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Brain disorders
medical conditions

Brain disorders

Explore the available health information, treatment context, and integrative evidence for Brain disorders.

Background
  • Because the brain controls almost all of the functions of the human body, injury to the brain can affect many different parts of the body. Brain disorders, which may be inherited or caused by infections, and head injuries can affect the way the brain works and upset the daily activities of the rest of the body.
  • The nervous system is the body's communication center. The central nervous system (CNS) includes the brain and the spinal cord while the peripheral nervous system (PNS) is composed of nerves. Together, the CNS and PNS control every function of the body, from breathing and blinking to memorizing facts for a test. Nerves from the spinal cord branch outward to the rest of the body. Sensory nerves gather information from the environment and send that information to the spinal cord, which then speeds the message to the brain. The brain makes sense of that message and fires off a response. Motor neurons deliver instructions from the brain to the rest of the body.
  • The brain is composed of three main parts: the forebrain, midbrain, and hindbrain. The forebrain consists of the cerebrum, thalamus, and hypothalamus (part of the limbic system). The midbrain consists of the tectum and tegmentum. The hindbrain is composed of the cerebellum, pons, and medulla.
  • The cerebrum or cerebral cortex is the largest part of the human brain. The cerebrum is associated with higher brain function, such as thought and memory. The cerebral cortex is divided into four sections, including the frontal lobe, parietal lobe, occipital lobe, and temporal lobe.
  • The frontal lobe is associated with reasoning, planning, parts of speech, movement, emotions, and problem solving. The parietal lobe is associated with movement, orientation, recognition, and perception of stimuli. The occipital lobe is associated with visual processing. The temporal lobe is associated with perception, memory, speech, and recognition of auditory stimuli.
  • A deep furrow divides the cerebrum into two halves, the left and right hemispheres. The corpus callosum is a bundle of axons that connects these two hemispheres. The two hemispheres look symmetrical but are proven to function slightly differently. The right hemisphere is associated with creativity while the left hemisphere is associated with logic abilities.
  • Nerve cells make up the gray surface of the cerebrum. White nerve fibers underneath carry signals between the nerve cells and other parts of the brain and body.
  • The neocortex occupies the bulk of the cerebrum. This is a six-layered structure of the cerebral cortex that is only found in mammals. It is believed that the neocortex is a recently evolved structure and that it is associated with "higher" information processing among more evolved animals (such as humans and other primates).
  • The cerebellum, or "little brain," is similar to the cerebrum in that it has two hemispheres and a highly folded surface or cortex. This structure is associated with regulation and coordination of movement, posture, and balance.
  • The limbic system, often referred to as the "emotional brain," is found buried within the cerebrum. The lymbic system contains the thalamus, hypothalamus, amygdala, and hippocampus.
  • Underneath the limbic system is the brain stem. The brain stem is composed of the midbrain, pons, and medulla. This structure is responsible for basic vital functions such as breathing, heartbeat, and maintenance of blood pressure. Scientists describe the brain stem as the "simplest" part of the human brain. In some animals that appeared early on the evolutionary scale (such as reptiles), the entire brain resembles a human brain stem.
  • Disorders of the brain can occur as the result of infection, such as meningitis and encephalitis, or traumatic head injury, such as a concussion or contusion.
Signs and Symptoms
  • Meningitis: In children, the symptoms of meningitis vary and depend on both the age of the child and the cause of the infection. Because the flu-like symptoms can be similar in both types of meningitis, particularly in the early stages, and bacterial meningitis can be very serious, it is important to quickly diagnose an infection.
  • The first symptoms of bacterial or viral meningitis can occur within days after a child has had a cold and runny nose, diarrhea and vomiting, or other signs of an infection. Other common symptoms include fever, lethargy (decreased consciousness), irritability, headache, photophobia (eye sensitivity to light), stiff neck, skin rashes, and seizures.
  • Infants with meningitis may not have the symptoms described above and might simply be extremely irritable or lethargic or have a fever. They may be difficult to comfort, even when picked up and rocked. Other symptoms of meningitis in infants can include jaundice (a yellowish tint to the skin), stiffness of the body and neck (neck rigidity), fever or lower-than-normal body temperature, poor feeding, a weak suck, a high-pitched cry, or bulging fontanelles (the soft spot at the top/front of the baby's skull).
  • Viral meningitis tends to cause flu-like symptoms, such as fever and runny nose, and may be so mild that the illness goes undiagnosed. Most cases of viral meningitis resolve completely within 7-10 days without any complications or need for treatment.
