| Neurological disorder | |
|---|---|
 | |
| Neurons in person withepilepsy, 40x magnified | |
| Specialty | Neurology  |
A neurological disorder is anydisorder of thenervous system. Structural,biochemical or electrical abnormalities in thebrain,spinal cord, or othernerves can result in a range ofsymptoms. Examples of symptoms includeparalysis,muscle weakness, poorcoordination, loss ofsensation,seizures,confusion,pain,tauopathies, andaltered levels of consciousness. There are manyrecognized neurological disorders; some are relatively common, but many are rare.
Interventions for neurological disorders include preventive measures,lifestyle changes,physiotherapy or othertherapy, neurorehabilitation,pain management,medication,operations performed byneurosurgeons, or a specific diet.[1][2] TheWorld Health Organization estimated in 2006 that neurological disorders and theirsequelae (direct consequences) affect as many as one billion people worldwide and identifiedhealth inequalities andsocial stigma/discrimination as major factors contributing to the associateddisability and their impact.[3]
Although the brain and spinal cord are surrounded by toughmembranes, enclosed in the bones of theskull and spinalvertebrae, and chemically isolated by theblood-brain barrier, they are very susceptible if compromised.Nerves tend to lie deep under the skin but can still become exposed to damage. Individualneurons, theneural circuits, and the nerves into which they form are susceptible to electrochemical and structural disruption.Neuroregeneration may occur in theperipheral nervous system and thus overcome or work around injuries to some extent, but it is thought to be rare in the brain and spinal cord.[citation needed]
The specific causes of neurological problems vary but can includegenetic disorders,congenital abnormalities ordisorders,infections,lifestyle, orenvironmental health problems such aspollution,malnutrition,brain damage,spinal cord injury,nerve injury, orgluten sensitivity (with or without intestinal damage or digestive symptoms).[2][4] Metal poisoning, where metals accumulate in the human body and disrupt biological processes, has been reported to induce neurological problems, at least in the case oflead.[4] The neurological problem may start in anotherbody system that interacts with the nervous system. For example,cerebrovascular disease involves brain injury due to problems with theblood vessels (cardiovascular system) supplying the brain;autoimmune disorders involve damage caused by the body's ownimmune system;lysosomal storage diseases such asNiemann–Pick disease can lead to neurological deterioration. TheNational Institute for Health and Care Excellence recommends considering the evaluation of underlyingcoeliac disease in people with unexplained neurological symptoms, particularlyperipheral neuropathy orataxia.[5]
In a substantial minority of cases of neurological symptoms, no neurologicalcause can be identified using current testing procedures, and such "idiopathic" conditions can invite different theories about what is occurring.[citation needed] Generally speaking, a substantial number of neurological disorders may have originated from a previous clinically not recognized viral infection. For example, it is thought that infection with theHepatitis E virus, which is often initially asymptomatic may provoke neurological disorders,[6] but there are many other examples as well.
Numerous examples have been described of neurological disorders that are associated withmutatedDNA repair genes (for reviews see[7]). Inadequate repair of DNA damages can lead directly to cell death andneuron depletion as well as disruptions in the pattern ofepigenetic alterations required for normal neuronal function.[citation needed]
Neurons are highly oxygenated cells and as a consequenceDNA damage caused by chronic exposure to endogenousreactive oxygen species is a substantial challenge for neurons.[8]Germline mutations deficient in therepair of DNA damages cause neuronal dysfunction and are etiologically linked to many neurological disorders.[8] For example, the neurological disorders,amyotrophic lateral sclerosis (ALS) andfrontotemporal dementia (FTD) are linked to DNA damage accumulation and DNA repair deficiency.[9]
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 betweencentral nervous system disorders andperipheral nervous system disorders. TheMerck Manual lists brain, spinal cord disorders, and nerve disorders in the following overlapping categories:[10]
| Nervous system | |
|---|---|
 Human nervous system | |
| Identifiers | |
| MeSH | D009422 |
| Anatomical terminology | |
Neurological disorders in non-humananimals are treated byveterinarians.[11][12]
There are a wide range of treatments for neurological disorders fromsurgery to neural rehabilitation.Neurotherapy relies on knowledge from traditional medicine and uses a scientific approach and evidence-based practice. Some of its methods are non-invasive. Neurotherapy is a medical treatment that involves the targeted systemic administration of an energetic stimulus or chemical agent to a specific neurological area.[13] Some neuromodulation techniques are still considered alternative medicine (medical procedures that are not easily integrated into the mainstream healthcare model) due to their novelty and lack of supporting evidence.[14] The wide range of neurotherapy methods can be divided into four domains depending on the use of energy stimulation: acoustic energy, electric energy, electromagnetic radiation, and magnetic energy.[13]
Aneurological examination can, to some extent, assess the impact of neurological damage and disease on brain function in terms ofbehavior,memory, orcognition.Behavioral neurology specializes in this area. In addition,clinical neuropsychology usesneuropsychological assessment to precisely identify and track problems in mental functioning, usually after some sort of brain injury or neurological impairment.[citation needed]
Alternatively, a condition might first be detected through the presence of abnormalities in mental functioning, and further assessment may indicate an underlying neurological disorder. There are sometimes unclear boundaries in the distinction between disorders treated within neurology, andmental disorders treated within the other medical specialty ofpsychiatry, or othermental health professions such asclinical psychology. In practice, cases may present as one type, but be assessed as more appropriate to the other.[15]Neuropsychiatry deals withmental disorders arising from specific identified diseases of the nervous system.[citation needed]
One area that can be contested is in cases ofidiopathic neurological symptoms - conditions where the cause cannot be established. It can be decided in some cases, perhaps byexclusion of any accepted diagnosis, that higher-level brain/mental activity is causing symptoms, referred to asfunctional symptoms, rather than the symptoms originating in the area of the nervous system from which they may appear to originate. Cases involving these symptoms are classified asfunctional disorders ("functional" in this context is usually contrasted with the old term "organic disease"). For example, infunctional neurologic disorder (FND), those affected present with various neurological symptoms such asfunctional seizures,numbness,paresthesia, andweakness, among others. Such cases may be contentiously interpreted as being "psychological" rather than "neurological."conversion disorder, If the onset functional symptoms appear to be causally linked to emotional states or responses to socialstress or social contexts, it may be referred to asconversion disorder.[16]
On the other hand,dissociation refers to partial or complete disruption of the integration of a person's conscious functioning, such that a person may feel detached from one's emotions, body and/or immediate surroundings. In extreme cases, this may be diagnosed asdepersonalization-derealization disorder. There are also conditions viewed as neurological where a person appears to consciously register neurological stimuli that cannot possibly be coming from the part of the nervous system to which they would normally be attributed, such asphantom pain orsynesthesia, or where limbs act without conscious direction, as inalien hand syndrome.
Conditions that are classed asmental disorders,learning disabilities, and forms ofintellectual disability, are not themselves usually dealt with as neurological disorders.Biological psychiatry seeks to understand mental disorders in terms of their basis in the nervous system, however. In clinical practice, mental disorders are usually indicated by amental state examination, or other type of structured interview or questionnaire process. At the present time,neuroimaging (brain scans) alone cannot accurately diagnose a mental disorder or tell the risk of developing one; however, it can be used to rule out other medical conditions such as abrain tumor.[17] In research, neuroimaging and other neurological tests can show correlations between reported and observed mental difficulties and certain aspects of neural function or differences in brain structure. In general, numerous fields intersect to try to understand the basic processes involved in mental functioning, many of which are brought together incognitive science. The distinction between neurological and mental disorders 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 andmind.[citation needed]
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