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2,648 results found

Tuberculous encephalopathy

Tuberculous (TB) encephalopathy is a rare manifestation of CNS tuberculosis and is exclusively seen in children and infants with pulmonary TB. It is characterized by cerebral edema sometimes with features similar to acute disseminated encephalomyelitis (ADEM), and may manifest with a variety of ...

Tuberculous meningitis

Tuberculous meningitis is the most common presentation of intracranial tuberculosis, and usually refers to infection of the leptomeninges. Uncommonly tuberculosis can be limited to the pachymeninges (dura mater), it is called tuberculous pachymeningitis and is discussed separately. The remaind...

Tuberculous otomastoiditis

Tuberculous otomastoiditis is an uncommon form of acute otomastoiditis that occurs secondary to tuberculosis infection, although its frequency is increasing as a result of greater population of immunocompromised patients. Clinical presentation Classically it is described as presenting with pa...

Tuberculous pachymeningitis

Tuberculous pachymeningitis is a rare form of CNS tuberculosis characterized by a chronic tuberculous infection leading to a dura mater involvement. Common sites of involvement are cavernous sinuses, floor of middle cranial fossa and tentorium. This condition should not be confused with the com...

Tuberculous rhombencephalitis

Tuberculous rhombencephalitis is a particular form of neurotuberculosis that affects primarily the hindbrain (brainstem and cerebellum) and usually is manifested as a tuberculoma. Please refer to the article on rhombencephalitis for a general discussion of that entity. Epidemiology Studies ha...

Tuberculous spondylitis versus pyogenic spondylitis

Tuberculous spondylitis and pyogenic spondylitis are both common causes of spinal infection. Imaging findings of these two diseases can be challenging to distinguish, yet crucial because the treatments for these infections are particularly different 2. Radiographic features Useful distinguishi...

Tuberculum sellae - occipital protuberance line

The tuberculum sellae-occipital protuberance line (TS-OP line), is an imaging reference line that runs almost parallel to the anterior commissure-posterior commissure line (AC-PC line) 1.It is a practical reference line for reformatting or tilting of the gantry during CT acquisition of the head ...

Tuberous sclerosis

Tuberous sclerosis, also known as tuberous sclerosis complex or Bourneville disease, is a neurocutaneous disorder (phakomatosis) characterized by the development of multiple benign tumors of the embryonic ectoderm (e.g. skin, eyes, and nervous system). Epidemiology Tuberous sclerosis has an in...

Tuberous sclerosis (diagnostic criteria)

The tuberous sclerosis diagnostic criteria have been developed to aid the diagnosis of tuberous sclerosis and have been updated in 2012 by the International Tuberous Sclerosis Complex Consensus Group (at time of writing - 2019) 1. Criteria Genetic criteria The identification of either a TSC1...

Tuberous sclerosis (mnemonic)

The findings of tuberous sclerosis can be remembered with the help of the following mnemonic: HAMARTOMAS Mnemonic H: hamartomas (CNS, retinal and skin) A: angiofibroma (facial) or adenoma sebaceum M: mitral regurgitation A: ash-leaf spots R: rhabdomyoma (cardiac) T: tubers (cortical, sub...

Tubulinopathy

Tubulinopathies refer to a wide spectrum of cortical malformations that result from defects in genes encoding the tubulin protein that regulates neuronal migration during brain development. Clinical presentation Some series report a high prevalence of seizures during infancy which may the init...

Tumefactive demyelinating lesion

Tumefactive demyelinating lesion (TDL), also sometimes referred to as monofocal acute inflammatory demyelination (MAID), is a locally aggressive form of demyelination, usually manifesting as a solitary lesion (or sometimes a couple of lesions) greater than 2 cm that may mimic a neoplasm on imagi...

Tumefactive multiple sclerosis

Tumefactive multiple sclerosis is a term used to describe patients with established multiple sclerosis who develop large aggressive demyelinating lesions, similar/identical in appearance to those seen in sporadic tumefactive demyelinating lesions (TDL). TDL is now considered to be a separate ent...

