Symptoms, Signs, Syndromes and Diseases
CHAPTER 14
Neurological Disorders
Basic Outline with notes
Symptoms, Signs, Syndromes and Diseases
A.Symptoms are reported by patient
B.Signs are observed by the examiner.
C.Syndromes are patterns of signs and symptoms that cluster together in a particular group of patients.
D. Epidemiology – the study of disease patterns that takes into account variations in geography, demographics, socioeconomic status, genetics, and infectious causes.
Head Trauma – Acquired Brain Injury or Traumatic Brain Injury
A.Penetrating wounds i.e. gunshot
1. Brainstem injury produces death.
2. Survival rate is low if bullet passes completely through brain.
3. Epilepsy
B.Blunt head injuries
1. Contusion – internal bleeding (bruising w/out penetration of skull)
a. effect may be severe and lasting.
b. effects are worse if consciousness is lost for long period of time
2. Concussion – no evidence of hemorrhage.
a. reversible disruption of neurological functions occur
b. Recovery begins with more primitive processes and progresses to higher processes.
3. Dementia Pugilistica – results from a history of repeated blunt head injuries.
a. Movement slow
b. Parkinson’s disease possible
c. Speech and thinking disrupted
d. Reflexes impaired
e. Enlarged ventricles indicate loss of brain tissue
f. There is little evidence of contusion, rather a series of concussions probably occur.
Seizure Disorders
A. Epilepsy –
Definition – Oldest known brain disorder. It is not a disease. It is a sign or symptom of an underlying neurological disorder. It is an abnormal electrical discharge from a group of cells in the brain. The type of seizure will depend upon the part of the brain where the abnormal electrical discharge arises.
EPILEPSY IS NOT INHERITED – NOT CONTAGIOUS
B. Causes and Triggers
Brain injury, poisoning, head trauma or stroke
1. Generalized Seizures
a. Tonic-Clonic (Grand Mal)
b. Absence – (Petit Mal)
2. Partial
a. Simple Partial (Jacksonian)
b. Complex Partial (Psychomotor or Temporal Lobe)
3. Non-Epileptic Seizures
a. drug induced
b. other factors
i. high fever
ii. increased excitement
iii. changes in body chemistry, i.e. low blood sugar
Cerebrovascular Accidents- Stroke
A. Definition – Result of a blockage of blood flow to the brain or bleeding in the brain.
1.Ischemic Stroke– blockage of blood flow
a. Plaque – fatty deposit that can build up on the walls of an artery decreasing the flow of blood to the brain tissue
b. Thrombus – blood clot on plaque surface
c. Embolus– wandering blood clot travels from heart or artery to narrower vessels in brain creating a blockage or embolism
d. Transient Ischemic Attack (TIA) – is a “mini-stroke” whose symptoms resemble ischemic stroke but disappear within 24 hours. Often this is a warning of an ischemic stroke.
2.Hemorrhagic Stroke – a blood vessel ruptures and bleeds within or near the brain. Nearby brain tissue is compressed and may suffer damage or die.
3. Aneurysm – abnormal thinning and protrusion that can form in the walls of the blood vessels. Aneurysms typically occur where blood vessels divide and branch off. Less than 15% of strokes are caused by aneurysms that bleed or rupture.
B. How Cell death occurs
1. When the blood supply to a region of the brain is interrupted, the oxygen and glucose in that region are quickly depleted.
2. Sodium-potassium transporters which regulate the balance of ions inside and outside the cell stop functioning.
3. Neural mechanisms become depolarized
4. This causes the release of glutamate
5. The activation of glutamate receptors further increases the inflow of sodium ions and causes cells to absorb excessive amounts of calcium.
6. The presence of excessive amounts of sodium and calcium within cells is toxic.
7. The intracellular sodium causes the cells to absorb water and swell.
8. The inflammation attracts microglia and activates them.
9. The microglia become phagocytic.
10. The phagocytic microglia begin destroying injured cells.
11. Inflammation attracts white cells.
12. These white cells can adhere to the walls of capillaries near the ischemic region and obstruct them.
13. The presence of excessive amounts of calcium in the cells activates a variety of calcium-dependent enzymes, many of which destroy molecules that are vital for normal cell functioning.
