Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

1,773 results found
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14-3-3 protein

14-3-3 protein is found in the cerebrospinal fluid (CSF), and is currently used to help identify patients with sporadic Creutzfeldt-Jakob disease (sCJD).  In diagnosing sCJD, the sensitivity of 14-3-3 protein is 92% and the specificity is 80% 1. A negative 14-3-3 assay may be helpful in reducin...
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18q syndrome

18q syndrome is a rare chromosomal anomaly where there is deletion of part of the long arm of chromosome 18.  Associated symptoms and findings vary widely, as does their severity.  Characteristic features include short stature, mental retardation and hypotonia, facial and distal skeletal abnorma...
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1p19q codeletion

1p19q codeletion stands for the combined loss of the short arm chromosome 1 (“1p”) and the long arm of chromosome 19 (“19q”) and is recognised as genetic marker predictive of therapeutic response (both chemotherapy and combined chemoradiotherapy) and overall longer survival in patients with diff...
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2-hydroxyglutarate

2-hydroxyglutarate is a metabolite that accumulates in the brains of patients with IDH-1 mutated (IDH-1 positive) brain tumours, 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 ...
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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...
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Aberrant arachnoid granulations

Aberrant arachnoid granulations (AbAG) 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. Occasionally, they are seen at the posterior temporal bone wall. Clinical presenta...
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Aberrant internal carotid artery

An aberrant internal carotid artery is a variant of the internal carotid artery (ICA) and represents a collateral pathway resulting from involution of the normal cervical portion (first embryonic segment) of the ICA 5. There is consequent enlargement of the usually small collaterals which cours...
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Abscess

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

The anterior commissure (AC) - posterior commissure (PC) line, also referred as the bicommissural line, has been adopted as a convenient standard by the neuroimaging community, and in most instances is the reference plane for axial imaging in everyday scanning. The creation of a standard image p...
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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 (...
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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...
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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 sk...
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Acoustic schwannoma

Acoustic schwannomas (a.k.a. vestibular schwannomas) are relatively common tumours that arise from the vestibulocochlear nerve (CN VIII) and represent ~80% of cerebellopontine angle masses. Bilateral acoustic schwannomas are strongly suggestive of neurofibromatosis type 2 (NF2). These tumours c...
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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 ...
Article

Acrania

Acrania is a rare lethal congenital anomaly characterised by an absence of the calvarium. 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 hemisph...
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Acrania anencephaly sequence

Acrania anencephaly sequence is the progression from a relatively normal-appearing brain (acrania) to an amorphous brain mass (exencephaly) to no recognizable brain tissue (anencephaly) 1. Epidemiology The acrania anencephaly sequence begins with acrania, which is the most common anomaly affec...
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Acromegaly

Acromegaly is the result of excessive growth hormone (GH) production in skeletally mature patients, most commonly from an adenoma of the pituitary. It most commonly affects adults in middle age and can result in severe disfigurement, serious complicating conditions, and premature death. It has ...
Article

Acute basilar artery occlusion

Acute occlusion of the basilar artery may cause brainstem or thalamic ischaemia 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. Epidemiology  Occlusions...
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Acute disseminated encephalomyelitis

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 of...
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Acute haemorrhagic leukoencephalitis

Acute haemorrhagic encephalomyelitis (AHEM), also known as acute haemorrhagic 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 encephalomyelit...
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Acute necrotising encephalitis of childhood

Acute necrotizing encephalitis of childhood (ANEC) 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 the brain stem tegmentum. Epidemiology ANEC i...
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Acute spinal cord ischaemia syndrome

Acute spinal cord ischaemia syndrome (ASCIS) is uncommon, but usually presents with profound neurological signs and symptoms, and prognosis is generally poor.  Epidemiology Acute spinal cord ischaemia syndrome represents only 5-8% of acute myelopathies 4,5 and <1% of all strokes 7. The demo...
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Acute versus chronic ischaemic stroke

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 oedema chronic: encephalomalacia; Wallerian degeneration hypoattenuation acute: more dense than CSF chron...
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ADC pseudonormalisation