Tumefactive perivascular spaces

Tumefactive perivascular spaces (TPVS) is a rare finding of enlargement of perivascular spaces. It is important to recognize this condition as it can be easily mistaken for a neoplasm and also rarely local mass effect from TPVS can result in a complication. Clinical presentation Small case ser...

Tumor pseudoprogression

Tumor pseudoprogression, also known just as pseudoprogression, corresponds to an increase of lesion size related to treatment, which simulates progressive disease. The term is largely used in brain tumors imaging follow-up, especially for high grade gliomas (e.g. glioblastoma), and is observed a...

Tumor pseudoresponse

Tumor pseudoresponse, also known just as pseudoresponse, refers to the phenomenon of tumors appearing to respond to a specific treatment on imaging criteria, when the lesion actually remains stable or has even progressed. The term is largely used in brain tumors imaging follow-up, especially fo...

Tumors of the meninges (differential)

Tumors of the meninges are a heterogeneous group of lesions which usually occur as extra-axial masses. Although a large number of lesions that can involve meninges are scattered throughout the WHO classification of CNS tumors, the main entities to be considered include: meningioma and numero...

Tumor-to-tumor metastasis

A tumor-to-tumor metastasis, also known as a collision tumor, is a rare metastatic process in which a primary malignant tumor ('donor') metastasizes to another tumor ('recipient'), most commonly a benign tumor such as a meningioma. Epidemiology Tumor-to-tumor metastasis is considered very rare...

Turcot syndrome

Turcot syndrome is one of the variations in polyposis syndromes. It is characterized by multiple colonic polyps and an increased risk of colon and primary brain cancers. Epidemiology Turcot syndrome is a rare disease. Patients typically present in the second decade 3. Pathology Turcot syndro...

Twig-like middle cerebral artery

Twig-like middle cerebral artery or rete mirabile anomaly describes a discontinuity of a single trunk of the middle cerebral artery with several small vessels reconstituting the artery and giving it a twig-like appearance. Distally, normal vascular anatomy of the MCA branches need to be present ...

Tympanic membrane retraction

Tympanic membrane retraction usually occurs when a portion of the tympanic membrane becomes weakened and is pulled inwards by the negative pressure within the middle ear. Pathology As the tympanic membrane is pulled inwards (medially), it can become draped over the ossicles, resulting in a va...

Typhoid fever

Typhoid fever or just typhoid is an infectious disease caused by the Salmonella enterica serovar Typhi bacterium, usually spread by the orofecal route. The condition is characterized by severe fever, acute systemic symptoms, with occasionally serious enterocolic complications. Terminology Do n...

Ulegyria

Ulegyria refers to a shrunken and flattened cortex usually due to global hypoxic ischemic injury in term infants, centering on the deepest portion of gyri, usually in the parasagittal region. It is here that perfusion is most tenuous and, therefore, most susceptible to ischemic damage. Clinical...

Ultrahigh field MRI

Ultrahigh field (UHF) magnetic resonance imaging refers to imaging done on any MRI scanner with a main magnetic field (B0) strength of 7 tesla or greater. Until recently purely a research tool, following the introduction of the first 7 T clinical scanner in 2017, there are now a slowly increasin...

Ultrasound carotids (summary)

This is a basic article for medical students and other non-radiologists. US (ultrasound) carotids is a standard test performed as part of the assessment of the cranial arterial blood supply. Reference article This is a summary article; we do not have a more in-depth reference article. Summar...

Uncal herniation

Uncal herniation is a subtype of transtentorial downward brain herniation that involves the uncus, usually related to cerebral mass effect increasing the intracranial pressure. Clinical presentation pupils and globe clinical features 3 initially, an ipsilateral dilated pupil that is unrespons...

Uncinate fasciculus

The uncinate fasciculus is a white matter tract that connects the uncus (Brodmann area 35), the anterior temporal areas (temporal pole; Brodmann area 38), the amygdala and the hippocampal gyrus (Brodmann areas 36 and 30) with areas of the frontal lobe (polar and orbital cortex); runs - forming a...

Unclassified cerebellar dysplasia

Unclassified cerebellar dysplasia is defined as focal or diffuse dysplasia of cerebellar hemispheres or vermis not associated with other known malformations or syndromes. Clinical presentation Can present with hypotonia, microcephaly or speech delay. Radiographic features MRI asymmetry or f...

