Mesencephalon See midbrain

Mesmer, Franz Anton (1734-1815) An Austrian physician whose system of treatment (known as mesmerism) was the forerunner of modern-day hypnosis. While still a student at the university of Vienna in 1766, Mesmer discovered the work of the Renaissance mystic physician Paracelsus. He tried to uncover a link between astrology and human health as a result of planetary forces transmitted through a subtle invisible fluid. By 1775, Mesmer began to teach that a person may transmit universal forces to others in the form of "animal magnetism" and based his therapeutic sessions on those beliefs. During these sessions, several people sat around a vat of dilute sulfuric acid while holding hands or touching iron bars sticking out of the solution.

Three years later, his beliefs became increasingly unpopular with other physicians and he was forced to leave Austria for Paris, where he continued to maintain a lucrative practice in mesmerism. However, here too physicians did not accept his beliefs. In 1784 King Louis XVI appointed a special scientific commission, which included U.S. statesman and inventor Benjamin Franklin, guillotine inventor J.I. Guillotin, and chemist A.L. Lavoisier, to investigate Mesmer's methods.

Their report found there was no scientific basis in his methods, noting that his cures were probably the result of a patient's own beliefs and imagination. However, the French Revolution ended his Parisian practice and sent him into exile in London.

still, those he had taught continued to practice his beliefs. Among his former students was the Marquis de Puysegur of Buzancy, who treated a young peasant who went into a state that would be today described as a hypnotic trance. Because it was like sleep but more like sleepwalking, Puysegur called the state "artificial somnambulism"; the term later became associated with a highly hypno-tizable person. But despite the peasant's alertness during the trance, when he awoke he had no recollection of what had happened. puysegur had discovered post-hypnotic amnesia, which had never before been described, and took the peasant to paris to meet Mesmer just before Mesmer left for London.

After Mesmer died in 1815, his followers were known as mesmerists and their technique was known as mesmerism.

mesmerism Also known as animal magnetism, this 18th-century system of treatment was the forerunner of modern-day hypnosis. Mesmerism was named for Austrian physician Franz Anton Mesmer (see mesmer, franz anton) who developed the practice while trying to uncover a link between astrology and health as a result of planetary forces transmitted through a subtle invisible fluid. By 1775, Mesmer began to teach that a person may transmit universal forces to others in the form of "animal magnetism" and based his therapeutic sessions on those beliefs. During these sessions, several people sat around a vat of dilute sulfuric acid while holding hands or iron bars sticking out of the solution. After he died in 1815, his followers were known as mesmerists and their technique was known as mesmerism.

One of his followers, Abbe Faria, renamed somnambulism lucid sleep and criticized Mesmer's theory that some sort of fluid transferred from the operator to the patient. He was one of the first to understand that the ability of a person to enter lucid sleep depended more on the patient than on the mesmerist. During the 19th century, mesmerism was renamed hypnotism after the Greek god of sleep (Hypnos), and the practice began to receive attention from the medical community of the time.

metacognition The awareness and knowledge of an individual's own mental processes; the ability to think about thinking. Metacognition refers to a person's understanding of what strategies are available for learning and what strategies are best used in which situations. ordinarily, these abilities develop in childhood; children learn that mental activities go along with decision making. They know when they know something and when they do not.

Metacognition skills are directly related to reading, writing, problem solving, and any process that requires error monitoring. students must be able to examine how they learn best and learn what resources they can draw upon in order to set and achieve academic goals.

microcephaly A rare neurological disorder in which the circumference of the head is smaller than the average for the age and gender of the infant or child. Microcephaly may be present at birth or it may develop in the first few years of life. The term is used when the head size is less than that of 97 percent to 99 percent of the population.

Symptoms

The signs of microcephaly may vary considerably, causing delay in a child's development that may range from very mild to profound. severely affected children often have cerebral palsy, epilepsy, visual problems, or feeding difficulties. In other cases, there is only minor intellectual impairment. in some children, microcephaly occurs together with other defects or another syndrome.

Cause

The disorder may be caused by a wide variety of conditions leading to abnormal growth of the brain, and is often a symptom of syndromes associated with chromosomal abnormalities. The great variation in the severity of microcephaly may be explained by the fact that it is caused by so many different abnormalities, both genetic and non-genetic.

