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Drusen, from the German word for node or geode (singular, "Druse"), are tiny yellow or white accumulations of extracellular material that build up between Bruch's membrane and the retinal pigment epithelium of the eye. The presence of a few small ("hard") drusen is normal with advancing age, and most people over 40 have some hard drusen. [1]
Alzheimer's disease (AD) is a chronic neurodegenerative disease that results in the loss of neurons and synapses in the cerebral cortex and certain subcortical structures, resulting in gross atrophy of the temporal lobe, parietal lobe, and parts of the frontal cortex and cingulate gyrus. [14]
The symptoms of CJD are caused by the progressive death of the brain's nerve cells, which are associated with the build-up of abnormal prion proteins forming in the brain. When brain tissue from a person with CJD is examined under a microscope, many tiny holes can be seen where the nerve cells have died. Parts of the brain may resemble a sponge ...
Subacute combined degeneration of spinal cord; Diagram of the principal fasciculi of the spinal cord. (In subacute combined degeneration of spinal cord, the "combined" refers to the fact that the dorsal columns and lateral corticospinal tracts are both affected, in contrast to tabes dorsalis which is selective for the dorsal columns.)
This nucleus is known for its large number of multipolar cells and its particularly reticular structure. The reticulotegmental nucleus is topographically related to pontine nuclei (non-reticular), being just dorsal to them. The reticulotegmental nucleus has been known to mediate eye movements, otherwise known as saccadic movement. [1]
Signs and symptoms are classified into three groups based on the affected functions of the frontal and temporal lobes: [8] These are behavioural variant frontotemporal dementia, semantic dementia, and progressive nonfluent aphasia. An overlap between symptoms can occur as the disease progresses and spreads through the brain regions. [14]
Clinically subcortical dementia usually is seen with features like slowness of mental processing, forgetfulness, impaired cognition, lack of initiative-apathy, depressive symptoms (such as anhedonia, negative thoughts, loss of self-esteem and dysphoria), loss of social skills along with extrapyramidal features like tremors and abnormal movements.
Vascular dementia can be caused by ischemic or hemorrhagic infarcts affecting multiple brain areas, including the anterior cerebral artery territory, the parietal lobes, or the cingulate gyrus. [5] On rare occasion, infarcts in the hippocampus or thalamus are the cause of dementia. [ 12 ]