Central nervous system diseases, also known as central nervous system disorders, are a group of

neurological disorder A neurological disorder is any disorder of the nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord or other nerves can result in a range of symptoms. Examples of symptoms include paralysis, muscle weakn ...

s that affect the structure or function of the

brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

, which collectively form the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

(CNS). These disorders may be caused by such things as infection, injury, blood clots, age related degeneration, cancer, autoimmune disfunction, and birth defects. The symptoms vary widely, as do the treatments. Central nervous system tumors are the most common forms of pediatric cancer. Brain tumors are the most frequent and have the highest mortality. Some disorders, such as substance addiction,

autism The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...

, and

ADHD Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...

may be regarded as CNS disorders, though the classifications are not without dispute.

Signs and symptoms

Every disease has different signs and

symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showi ...

. Some of them are persistent headache; pain in the face, back, arms, or legs; an inability to concentrate; loss of feeling; memory loss; loss of muscle strength;

tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, f ...

s; seizures; increased reflexes, spasticity, tics; paralysis; and slurred speech. One should seek medical attention if affected by these.

Causes

Trauma

Any type of traumatic brain injury (TBI) or injury done to the spinal cord can result in a wide spectrum of disabilities in a person. Depending on the section of the brain or spinal cord that experiences the trauma, the outcome may be anticipated.

Infections

Infectious diseases are transmitted in several ways. Some of these infections may affect the brain or spinal cord directly. Generally, an

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...

is a disease that is caused by the invasion of a microorganism or virus.

Degeneration

Degenerative spinal disorders involve a loss of function in the spine. Pressure on the spinal cord and nerves may be associated with herniation or disc displacement. Brain degeneration also causes central nervous system diseases (i.e.

Alzheimer's Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As t ...

Parkinson's Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

, and

Huntington's disease Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A general lack of coordination and an uns ...

s). Studies have shown that

obese Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...

people may have severe degeneration in the brain due to loss of tissue affecting

cognition Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, though ...

Structural defects

Common structural defects include birth defects,

anencephaly Anencephaly is the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development. It is a cephalic disorder that results from a neural tube defect that occurs when the rostral (head) end of the neural tube ...

, and

spina bifida Spina bifida (Latin for 'split spine'; SB) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, men ...

. Children born with structural defects may have malformed limbs, heart problems, and facial abnormalities. Defects in the formation of the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting o ...

include microgyria, polymicrogyria,

bilateral frontoparietal polymicrogyria Bilateral frontoparietal polymicrogyria is a genetic disorder with autosomal recessive inheritance that causes a cortical malformation. Our brain has folds in the cortex to increase surface area called gyri and patients with polymicrogyri have an ...

, and pachygyria.

CNS Tumors

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

is an abnormal growth of body tissue. In the beginning, tumors can be noncancerous, but if they become malignant, they are cancerous. In general, they appear when there is a problem with cellular division. Problems with the body's

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

can lead to tumors.

Autoimmune disorders

autoimmune disorder An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly ...

is a condition where in the immune system attacks and destroys healthy body tissue. This is caused by a loss of tolerance to proteins in the body, resulting in immune cells recognising these as 'foreign' and directing an immune response against them.

Stroke

A stroke is an interruption of the blood supply to the brain. Approximately every 40 seconds, someone in the US has a stroke. This can happen when a

blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide awa ...

is blocked by a

blood clot A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of cr ...

or when a blood vessel ruptures, causing blood to leak to the brain. If the brain cannot get enough oxygen and blood, brain cells can die, leading to permanent damage.

Functions

Spinal cord

The spinal cord transmits sensory reception from the

peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brai ...

. It also conducts motor information to the body's

skeletal muscles Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle ...

, cardiac muscles, smooth muscles, and

glands In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream ( endocrine gland) or into cavities inside the body or its outer surface ( exocrine gland). Structure ...

. There are 31 pairs of

spinal nerves A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the ...

along the spinal cord, all of which consist of both sensory and motor

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa ...

s. The spinal cord is protected by

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e and connects the peripheral nervous system to the brain, and it acts as a "minor" coordinating center.

Brain

The brain serves as the organic basis of

and exerts centralized control over the other organs of the body. The brain is protected by the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

; however, if the brain is damaged, significant impairments in cognition and physiological function or death may occur.

