Nervous system diseases

Multiple Sclerosis – Literally, “many hardenings,” MS is a disease of unknown cause that manifests as multiple hard plaques of degeneration of the insulating layer of nerve fibers in the central nervous system. The loss of insulation allows “short circuiting” of nerve impulses. Depending upon where the degeneration occurs, patients may suffer paralysis, sensory disturbances or blindness.

Cerebrovascular accident (CVA) – the fancy name for a “stroke”. A blood vessel in the brain may burst causing internal bleeding. Or, a clot may arise in a brain blood vessel (a thrombus), or arise elsewhere (embolus) and travel to get stuck in a brain vessel which then deprives brain tissue of oxygen. Depending upon the area of the brain involved, the patient may suffer paralysis, loss of speech or loss of vision.

Transient Ischemic Attack (TIA) – “Ischemia” was introduced previously in the circulatory diseases module referring to the heart. It literally means “not quite enough blood”. A short period of insufficient blood supply to the brain can have the same signs and symptoms as a stroke such as weakness in an arm, a partial loss of vision, but the problem lasts less than 24 hours. People who get TIA’s are at increased risk of having a stroke in the future.

Epilepsy – a Greek word for “seizure.” Convulsions is another term used. Seizures may have many causes and not all seizures are epilepsy. High fevers in young children may trigger seizures which are short in duration, easily controlled and, typically, have no permanent aftereffects. Epilepsy is a specific condition which may occur at any age, seizures are more intense, longer lasting in duration, and recur with some frequency. The condition may be controlled with medication, or if unresponsive to drugs, may require surgery.

Aphasia – loss of speech. The speech centers are located on the left side of the brain in a majority of people. If someone suffers a “stroke” (cerebrovascular accident-CVA), or traumatic brain injury, and it involves the left side of the brain, they may suffer speech impediments that vary over a spectrum of problems from difficulty in finding the right word, speaking slowly and with difficulty, or complete loss of speech. Actually, there are two speech centers. Injury described above involves the motor speech area, the area of the brain that produces language by integrating thoughts of speech with the movements of the larynx, lips and tongue. There is a second speech area, the receptive or sensory area, that enables us to understand speech. Injury to the latter results in still fluent speech, but the individual does not understand what they are hearing.

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