14. The damaged mitochondria produce free radicals – molecules with unpaired electrons that act as powerful oxidizing agents.
15. Free radicals are extremely toxic. They destroy nucleic acids, proteins and fatty acids.
Degenerative Disorders
A.Parkinson's Disease
1. Causes – Parkinson’s Disease is caused by degeneration of the nigrostriatal system- the dopamine-secreting neurons of the substantia nigra that send axons to the basial ganglia.
Scientists now have evidence that long-term exposure to toxic compounds, especially pesticides, can trigger the neurological disease. People with Parkinson’s disease lose 60% to 80% of their dopaimine-producing neurons. By the time the symptoms emerge 2/3 of the 500,000 neurons have been destroyed. A connection to rural living or farming has turned up world-wide. British Scientists reported online in September in the journal, Environmental Health Perspectives, that Since the early 1980’s a dozen published studies have reported an increase of 60% to 600% among people exposed to pesticides. They hope to pinpoint which chemical are most likely to be the specific ones implicated within the next two to five years. (Los Angeles Times, Sunday, November 27, 2005, Section A pages 1, 34-35.)
2. Symptoms – The primary symptoms of Parkinson’s disease are muscular rigidity; slowness of movement; a resting tremor or trembling; difficulty maintaining balance and gait; The patient may also eventually have difficulty walking, talking or completing other simple tasks.
3. Treatment- There is no cure for Parkinson’s disease. The most common drug is
L-dopa sold under the brand name Sinemet. Other drugs available are dopamine-agonists. These drugs work directly on the target cell of the substantia nigra in a way that imitates dopamine. There are drugs which are given for the tremor that work as muscarinic antagonists. Many of the drugs available have side-effects that include mental confusion, hallucinations and dyskinesia.
When L-dopa is no longer effective there are two procedures which have been used. The first is a surgical procedure known as a pallidotomy which destroys a part of the global pallidus The principal output of the basal ganglia comes from the internal division of the globus pallidus. (The caudate nucleus, putamen, and the globus pallidus are the three major components of the basial ganglia.) This output which is directed through the talalmus to the motor cortex is inhibitory.
The second is known as a thalamotomy which destroys a part of the thalamus has some positive effect on patients with dyskinesia and disabling tremors.
Deep-brain stimulation of the thalamus which uses electrical impulses similar to a pacemaker has been used with some success.
Fetal-tissue transplants have also tried for several years with mixed results.
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B.Huntington’s Disease
1. Cause – This is another disease of the basal ganglia. It is caused by degeneration of the caudate nucleus and putamen. This is a hereditary disorder, caused by a dominant gene on chromosome 4. It is a mutation in the normal gene. Each child of an HD parent has a 50-50 chance of inheriting the HD gene. If a child does not inherit the HD gene, he or she will not develop the disease and cannot pass it to subsequent generations.
2. Symptoms Where Parkinson’s disease causes a poverty of movements. Huntington’s disease causes uncontrollable ones. Loss of intellectual faculties, and emotional disturbance. This disease is progressive and eventually causes death.
3. Treatment – none known
http://www.ninds.nih.gov/disorders/huntington/huntington.html
C.Multiple Sclerosis
1. Cause- This is an autoimmune demyelinating disease. Myelin sheaths are attached by the person’s immune system, leaving hard patches of debris called sclerotic plaques. The disease is a choronic, unpredictable disease.
MS IS NOT CONTAGIOUS and is not directly inherited.
MS affects women more frequently than men most often in the late 20’s and early 30’s.
People who spend their childhood in places far from the equator ( above 40 degrees latitude) In the US from east to west, the 37th parallel extends from Newport News, VA to Santa Cruz, CA. The MS prevalence rate for the region below the 37th parallel is 57-78 cases per 100,000 people. The prevalence rate for those above the 37th parallel is 110 to 140 cases per 100,000 people.
