Neurological disorder
Encyclopedia
A neurological disorder is a disorder of the body
's nervous system
. Structural, biochemical or electrical abnormalities in the brain
, spinal cord
, or in the nerves leading to or from them, can result in symptoms such as paralysis
, muscle weakness
, poor coordination
, loss of sensation
, seizures, confusion
, pain
and altered levels of consciousness
. There are many recognized neurological disorders, some relatively common, but many rare. They may be revealed by neurological examination
and studied and treated within the specialities of neurology
and clinical neuropsychology
. Interventions include preventative measures, lifestyle changes
, physiotherapy or other therapy
, neurorehabilitation
, pain management
, medication
, or operations
performed by neurosurgeons. The World Health Organization
estimated in 2006 that neurological disorders and their sequelae affect as many as one billion
people worldwide, and identified health inequalities and social stigma
/discrimination
as major factors contributing to the associated disability
and suffering
.
Although the brain and spinal cord are surrounded by tough membranes
, enclosed in the bones of the skull
and spinal vertebrae, and chemically isolated by the so-called blood-brain barrier
, they are very susceptible if compromised. Peripheral nerves tend to lie deep under the skin but are also still relatively exposed to damage. And individual neurons, the building blocks of the nervous system, and the neural networks
into which they form, are susceptible to electrochemical and structural disruption. While neuroregeneration may occur in the peripheral nervous system, it is thought to be rare in the brain and spinal cord.
The specific causes vary by disorder and sometimes by individual case, but can include genetic disorder
s; congenital abnormalities
or disorders
; infections; lifestyle or environmental health
problems including malnutrition
; and brain injury
, spinal cord injury
or nerve injury
. The problem may start in another body system that interacts with the nervous system; for example cerebrovascular disorders involve brain injury due to problems with the blood vessels (cardiovascular system) supplying the brain, and autoimmune disorders involve damage caused by the body's own immune system
.
In a substantial minority of cases of neurological symptoms, no neural cause
can be identified using current testing procedures, and such "idiopathic
" conditions can invite different theories about what is occurring.
and peripheral nervous system (PNS) disorders
. The Merck Manual lists brain, spinal cord and nerve disorders in the following overlapping categories:
Neurological disorders in non-human animals are treated by veterinarians.
are not usually classed as primarily neurological. However the distinction can be a matter of some debate, either in regard to specific facts about the cause of a condition or in regard to the general understanding of brain and mind
. Furthermore the definition of disorder can be contested in regard to what is considered abnormal, dysfunctional, harmful or unnatural in neurological
, evolutionary
, psychometric
or social
terms.
While certain types of mental condition are not usually classified primarily as neurological disorders, and certain types of brain disorder are not usually classified primarily as mental conditions, there are now an array of basic sciences that deal with the continuum between the neural and the mental, including subspecialities of psychology
and neuroscience
such as neuropsychology
, cognitive neuropsychology
or cognitive (thought) neuroscience
, affective (emotion) neuroscience
, behavior neuroscience (also known as biopsychology), social neuroscience
, and neurophenomenology
(subjective experience and consciousness
).
These basic fields inform the applied medical and clinical disciplines of neurology
, psychiatry
and clinical psychology
, whose theories and treatments now routinely encompass a biopsychosocial model
. These disciplines in turn comprise subspecialities such as behavioral neurology
, neuropsychiatry
and clinical neuropsychology
that deal with cases where a connection between mental/behavioral problems and brain dysfunction is particularly called for. Biopsychiatry is the general term for the approach in psychiatry that seeks to explain all mental disorders primarily in terms of the biological functioning of the nervous system.
The conventional distinctions drawn between mind, brain and nervous system are to some extent mirrored by the various overlapping categories of clinical examination, namely mental state examination, neuropsychological assessment
and neurological examination
. At the present time a brain scan alone cannot accurately diagnose a mental disorder or tell the risk of developing one, but can be used to rule out other medical conditions such as a brain tumor
.
Such distinctions can affect the explanation given for idiopathic (of unknown origin) neurological symptoms if it is thought (perhaps by exclusion of any other diagnosis
) that higher brain/mental activity is causing symptoms that usually originate in other areas of the nervous system. Classic examples are "functional" seizures
, sensory numbness
, "functional" limb weakness
and functional neurological deficit
("functional" in this context is usually contrasted with the old term "organic disease
"). Such cases may be contentiously interpreted as being "psychological" rather than "neurological". In psychiatry some cases may then be classified as mental disorders, for example conversion disorder
if the symptoms appear to be causally linked to emotional states or responses to social stress. However there are also accepted neurological conditions of dissociation
where the brain/mind appears to register neurological stimuli that cannot possibly be coming from the part of the nervous system to which they would normally be attributed, such as phantom pain
or synesthesia
, or where limbs act without conscious direction, as in alien hand syndrome
.
