What are brain disorders? |

Causes and Symptoms

The cerebral cortex acts as a processor for sensory information and as an integrator of memory, interpretation, creativity, intellect, and passion. Disorders of the brain or brain defects can disrupt these processing or integrating functions. Disorders of the brain include such commonly heard terms as stroke, ischemia, dementia, seizure, and coma. Brain disorders may also occur as a result of infection, various tumors, traumas leading to blood clots (hematomas) or lack of oxygen (hypoxia), and cancer. Brain defects include anencephaly, a congenital defect in which a newborn lacks a brain, and hydrocephaly, commonly called “water on the brain.”

A stroke is any situation in which the blood supply to a region of the brain is lost. This can occur as a result of a cerebral hemorrhage, during which blood escapes from blood vessels to surround and compress brain tissue; cerebral thrombosis, whereby a clot attached to the wall of a blood vessel restricts the amount of blood flowing to a particular region; or an embolus, a foreign substance which may be a clot that migrates in the bloodstream, often to lodge in a smaller vessel in the brain. The embolus will block blood flow to some area. An embolus can originate from substances other than a blood clot, which is why health care staff often squirt fluid out of a needle before administering a shot or other therapy: to ensure that no air embolus, which could induce a stroke or prove fatal if it enters the brain, is injected.

Transient ischemic attacks
(TIAs) are often thought of as small strokes, but, technically, ischemia simply means that oxygen is not reaching the cells within a tissue. Basically, the mechanism is similar to a stroke, in that blood flow to a portion of the brain is compromised. Although blood actually reaches the brain tissue during ischemia, there is not a sufficient flow to ensure that all cells are receiving the oxygen necessary to continue cellular life. This condition is called hypoxia (low oxygen). If hypoxia is sustained over a sufficient period of time, cellular death occurs, causing irreversible brain damage.

The important differences between a stroke and a TIA are the onset and duration of symptoms, as well as the severity of the damage. Persons with atherosclerosis actually have fat deposits along the interior walls of their blood vessels. These people are vulnerable to experiencing multiple TIAs. Many TIAs are small enough to be dismissed and ignored; others are truly inapparent, causing no symptoms. This is unfortunate because TIAs often serve as a warning of an impending full-scale stroke. Action and treatments could be implemented, if medical advice is sought early, to decrease the likelihood of a stroke. Repeated TIAs also contribute to dementia.

Dementia is not the normal path for the elderly, nor is it a sign of aging. Dementia is a sign of neurological chaos and can be caused by diseases such as Alzheimer’s disease or Acquired immunodeficiency syndrome (AIDS). Although most elderly are not afflicted with dementia, nearly all have a slowing of reaction and response time. This slowing is believed to be associated with chemical changes within nerve cell membranes as aging occurs; slowing of reaction times is not necessarily indicative of the first steps on a path to dementia. In addition, forgetfulness may not be a sign of dementia, since it occurs at all ages. Forgetfulness is such a sign, however, if it is progressive and includes forgetting to dress or forgetting one’s name or date of birth.

While it is incorrect to say that dementia is caused by aging, it is correct to say that dementia is age-related. It may first appear in a person any time between the late thirties and the mid-nineties, but it usually begins to appear in the late seventies. Patients with Alzheimer’s disease are believed to account for about 20 percent of all cases of dementia. Other diseases cause dementia, including an autosomal-dominant genetic disease called Huntington’s disease.
Huntington’s disease manifests itself with a distinct chorea, or dance, of the body that is neither solicited nor controlled. This genetic disease is particularly cruel in that its symptoms appear in midlife, often after the adult has had offspring and passed on the gene. The disease continues to alter the intellect and personality of the afflicted one and progresses to the point of complete debilitation of the body and mind.