Diagnosis

Types of CNS disorders

Addiction

Addiction is a disorder of the brain's

reward system The reward system (the mesocorticolimbic circuit) is a group of neural structures responsible for incentive salience (i.e., "wanting"; desire or craving for a reward and motivation), associative learning (primarily positive reinforcement and cla ...

which arises through

transcriptional Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules calle ...

and

epigenetic In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are ...

mechanisms and occurs over time from chronically high levels of exposure to an addictive stimulus (e.g., morphine, cocaine, sexual intercourse, gambling, etc.).

Arachnoid cysts

Arachnoid cysts are

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...

covered by arachnoidal cells that may develop on the brain or spinal cord. They are a

congenital disorder A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities c ...

, and in some cases may not show symptoms. However, if there is a large cyst, symptoms may include headache, seizures,

ataxia Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...

(lack of muscle control),

hemiparesis Hemiparesis, or unilateral paresis, is weakness of one entire side of the body ('' hemi-'' means "half"). Hemiplegia is, in its most severe form, complete paralysis of half of the body. Hemiparesis and hemiplegia can be caused by different med ...

, and several others.

Macrocephaly Macrocephaly is a condition in which circumference of the human head is abnormally large. It may be pathological or harmless, and can be a familial genetic characteristic. People diagnosed with macrocephaly will receive further medical tests to ...

and

are common among children, while presenile dementia,

hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary i ...

(an abnormality of the dynamics of the cerebrospinal fluid), and

urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a common and distressing problem, which may have a large impact on quality of life. It has been identified as an important issue in geri ...

are symptoms for elderly patients (65 and older).

Attention deficit/hyperactivity disorder (ADHD)

ADHD is an organic disorder of the nervous system. ADHD, which in severe cases can be debilitating, has symptoms thought to be caused by structural as well as biochemical imbalances in the brain; in particular, low levels of the neurotransmitters

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 80% o ...

and norepinephrine, which are responsible for controlling and maintaining attention and movement. Many people with ADHD continue to have symptoms well into adulthood. Also of note is an increased risk of the development of

Dementia with Lewy bodies Dementia with Lewy bodies (DLB) is a type of dementia characterized by changes in sleep, behavior, cognition, movement, and regulation of automatic bodily functions. Memory loss is not always an early symptom. The disease worsens over time an ...

, or (DLB), and a direct genetic association of

Attention deficit disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms beco ...

* two progressive, and serious, neurological diseases whose symptoms often occur in people over age 65.

Autism

Autism is a neurodevelopmental disorder that is characterized by repetitive patterns of behavior and persistent deficits in social interaction and communication.

Brain tumors

Tumors of the central nervous system constitute around 2% of all cancer in the United States.

Catalepsy

Catalepsy is a nervous disorder characterized by immobility and muscular rigidity, along with a decreased sensitivity to pain. Catalepsy is considered a symptom of serious diseases of the nervous system (e.g.,

Epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...

, etc.) rather than a disease by itself. Cataleptic fits can range in duration from several minutes to weeks. Catalepsy often responds to

Benzodiazepines Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, ...

(e.g.,

Lorazepam Lorazepam, sold under the brand name Ativan among others, is a benzodiazepine medication. It is used to treat anxiety disorders, trouble sleeping, severe agitation, active seizures including status epilepticus, alcohol withdrawal, and che ...

) in pill and I.V. form.

Encephalitis

Encephalitis is an inflammation of the brain. It is usually caused by a foreign substance or a

viral infection A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. Structural Characteristics Basic structural characteristics, ...

. Symptoms of this disease include headache, neck pain, drowsiness, nausea, and fever. If caused by the

West Nile virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family '' Flaviviridae'', from the genus '' Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The v ...

, it may be lethal to humans, as well as birds and horses.

Epilepsy/Seizures

Epilepsy is an unpredictable, serious, and potentially fatal disorder of the nervous system, thought to be the result of faulty electrical activity in the brain. Epileptic seizures result from abnormal, excessive, or hypersynchronous neuronal activity in the brain. About 50 million people worldwide have epilepsy, and nearly 80% of epilepsy occurs in developing countries. Epilepsy becomes more common as people age. Onset of new cases occurs most frequently in infants and the elderly. Epileptic seizures may occur in recovering patients as a consequence of brain surgery.