Uncus

The uncus (plural: unci) is the innermost part of the anterior parahippocampal gyrus, part of the mesial temporal lobe. Gross anatomy The uncus is the most anterior portion of the medial parahippocampal gyrus. It belongs to the limbic system. Housing the primary olfactory cortex, it is part o...

Unverricht-Lundborg disease

Unverricht-Lundborg disease (ULD or EPM1) inherited neurodegenerative disorder which often results in a progressive myoclonic epilepsy. Epidemiology It is considered the most common single cause of progressive myoclonic epilepsy worldwide. Pathology Genetics It carries an autosomal recessiv...

Upper T sign

The upper T sign is one of the features useful in identifying the central sulcus of the cerebral cortex on cross-sectional imaging. It relies on identifying the superior frontal sulcus which intersects the precentral sulcus in a "T" junction, thus defining the precentral gyrus. The central sulc...

Uremic encephalopathy

Uremic encephalopathy (UE) is an acquired toxic syndrome characterized by delirium in patients with untreated or inadequately treated end-stage renal disease. Uremic encephalopathy is often associated with lethargy and confusion in the acute phase, which can progress to seizures, coma, or both i...

Urbach-Wiethe disease

Urbach-Wiethe disease, also known as lipoid proteinosis or hyalinosis cutis et mucosae, is a rare autosomal recessive genodermatosis that primarily affects the skin, upper respiratory tract, and central nervous system (CNS). Epidemiology Urbach-Wiethe disease is a very rare condition, with few...

U sign (central sulcus)

The U sign denotes the characteristic U-shaped appearance of the subcentral gyrus which surrounds the inferolateral end of the central sulcus and abuts the lateral (Sylvian) fissure. It has been found, at least in one study, to be the most reliable anatomical feature to identify the central sulc...

Uvula (disambiguation)

The uvula (plural: uvulae or uvulas) may refer to several different anatomical structures. When used as a standalone term it is usually understood to refer to the soft palate uvula. uvula (soft palate) uvula (cerebellum) uvula (male bladder) History and etymology Uvula is Latin for 'little ...

Vagoglossopharyngeal neuralgia

Vagoglossopharyngeal neuralgia is an uncommon presentation of glossopharyngeal neuralgia where the typical symptoms of pain are associated with cardiac symptoms including arrhythmias, asystole, and syncope. It is believed to be due to complex interconnections between the nervus intermedius, the...

Vagus nerve

The vagus nerve is the tenth (X) cranial nerve and provides the bulk of the parasympathetic input to the gastrointestinal system and to the heart. It is a complex mixed sensory, motor and parasympathetic nerve. Gross anatomy Central connections The vagus nerve arises as multiple rootlets at ...

Valproate-induced hyperammonemic encephalopathy

Valproate-induced hyperammonemic encephalopathy (VHE), also known as valproic acid-induced hyperammonemic encephalopathy, is a rare type of non-cirrhotic hyperammonemic encephalopathy caused by use of sodium valproate, a drug commonly used as an anti-epileptic and mood stabilizer. Epidemiology ...

Vanishing white matter disease

Vanishing white matter disease (VWM), also known as childhood ataxia with central hypomyelination (CACH), is an exceedingly rare entity only fully described in 1997, but due to its name sometimes over-represented in differentials for white matter disease. Epidemiology Most cases are encountere...

Variably protease-sensitive prionopathy

Variably protease-sensitive prionopathy (VPSPr) is a very rare type of sporadic human prion disease that was first described in 2008. Clinical presentation Clinical presentation is varied, but most patients demonstrate a combination of: progressive neuropsychiatric features: dementia and psyc...

Varicella zoster virus encephalitis

Varicella zoster virus (VZV) encephalitis can be due to either an immune reaction to primary infection or reactivation of latent infection in cranial nerve or dorsal root ganglia following childhood chickenpox. Manifestations following primary infection include: cerebellar ataxia meningoence...

VASARI MRI feature set

The VASARI (Visually AcceSAble Rembrandt Images) MRI feature set is a system designed to enable consistent description of gliomas using a set of defined visual features and controlled vocabulary. It is the result of work by The Cancer Imaging Archive (TCIA) who publish relevant guides to use, an...