MS is more common among Caucasians (particularly those of northern European ancestry).
Additionally, people who are born in the late winter and early spring are at higher risk.
While MS is not hereditary, having a first –degree relative such as a parent or sibling with MS increases an individual’s risk of developing the disease several-fold above the risk for the general population. Some neurologists theorize that MS develops because a person is born with a genetic predisposition to react to some environmental agent, which, upon exposure, triggers an autoimmune response.
There is a genetic marker that has been linked to MS in certain populations. A particular genetic trait occurs more frequently in people with MS than in those who do not have the disease.
2. Symptoms - This depends on the region of the brain attacked. The normal neural messages through the demylinated axons are interrupted.. Some symptoms may be mild such as numbness in the limbs or severe—paralysis or loss of vision. Initial symptoms are most often difficulty in walking, abnormal sensations such as numbness or “pins and needles” and pain and loss of vision due to optic neuritis, an inflammation of the optic nerve.
3. Treatment - The only known treatment is interferon Beta that modulates the responsiveness of the immune system. This reduces the frequency and severity of attacks. The disease is usually episodic.
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D. Alzheimer’s Disease ( to be discussed during Chapter 12 – Memory)
1. Cause – A severe degeneration of the hippocampus, entorhinal cortex, neocortex, (especially the frontal and temporal lobes), ocus coeruleus, and raphe nuclei.
Neuritic B-amyloid plaques – extra cellular deposits of a dense core protein.
Nerofibrillary tangles – dying neurons that contain intracellular accumulations of twisted protein filaments that formerly served as the cells’ internal skeleton.
Some forms of Alzheimer’s are hereditary – mutation of APP gene Also mutation of gene for apoE4.
Most also agree that most forms of Alzheimers’ disease are NOT hereditary. The accumulation of B-amyloid is probably due to head injury, infections, excessive use of alcohol or exposure to toxic substances.
The immune system may contribute to the brain damage associated with Alzheimer’s disease.
Some investigators believe that microglia may be responsible for the production of deposits of B-amyloid. People who had been treated with anti-inflammatory drugs seemed to have a particularly low rate of Alzheimer’s disease.
2. Symptoms – Degenerative disorder characterized by progressive loss of memory and other mental functions. The disease is progressive and leads to death.
3. Treatment – Possible treatments include vaccination against B-amyloid and drugs that inactivate certain forms of secretase.
Brain Tumors
A.Who get Brain Tumors - About 29,000 people in the US are diagnosed with primary brain tumors each year, and nearly 13,000 people die. In children, brain tumors are the cause of one quarter of all cancer deaths. Sixty percent of all children with brain or spinal cord tumors will survive into adulthood. The overall annual incidence of primary brain tumors in the U.S. is 11 to 12 per 100,000 people. For primary malignant brain tumors, the rate is 6 to 7 per 100,000.
The number of people who develop brain tumors and die from them has increased – perhaps as much as 300% over the past three decades, possibly because of better diagnostic procedures i.e. CAT and MRI. Increases in childhood brain tumors, may be due to other unknown causes. Environmental factors are suspected.
B.About Brain Tumors
1. Benign – A benign brain tumor consists of very slow growing cells, has distinct borders and rarely spreads to other locations. A brain tumor composed of benign cells, but located in a vital area – may be considered life threatening even though it isn’t malignant.
Almost half (4.8 per 100,000) of all primary brain tumors are relatively benign and can be successfully treated.
2. Malignant – a malignant brain tumor is life-threatening. Malignant (cancerous) brain tumors may spread to other locations in the brain and spine. Malignant tumors invade and destroy healthy tissue. They lack distinct borders due to their tendency to send “roots” into nearby normal tissue. They may also shed cells that travel to distant parts of the brain and spine by way of the cerebrospinal fluid.
3. Primary – A tumor that starts in the brain is a primary brain tumor. Glioblastoma, multiforme, astrocytoma and medullo-blastoma are examples of primary brain tumors.
