More than 600 disorders afflict the nervous system. Neurodegenerative diseases are defined as hereditary and sporadic conditions which are characterized by progressive nervous system dysfunction. These disorders are often associated with atrophy of the affected central or peripheral structures of the nervous system. They include diseases such as Alzheimer's Disease and other dementias, Brain Cancer, Degenerative Nerve Diseases, Encephalitis, Epilepsy, Genetic Brain Disorders, Head and Brain Malformations, Hydrocephalus, Stroke, Parkinson's Disease, Multiple Sclerosis, Amyotrophic Lateral Sclerosis (ALS or Lou Gehrig's Disease), Huntington's Disease, Prion Diseases, and others.

The framework of health information on neurodegenerative diseases sometimes includes brain diseases, defined as pathologic conditions also affecting the brain (composed of the intracranial components of the central nervous system). This includes (but is not limited to) the cerebral cortex; intracranial white matter, basal ganglia, thalamus, hypothalamus, brain stem, and cerebellum (MeSH definition).
  Multiple sclerosis (MS) is a disorder of the central nervous system (brain and spinal cord) caused by lesions in the white matter of the central nervous system that degenerate the myelin sheath, marked by lack of muscle coordination, muscle weakness, speech problems, paresthesia, and visual impairments. It is the major cause of non-traumatic disability in young adults. It clinically manifests with signs of multiple neurological dysfunctions (e.g., visual and sensory disturbances, limb weakness, gait problems, and bladder and bowel symptoms) followed by either recovery, or by increasing disability over time due to irreversible functional impairment (Ebers, 1998). However, aspecific symptoms such as fatigue (80% patients) can alone interfere with patients’ quality of life and productivity.

There are no specific tests for the diagnosis of MS. Diagnostic criteria require evidence of dissemination of neurological signs and symptoms in space and time, based on history, clinical, and paraclinical evidences. There is no cure for MS, but disease-modifying treatments have been available for the past 10 years.
Estimates of the number of people affected by Multiple Sclerosis throughout the world range between 1.1 million and 2.5 million. No data on prevalence or incidence have been systematically collected.
  Creutzfeld-Jacob disease (CJD), also known as subacute spongiform encephalopathy, is a progressive, inevitably fatal infection that produces muscle spasms and progressive loss of mental function. Although it occurs worldwide, little is known about how it is usually spread. Initially, patients experience problems with muscular coordination; personality changes, including impaired memory, judgment, and thinking; and impaired vision. People with the disease also may experience insomnia, depression, or unusual sensations. CJD does not cause a fever or other flu-like symptoms. Pneumonia and other infections often occur in these patients and can lead to death.

A disease similar to CJD occurs in sheep (scrapie) and in cattle (mad-cow disease, BSE). The infection is transmitted to offspring, and it is speculated that it can be acquired by eating infected tissues. Diagnosis of CJD is usually not confirmed while the person is alive, as some brain tissue is required for testing. Consequently, reported figures for CJD cases include both definite and probable cases.
CJD has some aetiological subtypes: Definite sporadic cases will have had the diagnosis pathologically confirmed; they have no identifiable cause, and account for 85% of all cases. Probable sporadic cases have recognised symptoms and certain clinical features, but have not been confirmed pathologically. Iatrogenic cases are those where infection appears to have occurred accidentally as the result of a medical procedure. Familial cases occur in families associated with certain mutations or where there is probable CJD in a first degree relative; they form 10-15% of all cases. GSS refers to the rare Gerstmann-Straussler-Scheinker syndrome, while nvCJD is the new variant first reported in 1996.

There are several known variants of CJD. These variants differ somewhat in the symptoms and course of the disease. For example, a variant form of the disease—called new variant or variant (nv-CJD, v-CJD), described in United Kingdom and France—begins primarily with psychiatric symptoms, affects more younger patients than other types of CJD, and has a longer than usual duration from onset of symptoms to death. Another variant, called the panencephalopathic form, occurs primarily in Japan and has a relatively long course, with symptoms often progressing for several years.