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

Adie syndrome was named after the British physician and neurologist William John Adie (b. 1886 - d. 1935).  It consists of a classic triad of: diaphoreseis absent deep tendon reflexes, e.g. ankle jerk an Adie pupil: tonically dilated and responds poorly or not at all to light It is thought ...
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Adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is an X-linked inherited metabolic peroxisomal disorder characterised by lack of oxidation of very long chain fatty acids (VLCFAs) that results in severe inflammatory demyelination of the periventricular deep white matter with posterior-predominant pattern and early in...
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Ageing blood on MRI

The imaging characteristics of blood on MRI are variable and change with the age of the blood. In general, five stages of haematoma evolution are recognised: hyperacute intracellular oxyhaemoglobin isointense on T1 isointense to hyperintense on T2 acute (1 to 2 days) intracellular deoxyh...
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Ageing blood on MRI (mnemonic)

Ageing blood on MRI is dependent on the varying MR signal characteristics of haemorrhagic 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 ageing blood through the five stag...
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Agnosia

Agnosia is a neurological disorder characterised by an inability to identify an object despite both having knowledge of that object and sensory input that is functional. For example a patient with posterior cortical atrophy, which characteristically has visual agnosia, will be unable to identify...
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Agrammatic variant primary progressive aphasia

Agrammatic variant primary progressive aphasia, also known as progressive nonfluent aphasia (PNFA) is one of the clinical neurodegenerative diseases associated with fronto-temporal lobar degeneration (FTLD) and is a subtype of language variant front-temporal lobar degeneration (lvFTLD).  PNFA i...
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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). Clinical features The typical presentation in infancy is with a triad of: infantile spasms: salaa...
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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.
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Alberta stroke program early CT score

The Alberta stroke programe early CT score (ASPECTS) 1 is a 10-point quantitative topographic CT scan score used in patients with middle cerebral artery (MCA) stroke. Segmental assessment of the MCA vascular territory is made and 1 point is deducted from the initial score of 10 for every region ...
Article

Alexander disease

Alexander disease (AD), 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 recognised. As with many other diseases with variable age of presentation, the...
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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...
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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. Historical context The word allodynia is derived from from the Greek words άλλος (állos) meaning "other"...
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Alobar holoprosencephaly

Alobar holoprosencephaly is a subtype of holoprosencephaly (HPE), and is the most severe of the classical three subtypes, with both semilobar holoprosencephaly and lobar holoprosencephaly having less severe clinical manifestations. For a general discussion of epidemiology, clinical presentation...
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Alpha-thalassemia/mental retardation syndrome X-linked (ATRX)

Alpha-thalassemia/mental retardation syndrome X-linked (ATRX) has recently been recognised as an important genomic marker of gliomas. Loss/mutation of ATRX is almost never seen in patients with 1p/19q co-deletion (i.e. they are essentially mutually exclusive). These two markers are helpful in se...
Article

Alzheimer disease

Alzheimer disease (AD) 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.  ...
Article

Ambient cistern

The ambient cistern is part of the subarachnoid cisterns. Gross anatomy The ambient cistern is a thin, sheet-like extension of the quadrigeminal cistern that extends laterally surrounding around the midbrain. It acts as the connection between the quadrigeminal cistern and the interpeduncular c...
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Ameloblastic fibroma

Ameloblastic fibromas, appear as unilocular lucent mandibular lesions, most frequently in the posterior mandible and are usually associated with impacted teeth, centred on the un-erupted crown. They therefore appear very similar to unilocular ameloblastomas. They are composed of enamel and embry...
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Amygdala

Amygdala 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 structure, located dorsomedially in the temporal lobe, forming the ventral superior, and medial walls of the inferior horn of the lateral ventricle. Th...
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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. Epidemiology ALS typically is diagnosed in middle age. There is a recognised male predilection 1....
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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).  On imaging, these tumours share common features with diffuse low grade astrocytomas, however they tend to present...
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Anaplastic ependymoma

