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2,638 results found

14-3-3 protein

14-3-3 proteins are found in the cerebrospinal fluid (CSF) and are currently used to help identify patients with sporadic Creutzfeldt-Jakob disease (sCJD). Seven distinct 14-3-3 proteins have been found in humans. In diagnosing sCJD, the sensitivity of 14-3-3 protein is 92%, and its specifici...

18q-deletion syndrome

18q-deletion syndrome is a rare chromosomal anomaly where there is a deletion of part of the long arm of chromosome 18. Associated symptoms and findings vary widely, as do their severity. Characteristic clinical features include short stature, intellectual disability, hypotonia, facial, and dist...

1p19q codeletion

1p19q codeletion stands for the combined loss of the short arm chromosome 1 (i.e. 1p) and the long arm of chromosome 19 (i.e. 19q) and is recognized as a genetic marker predictive of therapeutic response to both chemotherapy and combined chemoradiotherapy and overall longer survival in patients ...

2-hydroxyglutarate

2-hydroxyglutarate is a metabolite that accumulates in the brains of patients with IDH-1 mutated (IDH-1 positive) brain tumors, particularly diffuse low-grade gliomas. Although not in widespread clinical use, it is likely that 2-hydroxyglutarate, which resonates at 2.25 ppm, will be able to be d...

ABC/2

ABC/2, also confusingly written as 1/2ABC in some literature, is a fast and simple method for estimating the volume of intracerebral hemorrhage (or any other ellipsoid lesion for that matter) which does not require volumetric 3D analysis or software. Intracerebral hemorrhage volume is an import...

Abducens nerve

The abducens nerve is the sixth cranial nerve. It courses from its nucleus located in the dorsal pons to its innervation of the lateral rectus muscle and can be divided into four parts: nucleus and intraparenchymal portion cisternal portion cavernous sinus portion orbital portion Gross anat...

Abducens nerve palsy

Abducens nerve palsy, or sixth nerve palsy, results in weakness of the ipsilateral lateral rectus muscle. Clinical presentation Patients present with horizontal diplopia with an inability to abduct the ipsilateral eye, thereby resulting in an esotropia (nasal deviation of the eye). Pathology ...

Abducent nucleus

The abducent or abducens nucleus is a small motor nucleus in the pons for the abducens nerve. Gross Anatomy The nucleus is located in the paramedian dorsal lower pons in the floor of the fourth ventricle lateral to the medial longitudinal fasciculus. The nucleus forms a longitudinal paramedian...

Aberrant arachnoid granulations

Aberrant arachnoid granulations, also known as arachnoid pits, are arachnoid granulations that penetrated the dura but failed to migrate normally in the venous sinus. They are most often located in the greater wing of the sphenoid bone and may be seen in idiopathic intracranial hypertension. Occ...

Aberrant internal carotid artery

Aberrant internal carotid artery is a variant of the internal carotid artery and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the internal carotid artery 5. Gross anatomy There is consequent enlargement of the usually sma...

Abscess

Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1: a central core consisting of necrotic inflammatory cells and local tissue peripheral halo of viable neutrophils surrounded by a 'capsule' with dilated blood vessel...

Absent posterior limb sign

The absent posterior limb sign is one of the main MRI findings of prognostic significance in term neonates with suspected hypoxic-ischemic brain injury. An absent posterior limb sign is defined as loss of the normally distinct hyperintensity on T1-weighted images in the posterior part of the pos...

Absent septum pellucidum

An absent septum pellucidum may rarely be an isolated finding, or more commonly be seen in association with a variety of conditions. Epidemiology The septum pellucidum is partly or entirely absent in 2 or 3 individuals per 100,000 in the general population. Pathology An absent septum pelluc...

Abusive head trauma

Abusive head trauma is a term that is used for inflicted head injury that has occurred by either shaking, impact head trauma, or both, as part of the spectrum of non-accidental injury (NAI). Pathology Intracranial injuries Subdural hemorrhage in a child should be viewed with suspicion. Most o...

Aceruloplasminemia

Aceruloplasminemia is an autosomal recessive type of neurodegeneration with brain iron accumulation and disorder of iron metabolism caused by a mutation in the ceruloplasmin (CP) gene resulting in the production of dysfunctional ceruloplasmin. Epidemiology Aceruloplasminemia is a very rare dis...

Acalculia

Acalculia (or acquired dyscalculia) represents the acquired loss of the ability to perform simple arithmetic tasks secondary to CNS pathology. It is not to be confused with developmental dyscalculia, which is a different entity and represents developmental disturbance of computational ability. ...