Some symptoms of CJD can be similar to symptoms of other progressive neurological disorders, such as Alzheimer’s or Huntington’s disease. However, CJD causes unique changes in brain tissue which can be seen at autopsy. It also tends to cause more rapid deterioration of a person’s abilities than Alzheimer’s disease or most other types of dementia.
  While acute pain is a normal sensation triggered in the nervous system to alert you to possible injury and the need to take care of yourself, chronic pain is different. Chronic pain persists. Pain signals keep firing in the nervous system for weeks, months, even years. Common chronic pain complaints include headache, low back pain, cancer pain, arthritis pain, neurogenic pain (pain resulting from damage to the peripheral nerves or to the central nervous system itself), psychogenic pain (pain not due to past disease or injury or any visible sign of damage inside or outside the nervous system).

The pain of a migraine headache is often described as an intense pulsing or throbbing pain in one area of the head. It is often accompanied by extreme sensitivity to light and sound, nausea, and vomiting. Migraine is three times more common in women than in men. For many years, scientists believed that migraines were linked to the dilation and constriction of blood vessels in the head. Investigators now believe that migraine is caused by inherited abnormalities in genes that control the activities of certain cell populations in the brain. 
Key finding were:

• Chronic pain strikes one in five (19%) adults across Europe
• Over one third of European households have at least one pain sufferer (chronic or otherwise)
• Two-thirds of chronic pain sufferers experience moderate pain, while one-third experience severe pain (as rated on a 1–10 scale)
• The most common source of pain reported by chronic pain sufferers is the back (24%),and the most common cause is arthritis/osteoarthritis (35%)
• People with chronic pain have been suffering on average for 7 years, some for 20 years or more (21%)
• One third of patients suffer chronic pain at all times – 24 hours a day, 365 days a year.

Parkinson's disease (PD) is a chronic, progressive neurological disorder for which at present there is no known cure. The core symptoms are tremor, rigidity (stiffness), bradykinesia (slowness of movement) and postural instability (balance difficulties). It is the second most common neurodegenerative disease, affecting more than 1 per 1 000 people. It affects men and women equally. Although PD is most common in the over 60's, many people are diagnosed in their 40's and younger.
  Huntington's disease (HD) results from genetically programmed degeneration of brain cells, called neurons, in certain areas of the brain. This degeneration causes uncontrolled movements, loss of intellectual faculties, and emotional disturbance. HD is a familial disease, passed from parent to child through 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. A person who inherits the HD gene will sooner or later develop the disease. The rate of disease progression and the age of onset vary from person to person. A genetic test, coupled with a complete medical history and neurological and laboratory tests, helps physicians diagnose HD. In 1 to 3 percent of individuals with HD, no family history of HD can be found.
  Epilepsy is a disorder of the brain characterised by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological, and social consequences of the condition. The definition of epilepsy requires the occurrence of at least one epileptic seizure. The definition of epilepsy requires the occurrence of at least one epileptic seizure. Depending on the location of abnormal electrical activity, seizures can have a variety of manifestations, ranging from mild impairment of consciousness to severe and potentially life-threatening convulsions.
Studies determining the prevalence of epilepsy in Europe are numerous and have used a variety of methodologies. The majority of these European studies have been conducted in the UK, Nordic, Baltic and Western Mediterranean countries.
  Early diagnosis can be an important factor in the outcome of tumors in the brain. Brain tumors are the second leading cause of cancer death in children under age 15 and the second fastest growing cause of cancer death among those over age 65. Over the next year, more than 100,000 people in the United States will be diagnosed with a brain tumor.
Types of Brain Tumors
Primary Brain Tumors
Tumors that begin in brain tissue are known as primary brain tumors and are classified by the type of tissue in which they originate. The most common brain tumors are gliomas, which begin in the glial or supportive tissue. There are several types of gliomas:

• Astrocytomas — These tumors arise from small, star-shaped cells called astrocytes. They may grow anywhere in the brain or spinal cord. In adults, astrocytomas most often arise in the cerebrum. In children, they occur in the brain stem, the cerebrum and the cerebellum. A grade III astrocytoma is sometimes called anaplastic astrocytoma. A grade IV astrocytoma is usually called glioblastoma multiforme.
• Brain stem gliomas — These tumors occur in the lowest, stem-like part of the brain. The brain stem controls many vital functions. Most brain stem gliomas are high-grade astrocytomas.
• Ependymomas — These tumors usually develop in the lining of the ventricles. They may also occur in the spinal cord. Although these tumors can develop at any age, they are most common in childhood and adolescence.
• Oligodendrogliomas — These tumors occur in the cells that produce myelin, the fatty covering that protects nerves. These tumors usually arise in the cerebrum. They are rare, grow slowly and usually do not spread into surrounding brain tissue. They occur most often in middle-aged adults but have been found in people of all ages.

There are other types of brain tumors that do not begin in glial tissue. Some of the most common are described below:

• Medulloblastomas — These tumors were once thought to develop from glial cells. However, recent research suggests that these tumors develop from primitive or developing nerve cells that normally do not remain in the body after birth. For this reason, medulloblastomas are sometimes called primitive neuroectodermal tumors (PNET). Most medulloblastomas arise in the cerebellum; however, they may occur in other areas as well. These tumors occur most often in children and are more common in boys than in girls.
• Meningiomas — These tumors grow from the meninges, or membranes that enclose the brain and spinal cord. They are usually benign. Because these tumors grow very slowly, the brain may be able to adjust to their presence. Meningiomas often grow quite large before they cause symptoms. They occur most often in women between 30 and 50 years of age.
• Schwannomas — These tumors are benign and begin in Schwann cells, which produce the myelin that protects the acoustic nerve, or the nerve of hearing. They occur mainly in adults. These tumors affect women twice as often as men.
• Craniopharyngiomas — These tumors develop in the region of the pituitary gland near the hypothalamus. They are usually benign but are sometimes considered malignant because they can press on or damage the hypothalamus, a region of the brain, and affect vital functions. These tumors occur most often in children and adolescents.
• Germ cell tumors — These tumors arise from developing sex cells or germ cells. The most frequent type of germ cell tumor in the brain is the germinoma.
• Pineal region tumors — These tumors occur in or around the pineal gland, a tiny organ near the center of the brain. The tumor can be slow growing (pineocytoma), or fast growing (pineoblastoma). The pineal region is very difficult to reach, and these tumors often cannot be removed.

Secondary Brain Tumors
Metastasis is the spread of cancer. Cancer that begins in other parts of the body may spread to the brain and cause secondary tumors. These tumors are not the same as primary brain tumors. Cancer that spreads to the brain is the same disease and has the same name as the original or primary cancer. For example, if lung cancer spreads to the brain, the disease is called metastatic lung cancer because the cells in the secondary tumor resemble abnormal lung cells, not abnormal brain cells.
Treatment for secondary brain tumors depends on where the cancer started and the extent of the spread as well as other factors, including the patient's age, general health and response to previous treatment.
  Early diagnosis can be an important factor in the outcome of tumors in the spinal cord. Primary spinal cord tumors — tumors that originate in the spine rather than spread to the spine from elsewhere in the body — are usually benign. They are so rare that they account for only a half of one percent of all newly diagnosed tumors. Malignant primary tumors of the spinal cord are even less common.
Most spinal cord cancers are metastatic or secondary cancers, meaning they arise from cancers that have spread to the spinal cord. Cancers that may spread to the spine include lung, breast, prostate, head and neck, gynecologic, gastrointestinal, thyroid, melanoma, renal cell carcinoma and others.
  Rare diseases are life-threatening or chronically debilitating diseases with a low prevalence and a high level of complexity. Most of them are genetic diseases resulting from environmental exposures during pregnancy or later in life, often in combination with genetic susceptibility, the others being rare cancers, auto-immune diseases, congenital malformations, toxic and infectious diseases among other categories. There is also a great diversity in the age at which the first symptoms occur but half of Rare Diseases can appear at birth or during childhood. The European Commission is supporting some specific networks on neurological rare diseases.
  Brain Mapping
The brain is the most complicated organ in our body. Every area has a specific function that controls everything that we do. For years, doctors have had a rough map of the brain, but never to the degree that they could operate and know for sure how to avoid every critical portion since each person brain is unique, causing variations in the map. This fact, combined with the sheer complexity of the brain, has challenged neurosurgeons for years.
An advanced brain mapping technique has enabled doctors to remove as much of a brain tumor possible while minimizing the impact on the crucial areas of the brain that control movement, speech and the senses.
By using 3-dimensional imaging technology to operate on the brain, surgeons can accurately target their dissection down to the smallest degree. The goal is to remove all or most of the tumor without producing any permanent neurological deficit in the patient.