Human body
The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...
's nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
. Structural, biochemical or electrical abnormalities in the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
, spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
, or in the nerves leading to or from them, can result in symptoms such as paralysis
Paralysis
Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...
, muscle weakness
Muscle weakness
Muscle weakness or myasthenia is a lack of muscle strength. The causes are many and can be divided into conditions that have true or perceived muscle weakness...
, poor coordination
Motor coordination
thumb|right|Motor coordination is shown in this animated sequence by [[Eadweard Muybridge]] of himself throwing a diskMotor coordination is the combination of body movements created with the kinematic and kinetic parameters that result in intended actions. Such movements usually smoothly and...
, loss of sensation
Sensory system
A sensory system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory receptors, neural pathways, and parts of the brain involved in sensory perception. Commonly recognized sensory systems are those for vision, hearing, somatic...
, seizures, confusion
ConFusion
ConFusion is an annual science fiction convention organized by the Stilyagi Air Corps and its parent organization, the Ann Arbor Science Fiction Association. Commonly, it is held the third weekend of January. It is the oldest science fiction convention in Michigan, a regional, general SF con...
, pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
and altered levels of consciousness
Altered level of consciousness
An altered level of consciousness is any measure of arousal other than normal. Level of consciousness is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousness may be classed as lethargy; someone in this state can be...
. There are many recognized neurological disorders, some relatively common, but many rare. They may be revealed by neurological examination
Neurological examination
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired...
and studied and treated within the specialities of neurology
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
and clinical neuropsychology
Clinical neuropsychology
Clinical neuropsychology is a sub-field of psychology concerned with the cognitive function of individuals with neurological and psychiatric disorders. Neuropsychological assessment examines cognitive function in the broadest sense, including the behavioural, emotional, social and functional status...
. Interventions include preventative measures, lifestyle changes
Lifestyle medicine
Lifestyle medicine is defined as the application of environmental, behavioural, medical and motivational principles to the management of lifestyle-related health problems in a clinical setting...
, physiotherapy or other therapy
Therapy
This is a list of types of therapy .* Adventure therapy* Animal-assisted therapy* Aquatic therapy* Aromatherapy* Art and dementia* Art therapy* Authentic Movement* Behavioral therapy* Bibliotherapy* Buteyko Method* Chemotherapy...
, neurorehabilitation
Neurorehabilitation
Neurorehabilitation is a complex medical process which aims to aid recovery from a nervous system injury, and to minimize and/or compensate for any functional alterations resulting from it....
, pain management
Pain management
Pain management is a branch of medicine employing an interdisciplinary approach for easing the suffering and improving the quality of life of those living with pain. The typical pain management team includes medical practitioners, clinical psychologists, physiotherapists, occupational therapists,...
, medication
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
, or operations
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
performed by neurosurgeons. The World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
estimated in 2006 that neurological disorders and their sequelae affect as many as one billion
1000000000 (number)
1,000,000,000 is the natural number following 999,999,999 and preceding 1,000,000,001.In scientific notation, it is written as 109....
people worldwide, and identified health inequalities and social stigma
Social stigma
Social stigma is the severe disapproval of or discontent with a person on the grounds of characteristics that distinguish them from other members of a society.Almost all stigma is based on a person differing from social or cultural norms...
/discrimination
Discrimination
Discrimination is the prejudicial treatment of an individual based on their membership in a certain group or category. It involves the actual behaviors towards groups such as excluding or restricting members of one group from opportunities that are available to another group. The term began to be...
as major factors contributing to the associated disability
Disability
A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these.Many people would rather be referred to as a person with a disability instead of handicapped...
and suffering
Suffering
Suffering, or pain in a broad sense, is an individual's basic affective experience of unpleasantness and aversion associated with harm or threat of harm. Suffering may be qualified as physical or mental. It may come in all degrees of intensity, from mild to intolerable. Factors of duration and...
.
Causes
Meninges
The meninges is the system of membranes which envelopes the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.-Dura...