Accessory middle cerebral artery

The accessory middle cerebral artery is a variant of the middle cerebral artery (MCA) that arises from the anterior cerebral artery (ACA). It is different from a duplicated middle cerebral artery, in which the duplicated vessel originates also from the distal end of the internal carotid artery (...

Achondroplasia

Achondroplasia is a congenital genetic disorder resulting in rhizomelic dwarfism and is the most common skeletal dysplasia. It has numerous distinctive radiographic features. Epidemiology It occurs due to sporadic mutations in the majority of cases but can be inherited as an autosomal dominan...

Achondroplastic base of skull abnormalities

Achondroplasia is the most common cause of short-limb dwarfism. (For a general discussion, see the generic article on achondroplasia.) As the skull base forms by endochondral ossification whereas the skull vault by membranous ossification, there is a marked discrepancy in relative size as the s...

Acquired hepatocerebral degeneration

Acquired hepatocerebral degeneration is an uncommon irreversible extrapyramidal neurodegenerative condition encountered in patients with cirrhotic chronic liver disease, resulting in widespread cerebral, basal ganglia and cerebellar damage. Terminology Acquired hepatocerebral degeneration is ...

Acquired tonsillar ectopia

Acquired tonsillar ectopia is usually thought of as a subgroup of cerebellar tonsillar ectopia in which downward displacement of the cerebellar tonsils is secondary to another well defined and distinct pathological process. This is to distinguish it from Chiari I malformations and low-lying tons...

Acquired tracheo-esophageal fistula

An acquired tracheo-esophageal fistula refers to a pathological communication between the trachea and esophagus due to a secondary cause Pathology Acquired causes of tracheo-esophageal fistulae can be divided into those that are related to malignancy (common) and those from other causes (unco...

Acrania

Acrania is a rare lethal congenital anomaly characterized by an absence of the calvaria. Epidemiology The estimated incidence is at ~1:1000 pregnancies 4. Pathology The condition is thought to result from abnormal migration of mesenchymal tissue, which normally covers the cerebral hemisphe...

Acrania anencephaly sequence

Acrania anencephaly sequence is the progression from a relatively normal-appearing exposed brain due to an absent cranium (acrania) to an amorphous brain mass (exencephaly) to no recognisable brain tissue (anencephaly) 1. Epidemiology The acrania anencephaly sequence begins with acrania, which...

Acromegaly

Acromegaly is the result of excessive growth hormone production in skeletally mature patients, most commonly from a pituitary adenoma. The same excess of growth hormone in individuals whose epiphyses have not fused will result in gigantism (excessively tall stature). Epidemiology Acromegaly ...

Acute bacterial meningitis complications (mnemonic)

The complications of acute bacterial meningitis can be remembered using the mnemonic: HACTIVE Mnemonic H: hydrocephalus A: abscess C: cerebritis / cranial nerve lesion T: thrombosis I: infarct V: ventriculitis/vasculopathy E: extra-axial collection: empyema and hygroma Related articles...

Acute basilar artery occlusion

Acute occlusion of the basilar artery may cause brainstem or thalamic ischemia or infarction. It is a true neuro-interventional emergency and, if not treated early, brainstem infarction results in rapid deterioration in the level of consciousness and ultimately death. It is one of the posterior ...

Acute cerebellitis

Acute cerebellitis and acute cerebellar ataxia represent a spectrum of inflammatory processes characterized by sudden onset cerebellar dysfunction. It usually affects children and is related as a consequence of primary or secondary infection, or much less commonly as a result of a post-vaccinati...

Acute disseminated encephalomyelitis (ADEM)

Acute disseminated encephalomyelitis (ADEM), as the name would suggest, is featured by a monophasic acute inflammation and demyelination of white matter typically following a recent (1-2 weeks prior) viral infection or vaccination 4,6. Grey matter, especially that of the basal ganglia, is also o...

Acute hemorrhagic leukoencephalitis

Acute hemorrhagic encephalomyelitis (AHEM), also known as acute hemorrhagic leukoencephalitis (AHLE), Hurst disease or Weston Hurst syndrome, is a very rare form of demyelinating disease. It occurs sporadically and may be considered as the most severe form of acute disseminated encephalomyelitis...

Acute necrotizing encephalopathy

Acute necrotizing encephalopathy, also referred as acute necrotizing encephalopathy of childhood, is a rare type of encephalopathy characterized by multiple bilateral brain lesions, mainly involving the thalami, but also the putamina, internal and external capsules, cerebellar white matter, and ...