A seizure occurs when a collection of neurons misfires, sending nerve impulses that are neither solicited nor controllable. In the everyday use of the term, seizure describes a condition of epilepsy or convulsion. Medically speaking, a seizure is a sign of an underlying problem within the gray matter of the brain; it is the most common neurological disorder.
Epilepsy is a term used to describe a condition of repeated seizures, while convulsion is a term generally applied to describe an isolated seizure. A seizure may occur as a consequence of extreme fever or a violent blow to the head. Seizures are also associated with metabolic disorders, such as hypoglycemia (low blood sugar); trauma causing a loss of blood or oxygen to a region, such as in a newborn after a traumatic birth; toxins, as seen in drug abuse or withdrawal; or bacterial or viral encephalitis or meningitis. In addition, about one-third of those
persons who survive a gunshot wound to the head will experience seizures afterward. In closed head trauma, which can occur in a sporting or automobile accident, there is a 5 percent chance of post-trauma seizures.

Loss of consciousness can be caused by a violent impact to the head, a lack of oxygen or blood flow to the head, a metabolic imbalance, or the presence of a toxin such as alcohol. Usually, this is a transient event, but it may become a permanent condition. When this happens, a person is said to be in a coma. A comatose person exists in a nonresponsive state and may be assessed for brain death. Brain death is a legally defined term which means that no electrical activity in the brain is seen on an electroencephalogram (EEG). Thus some comatose patients may be determined to be brain-dead, particularly if the condition is deemed irreversible.

Brain defects are not common, but they do occur. One particularly tragic defect is the absence of a brain in a newborn, called anencephaly. Death usually occurs within a few hours of birth. Although anencephaly is rare and generally associated with a genetic factor, there have been cases in population clusters, such as one in the Rio Grande area of south Texas, suggesting that an environmental factor may contribute to these defects.

Another defect that may appear in newborns or in an infant’s first months of life is
hydrocephalus. Although the descriptive term “water on the brain” is often used, the condition does not involve a collection of water in the cranium; rather, it involves an accumulation of
cerebrospinal fluid (CSF). CSF is the fluid that insulates the brain and allows it to “float” under the bony cranial encasement. As the ventricles, or spaces, in the brain fill with CSF, bulging occurs and pressure builds to the point of compressing the surrounding brain tissue. This can be very painful and is fatal if untreated. Hydrocephalus can be caused by an overproduction of CSF or a blockage of the CSF drainage from the ventricles of the brain. The symptoms often include a protrusion or abnormal shape of the cranium. In newborns, the skull bones have not yet sutured (fused) to one another, so the soft bones are pushed apart, causing unusual head shapes. This is a warning sign. Another sign is observed if a newborn’s head has a circumference greater than
35.5 centimeters (14 inches); if that is the case, the newborn must be immediately checked for hydrocephalus. Adolescents and adults may also experience hydrocephalus. This can be a response to head trauma, infection, or the overproduction of CSF. The symptoms include lethargy, headache, dullness, blurred vision, nausea, and vomiting.

Treatment and Therapy

TIAs
can progress to strokes. In fact, about 30 percent of those diagnosed with TIA will have a major stroke within the subsequent four years. One of the most prevalent causes of TIAs is hypertension. Hypertension is known as the “silent killer” because many persons with this problem ignore the subtle symptoms of fatigue, headache, and general malaise. Hypertension is also known as a good predictor of major strokes if left untreated. Thus, hypertensive persons need to be diagnosed as such in order to control their blood pressure. This allows them to avoid or delay either a major stroke or multiple TIAs. Management for the hypertensive’s blood pressure may include taking diuretics and hypotensive drugs (to lower the blood pressure). If taken diligently, these drugs offer longevity and quality of life to the sufferer. Aside from hypertension, TIAs may be induced in some metabolic disorders, which should be corrected if possible, or by constricted blood vessels. Sometimes, surgery on such vessels can stop the ischemic attacks and
prevent or delay the onset of a stroke.

Although TIAs lead to strokes, strokes are not necessarily preceded by a TIA. Nearly 90 percent of all major strokes occur without a TIA warning. Sadly, hypertension is the main contributor to this number. Measures can be taken to avoid strokes. This includes maintaining cardiovascular health by exercising, not smoking, and managing hypertension, diabetes mellitus, or other problems that may place stresses on the body’s chemical balance.

Dementia is so poorly understood in terms of causes that a rational probe of drug therapy or a cure is nearly impossible. The drugs most often used in dementia treatment, the ergoloid mesylates, are used to manage the symptoms; namely, the confused mind. These drugs, however, do not stop or prevent the unexplained cellular degeneration associated with dementia. It is interesting to note that a tiny subgroup within those persons suffering from Alzheimer’s disease have greatly improved in mental status with the drug tacrine. It is unfortunate that all patients are not responsive to this drug—a fact which suggests that Alzheimer’s disease is a complex condition.