  • Most cases of meningitis, both viral and bacterial, result from infections that are contagious. Contagious viruses and bacteria are spread via tiny drops of fluid from the throat and nose of someone who is infected. The drops may become airborne when the person coughs, laughs, talks, or sneezes. They then can infect others when breathed in or if others touch the drops and then touch their own noses or mouths. Sharing food, drinking glasses, eating utensils, tissues, or towels all can transmit infection as well. Some infectious organisms can spread through an individual's stool, and someone who comes in contact with the stool (such as a child in day care) may contract the infection.
  • Infection is most often spread between people who are in close contact. Casual contact at school or work with an infected individual usually will not transmit the infectious agent.
  • Encephalitis: Encephalitis may cause fever, headache, poor appetite, loss of energy, or a generally ill feeling. In more severe cases, other symptoms might occur including: high fever; severe headache; photophobia (sensitivity to light); nausea and vomiting; stiff neck; confusion; sleepiness, difficulty waking or unconsciousness; or convulsions (seizures).
  • When encephalitis follows a common illness like chickenpox (Varicella zoster), the signs and symptoms of that illness usually precede symptoms of inflammation in the brain. However, encephalitis can also appear without warning. If symptoms of encephalitis are present, it is important to contact a doctor immediately.
  • Traumatic brain injury (TBI): Some symptoms of traumatic brain injury (TBI) are evident immediately, while others are not evident until several days or weeks after the injury.
  • With mild TBI, the individual may remain conscious or may lose consciousness for a few seconds or minutes. The individual may also feel dazed or confused for several days or weeks after the initial injury. Other symptoms include headache; mental confusion; lightheadedness; dizziness; double vision, blurred vision, or tired eyes; ringing in the ears; bad taste in the mouth; fatigue or lethargy; a change in sleep patterns; behavioral or mood changes; or trouble with memory, concentration, or calculation. Symptoms may remain the same or get better; worsening symptoms indicate a more severe injury.
  • With moderate or severe TBI, the individual may show these same symptoms, but may also have loss of consciousness; personality change; a severe, persistent, or worsening headache; repeated vomiting or nausea; seizures; inability to awaken; dilation (widening) of one or both pupils; slurred speech; weakness or numbness in the extremities; loss of coordination; or increased confusion, restlessness, or agitation. The coexistence of vomiting and neurological problems (such as weakness in a limb) is an important indicator that the condition is worsening.
  • Small children with moderate to severe TBI may show some of these signs as well as signs specific to this population, including persistent crying, inability to be consoled, or refusal to nurse or eat.
  • Anyone with signs of moderate or severe TBI should receive immediate emergency medical attention.
Diagnosis
  • Meningitis and encephalitis
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  • For both meningitis and encephalitis, diagnosis can be made by withdrawing a small sample of spinal fluid for examination during a procedure called a lumbar puncture (spinal tap). A spinal tap is usually done in a hospital or clinical setting and involves inserting a needle into the middle of the lower back and collecting some drops of fluid. The procedure can be slightly uncomfortable but is rarely painful with the use of a local anesthetic. The entire procedure usually takes about 45 minutes. Once the procedure is complete, the individual will need to lie flat for 20 minutes to one hour.
  • Laboratory analysis of the spinal fluid will confirm whether the meninges are infected as well as what bacteria or virus may be causing the infection.
  • To test for the presence of suspected bacteria or viruses in newborns, doctors may check stomach fluids with a small tube passed down the throat. The infant's feces may also be checked for the presence of bacteria or viruses.
  • Polymerase chain reaction analysis: If meningitis is suspected, a DNA-based test known as a polymerase chain reaction (PCR) can be ordered to check for the presence of bacteria or viruses that may cause meningitis or encephalitis.
  • Brain imaging: A computerized tomography (CT) or magnetic resonance imaging (MRI) scan may reveal swelling of the brain that may occur in encephalitis or meningitis.
  • Electroencephalography (EEG): An electroencephalography (EEG) procedure measures the waves of electrical activity produced by the brain. An EEG is often used to diagnose and manage seizure disorders. A number of small electrodes are attached to the scalp. The electrodes pick up the electrical impulses from the brain and send them to an instrument that records the brain waves. An abnormal EEG result may suggest encephalitis, but a normal result does not rule out the disease.
  • Traumatic brain injury
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  • Neurological examination: If a traumatic brain injury (TBI) is suspected, a complete neurological evaluation is performed to rule out conditions requiring neurosurgical attention, such as hematomas (blood clots), depressed skull fractures, and elevated intracranial pressure (ICP). X-rays, CT scans, and/or MRI scans may be performed to determine if the bones of the skull are fractured and if bone fragments have penetrated the brain tissue.
  • Alertness and orientation of the individual will be assessed. The individual may be presented with a series of questions to determine if he or she can open their eyes, move, speak, and understand what is happening around them. If possible, a detailed medical history is obtained to identify any previous injuries, existing seizure disorders, learning disabilities, prior psychiatric or psychological treatment, and/or substance abuse.