Acute spinal cord ischemia syndrome

Acute spinal cord ischemia syndrome is uncommon, but usually presents with profound neurological signs and symptoms, and the prognosis is poor. Epidemiology Acute spinal cord ischemia syndrome represents only 5-8% of acute myelopathies 4,5 and <1% of all strokes 7. The demographic of affected...

Acute stroke symptoms (mnemonic)

Useful mnemonics to remember the symptoms of acute stroke are: FAST BE-FAST Mnemonics FAST F = face (look uneven?) A = arm (drift down?) S = speech (sound strange or difficulty speaking) T = time (brain cells die every second) BE-FAST B = balance (sudden loss of balance) E = eye (sudd...

Acute vs chronic ischemic stroke (CT)

Differentiating between acute and chronic infarction on a CT brain is an important skill for many health professionals particularly in the emergency setting: pathology acute: cytotoxic edema chronic: encephalomalacia; Wallerian degeneration hypoattenuation acute: more dense than CSF chroni...

ADC pseudonormalization

ADC pseudonormalization is a normal phase encountered in the subacute stage of ischemic stroke and represents an apparent return to normal healthy brain values on ADC maps which does not, however, represent true resolution of ischemic damage. ADC pseudonormalization is seen typically around 1 w...

Adie pupil

Adie pupil (also known as tonic pupil) is caused by idiopathic degeneration of the ciliary ganglion, which sometimes occurs following a viral or bacterial illness. It is usually unilateral and typically affects young females 1. Adie pupil represents a large dilated "tonic pupil", which does not...

Adie syndrome

Adie syndrome, also known as Holmes-Adie syndrome, is a rare neurological disorder. Epidemiology Adie syndrome is a rare condition which is most commonly seen in young females in their fourth decade of life 2,3. Clinical presentation Patients most commonly present with a classic triad of: d...

Adrenal vein sampling

Adrenal vein sampling (AVS) is a procedure where blood is collected from the adrenal veins via catheter to confirm autonomous hormone production, if it is unilateral or bilateral, and to guide further treatment. Indication Adrenal vein sampling is commonly performed in primary aldosteronism, b...

Adrenomyeloneuropathy

Adrenomyeloneuropathy is a form of X-linked adrenoleukodystrophy characterized by pronounced involvement of the spinal cord with only minor involvement of the cerebral white matter. Clinical presentation Clinical presentation depends on whether or not there is also cerebral involvement. In ...

Adult leukodystrophies

Adult-onset leukodystrophies are uncommon compared to those that present in childhood and in most instances are a delayed and atypical presentation of conditions more common in childhood. They are important differential considerations when assessing adults with white matter diseases. Terminolo...

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), also known as hereditary diffuse leukoencephalopathy with spheroids (HDLS) and pigmentary orthochromatic leukodystrophy (POLD), refers to a rare inherited autosomal dominant disease characterized by an adult-onset l...

Aging blood on MRI (mnemonic)

Aging blood on MRI is dependent on the varying MRI signal characteristics of hemorrhagic collections with time and can be very useful in correlating the imaging findings with the clinical picture. However, as it can be complicated to recall the MRI features of aging blood through the five stages...

Agenesis (general)

The biological/medical term agenesis (plural: ageneses) refers to failure of an organ to grow or develop during the embryological period. Examples include: appendiceal agenesis cerebellar agenesis corpus callosum agenesis dental agenesis (anodontia) diaphragmatic agenesis dorsal pancreati...

Agnosia

Agnosia is a neurological disorder characterized by an inability to identify an object despite both having knowledge of that object and functional sensory input. For example, a patient with posterior cortical atrophy who characteristically has visual agnosia, will be unable to identify a hammer,...

Agraphia

Agraphia represents acquired impairments of writing ability secondary to damage or dysfunction of the central nervous system. Impairments caused solely by motor dysfunction (e.g. hand paresis or tremor) are not considered to be forms of agraphia 1. Clinical presentation Agraphia is rarely an i...

AICA-PICA dominance

AICA-PICA dominance refers to the principle that the cerebellar vascular territory supplied by the anterior inferior cerebellar artery and posterior inferior cerebellar artery have a reciprocal arrangement. That is the size of the AICA and the subsequent territory it supplies is inversely propor...

Aicardi-Goutières syndrome

Aicardi-Goutières syndrome is a rare hereditary neurodegenerative disease which usually presents in early infancy with systemic and central nervous system inflammatory syndrome characterized by hepatosplenomegaly, vasculopathy and encephalopathy. Many of the features are similar to congenital TO...