Seizures are treated pharmacologically according to type. Carbamazepine, phenobarbital, phenytoin, and valproate are some of the drugs available to treat seizure disorders. Barbiturates may also be used in certain cases. Most of these drugs are highly effective when taken as prescribed, and patient noncompliance is the main cause of drug failure. Sometimes, two drugs are combined in therapy. It should be mentioned that pregnant women with epilepsy are urged to continue taking antiepilepsy drugs during pregnancy since a maternal seizure may be more damaging to the fetus than the drug itself.

Some forms of
hydrocephalus can be corrected surgically by performing a CSF shunt from the cranium to the peritoneal (abdominal) region, where the fluid can be eliminated from the body as waste. This is not without risk, and the introduction of infection into the brain is a major concern.

Perspective and Prospects

The therapies in use for brain diseases and disorders have been derived from the practical experience of physicians, the laboratory research of scientists, and the hopes of multitudes of doctors, patients, families, and friends. Medical science has done much to improve the lives of those who suffer with seizures, to reduce the risk of strokes to the hypertensive person and those with TIAs, and is making great progress in treating certain kinds of dementia. Yet much remains to be done.

While one can argue that much is known about the human brain, it would be erroneous to argue that the human brain is fully understood. Despite centuries of research, the brain, as it functions in health, remains largely a mystery. Since the healthy brain is yet to be understood, it is not surprising that the medical community struggles to determine what goes wrong in dementia, seizure, or mental illness or to discover drug therapies that can cross the blood-brain barrier. Thus, the human brain is the uncharted frontier in medicine. As technology improves to support researchers and medical practitioners in their pursuits of cures and treatments for brain diseases and disorders, one can only remain hopeful for the future ability to restore health to the damaged human brain.

In April 2013, US president Barack Obama announced the launch of the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, a research initiative tasked with finding new ways to prevent, treat, and cure brain disorders and injuries. The Defense Advanced Research Projects Agency, National Institutes of Health, and National Science Foundation will fund approximately $100 million in research starting in fiscal year 2014.

Bibliography:

American Medical Association. American Medical Association Family Medical Guide. 4th rev. ed. Hoboken, N.J.: Wiley & Sons, 2004.

Bannister, Roger. Brain and Bannister’s Clinical Neurology. 7th ed. New York: Oxford U P, 1992.

Bloom, Floyd E., M. Flint Beal, and David J. Kupfer, eds. The Dana Guide to Brain Health. New York: Dana, 2006.

Castle, Lana R., and Peter C. Chybrow. Bipolar Disorder Demystified: Mastering the Tightrope of Manic Depression. New York: Avalon, 2003.

Dana Foundation. Dana Foundation, 2013.

Freeman, John M., Eileen P. G. Vining, and Diana J. Pillas. Seizures and Epilepsy in Childhood: A Guide. 3d ed. Baltimore: Johns Hopkins UP, 2002.

Heilman, Kenneth M. Matter of Mind: A Neurologist’s View of Brain-Behavior Relationships. New York: Oxford UP, 2002.

Mace, Nancy L., and Peter V. Rabins. The Thirty-six-Hour Day: A Family Guide to Caring for People with Alzheimer Disease, Other Dementias, and Memory Loss in Later Life. 4th ed. Baltimore: Johns Hopkins UP, 2006.

MedlinePlus. "Brain Diseases." MedlinePlus, May 3, 2013.

Parsons, Malcolm, and Michael Johnson. Diagnosis in Color: Neurology. New York: Mosby, 2001. A

Office of the Press Secretary. "Fact Sheet: BRAIN Initiative." White House, Apr. 2, 2013.

Wiederholt, Wigbert C. Neurology for Non-neurologists. 4th ed. Philadelphia: Saunders, 2000.

Woolsey, Thomas A., Joseph Hanaway, and Mokhtar Gado. Brain Atlas: A Visual Guide to the Human Central Nervous System. 3d ed. Hoboken, N.J.: Wiley, 2008.