Vascular dementia

Vascular dementia, also known as vascular cognitive impairment, is the second most common cause of dementia after the far more common Alzheimer disease. It is primarily seen in patients with atherosclerosis and chronic hypertension and results from the accumulation of multiple white matter lesio...

Vasculopathies caused by varicella zoster virus

Vasculopathies caused by varicella zoster virus (VZV) represent a group of illnesses involving both small and large CNS arteries caused by a inflammatory process involving the media and the vascular endothelium. Usually it occurs in immunocompromised individuals due the viral reactivation and sp...

Vasogenic cerebral edema

Vasogenic cerebral edema refers to a type of cerebral edema in which the blood brain barrier (BBB) is disrupted (cf. cytotoxic cerebral edema, where the blood-brain barrier remains intact). It is an extracellular edema which mainly affects the white matter via leakage of fluid from capillaries. ...

Vein of Galen

The vein of Galen, also known as the great cerebral vein or great vein of Galen, is a short valveless trunk formed by the union of the two internal cerebral veins and basal veins of Rosenthal. Gross anatomy It lies in the quadrigeminal cistern and curves backward and upward around the posterio...

Vein of Galen aneurysmal malformation

Vein of Galen aneurysmal malformations (VGAMs), probably better termed as median prosencephalic arteriovenous fistulas, are uncommon intracranial anomalies that tend to present dramatically during early childhood with features of a left-to-right shunt and high-output cardiac failure. Epidemiolo...

Velum interpositum

The velum interpositum is a small membrane containing a potential space just above and anterior to the pineal gland which can become enlarged to form a cavum velum interpositum. Gross anatomy The velum interpositum is formed by an invagination of pia mater forming a triangular membrane the ap...

Venous circle of Trolard

The anastomotic venous circle of the base of the brain 1, also referred to as the venous circle of Trolard 2,3,5, is an inconsistently found venous homologue of the better-known arterial circle of Willis. It should not be confused with other venous structures also described by Trolard such as t...

Venous distension sign

The venous distension sign is a finding that may be identified on sagittal imaging of the dural venous sinuses which is said to have a diagnostic sensitivity and specificity of 94% for intracranial hypotension. The sign is positive when there is a convex inferior margin of the midportion of the...

Venous vascular malformation of the facial nerve

Venous vascular malformations of the facial nerve, previously known as facial nerve hemangiomas, are rare benign vascular malformations of the facial nerve usually presenting as a facial nerve palsy, which can be rapid in onset mimicking a Bell palsy. Terminology As they do not appear to have...

Ventral cord herniation

Ventral cord herniation, also known by a variety of other terms such as spontaneous thoracic cord herniation or idiopathic spinal cord herniation, is a rare cause of focal myelopathy due to herniation of the thoracic cord through a dural defect. Post-surgical cord herniation can occur at any l...

Ventral cord syndrome

Ventral cord syndrome (also known as anterior cord syndrome) is one of the incomplete cord syndromes and affects the anterior parts of the cord resulting in a pattern of neurological dysfunction dominated by motor paralysis and loss of pain, temperature and autonomic function. Anterior spinal ar...

Ventral horn

The ventral horn of the spinal cord is one of the grey longitudinal columns found within the spinal cord. It contains the cell bodies of the lower motor neurons which have axons leaving via the ventral spinal roots on their way to innervate muscle fibers. Gross anatomy On transverse section of...

Ventricular system

The ventricular system in the brain is composed of cerebrospinal fluid (CSF)-filled ventricles and their connecting foramina. CSF is produced by ependymal cells which line the ventricles. They are continuous with the central canal. Ventricles contain around 20% of the total average adult CSF vol...

Ventriculitis

Ventriculitis (plural: ventriculitides) refers to inflammation, usually due to infection, of the ependymal lining of the cerebral ventricles. It is most often due to meningitis. Terminology The entity or closely related variants have also been variously referred to as ependymitis, ventricular ...

Ventriculoatrial shunt

Ventriculoatrial shunting is an alternative option for the diversion of CSF and relief of hydrocephalus. In this technique, the distal catheter is placed in the right atrium or even in the superior vena cava 1,2. It is not the only alternative for the traditional ventriculoperitoneal shunt, an...