Aicardi syndrome

Aicardi syndrome is a rare severe developmental disorder. It results from an X-linked genetic defect that is fatal in males and therefore only manifests in females (except for rare 47, XXY cases). Note: Aicardi syndrome is distinct from Aicardi-Goutieres syndrome although both are named after J...

AIDS-defining illness

AIDS-defining illnesses are conditions that in the setting of a HIV infection confirm the diagnosis of AIDS and do not commonly occur in immunocompetent individuals 2. According to the CDC surveillance case definition 1, they are: Infectious bacterial infections: multiple or recurrent candidi...

AIDS-related diffuse large B-cell lymphoma

AIDS-related diffuse large B-cell lymphomas are one of the immunodeficiency-associated CNS lymphomas, and in western countries represented a dramatic increase in primary CNS lymphoma during the HIV/AIDS epidemic of the 1980s, although the incidence is likely lower in patients treated with HAART ...

Air bubble artifact

The air bubble artifact on CT is due to the presence of abnormal gas in the oil coolant which surrounds the x-ray tube. The artifact manifests as subtle low density, which has only been described on brain scans. Cause The x-ray tube in a CT scanner is prevented from overheating by a heat excha...

Air bubble sign (tension pneumocephalus)

The air bubble sign is seen on CT of the brain and represents multiple small foci of air within the subarachnoid space, especially the Sylvian fissure.1 Although described as a sign of tension pneumocephalus it is also seen in pneumocephalus without elevated pressures.2 It should not be confus...

Alanine peak

Alanine is one of the compounds examined in MR spectroscopy. It resonates at 1.48 ppm chemical shift. It is elevated in meningiomas.

Alberta stroke program early CT score (ASPECTS)

The Alberta stroke programme early CT score (ASPECTS) 1 is a 10-point quantitative topographic CT scan score used in patients with middle cerebral artery (MCA) stroke. It has also been adapted for the posterior circulation (see below). Scoring system Segmental assessment of the middle cerebra...

Alcoholic cerebellar degeneration

Alcoholic cerebellar degeneration is a common type of acquired cerebellar ataxia characterized by chronic vermian atrophy 1. It is a sequela of chronic alcohol abuse or malnutrition and has also been described in the literature as alcohol-related cerebellar degeneration, alcohol-induced cerebell...

Alexander disease

Alexander disease, also known as fibrinoid leukodystrophy, is a rare fatal leukodystrophy, which usually becomes clinically evident in the infantile period, although neonatal, juvenile and even adult variants are recognized. As with many other diseases with variable age of presentation, the earl...

Alexia

Alexia (or acquired dyslexia) is a neurological term refers to an acquired impairment of reading resulting from damage of critical brain areas. Clinical presentation Alexia can manifest itself as an impairment of oral reading and reading comprehension alike and can occur in combination with va...

Alien limb syndrome

Alien limb syndrome is a rare neurological phenomenon in which a patient has the impression that their limb does not belong to them and is controlled by some external force 1. It can occur in a number of neurodegenerative diseases, typically those with cortical involvement, including: cortico...

Allodynia

Allodynia refers to pain due to a stimulus which does not normally provoke pain. Temperature or physical stimuli can provoke allodynia, and it often occurs after injury to a site. Etymology The word allodynia is derived from the Greek words άλλος (állos) meaning "other" and οδύνη (odýni) meani...

Alobar holoprosencephaly

Alobar holoprosencephaly is a subtype of holoprosencephaly and is the most severe of the classical three subtypes, with both semilobar and lobar holoprosencephaly having less severe clinical manifestations. For a general discussion of epidemiology, clinical presentation, and pathology, please r...

Alpers syndrome

Alpers syndrome, also known as Alpers-Huttenlocher syndrome or progressive cerebral poliodystrophy, is a rare childhood neurodegenerative POLG-related disorder. Along with Leigh syndrome, it is one of the commonest childhood mitochondrial disorders 1. Epidemiology Alpers syndrome is incredibl...

Alpha thalassemia/intellectual disability syndrome X-linked (ATRX) gene (tumor marker)

Alpha-thalassemia/intellectual disability syndrome X-linked (ATRX) gene is an important genomic marker of gliomas and is either intact (ATRX wild-type) or mutated (ATRX-mutant) and is correlated with other important genomic markers including IDH, 1p19q codeletion and p53 expression 1,2. ATRX a...