Anaplastic ependymomas (WHO grade III ependymoma) are characterised by a higher proliferative rate and a greater tendency to infiltrate surrounding brain or disseminate into cerebrospinal fluid causing drop metastases 1. Epidemiology About 25% of ependymomas exhibit features of anaplasia with ...
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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 tumours and demonstrate aggressive local growth and high recurrence rate.  It should be n...
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Ancient schwannoma

Ancient schwannomas are long-standing, slow growing schwannomas with advanced degeneration. These can have calcification, hyalinization, and cystic cavitation that can be identified on imaging. The term “ancient” has been traditionally used to describe schwannomas showing degenerative changes an...
Article

Anencephaly

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

Angiocentric glioma is one of the brain tumours introduced in the 2007 WHO brain tumour classification, and it is a WHO grade I 1. It has been considered to be one of the rare neuroepithelial tumours. It is a cortical based tumour and is mostly epileptogenic.  On imaging they usually present as...
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Angiolipoma

Angiolipomas (also sometimes known as haemangiolipomas, vascular lipomas, and fibromyolipomas) are rare soft tissue tumours composed of mature adipocytes and vessels. They can occur essentially anywhere, and can be subclassified into infiltrating and non-infiltrating varieties 1.  The most comm...
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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 tumours does not clearly deviate from that of more common histological variants of meningiomas and is thus no...
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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...
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Anoxic brain injury

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

The anterior cerebral artery along with the middle cerebral artery forms at the termination of the internal carotid artery. 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 branches; pericallosa...
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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 ischaemic strokes 1,2.  Clinical presentation ACA stroke syndrome presents as 1,2,3: dy...
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Anterior choroidal artery

The anterior choroidal artery (AChA) supplies several crucial anatomical structures of the brain important for vision and motor control. Identification of AChA is important because of its strategic and extensive area of supply as well as large variations in the territorial distribution. Gross a...
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Anterior choroidal artery syndrome

Anterior choroial artery syndrome is a rare entity characterised by the triad of hemiplegia, hemianaesthesia and contralateral hemianopia as a result of infarct in AChA territory. The syndrome may also be associated with neuropsychological disorders, including left neglect syndrome in right-sid...
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Anterior commissure

The anterior commissure (AC) is a transversely oriented commissural white matter tract that connects the two cerebral hemispheres along the midline. It is a very important anatomical landmark that connects different parts of the limbic system on both sides and plays a role in the interhemispheri...
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Anterior communicating artery

The anterior communicating artery (ACOM) arises from the anterior cerebral artery and acts as an anastomosis between the left and right anterior cerebral circulation. It is about 4mm in length and demarcates the junction between the A1 and A2 segments of the anterior cerebral artery. Branches ...
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Anterior cord syndrome

Anterior cord syndrome (also known as Beck's syndrome or anterior spinal artery syndrome) is a clinical subset of spinal cord injury syndromes, due to ischaemia/infarction of the anterior two-thirds of the spinal cord, typically sparing posterior third. Clinical presentation Patient present wi...
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Anterior ethmoidal foramen

The anterior ethmoid foramen is a small opening in the ethmoid bone. It is the anatomical border of anterior and posterior ethmoid air cells. It transmits the anterior ethmoidal artery, vein and nerve. The anterior ethmoid foramen is situated 25mm away from the lacrimal crest, 12 mm anterior to...
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Anterior horn syndrome

Anterior horn syndrome is a fairly generic term used to refer to flaccid paralysis and areflexia due to involvement of the anterior grey matter horns of the spinal cord. Sensation is typically preserved.  Causes of anterior horn syndrome include:  anterior spinal artery ischaemia  poliomyelit...
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Anterior inferior cerebellar artery

The anterior inferior cerebellar artery (AICA) is one of three vessels that provides arterial blood supply to the cerebellum. It has a variable origin, course and supply, with up to 40% of specimens not having an identifiable standard AICA. The amount of tissue supplied by the AICA is variable (...
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Anterior inferior cerebellar artery (AICA) infarct

Anterior inferior cerebellar artery (AICA) territory infarcts are much less common than posterior inferior cerebellar artery (PICA) infarcts. Epidemiology AICA territory infarcts are rare, comprising ~1% of ischaemic cerebellar strokes 2.  Clinical presentation AICA stroke syndrome presents ...
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Anterior ramus of the lateral sulcus