Autosomal recessive microcephaly This type of microcephaly occurs when two healthy parents each carry a faulty gene and they both pass on one copy of this gene to the affected child. Although the chances of both parents carrying the faulty gene are usually rare, the chances are much higher if the parents are closely related. If both parents carry a faulty recessive gene, the chance of conceiving an affected child is one in four.

Autosomal dominant microcephaly In this type of microcephaly, only one of the parents has a faulty gene. If it is passed to the child, it overrides the normal copy from the other parent and is said to be dominant. A parent with a dominant microcephaly gene has a 50 percent chance of passing on that gene (1 in 2).

X chromosome linked microcephaly This is caused by a faulty gene located on the x chromosome; this type of genetic disorder is usually diagnosed when a healthy female carrier of the faulty gene has an affected son and another affected close male blood relative. The chance of passing on this gene is one in four when the mother is known to be a carrier.

Chromosomal defects Humans normally have 46 chromosomes grouped in 23 pairs that carry the genetic code. In some cases, a genetic fault may occur at the chromosomal level. For example, individuals with Down syndrome have an extra copy of chromosome 21. In these cases of chromosome problems, microcephaly is often present along with other problems.

Prenatal infections Microcephaly can be caused by a prenatal infection with certain viruses and parasites which are able to cross the placenta. often the symptoms of these infections may be very mild or even totally absent as far as the mother is concerned. Infections known to cause microcephaly include rubella (German measles), toxoplasmosis (a parasitic infection) and cytomegalovirus (CMV).

Environmental factors External factors such as exposure to radiation or severe substance abuse by the mother can lead to microcephaly.

Maternal illness during pregnancy Examples of microcephaly caused by maternal illness during pregnancy are rare, but maternal phenylketonuria is one example.

Infections in early infancy Meningitis (inflammation of the membranes that line the brain and spinal cord) and genital herpes are possible cause of neonatal microcephaly if the infection is active at the time of birth. Other possible causes can include fetal stroke or oxygen starvation at birth.

Symptoms

Infants with microcephaly are born with either a normal or reduced head size. Subsequently, the head fails to grow while the face continues to develop at a normal rate, producing a child with a small head, a large face, a receding forehead, and a loose, often wrinkled scalp. As the child grows older, the smallness of the skull becomes more obvious, although the entire body also is often underweight and dwarfed. Development of motor functions and speech may be delayed. Hyperactivity and mental retardation are common occurrences, although the degree of each varies. Convulsions may also occur. Motor ability varies, ranging from clumsiness to spastic quadri-plegia.

Treatment

There is no specific treatment for microcephaly, other than to treat symptoms. A serious attempt should be made to identify a specific cause of the disorder. In general, life expectancy for individuals with microcephaly is low and the prognosis for normal brain function is poor. The prognosis varies, depending on the presence of other problems.

midbrain Also known as the mesencephalon, this is one of the three divisions of the brain stem. Found in the upper part of the brain stem situated above the pons, the midbrain serves as a connecting link between the hindbrain and the forebrain. The midbrain is the origin of the cranial nerves that control five of the six muscles that move the eye and the muscle that controls the size and reactions of the pupils; it helps maintain balance and receives information about positioning of muscles around eyes and jaw.

The mesencephalon is made up of three main parts: the tectum (containing auditory and visual relay stations, called the inferior and superior colli-culi), the tegmentum (containing the midbrain reticular formation that controls attention, the substantia nigra and the red nucleus, both of which are involved in motor control.

migraine A severe headache with accompanying symptoms of nausea, diarrhea, visual disturbances, and depression that attacks about 8 million Americans—75 percent of them women. The symptoms of migraine can occur at any age, although it is common to see the first headache during the teenage years. Most patients have had the first attack by the time they are 40 years old; attacks often recur, but tend to get less severe as a patient ages. Most people with migraine have family members who also have the disorder.

Symptoms

What characterizes a migraine and differentiates it from other types of headache is its specific symptoms. of course, not all migraine sufferers experience the same symptoms, and different symptoms can occur at different times. These include:

• Throbbing or pounding pain—Unlike other types of head pain, migraine pain is a relentless throbbing or pounding as though the pulse is beating severely in the head. The pain usually begins on one side of the head, at the temple, and can spread downward to the eye, face, and even the neck.