Alport syndrome

Alport syndrome is an X-linked dominant disease characterized by progressive sensorineural hearing loss, renal disease and, at times, ocular lesions. Clinical presentation hematuria sensorineural hearing loss: typically high frequency 2 ocular abnormalities anterior lenticonus: most common ...

Alzheimer disease

Alzheimer disease is a common neurodegenerative disease, responsible for 60-80% of all dementias, and imposing a significant burden on developed nations. It is the result of accumulation and deposition of cerebral amyloid-β (Aβ) and is the most common cerebral amyloid deposition disease. Epide...

Alzheimer type I glia

Alzheimer type I glia are a type of glial cell. They are large multinucleated astrocytes encountered in glial tumors and progressive multifocal leukoencephalopathy (PML) 1.

Alzheimer type II glia

Alzheimer type II glia are a type of glial cell. They are a pathological reactive astrocyte seen in the brain, unrelated to Alzheimer disease. They are seen most frequently in Wilson disease, but also in other systemic metabolic disorders, particularly those with elevated ammonia levels, typical...

Amaurosis fugax

Amaurosis fugax is the transient monocular loss of vision, normally lasting a few seconds to a few minutes, secondary to vascular ischemia or insufficiency. Epidemiology It has an incidence of 50,000 per year in the United States. Clinical presentation Patients present with transient monoc...

Ambient cistern

The ambient cistern is part of the subarachnoid cisterns, filled with CSF. Gross anatomy The ambient cistern is a thin, sheet-like extension of the quadrigeminal cistern that extends laterally around the midbrain and posterior to the thalami. It acts as the connection between the quadrigeminal...

American Journal of Neuroradiology (AJNR)

American Journal of Neuroradiology (AJNR) is the premier publication of the American Society of Neuroradiology and was first published in 1980. Its founding editor was Juan M Taveras (1919-2002), the pioneering American neuroradiologist, who was a co-founder of the American Society of Neuroradio...

American Society of Neuroradiology

American Society of Neuroradiology (ASNR) was established in 1962 to ensure that neuroradiologists in the United States could freely exchange ideas and act with a common voice. It publishes the American Journal of Neuroradiology (AJNR). History At the VIth Symposium Neuroradiologicum held in R...

Amygdala

The amygdala (plural: amygdalae) is a very well studied part of the limbic system and forms part of the mesial temporal lobe. Gross anatomy The amygdala is a complex grey matter structure located anterior and superior to the temporal horn of the lateral ventricle and head of the hippocampus. ...

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig disease or Charcot disease, is the most common form of motor neuron disease 1,4 resulting in progressive weakness and eventual death due to respiratory insufficiency. Epidemiology ALS typically is diagnosed in middle age. There is a...

Anaplastic astrocytoma

Anaplastic astrocytomas are WHO grade III lesions, with imaging appearances and prognosis between those of diffuse low-grade astrocytomas (WHO grade II) and glioblastomas (WHO IV), and similarly, they are classified on the basis of IDH mutation as IDH-mutant, IDH-wild-type and NOS (when IDH stat...

Anaplastic ependymoma

Anaplastic ependymomas (WHO grade III ependymomas), in comparison to lower grade ependymomas, are characterized by a higher proliferative rate and a greater tendency to infiltrate surrounding brain or disseminate into cerebrospinal fluid causing drop metastases 1. The relevance of grading ependy...

Anaplastic ganglioglioma

Anaplastic gangliogliomas are uncommon aggressive variants of the far more common low-grade ganglioglioma (WHO grade I). In the current WHO classification of CNS tumors (2016), no criteria have been agreed upon for a ganglioglioma WHO grade II tumor 1. Pathology In anapestic gangliogliomas, t...

Anaplastic meningioma

Anaplastic meningiomas (also known as malignant meningiomas) are uncommon, accounting for only ~1% of all meningiomas 1. Along with rhabdoid meningioma and papillary meningioma are considered WHO grade III tumors and demonstrate aggressive local growth and high recurrence rate. It should be no...

Anaplastic oligodendroglioma

Anaplastic oligodendroglioma is a WHO grade III diffuse infiltrating glioma that has histological features of anaplasia, and molecular markers consistent with an oligodendroglioma (1p19q co-deletion and IDH mutation) as per the current (2016) WHO classification of CNS tumors 1. They make up 20-5...

Anaplastic oligodendroglioma NOS

Anaplastic oligodendroglioma NOS (not-otherwise-specified) is a diagnosis in the current (2016) WHO classification of CNS tumors denoting a diffuse infiltrating glioma that has histological features of anaplastic oligodendroglioma, but without 1p19q co-deletion status or IDH mutation status bein...