  • The individual's degree of consciousness is assessed to determine the severity of brain injury and predict the chances for recovery. Doctors typically use the Glasgow Coma Scale (GCS), which measures the individual's ability to speak, move, and open his or her eyes. The more severe the injury, the lower the total score, suggesting little chance for complete recovery. The longer the length of a coma, the more severe the injury.
  • The neurological examination may uncover signs of the severity of injury such as increased reflexes and muscle tone (spasticity), abnormal movements (tremors), difficulty swallowing, or slurring of speech, all of which may indicate a moderate to severe head injury.
  • Imaging: Imaging tests using computer-assisted brain scans help visualize damage to the brain. The most common of these is the computerized tomography (CT) scan, a two-dimensional X-ray technique that produces cross-sectional images of the brain. CT scans can detect physical changes in the brain such as hematomas and swelling, which may require immediate treatment. The procedure is painless and takes 15-45 minutes, during which the patient must lie completely still.
  • Another useful diagnostic test is magnetic resonance imaging (MRI scan), which uses a large magnet and radio waves to generate computerized images of the brain without exposing the patient to X-ray radiation. MRIs produce high resolution images of brain structures and are painless. The patient must lie on a flat table in the machine, typically shaped like a long tube. An MRI can take up to 60 minutes. If the individual is sensitive to enclosed places, a mild sedative such as lorazepam (Ativan®) may be used. Open-sided MRIs are now available that decrease problems with closed spaces.
  • An angiogram is a test used to examine blood vessels in the brain. Performing an angiogram involves injecting dye into an artery supplying blood to the brain by means of a catheter inserted into an artery, typically in the groin or forearm. The individual may not be allowed to eat and drink for four to six hours before the test. Before the test, the individual may be given a mild sedative. The radiologist will use a local anesthetic (such as lidocaine) at the injection site so that no pain will be felt. The radiologist will then put a very small tube (catheter) into the blood vessels in the selected artery. This catheter is passed through the other blood vessels in the body until it reaches the neck. The radiologist will then position the tube into different blood vessels in the neck. During this time, injections of a special dye known as a contrast agent are given that help to give more detail on the pictures. The injection may give the individual a general warm feeling that goes away quickly. Before the pictures are taken, the radiographer will move the equipment around the individual into the correct position; pictures are taken during further injections. Problems with the blood vessels of the brain can be seen on the X-ray. When all the required information has been collected, the tube in the artery will be removed by the radiologist. The point where the tube was inserted will be pressed on for up to ten minutes to seal it and stop any bleeding. The test takes one to three hours.
  • An intracranial pressure (ICP) monitor is a device used to measure the pressure that is exerted on the brain. To measure ICP, a small tube is placed into or on top of the brain through a small hole in the skull and connected to a transducer that registers the pressure. ICP increases in response to injury or infection involving the brain.
Complications
  • The complications of meningitis and encephalitis can be severe, and often require immediate medical attention. Without immediate treatment, permanent neurological damage may result, including hearing loss, blindness, loss of speech, learning disabilities, behavior problems, brain damage, and paralysis.
  • Non-neurological complications may include kidney failure and adrenal gland failure. The adrenal glands produce a number of important hormones including cortisol, the stress hormone. Higher and more prolonged levels of cortisol in the bloodstream (like those associated with chronic stress) have been shown to have negative effects, such as impaired cognitive performance, suppressed thyroid function, blood sugar imbalances, decreased bone density, decreased muscle tissue, increased blood pressure, lowered immunity and inflammatory responses in the body, and increased abdominal fat.
  • Bacterial infections of the central nervous system progress quickly. Within a matter of days, the disease can lead to shock and death.
  • Disabilities resulting from a traumatic brain injury (TBI) depend upon the severity and location of the injury, as well as the age and general health of the individual. Some common disabilities include problems with cognition (thinking, memory, and reasoning), sensory processing (sight, hearing, touch, taste, and smell), communication (expression and understanding), and behavior or mental health (depression, anxiety, personality changes, aggression, acting out, and social inappropriateness).
  • Head injuries may result in an unresponsive state in which an individual can only be aroused briefly by a strong stimulus, such as sharp pain. More serious head injuries may result in a coma, a state in which an individual is totally unconscious, unresponsive, unaware, and unable to be aroused. Severe brain injuries may also result in a vegetative state or persistent vegetative state. A vegetative state is a coma in which an individual is unconscious and unaware of his or her surroundings, but continues to have a sleep-wake cycle and periods of alertness. A persistent vegetative state (PVS) is a coma in which an individual stays in a vegetative state for more than a month.
Treatment
  • Meningitis: Treatment for meningitis depends on the organism causing the infection, the individual's age, the extent of the infection, and the presence of other medical conditions or complications of meningitis, such as seizures.
