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.
  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.