Question

What are the main degenerative diseases of the nervous system?

Answer 1

The degenerative disorders generally are characterized by the loss of neurons and secondary scarring without evidence of major inflammation or necrosis of tissue. Many diseases classified as degenerative are now known to be associated with specific metabolic deficiencies or have other definite causes. Others are transmitted by infectious agents. The main degenerative diseases of nervous dydtem are as follows:-

1) Alzheimer disease:- It is characterized pathologically by neurofibrillary accumulation in the neurons as well as senile plaques containing substantial amounts of beta amyloid configured proteins. Since the pathologic changes are identical in most cases of old-age dementia. The pathologic changes in persons with Alzheimer's disease are most severe in the hippocampi. This is the reason that loss of recent memory is an early clinical feature.Therefore, trouble finding nouns and constructional apraxia are also common early signs. There is early loss of cholinergic neurons in the nucleus basalis and drugs that inhibit central nervous system acetylcholinesterase improve symptoms of the condition modestly. As the illness progresses it involves more of the cortex, with more severe cognitive loss and eventually frontal lobe disturbances become prominent.

2) Pick's disease:- Pick's disease is a rare condition that can run in families and results in degeneration of the frontal and temporal lobes of the brain. This can be severe in some cases, permitting reasonably accurate diagnosis on the basis of imaging. However, most cases are not so easy to diagnose, especially at the onset. This condition tends to present in one of two ways. Firstly, it may present as disordered behavior (usually either with disinhibited behavior or with apathy). The disinhibited behaviors include agitation, socially inappropriate behavior or impulsivity. There is usually a lack on insight into their condition and a lack of empathy. The second presentation is dominated by language problems, usually accompanied by behavioral problems. Despite these deficits, memory and spatial skills remain intact.

3) Spinocerebellar ataxia :- This disease is an autosomal recessive condition that usually begins in late childhood, but whose onset can be delayed until early adulthood. Several spinal cord pathways are progressively damaged including the dorsal columns and the lateral columns (upper motor neurons) as well as cerebellar pathways. After a reasonably normal early childhood, progressive clumsiness of gait and skeletal deformity (such as scoliosis) are noted. Most of the other spinocerebellar ataxias begin in adulthood. The best known of these are the autosomal dominant SCAs, where specific genes and, for many, gene products are known.