  • Most people with viral meningitis start to improve within three days of feeling ill and recover fully within two weeks. However, it is important to seek medical attention if symptoms of meningitis develop so that bacterial meningitis, which is more serious, can be ruled out. With mild cases of viral meningitis, the individual may only need treatments for pain and dehydration, such as acetaminophen (Tylenol®) to control pain and fever. If the individual does not improve or if symptoms worsen, further testing may be needed to check for other causes of illness.
  • Prescription antibiotics are usually given through a vein (intravenously or IV) to treat meningitis. Antibiotics are given only when bacteria are causing the infection.
  • If meningitis is causing increased intracranial pressure (ICP), corticosteroid medicines, such as dexamethasone (Decadron®), may be given to relieve the pressure.
  • If seizures occur, the individual's surroundings should be kept quiet and calm. Medicines such as phenobarbital or dilantin (Phenytoin®) can help stop the seizures.
  • Oxygen may be given to assist breathing and to increase the amount of oxygen in all parts of the body. Oxygen may be delivered through a hood or tent placed over the body, a face mask placed over the nose and mouth, a nose piece (nasal cannula) held loosely under the nose, or, in severe cases, a tube through the mouth into the trachea (windpipe).
  • The individual may need to drink extra liquids because infections increase the body's need for fluids. Increasing liquids also reduces the possibility of dehydration. Liquids are given through a vein (intravenously or IV) if infection is present, if the patient is vomiting, or if the patient is unable to consume sufficient liquids orally.
  • Encephalitis: Choice of treatment for encephalitis will depend on the cause. Bacterial encephalitis is treated with antibiotics. Viral encephalitis is usually treated with antiviral drugs including acyclovir (Zovirax®), ganciclovir (Cymevene®), foscarnet (Foscavir®), ribovarin (Virazole®), and AZT (Retrovir®).
  • The symptoms of encephalitis may be treated with a number of different drugs. Corticosteroids, including prednisone (Deltasone®) and dexamethasone (Decadron®), are sometimes prescribed to reduce inflammation and brain swelling. Anticonvulsant drugs, including dilantin (Phenytoin®), are used to control seizures. Fever may be reduced with acetaminophen (Tylenol®) or other fever-reducing drugs.
  • Herpes encephalitis can cause rapid death if not diagnosed and treated promptly. Medication is usually started immediately when the doctor suspects herpes without waiting for confirmatory results. The recommended treatment is acyclovir (Zovirax®) given intravenously (IV or into the veins) for two to three weeks. Acyclovir-resistant herpes encephalitis can be treated with foscarnet (Foscavir®). Liver and kidney functions should be monitored throughout the course of medication.
  • The most severe symptoms of encephalitis, such as seizures, generally last up to one week, but full recovery may take weeks or longer.
  • Traumatic brain injury (TBI): Call 911. Anyone with signs of moderate or severe traumatic brain injury (TBI) should receive medical attention as soon as possible. Because little can be done to reverse the initial brain damage caused by trauma, medical personnel try to stabilize an individual with TBI and focus on preventing further injury. Primary concerns include insuring proper oxygen supply to the brain and the rest of the body, maintaining adequate blood flow, and controlling blood pressure. Imaging tests help in determining the diagnosis and prognosis of a TBI patient. Those with mild to moderate injuries may receive skull and neck X-rays to rule out bone fractures or spinal instability. For moderate to severe cases, the imaging test is a computed tomography (CT) scan.
  • Moderately to severely injured patients receive rehabilitation that involves individually tailored treatment programs comprising physical therapy, occupational therapy, speech/language therapy, physical medicine, psychology/psychiatry, and social support.
  • Approximately half of patients with severe head injuries will require surgery to remove or repair hematomas (blood clots) or contusions (bruised brain tissue).
  • Medical attention for a brain injury is necessary if an individual becomes unusually drowsy, develops a severe headache or stiff neck, vomits more than once, loses consciousness (even if only briefly), or behaves abnormally.
  • For a moderate to severe head injury, healthcare professionals recommend calling 911.
  • For a mild head injury, no specific treatment may be needed. However, healthcare professionals recommend close supervision of the individual for any concerning symptoms over the next 24 hours. The symptoms of a serious head injury can be delayed. While the person is sleeping, it is important to wake him or her every two to three hours and ask simple questions to check alertness, such as "What is your name?"
  • If a child begins to play or run immediately after getting a bump on the head, serious injury is unlikely. However, as with anyone with a head injury, watch the child closely for 24 hours after the incident.
  • Over-the-counter pain medicine, such as acetaminophen (Tylenol®) or ibuprofen (Advil®), may be used for a mild headache. Aspirin may increase the risk of bleeding and is not recommended by healthcare professionals for use in TBI.
References
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