, enclosed in the bones of the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
and spinal vertebrae, and chemically isolated by the so-called blood-brain barrier
Blood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
, they are very susceptible if compromised. Peripheral nerves tend to lie deep under the skin but are also still relatively exposed to damage. And individual neurons, the building blocks of the nervous system, and the neural networks
Neural Networks
Neural Networks is the official journal of the three oldest societies dedicated to research in neural networks: International Neural Network Society, European Neural Network Society and Japanese Neural Network Society, published by Elsevier...
into which they form, are susceptible to electrochemical and structural disruption. While neuroregeneration may occur in the peripheral nervous system, it is thought to be rare in the brain and spinal cord.
The specific causes vary by disorder and sometimes by individual case, but can include genetic disorder
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....
s; congenital abnormalities
Congenital abnormality
A congenital anomaly is a condition which is present at the time of birth which varies from the standard presentation....
or disorders
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
; infections; lifestyle or environmental health
Environmental health
Environmental health is the branch of public health that is concerned with all aspects of the natural and built environment that may affect human health...
problems including malnutrition
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
; and brain injury
Brain injury
A brain injury is any injury occurring in the brain of a living organism. Brain injuries can be classified along several dimensions. Primary and secondary brain injury are ways to classify the injury processes that occur in brain injury, while focal and diffuse brain injury are ways to classify...
, spinal cord injury
Spinal cord injury
A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...
or nerve injury
Nerve injury
Nerve injury is injury to nervous tissue. There is no single classification system that can describe all the many variations of nerve injury. Most systems attempt to correlate the degree of injury with symptoms, pathology and prognosis...
. The problem may start in another body system that interacts with the nervous system; for example cerebrovascular disorders involve brain injury due to problems with the blood vessels (cardiovascular system) supplying the brain, and autoimmune disorders involve damage caused by the body's own immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
.
In a substantial minority of cases of neurological symptoms, no neural cause
Etiology
Etiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....
can be identified using current testing procedures, and such "idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
" conditions can invite different theories about what is occurring.
Classification
Neurological disorders can be categorized according to the primary location affected, the primary type of dysfunction involved, or the primary type of cause. The broadest division is between central nervous system (CNS) disordersCentral nervous system disease
A central nervous system disease can affect either the spinal cord or brain , both part of the central nervous system. The central nervous system controls behaviors in the human body, so this can be a fatal illness.-Spinal Cord:...
and peripheral nervous system (PNS) disorders
Peripheral neuropathy
Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....
. The Merck Manual lists brain, spinal cord and nerve disorders in the following overlapping categories:
- BrainBrainThe brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
:- Brain damageBrain damage"Brain damage" or "brain injury" is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors...
according to cerebral lobeLobes of the brainBrain lobes were originally a purely anatomical classification, but have been shown also to be related to different brain functions. The telencephalon , the largest portion of the human brain, is divided into lobes, but so is the cerebellum...
(see also lower brain areas such as basal gangliaBasal gangliaThe basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
, cerebellumCerebellumThe cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
, brainstem):- Frontal lobe damageFrontal lobe disorderFrontal lobe disorder is an impairment of the frontal lobe that occurs as a result of a number of diseases as well as head trauma. The frontal lobe of the brain plays a key role in higher mental functions such as motivation, planning, social behaviour, and speech production...
- Parietal lobeParietal lobeThe parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
damage - Temporal lobeTemporal lobeThe temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
damage - Occipital lobeOccipital lobeThe occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
damage
- Frontal lobe damage
- Brain dysfunction according to type:
- AphasiaAphasiaAphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....
(language) - DysarthriaDysarthriaDysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes...
(speech) - ApraxiaApraxiaApraxia is a disorder caused by damage to specific areas of the cerebrum. Apraxia is characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire and the physical ability to perform the movements...
(patterns or sequences of movements) - AgnosiaAgnosiaAgnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...
(identifying things/people) - AmnesiaAmnesiaAmnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...
(memory)
- Aphasia
- Brain damage
- Spinal cordSpinal cordThe spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
disorders (see spinal pathologyMyelopathyMyelopathy refers to pathology of the spinal cord. When due to trauma, it is known as spinal cord injury. When inflammatory, it is known as myelitis. Disease that is vascular in nature is known as vascular myelopathy....
, injurySpinal cord injuryA spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...
, inflammationMyelitisMyelitis is a disease involving inflammation of the spinal cord, which disrupts central nervous system functions linking the brain and limbs. The name is derived from Greek referring to the "spinal cord", and the suffix -itis, which denotes inflammation....
