-synuclein, ubiquitin, and
associated enzymes. With idiopathic Parkinson disease, Lewy bodies
are typically found in the substantia nigra, nucleus basalis of Meynert,
dorsal raphe, locus ceruleus, dorsal motor nucleus of the vagus nerve,
and hypothalamus. In cases Lewy body dementia, cortical Lewy bodies
are prominent, but there are typically findings of Alzheimer disease as
well. (Kövari et al, 2009)