The anterior ramus of the lateral sulcus, is located at the very anterior end of the lateral sulcus (sylvian fissure), just anterior to the ascending ramus, and passes superiorly into the inferior frontal gyrus separating the pars orbitalis form the pars triangularis of the frontal operculum.  ...
Article

Anterior sacral meningocele

Anterior sacral meningocele is a congenital defect seen in the anterior aspect of the spine. It is defined as a meningeal cyst that occurs in the presacral space secondary to agenesis of a portion of the anterior sacrum.  Pathology Associations In approximately 50% of cases, associated malfor...
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Anterior spinal artery

The anterior spinal artery supplies the anterior portion of the spinal cord and arises from the vertebral artery in the region of the medulla oblongata. The two arteries (one of which is usually bigger than the other) anastamose in the midline to form a single anterior spinal artery at the level...
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Anterior temporal artery

The anterior temporal artery is usually a branch of the M1 segment of the middle cerebral artery (MCA) that curves out of the Sylvian fissure and runs over the temporal lobe to supply the anterior third of the superior, middle and inferior temporal gyri.  Variant anatomy The temporopolar arter...
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Anterior temporal lobe perivascular spaces

Anterior temporal lobe perivascular spaces are recently recognised special variants of tumefactive perivascular spaces, which can mimic cystic tumours with surrounding oedema. Epidemiology A predilection for women has been reported 1. Age range is wide, from 24 to 86 years old reported 1. Cli...
Article

Anti NMDA receptor encephalitis

Anti N-methyl-D-aspartic acid (NMDA) receptor encephalitis is an autoimmune encephalitis with antibodies against the NMDA receptors. It is sometimes considered a form of autoimmune limbic encephalitis. It usually affects young patients particularly young females, in about 60% of whom ovarian ter...
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Antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder. It is usually defined as the clinical complex of vascular occlusion and ischaemic events occurring in patients who have circulating antiphospholipid antibodies. Pathology Patients have circulating antiphospholipid antibodies cr...
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Apraxia

Apraxia is the inability to perform tasks which the patient has perviously learned and has no physical impairment which would preclude them from performing them 1.  Typically apraxia stems from damage to the parietal lobes. 
Article

Aprosencephaly

Aprosencephaly is an extremely rare anomaly fetal cerebral development the derivatives of the telencephalon as well as the diancephalon are absent or dysplastic, while more caudal structures are normal or mildly deformed. It falls under the aprosencephaly / atelencephaly spectrum (AAS)  See als...
Article

Aquaporin

Aquaporin is a family of transmembrane water channels found throughout the body of both humans and many other species, facilitating the passage of water, cations and gasses 1.  At least 13 types of aquaporin have been described, and these are variably expressed.  Aquaporin 4 Aquaporin 4 (AQP4...
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Aqueduct stenosis

Aqueductal stenosis (AS) is a the most common cause of congenital obstructive hydrocephalus, but can also be seen in adults as an acquired abnormality.  Epidemiology Congenital aqueductal stenosis has an estimated incidence is at ~1:5000 births although the reported range varies greatly (3.7:1...
Article

Arachnoid cyst

Arachnoid cysts are relatively common benign and asymptomatic lesions occurring in association with the central nervous system, both within the intracranial compartment (most common) as well as within the spinal canal. They are usually located within the subarachnoid space and contain CSF.  On ...
Article

Arachnoid cyst: fetal presentation

A fetal arachnoid cyst is term given when an arachnoid cyst is diagnosed in utero. For a general discussion of arachnoid cysts refer to the parent article. Pathology They can be classified as being primary or secondary 2. primary (congenital) arachnoid cysts: result from a benign accumulation...
Article

Arachnoid granulation

Arachnoid granulations, also known as a Pacchionian granulation, are projections of the arachnoid membrane (villi) into the dural sinuses that allow CSF entrance from the subarachnoid space into the venous system. They most frequently occur in a parasagittal location with the transverse and sup...
Article