• Nausea and vomiting—While nausea and vomiting can be caused by a number of factors, it may also accompany migraines in some sufferers.

• Aura—Some people experience visual disturbances, known as aura immediately before a migraine begins. The aura may look like a shimmer or colored lights, or may involve partial vision loss for 10 to 20 minutes.

• One-sided head pain—Migraine sufferers almost always complain of throbbing pain on only one side of the head, usually around the temple, but sometimes a migraine causes pain all over the head.

• Pain aggravated by activity—The simple act of moving may be difficult, and pain may be aggravated or worsened by activity.

• Sensitivity to light, sounds, and smells— During (and sometimes prior to) a migraine attack, many sufferers experience strong, painful reactions to light, loud noises, and certain odors.

Triggers

For many patients, specific environmental or internal factors can trigger headache severity or frequency, such as drinking alcohol, sleep deprivation, artificial food additives such as MSG, menstruation, stress, and medication. Sexual activity and heavy exercise may trigger a migraine in some patients. pregnancy may either cause the headaches to increase in frequency, or result in temporary improvement.

Causes

Many studies have confirmed that the initial aura of migraine is explained by a reduction in blood flow to specific areas of the cerebral cortex to the occipital lobes, the part of the brain involved in vision. Theories regarding the actual headache and pain in migraine are based on an understanding of the complex pain-sensitive structures in the head. While the brain itself has no pain receptors, the meninges (the ultrathin membranes that surround the brain), blood vessels, and bony anatomy of the head have an intricate system of small nerve branches that are sensitive to pain. The trigeminal nerve in particular has been found to widen blood vessels and subsequently increase blood flow. When the trigeminal system is activated, neuro-chemicals are released into different parts of the brain that may in turn activate specific blood cells and cause them to release substances that cause inflammation.

An important substance within the brain called serotonin is thought to be a key chemical compound in antimigraine activity. This accounts for the fact that many of the drugs successfully used to treat migraine are related to the serotonin molecule and may mimic some of its actions.

Treatment

Many new drugs have recently been developed to treat migraines. The use of medication can be divided into two categories: It can treat the patient with an acute migraine, or it can help prevent migraine or decrease its frequency or severity.

It is important for the migraine sufferer to take medication as soon as possible in an attack, to return to normal activity as soon as possible. This form of nonpreventive therapy is useful in patients with relatively infrequent migraines— at most, a few per month. It also is often necessary to use some symptomatic treatment in patients who still have breakthrough headaches despite using prophylactic drugs. Any of the following medications when used often can lead to rebound headaches, a syndrome caused by overusing medication. Analgesic rebound headaches sometimes become worse after a previous dose of medication begins to wear off, requiring more medication to be taken. They usually are seen in patients who take medication for pain more than four days a week. This overuse also can interfere with the effectiveness of prophylactic headache treatment.

• Acetaminophen and aspirin may help a few patients with mild migraine symptoms.

• Nonsteroidal anti-inflammatory drugs (NSAIDs) include naproxen, indomethacin, and ibupro-fen.

• Compounds of butalbital, acetaminophen, and caffeine can be helpful for patients with occasional headaches, but compounds with butal-bital can become addicting. They may also make people drowsy and interfere with usual activities.

• Ultram (tramadol), a relatively new medication, can be quite effective in both acute and chronic pain syndromes, and be helpful in some patients with migraine. It does not cause the gastrointestinal upset that many medications can.

• Compound of acetaminophen, dichioraiphen-azone, isometheptene (Midrin): This medication relieves migraine, tension, and vascular headaches by constricting blood vessels in the brain.

• Opiates (codeine, hydrocodone, oxycodone, propoxyphene), a potent class of medication, may be needed in some patients but can lead to drug addiction. These should only be used when other treatments fail.

• Serotonin receptor medications treat migraine by acting on cerebral blood vessels and inflammation.

• Triptans act rapidly to relieve the pain of the headache and associated symptoms and can be taken at any point in time during the headache, for migraine both with and without aura. They are usually well tolerated and not associated with the sedation that some other drugs can cause. They should be used only for symptomatic treatment, not on a frequent, chronic basis. Some of the more common choices available include sumatriptan (Imitrex), zolmitriptan (Zomig), and rizatriptan (Maxalt).