) - Peripheral nervous system disordersPeripheral neuropathyPeripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....
- Cranial nerve disorders
- Autonomic nervous system disorders
- Seizure disorders such as epilepsyEpilepsyEpilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
- Movement disorderMovement disorderMovement disorders include:* Akathisia * Akinesia * Associated Movements * Athetosis...
s such as Parkinson's diseaseParkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system... - Sleep disorderSleep disorderA sleep disorder, or somnipathy, is a medical disorder of the sleep patterns of a person or animal. Some sleep disorders are serious enough to interfere with normal physical, mental and emotional functioning...
s - Headaches (including migraineMigraineMigraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
) - Lower back and neck pain (see Back painBack painBack pain is pain felt in the back that usually originates from the muscles, nerves, bones, joints or other structures in the spine.The pain can often be divided into neck pain, upper back pain, lower back pain or tailbone pain...
) - Other painPainPain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
(see Neuropathic painNeuropathic painNeuropathic pain results from lesions or diseases affecting the somatosensory system. It may be associated with abnormal sensations called dysesthesia, which occur spontaneously and allodynia that occurs in response to external stimuli. Neuropathic pain may have continuous and/or episodic ...
) - DeliriumDeliriumDelirium or acute confusional state is a common and severe neuropsychiatric syndrome with core features of acute onset and fluctuating course, attentional deficits and generalized severe disorganization of behavior...
and dementiaDementiaDementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
such as Alzheimer's diseaseAlzheimer's diseaseAlzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death... - DizzinessDizzinessDizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....
and vertigoVertigoVertigo is a form of dizziness.Vertigo may also refer to:* Vertigo , a 1958 film by Alfred Hitchcock**Vertigo , its soundtrack** Vertigo effect, or Dolly zoom, a special effect in film, named after the movie... - StuporStuporStupor is the lack of critical cognitive function and level of consciousness wherein a sufferer is almost entirely unresponsive and only responds to base stimuli such as pain. This is often mistaken for delirium and treated with Haldol and or other anti-psychotic drugs...
and comaComaIn medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as... - Head injuryHead injuryHead injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....
- StrokeStrokeA stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
(CVA, cerebrovascular attack) - Tumors of the nervous system (e.g. cancerCancerCancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
) - Multiple sclerosisMultiple sclerosisMultiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
(MS) and other demyelinating diseaseDemyelinating diseaseA demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This impairs the conduction of signals in the affected nerves, causing impairment in sensation, movement, cognition, or other functions depending on which nerves are involved.The term...
s - Infections of the brain or spinal cord (including meningitisMeningitisMeningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
) - PrionPrionA prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...
diseases (a type of infectious agent) - Complex regional pain syndromeComplex regional pain syndromeComplex regional pain syndrome is a chronic progressive disease characterized by severe pain, swelling and changes in the skin. It often affects an arm or a leg and may spread to another part of the body.Though treatment is often unsatisfactory, early multimodal therapy can cause dramatic...
(CRPS) (a chronic pain condition.)
Neurological disorders in non-human animals are treated by veterinarians.
Neural and mental dysfunction
Mental disorders, learning disabilities and mental retardationMental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
are not usually classed as primarily neurological. However the distinction can be a matter of some debate, either in regard to specific facts about the cause of a condition or in regard to the general understanding of brain and mind
Mind
The concept of mind is understood in many different ways by many different traditions, ranging from panpsychism and animism to traditional and organized religious views, as well as secular and materialist philosophies. Most agree that minds are constituted by conscious experience and intelligent...
. Furthermore the definition of disorder can be contested in regard to what is considered abnormal, dysfunctional, harmful or unnatural in neurological
Neurodiversity
Neurodiversity is a "controversial concept [that] ... regards atypical neurologicaldevelopment as a normal human difference". According to Jaarsma and Welin , the "neurodiversity movement was developed in the 1990s by online groups of autistic persons...
, evolutionary
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
, psychometric
Psychometrics
Psychometrics is the field of study concerned with the theory and technique of psychological measurement, which includes the measurement of knowledge, abilities, attitudes, personality traits, and educational measurement...
or social
Norm (sociology)
Social norms are the accepted behaviors within a society or group. This sociological and social psychological term has been defined as "the rules that a group uses for appropriate and inappropriate values, beliefs, attitudes and behaviors. These rules may be explicit or implicit...
terms.