4. Metastatic – a metastatic brain tumor is formed by cancer cells originating else-where in the body and then traveled to the brain. For example, cancers of the lung, breast, colon and melanoma frequently spread to the brain. All metastatic brain tumors are malignant.
C.Symptoms –
Headaches are the most common initial symptom and the majority of patients experience headaches sometime during the course of their disease.
Seizures are another common symptom. About half of all patients experience some form of seizure during the course of their illness.
Mental changes frequently occur. These can include problems with memory, speech and communication, reasoning, or concentration. They can be caused directly by the tumor or by increased pressure within the skull.
Nausea and vomiting; drowsiness; vision problems often caused by intercranial pressure.
Many other symptoms are due to a tumor’s effect on specific brain structures.
American Brain Tumor Association – 2720 River Road, Des Plaines, Illinois 60018-4110
(847) 827-9910
Disorders Caused by Infectious Diseases -
A.Encephalitis – definition
Caused by Virus, affect the entire brain.
1. Causes
a. Herpes Simplex virus – trigeminal nerve ganglia attacks the frontal and temporal lobes.
b. Acute anterior poliomyelitis (“polio”) – Virus that attack the motor neurons in the brain and spinal cord.
c. Rabies- Virus acquired by animal bite. Travels through peripheral nerves and attacks the brain.
B.Meningitis – infection of meninges, the layers of connective tissue that surround the central nervous system. Meningitis is an infection of the fluid in the spinal cord and the fluid that surrounds the brain. Meningitis is usually caused by an infection with a virus or a bacterium. Knowing whether meningitis is caused by a virus or a bacterium is important because of differences in the seriousness of the illness and the treatment needed.
1. Causes
a. Viral meningitis is caused by any of a number of different viruses, many of which are associated with other diseases. About half of the cases in the United States are caused by common intestinal viruses. Occasionally, children with mumps or herpes virus infection develop viral meningitis. Mosquito-borne viruses also cause some cases each year. In many cases, a specific virus cannot be identified.
Viral meningitis is usually relatively mild. It clears up in a week or two without specific treatment. Viral meningitis is also called aseptic meningitis.
b. Bacterial Meningitis – more serious is general caused by an ear infection, a head injury or an embolus from a heart infection. Bacterial meningitis is very serious. Severe bacterial meningitis can result in brain damage and even death.
2. Symptoms –
Headache, stiff neck and depending on severity, convulsions, confusion or loss of consciousness, and sometimes death.
C.AIDS dementia
1. Causes
AIDS Dementia Complex (ADS) is not a true opportunistic infection. It is one of the few conditions caused directly by the HIV virus.
“HIV infection of the brain occurs early after initial exposure to the virus, probably within the first few months. However, the infection remains clinically silent over many years; most HIV-infected individuals do not develop cognitive symptoms until many years later, after the onset of full-blown AIDS.
The initial trigger that causes the emergence of AIDS dementia in some patients after years of silent brain infection is unknown. One key factor may be the development of certain "neurovirulent" HIV strains due to genetic changes in the virus within an individual who has been infected with HIV for many years. Other factors may relate to the gradual increase in total virus load within an infected individual over time, leading to increased levels of potentially neurotoxic factors produced by the virus or infected cells.”
2. Symptoms
“The initial symptoms of AIDS dementia are usually mild and occur gradually. The early symptoms may include memory loss, impaired mental concentration, and slowness in performing mental tasks. For example, affected individuals may feel less quick in their thinking or notice that they lose track during conversation or while reading. Family members and friends may notice behavioral abnormalities, such as personality changes, loss of interest in activities, or social withdrawal. Depression is another common symptom. However, depression can also be caused by the psychological stress of HIV infection and is not invariably attributable to AIDS dementia.” Darlene M. Gaeser, Ph.D. The Fielding Institute, Santa Barbara, CA.
http://www.med.harvard.edu/publications/On_The_Brain/Volume5/Number1/AIDS.html