Arachnoid mater

The arachnoid mater forms the middle layer of the meninges and together with the pia mater is sometimes referred to as the leptomeninges.  Gross anatomy The arachnoid mater is an membrane that comes into direct contact with the dura mater and is separated from the pia mater by a CSF filled spa...
Article

Arachnoiditis

Arachnoiditis is a broad term encompassing inflammation of the meninges and subarachnoid space. Terminology Arachnoiditis affecting the cauda equina may be referred to as spinal/lumbar adhesive arachnoiditis.  Clinical presentation Lumbar spine arachnoiditis can result in leg pain, sensory c...
Article

Area postrema

The area postrema is one of the so-called circumventricular organs located on the dorsal inferior surface of the medulla oblongata at the caudal end of the fourth ventricle. The specialised ependymal cells in the area postrema detect toxins in the blood and act as a vomit-inducing centre, along...
Article

Arnold's nerve

Arnold's nerve is the auricular branch, also known as the mastoid branch, of the vagus nerve (CN X). Origin and course Arnold's nerve originates from the superior ganglion of the vagus nerve and also has a small contribution from the inferior ganglion of the glossopharyngeal nerve. It ascends ...
Article

Arterial spin labelling (ASL) MR perfusion

Arterial spin labelling (ASL) MR perfusion is an MR perfusion technique which does not require intravenous administration of contrast (unlike DSC perfusion and DCE perfusion). Instead it exploits the ability of MRI to magnetically label arterial blood below the imaging slab. The parameter most c...
Article

Arterial supply of the head and neck

The arteries of the head and neck are branches of the common carotid and and subclavian arteries. common carotid external carotid superior thyroid superior laryngeal ascending pharyngeal lingual facial occipital posterior auricular superior temporal maxillary (1st part) mandibular a...
Article

Artery of Adamkiewicz

The artery of Adamkiewicz, also known as the great anterior radiculomedullary artery or arteria radicularis anterior magna, is the name given to the dominant thoracolumbar segmental artery that supplies the spinal cord. Gross anatomy Origin The artery of Adamkiewicz has a variable origin but ...
Article

Artery of Percheron

The artery of Percheron is a rare variant of the posterior cerebral circulation characterised by a solitary arterial trunk that supplies blood to the paramedian thalami and the rostral midbrain bilaterally. Gross anatomy The term is used to refer to a solitary arterial trunk that branches from...
Article

Artery of Percheron territory infarct

Artery of Percheron territory infarct is rare, on account of the relative rarity of the artery of Percheron, and presents with a variety of signs and symptoms collectively termed the paramedian thalamic syndrome. It is a type of posterior circulation infarction. On imaging, it is classically ch...
Article

Ascending ramus of the lateral sulcus

Ascending ramus of the lateral sulcus, is located at the anterior end of the lateral sulcus (sylvian fissure), just posterior to the anterior ramus, and passes superiorly into the inferior frontal gyrus separating the pars triangularis from the pars opercularis of the frontal operculum.  Termin...
Article

Ascending transtentorial herniation

Ascending transtentorial herniation is a situation where space occupying lesions in the posterior cranial fossa cause superior displacement of superior parts of cerebellum through the tentorial notch.  Clinical presentation nausea and/or vomiting  rapid progression toward decreased level of c...
Article

ASIA impairment scale

This scale was developed by American Spinal Injury Association in 2006, and at the time of writing (July 2016), remains the most widely used scale. The American Spinal Injury Association (ASIA) impairment scale is part of the ASIA spinal cord injury classification. It divides spinal cord injuri...
Article

Astroblastoma

Astroblastomas are an uncommon primary neuroepithelial tumours which, along with choroid gliomas of the third ventricle and angiocentric gliomas, are grouped as other neuroepithelial tumours in the 2007 version of the WHO classification of CNS tumours. Epidemiology They occur at all ages range...
Article

Astrocytic tumours

Astrocytic tumours are primary central nervous system (CNS) tumours. They arise from astrocytes and are the most common glial tumour. They can be divided into those that are diffuse in growth (the vast majority with poorer prognosis and given a higher grade (see diffuse astrocytoma grading) and...

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