Infection

A number of different

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...

s (i.e., certain

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...

es,

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

protozoa Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

, and

prion Prions are misfolded proteins that have the ability to transmit their misfolded shape onto normal variants of the same protein. They characterize several fatal and transmissible neurodegenerative diseases in humans and many other animals. It i ...

s) can cause

s that adversely affect the brain or spinal cord.

Locked-in syndrome

A medical condition,

Locked-in syndrome Locked-in syndrome (LIS), also known as pseudocoma, is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for vertical eye movements and bli ...

usually resulting from a stroke that damages part of the brainstem, in which the body and most of the facial muscles are paralysed but consciousness remains and the ability to perform certain eye movements is preserved.

Meningitis

Meningitis is an inflammation of the

meninges In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in ...

(membranes) of the brain and spinal cord. It is most often caused by a bacterial or viral infection. Fever, vomiting, and a stiff neck are all symptoms of meningitis.

Migraine

A chronic, often debilitating

characterized by recurrent moderate to severe headaches, often in association with a number of autonomic nervous system symptoms.

Multiple sclerosis

Multiple sclerosis (MS) is a chronic, inflammatory

demyelinating disease A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This damage impairs the conduction of signals in the affected nerves. In turn, the reduction in conduction ability causes deficiency i ...

, meaning that the

myelin sheath Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...

s is damaged. Symptoms of MS include visual and sensation problems, muscle weakness, numbness and tingling all over, muscle spasms, poor coordination, and depression. Also, patients with MS have reported extreme fatigue and dizziness, tremors, and bladder leakage.

Myelopathy

Myelopathy is an injury to the spinal cord due to severe compression that may result from trauma, congenital stenosis, degenerative disease or disc herniation. The spinal cord is a group of nerves housed inside the spine that runs almost its entire length.

Tourette's

Tourette's syndrome is an inherited neurological disorder. Early onset may be during childhood, and it is characterized by physical and verbal tics. Tourette's often also includes symptoms of both OCD and

indicating a link between the three disorders. The exact cause of Tourette's, other than genetic factors, is unknown.

Neurodegenerative disorders

Alzheimer's

Alzheimer's is a neurodegenerative disease typically found in people over the age of 65 years. Worldwide, approximately 24 million people have

dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...

; 60% of these cases are due to Alzheimer's. The ultimate cause is unknown. The clinical sign of Alzheimer's is progressive cognition deterioration.

Huntington's disease

Huntington's disease is a degenerative neurological disorder that is inherited. Degeneration of neuronal cells occurs throughout the brain, especially in the

striatum The striatum, or corpus striatum (also called the striate nucleus), is a nucleus (a cluster of neurons) in the subcortical basal ganglia of the forebrain. The striatum is a critical component of the motor and reward systems; receives gluta ...

. There is a progressive decline that results in abnormal movements. Statistics show that Huntington's disease may affect 10 per 100,000 people of Western European descent.

Parkinson's

Parkinson's disease, or PD, is a progressive illness of the nervous system. Caused by the death of dopamine-producing brain cells that affect motor skills and speech. Symptoms may include bradykinesia (slow physical movement), muscle rigidity, and tremors. Behavior, thinking, sensation disorders, and the sometimes co-morbid skin condition Seborrheic dermatitis are just some of PD's numerous nonmotor symptoms.

, Attention deficit/hyperactivity disorder (ADHD) and Bi-polar disorder, all appear to have some connection to one another, as all three nervous system disorders involve lower than normal levels of the brain chemical

(In ADHD, Parkinson's, and the depressive phase of Bi-polar disorder.) or too much dopamine (in Mania or Manic states of Bi-polar disorder) in different areas of the brain:

Treatments

There are a wide range of treatments for central nervous system diseases. These can range from surgery to neural rehabilitation or prescribed medications.

References

External links

{{Authority control Central nervous system disorders

Signs and symptoms

Causes

Trauma

Infections

Degeneration

Structural defects

CNS Tumors

Autoimmune disorders

Stroke

Functions

Spinal cord

Brain

Diagnosis

Types of CNS disorders

Addiction

Arachnoid cysts

Attention deficit/hyperactivity disorder (ADHD)

Autism

Brain tumors

Catalepsy

Encephalitis

Epilepsy/Seizures

Infection

Locked-in syndrome

Meningitis

Migraine

Multiple sclerosis

Myelopathy

Tourette's

Neurodegenerative disorders

Alzheimer's

Huntington's disease

Parkinson's

Treatments

See also

References

External links