Anaplastic pleomorphic xanthoastrocytoma

Anaplastic pleomorphic xanthoastrocytomas are a more aggressive and less common version of pleomorphic xanthoastrocytoma (PXA). In the current (2016) WHO classification of CNS tumors, they are considered WHO grade III lesions (whereas pleomorphic xanthoastrocytomas are WHO grade II tumors) 1. ...

Anatomy curriculum

The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists. General anatomy Neuroanatomy Head and neck anatomy Thoracic anatomy Abdominal and pelvic anatomy Spinal anat...

Ancient schwannoma

Ancient schwannomas are long-standing, benign (WHO grade I) slow growing schwannomas with advanced degeneration. The term “ancient” has been traditionally used to describe schwannomas showing degenerative changes and diffuse hypocellular areas 1-3. Pathology These tumors demonstrate nuclear pl...

Anencephaly

Anencephaly is the most severe form of cranial neural tube defect (NTD) and is characterized by an absence of cortical tissue (although the brainstem and cerebellum may be variably present) as well as an absence of the cranial vault. The morphological spectrum within anencephaly ranges from holo...

Angiocentric glioma

Angiocentric gliomas are rare superficial slow-growing brain tumors typically presenting in young patients with intractable partial epilepsy 1-6. They were first introduced in the 2007 (4th) edition of the WHO brain tumor classification, and are classified as WHO grade I tumors 1. For a genera...

Angiolipoma

Angiolipomas (also sometimes known as haemangiolipomas, vascular lipomas, and fibromyolipomas) are rare soft tissue tumors composed of mature adipocytes and vessels. They can occur essentially anywhere and can be subclassified into infiltrating and non-infiltrating variants 1. Please refer to ...

Angiomatous meningioma

Angiomatous meningiomas are a rare histological variant of WHO grade I meningiomas and account for only 2.1% of all meningiomas 1,3. The epidemiology and clinical presentation of these tumors do not clearly deviate from that of more common histological variants of meningiomas and is thus not r...

Angular artery (MCA branch)

The angular artery (branch of the middle cerebral artery (MCA)) is an M4 branch of the middle cerebral artery (it is not the same as the facial artery angular artery branch). The artery arises from the posterior part of the Sylvian fissure and runs posteriorly. On lateral angiogram it forms a d...

Angular gyrus

The angular gyrus is a portion of the parietal lobe of the brain. It is one of the two parts of the inferior parietal lobule, the other part being the supramarginal gyrus. It plays a part in language and number processing, memory and reasoning 1. Gross anatomy Relations It lies as a horseshoe...

Anorexia nervosa

Anorexia nervosa is a psychiatric disorder characterized by distorted self-perception of body weight leading to starvation, obsession with remaining underweight, and an excessive fear of gaining weight. One in five patients with anorexia dies due to complications of the disease. Epidemiology T...

Anorexia nervosa (CNS manifestations)

The CNS manifestations of anorexia nervosa are common but varied with most of the imaging features non-specific in their own right. For a general discussion, and for links to other system specific manifestations, please refer to the article on anorexia nervosa. Epidemiology Studies have iden...

Anosmia

Anosmia (also known as anosphresia or olfactory anesthesia) is the complete absence of the sense of smell. Terminology In addition to anosmia, there is also hyposmia (a.k.a. microsmia or olfactory hypoesthesia) representing a diminished sense of smell and parosmia (a.k.a. dysosmia or paraosmi...

Anoxic brain injury

Anoxic brain injury, also known as global hypoxic-ischemic injury, is seen in all age groups (from antenatal to the elderly) as a result of numerous etiologies. The pattern of injury depends on a number of factors including: age of the patient (brain maturity) neonatal hypoxic-ischemic encepha...

Anterior cerebral artery

The anterior cerebral artery (ACA) along with the middle cerebral artery (MCA) forms at the termination of the internal carotid artery (ICA). It is the smaller of the two, and arches anteromedially to pass anterior to the genu of the corpus callosum, dividing as it does so into its two major bra...

Anterior cerebral artery (ACA) infarct

Anterior cerebral artery (ACA) territory infarcts are much less common than either middle or posterior cerebral artery territory infarcts. Epidemiology ACA territory infarcts are rare, comprising ~2% of ischemic strokes 1,2. Clinical presentation ACA stroke syndrome presents as 1-3: dysarth...

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