While certain types of mental condition are not usually classified primarily as neurological disorders, and certain types of brain disorder are not usually classified primarily as mental conditions, there are now an array of basic sciences that deal with the continuum between the neural and the mental, including subspecialities of psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
and neuroscience
Neuroscience
Neuroscience is the scientific study of the nervous system. Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics,...
such as neuropsychology
Neuropsychology
Neuropsychology studies the structure and function of the brain related to specific psychological processes and behaviors. The term neuropsychology has been applied to lesion studies in humans and animals. It has also been applied to efforts to record electrical activity from individual cells in...
, cognitive neuropsychology
Cognitive neuropsychology
Cognitive neuropsychology is a branch of cognitive psychology that aims to understand how the structure and function of the brain relates to specific psychological processes. It places a particular emphasis on studying the cognitive effects of brain injury or neurological illness with a view to...
or cognitive (thought) neuroscience
Cognitive neuroscience
Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain...
, affective (emotion) neuroscience
Affective neuroscience
Affective neuroscience is the study of the neural mechanisms of emotion. This interdisciplinary field combines neuroscience with the psychological study of personality, emotion, and mood.-Brain areas related to emotion:...
, behavior neuroscience (also known as biopsychology), social neuroscience
Social neuroscience
Social neuroscience is an interdisciplinary field devoted to understanding how biological systems implement social processes and behavior, and to using biological concepts and methods to inform and refine theories of social processes and behavior. Humans are fundamentally a social species, rather...
, and neurophenomenology
Neurophenomenology
Neurophenomenology refers to a scientific research program aimed to address the hard problem of consciousness in a pragmatic way. It combines neuroscience with phenomenology in order to study experience, mind, and consciousness with an emphasis on the embodied condition of the human mind...
(subjective experience and consciousness
Consciousness
Consciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
).
These basic fields inform the applied medical and clinical disciplines of neurology
Neurology
Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
, psychiatry
Psychiatry
Psychiatry is the medical specialty devoted to the study and treatment of mental disorders. These mental disorders include various affective, behavioural, cognitive and perceptual abnormalities...
and clinical psychology
Clinical psychology
Clinical psychology is an integration of science, theory and clinical knowledge for the purpose of understanding, preventing, and relieving psychologically-based distress or dysfunction and to promote subjective well-being and personal development...
, whose theories and treatments now routinely encompass a biopsychosocial model
Biopsychosocial model
The biopsychosocial model is a general model or approach that posits that biological, psychological , and social factors, all play a significant role in human functioning in the context of disease or illness...
. These disciplines in turn comprise subspecialities such as behavioral neurology
Behavioral neurology
Behavioral neurology is a subspecialty of neurology that studies the neurological basis of behavior, memory, and cognition, the impact of neurological damage and disease upon these functions, and the treatment thereof. Two fields associated with behavioral neurology are neuropsychiatry and...
, neuropsychiatry
Neuropsychiatry
Neuropsychiatry is the branch of medicine dealing with mental disorders attributable to diseases of the nervous system. It preceded the current disciplines of psychiatry and neurology, in as much as psychiatrists and neurologists had a common training....
and clinical neuropsychology
Clinical neuropsychology
Clinical neuropsychology is a sub-field of psychology concerned with the cognitive function of individuals with neurological and psychiatric disorders. Neuropsychological assessment examines cognitive function in the broadest sense, including the behavioural, emotional, social and functional status...
that deal with cases where a connection between mental/behavioral problems and brain dysfunction is particularly called for. Biopsychiatry is the general term for the approach in psychiatry that seeks to explain all mental disorders primarily in terms of the biological functioning of the nervous system.
The conventional distinctions drawn between mind, brain and nervous system are to some extent mirrored by the various overlapping categories of clinical examination, namely mental state examination, neuropsychological assessment
Neuropsychological assessment
Neuropsychological assessment was traditionally carried out to assess the extent of impairment to a particular skill and to attempt to locate an area of the brain which may have been damaged after brain injury or neurological illness...
and neurological examination
Neurological examination
A neurological examination is the assessment of sensory neuron and motor responses, especially reflexes, to determine whether the nervous system is impaired...
. At the present time a brain scan alone cannot accurately diagnose a mental disorder or tell the risk of developing one, but can be used to rule out other medical conditions such as a brain tumor
Brain tumor
A brain tumor is an intracranial solid neoplasm, a tumor within the brain or the central spinal canal.Brain tumors include all tumors inside the cranium or in the central spinal canal...