• Ergots are a class of medications used for many years to treat migraines. They work much like triptans, by blocking blood vessel dilation, preventing inflammation, and acting on serotonin systems. Ergots include DHE (dihydroergota-mine, Migranal), or ergotamine tartrate (Cafer-got). Ergots can produce side effects similar to those of triptans, including tingling, numbness, flushing, chest tightness, and dizziness. Triptans and ergots should be prescribed with great caution for anyone with risk factors for heart attack or other vascular disease. This includes men over 40, women who have completed menopause, persons with high blood pressure, diabetes, high cholesterol, or who have a history of heart disease.

• Antiemetics (antinausea medications) can help control the nausea and vomiting that may accompany migraine and also can treat the migraine itself in some cases. One commonly prescribed agent is prochlorperazine (Compa-zine) can be very effective when used intravenously to treat acute migraine.

Preventive Treatment

The goal behind daily preventive treatment is to decrease the frequency and severity of migraine. These drugs are usually reserved for patients who have fairly frequent headaches and headaches that do not respond to symptomatic treatment. These medications often help make the situation more tolerable, without completely eliminating migraines. Some patients may require treatment with more than one preventive agent, but this should be tried only after treatment with one agent. If the headaches become well controlled, most clinicians recommend tapering the dosages, or discontinuing the medication, if possible.

Beta blockers These drugs likely work on the central nervous system, as well as on serotonin systems. (They have been used for high blood pressure, heart disease, and heart arrhythmias for many years.) They must be taken daily and should be started at the lowest possible dosage. They should not be used in patients with asthma, and in some patients with specific abnormalities within the heart, and should be used with caution in diabetics. Side effects include drowsiness and light-headedness. commonly used beta blockers include propranolol (Inderal) and atenolol (Tenormin).

Antidepressants Antidepressants can treat migraine through their action on serotonin systems. The more commonly used agents are the tri-cyclics, which are usually taken once a day at bedtime, as they can produce drowsiness. They should be started at the lowest possible dosage to avoid side effects such as drowsiness, dry mouth, and dizziness. commonly used drugs include amitriptyline (Elavil), nortriptyline (Pamelor) and desipramine (Norpramine). Some patients may respond to the newer antidepressants called SSRIs (selective serotonin reuptake inhibitors), such as Prozac. Although they are usually better tolerated than the tricyclic antidepressants, they tend not to be as effective in treatment of migraine. Examples include paroxetine (Paxil), sertraline (Zoloft), and fluoxetine (Prozac).

Valproate (Depakote) This drug has been used to treat seizures for many years, and has also been approved to treat migraine. It is an oral medication which should be taken daily, usually in two divided doses. Laboratory tests, including the blood level of the drug, liver function testing, and a complete blood count, should be monitored. side effects noted are nausea, diarrhea, hair loss, and weight gain.

Calcium channel blockers (verapamil, Norvasc)

These medications are taken orally, either once a day or in divided doses. (They are also used to treat high blood pressure and heart disease.) No blood monitoring is necessary, but side effects can include lightheadedness, drowsiness, and constipation.

Miscellaneous Treatment

There are other types of alternative treatments that some patients explore in their efforts to control migraines, such as biofeedback, TENs units, acupuncture, and so on.

In biofeedback therapy, patients can learn how to reduce pain with a relaxation response that is as effective as Inderol without the side effects. Using a TENs unit can stimulate nerves and reduce muscle spasm in patients with tension and migraine headaches. A health care practitioner's prescription is needed for insurance coverage of these units, which are usually available through medical supply companies. some chiropractors and physical therapists loan these devices out to patients for a small deposit.

Acupuncture has been effective for some patients in controlling their migraines. Patients should choose a practitioner who holds a full doctorate degree in Chinese medicine, an O.M.D. (Oriental Medicine Doctor), or Lic.Ac (licensed acupuncturist). These practitioners are required to complete several years of training and often have completed internships in China, Japan, or Korea. The letters TCM (Traditional Chinese Medicine) after the name mean that the doctor has additional training in prescribing Chinese herbs. The more knowledge practitioners have about chinese medicine and its supporting philosophy, the more able they are to diagnose and treat symptoms.

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