Minimize Impact on Healthy Tissue - During the surgery, the patient is awake for a portion of the surgical procedure to help surgeons with an understanding of the functional areas of the brain near the tumor. This allows doctors to map out their path to a successful surgery while minimizing impact on healthy, vital tissue.
The patient is allowed to return to consciousness after the brain has been exposed, and then interacts with the team as they stimulate areas of the brain near the tumor.
For example, the neurosurgeon may stimulate the brain where it controls feelings in the mouth and gums, causing the patient to experience tingling or tongue twitching. Language testing is also performed.
Once the areas of the eloquent cortex have been identified, the patient is put back under general anesthesia and the surgery is completed.
Brain mapping is also being used to treat other diseases such as epilepsy.

Cyberknife
The CyberKnife — one of the most advanced forms of radiosurgery — is a painless, non-invasive treatment that delivers high doses of precisely targeted radiation to destroy tumors or lesions within the body. It uses a robotic arm to deliver highly focused beams of radiation. The flexibility of the robotic arm makes it possible to treat areas of the body, such as the spine and spinal cord, that can't be treated by other radiosurgery techniques.

Procedure - Radiosurgery minimizes radiation exposure to healthy tissue surrounding the tumor. Compared to other radiosurgical treatments, the CyberKnife offers several advantages to patients, including rapid relief from pain and other symptoms.
Treatments are performed on an outpatient basis, with each treatment lasting between 30 to 90 minutes. The number of treatments vary depending on the tumor size, location and shape but typically only one to five daily sessions are required. The CyberKnife allows patients to lie comfortably on the procedure table without anesthesia while the robotic arm moves, without touching them, to treat all areas of the tumor.
Recovery is often immediate, given its low risk of complications and damage to health tissue.
Some conditions may be treated with a different non-invasive radiotherapy device called the Gamma Knife, which also delivers a single, finely focused, high dose of radiation.

Deep Brain Stimulation
Deep Brain Stimulation (DBS) is an advanced form of brain surgery that was developed to treat Parkinson's disease. It has been used for those with dystonia, a disorder characterized by involuntary muscle contractions that force certain parts of the body into abnormal, sometimes painful, movements or postures. DBS has also helps those suffering from essential tremors, tremors associated with multiple sclerosis and those suffering from severe depression.
Functioning like a "pacemaker" for the brain, DBS uses electrodes implanted in the brain to send out electrical impulses to different areas in the brain linked to disorders. The surgery and electrical impulse treatment do not destroy brain tissue.
When treating Parkinson's disease, for example, the inserted DBS device called a neurostimulator, sends electrical impulses through the wire into the brain to control the movement center. The stimulation blocks abnormal activity in the brain and relieves patients of tremors, rigidity, slowness of movement, stiffness and may help with other problems associated with their conditions. It does not, however, cure patients of their disorders.
The electrode stimulation can be adjusted as the patient's condition changes.