.
Such distinctions can affect the explanation given for idiopathic (of unknown origin) neurological symptoms if it is thought (perhaps by exclusion of any other diagnosis
Diagnosis of exclusion
A diagnosis of exclusion is a medical condition reached by a process of elimination, which may be necessary if presence cannot be established with complete confidence from examination or testing...
) that higher brain/mental activity is causing symptoms that usually originate in other areas of the nervous system. Classic examples are "functional" seizures
Psychogenic non-epileptic seizures
Psychogenic non-epileptic seizures , also known as Non-Epileptic Attack Disorders, are events superficially resembling an epileptic seizure, but without the characteristic electrical discharges associated with epilepsy. Instead, PNES are psychological in origin, and may be thought of as similar to...
, sensory numbness
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
, "functional" limb weakness
Functional weakness
Functional weakness is weakness of an arm or leg due to the nervous system not working properly. It is not caused by damage or disease of the nervous system...
and functional neurological deficit
Functional Neurological Deficit
The diagnosis of Functional Neurological Deficit provides an umbrella term for a variety of symptoms of apparent neurological origin but which current models struggle to explain psychologically or organically. Presentation may be similar to a wide range of other neurological conditions from...
("functional" in this context is usually contrasted with the old term "organic disease
Organic disease
An organic disease is one which involves or affects physiology or bodily organs. A disease in which there is a physiological change to some tissue or organ of the body....
"). Such cases may be contentiously interpreted as being "psychological" rather than "neurological". In psychiatry some cases may then be classified as mental disorders, for example conversion disorder
Conversion disorder
Conversion disorder is a condition in which patients present with neurological symptoms such as numbness, blindness, paralysis, or fits without a neurological cause. It is thought that these problems arise in response to difficulties in the patient's life, and conversion is considered a psychiatric...
if the symptoms appear to be causally linked to emotional states or responses to social stress. However there are also accepted neurological conditions of dissociation
Dissociation
Dissociation is an altered state of consciousness characterized by partial or complete disruption of the normal integration of a person’s normal conscious or psychological functioning. Dissociation is most commonly experienced as a subjective perception of one's consciousness being detached from...
where the brain/mind appears to register neurological stimuli that cannot possibly be coming from the part of the nervous system to which they would normally be attributed, such as phantom pain
Phantom pain
Phantom pain sensations are described as perceptions that an individual experiences relating to a limb or an organ that is not physically part of the body. Limb loss is a result of either removal by amputation or congenital limb deficiency . However, phantom limb sensations can also occur following...
or synesthesia
Synesthesia
Synesthesia , from the ancient Greek , "together," and , "sensation," is a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway...
, or where limbs act without conscious direction, as in alien hand syndrome
Alien hand syndrome
Alien hand syndrome is a neurological disorder in which the afflicted person's hand appears to take on a mind of its own...
.
See also
- Central nervous systemCentral nervous systemThe central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
- Central nervous system diseaseCentral nervous system diseaseA central nervous system disease can affect either the spinal cord or brain , both part of the central nervous system. The central nervous system controls behaviors in the human body, so this can be a fatal illness.-Spinal Cord:...
- Human brainHuman brainThe human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
- ICD-10 Chapter VI: Diseases of the nervous systemICD-10 Chapter VI: Diseases of the nervous system- Inflammatory diseases of the central nervous system :* Bacterial meningitis, not elsewhere classified** Haemophilus meningitis** Pneumococcal meningitis** Streptococcal meningitis** Staphylococcal meningitis** Other bacterial meningitis...
- Mental illnessMental illnessA mental disorder or mental illness is a psychological or behavioral pattern generally associated with subjective distress or disability that occurs in an individual, and which is not a part of normal development or culture. Such a disorder may consist of a combination of affective, behavioural,...
- NeuroplasticityNeuroplasticityNeuroplasticity is a non-specific neuroscience term referring to the ability of the brain and nervous system in all species to change structurally and functionally as a result of input from the environment. Plasticity occurs on a variety of levels, ranging from cellular changes involved in...
External links
- Disorder Index of the National Institute of Neurological Disorders and StrokeNational Institute of Neurological Disorders and StrokeThe National Institute of Neurological Disorders and Stroke is a part of the U.S. National Institutes of Health . It conducts and funds research on brain and nervous system disorders and has a budget of just over US$1.5 billion...