Nervous System Pathological Conditions



Nervous System Pathological Conditions

Medical Terminology

I. Brain cells die in a few minutes when deprived of oxygen. Adult nerve cells do not undergo cell division and can not replace themselves.

II. Neurological diseases are classified as follows:

A. Congenital

B. Degenerative, Movement, and Seizure

C. Infectious

D. Neoplastic

E. Traumatic

F. Vascular

III. Congenital Disorders

A. Hydrocephalus – Abnormal accumulation of CSF in the brain

1. Shunt is placed in ventricle and drained into peritoneal space

2. Usually congenital or can occur in adults due to tumors and infections

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B. Spina Bifida – Congenital defect in spinal column due to imperfect union of vertebral parts

1. Spina Bifida Occulta – Vertebral lesion is covered with skin and is evident only on x-rays; outer appearance may have small dimple with tuft of hair

2. Spina Bifida Cystica – More severe type of spina bifida; involves protrusion of meninges (meningocele) or protrusion of meninges and spinal cord (meningomyelocele); surgery may be needed to remove herniated tissue

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IV. Degenerative, Movement, and Seizure Disorders

A. Alzheimer Disease (AD) – Brain disorder marked by deterioration of mental capacity (dementia) beginning in middle age

1. Develops gradually

2. Early sign is memory loss for recent events, persons and places

3. Followed by impairment of judgment, comprehension, and intellect

4. Autopsy reveals atrophy of cerebral cortex and widening of cerebral sulci

5. Etiology: unknown but may be due to genetics

B. Amyotrophic Lateral Sclerosis (ALS) – Progressive disorder characterized by degeneration of motor neurons in the spinal cord and brain stem; a.k.a Lou Gehrig disease

1. Adult onset; more common in men than in women

2. Symptoms include weakness in skeletal muscles, difficulty in swallowing and talking, and dyspnea as the respiratory muscles become affected.

3. Muscles atrophy and pt. become quadriplegic

C. Epilepsy – Chronic brain disorder characterized by recurrent seizure activity

1. Seizure – abnormal, sudden excessive discharge of electrical activity within the brain.

2. Usually due to underlying brain pathological conditions such as brain tumors, meningitis, etc.

3. Types of seizures

a. Gran mal – sudden loss of consciousness, falling down and tonic contractions followed by clonic contractions (stiffening followed by twitching and jerking)

b. May be preceded by aura which is a sensation prior to symptoms occurring; examples: twitching of arm, dizziness, visual disturbances

c. Petit mal – minor form of seizure consisting of momentary clouding of consciousness and loss of contact with the environment

D. Huntington Disease – Degenerative changes occur in cerebrum involving bizarre, abrupt, involuntary, dance-like movements; hereditary disorder

1. Adult onset usually between ages of 30 and 45

2. Mental decline with uncontrollable, irregular, jerking movements of arms, legs and face

3. Due to genetic defect

E. Multiple Sclerosis (MS) – Destruction of myelin sheath on neurons in CNS and its replacement by plaques of sclerotic tissue

1. Adult onset between ages 20-40

2. Have long periods of remission and then relapse

3. Demyelination prevents conduction of nerve impulses through axon

4. Symptoms include paresthesias (numbness, prickly, stinging or burning), muscle weakness, unsteady gait and paralysis; may have blurred and double vision and speech disturbances

5. Thought to be an autoimmune disease in which lymphocytes react against myelin

F. Myasthenia Gravis – Neuromuscular disorder characterized by relapsing weakness of skeletal muscles

1. Autoimmune disorder

2. Antibodies block the neurotransmitter acetylcholine from transmitting nervous impulses from nerve to muscle cell resulting in failure of contractions

3. Eye muscles are affected causing drooping of the eyelid; also affects muscles of the face, tongue, and extremities

G. Parkinson Disease – Degeneration of nerves in the brain leading to tremors, weakness of muscles, and slowness of movement

1. Caused by deficiency of dopamine which is a neurotransmitter

2. Symptoms include stooped posture, shuffling gait, muscle stiffness (rigidity) and tremor of the hands.

H. Tourette Syndrome – Neurological disorder marked by involuntary, spasmodic, twitching movements; uncontrollable vocal sounds; and inappropriate words

1. Begins with tics – twitching of the eyelid and muscles of the face

2. Associated with either an excess of dopamine or hypersensitivity to dopamine

V. Infectious Disorders

A. Meningitis – Inflammation of the meninges

1. Caused by meningococcal or streptococcal bacteria or viruses

2. Symptoms include fever, headache, photophobia (sensitivity to light) and stiff neck

B. Shingles – Viral disease affecting peripheral nerves

1. Blisters and pain spread over skin in pattern following peripheral nerves.

2. Caused by herpes virus which causes chickenpox

3. Herpes virus remains in body after person has it and is reactivated resulting in shingles

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VI. Neoplastic Disorders

A. Brain Tumors – abnormal growth of brain tissue and meninges

B. Symptoms: swelling and hydrocephalus

C. 25%-30% of brain tumors are the result of metastasis from other locations such as the lungs, breast, skin, kidney and gastrointestinal tract

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VII. Traumatic Disorders

A. Cerebral Concussion – Brief loss of consciousness after injury, usually clears within 24 hours

1. No evidence of structural damage to brain tissue

2. Severe concussions may lead to coma

B. Cerebral Contusion – Bruising of brain tissue as a result of direct trauma to the head; neurological deficits persist longer than 24 hours

1. Usually associated with fracture of skull

2. Subdural and epidural hematomas occur

3. Can lead to permanent brain injury or epilepsy

VIII. Cerebrovascular Accident (CVA) – Disruption in the normal blood supply to brain

A. A.K.A. stroke

B. Localized area of ischemia

C. Three types of strokes

1. Thrombotic – Blood clot in arteries leading to brain resulting in occlusion of vessels

a. Prior to total occlusion patient may experience symptoms that point to gradual occlusion of blood vessels. These episodes are known as transient ischemic attacks (TIAs)

3. Embolic – An embolus (clot breaks off from area of body) travels to cerebral arteries and occludes a small vessel.

a. Occurs very suddenly

4. Hemorrhagic – bursting forth of blood from cerebral artery

a. Often fatal

b. Results from advancing age

c. If hemorrhage is small the blood is reabsorbed and patient can make good recovery with only slight disability

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