Procedure - DBS surgery involves putting the tip of a hair-thin wire inside the brain in a special area that controls movement. The patient is awake during surgery to allow the surgical team to assess the patient's brain functions. The small wire runs up through a small hole in the skull and under the scalp, down to a small device implanted under the collarbone. Local anesthetic is applied to these areas, and the patient is occasionally sedated.
While the electrode is being advanced through the brain, the patient does not feel any pain. Most dystonia patients have two implants — one on each side of the brain.
The most serious potential risk associated with the procedure is bleeding in the brain, which can lead to stroke. Risk of stroke ranges from 1 percent to 3 percent among patients. Infection, which occurs in 3 percent to 4 percent of patients, is another risk. If infection occurs, it is usually not life threatening, but may require removal of the entire DBS system.
 
Gamma Knife
The Gamma Knife is an advanced radiation treatment for adults and children with small to medium brain tumors, abnormal blood vessel formations called arteriovenous malformations, epilepsy, trigeminal neuralgia, a nerve condition that causes chronic pain, and other neurological conditions.
Despite its name, the Gamma Knife isn't a knife but is a machine that delivers a single, finely focused, high dose of radiation to its target, while causing little or no damage to surrounding tissue. Abnormalities measuring less than 3 centimeters, or 1 inch in diameter, can be treated with the Gamma Knife.
Today, patients with serious disorders can be treated with this noninvasive procedure in one day with no overnight hospital stay.

Who Should Have Gamma Knife Treatment - Factors considered in evaluating a patient for Gamma Knife treatment include a patient's age and general medical condition, location and size of the brain abnormality and previous treatments. If it is decided that Gamma Knife is not the best treatment option, other treatments will be discussed.
Some conditions are more effectively treated with a non-invasive radiosurgery device called the CyberKnife that uses a robotic arm to deliver highly focused beams of radiation. Radiation exposure to other parts of the body is extremely low, making it an excellent option for children and women of childbearing age.

Preparing for Treatment - Prior to a Gamma Knife procedure, patients visit the hospital for possible blood tests, and to meet with the doctors and nurse who will participate in the procedure. Depending on your condition, your doctors may include a radiation oncologist or neurosurgeon. During your pre-procedure consultation, your doctor will record your medical history, perform a physical examination and provide time for you to ask questions.

Procedure - The technique that allows the Gamma Knife to precisely target areas within the brain is called stereotaxy. Stereotactic radiosurgery is performed with the aid of imaging techniques called computerized tomography (CT) scanning,magnetic resonance imaging (MRI) and angiography. These are used together with special computer-assisted instruments to provide 3-D views of the target and surrounding brain structures. By studying these images, your doctor can accurately locate the abnormality within the brain, then precisely focus the gamma radiation beams on the abnormality.
The neurosurgeon will use local anesthesia to numb four spots on your scalp and forehead before attaching a "stereotactic frame." This frame allows highly precise treatment.
The treatment time will depend on your diagnosis. While the treatment is administered, you will lie on a treatment couch. Your head will be held still during the session while 192 small radiation beams are focused simultaneously at the target. The size of the focal spot can be adjusted and multiple focal spots can be combined together to deliver a high radiation dose precisely to one target or to multiple targets of almost any shape, anywhere in the brain.
During treatment, there's no pain. After treatment, the head frame is removed and small adhesive bandages are applied where the sterotactic frame was secured.

Recovery - You may be discharged shortly after the procedure. Some patients experience a mild headache, which can be treated with medication. Discharge and follow-up instructions will be explained and you'll receive an instructional handout.
The process of Gamma Knife treatment for children is similar to the process for adults, but special care is provided for pediatric patients including imaging studies before treatment, anesthesia tailored for children, recovery and subsequent treatment, if required.