Ventriculogallbladder shunt

Ventriculogallbladder shunts are a rare form of cerebrospinal fluid diversion, used when a ventriculoperitoneal shunt is not possible (e.g. intra-abdominal adhesions, peritonitis). Differential diagnosis a ventriculoperitoneal shunt in a right upper quadrant CSFoma See also ventriculoperiton...

Ventriculomegaly

Ventriculomegaly is defined as enlargement of the ventricles. Simply, there are two causes: hydrocephalus communicating non-communicating parenchymal atrophy Refer to the article on hydrocephalus vs atrophy for more details on how to differentiate both entities.

Ventriculoperitoneal shunt

Ventriculoperitoneal (VP) shunts are a device used to shunt cerebrospinal fluid in the treatment of hydrocephalus. As the name suggests, a catheter is placed with its tip in the ventricle. The external portion of the catheter is connected to a valve that regulates the flow of CSF based on a pre...

Ventriculopleural shunt

Ventriculopleural shunting is an alternative option for the diversion of CSF and relief of hydrocephalus. In this technique, the distal catheter is placed in the pleural space. It is an alternative to a ventriculoperitoneal shunt (often considered a next most used alternative). Complications s...

Ventriculus terminalis

The ventriculus terminalis (or persistent terminal ventricle, or terminal ventricle of Krause, or 5th ventricle) is an ependymal-lined fusiform dilatation of the terminal central canal of the spinal cord, positioned at the transition from the tip of the conus medullaris to the origin of the filu...

Venus necklace

A Venus necklace is a term almost never used, but for the sake of completeness is included here. It has been used by some authors 1 to describe a series of T2 hyperintense lesions on the inferior surface of the corpus callosum in the midline (callososeptal interface), most frequently seen in mul...

Vermian lobulation

Evaluation of vermian lobulation is essential in assessment of the vermian maturity. MRI is a useful tool in assessment of the fetal posterior fossa. Radiographic features Normal vermian lobulation by weeks 1: by 21 weeks: the prepyramidal fissure can be seen between the tuber and pyramis 21...

Vermian maturity assessment (approach)

Radiological evaluation of the posterior fossa is an essential part of the routine fetal assessment, including vermian maturity assessment. Radiographic features Ultrasonography is a readily available diagnostic tool in the assessment of the fetal posterior fossa but is sometimes limited due t...

Vermis

The vermis (pl: vermes) of the cerebellum is an unpaired medial structure which separates the cerebellar hemispheres. The neocerebellar posterior lobes join in the midline behind the primary fissure to separate the vermis into superior and inferior portions. The vermis can be further subdivided ...

Vernet syndrome

Vernet syndrome, also known as jugular foramen syndrome, is a constellation of cranial nerve palsies due to compression from a jugular foramen lesion, such as a glomus jugulare tumor, schwannoma, or metastasis 2. Clinical presentation It consists of motor paralysis of: glossopharyngeal nerve ...

Verocay bodies

Verocay bodies are a histological feature of schwannomas and represent a particular growth pattern of Antoni type A pattern in which tumor cells form alternating parallel rows of nuclear palisades separated by regions of acellularity 1.

Vertebral artery dissection

Vertebral artery dissection, like arterial dissection elsewhere, is a result of blood entering the media through a tear in the intima of the vertebral artery. It is potentially lethal and can be difficult to diagnose clinically and radiologically. Epidemiology Vertebral artery dissections have...

Vertebral artery thrombosis

Vertebral artery thrombosis results in complete or partial occlusion of the vertebral artery and alteration of blood flow to the posterior cerebral circulation. Ischemia or infarction to structures supplied by these arteries may result in a range of symptoms. brainstem cerebellum occipital lo...

Vertebral scalloping

Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring). Posterior scalloping Causes of...

Vestibular neuritis

Vestibular neuritis refers to the situation where there inflammation of the vestibular nerve/vestibulocochlear nerve. It can be associated with labyrinthitis. The vestibular nerve is a large division of cranial nerve eight (CN VIII) that transfers the equilibrium information from the inner ear ...

Vestibular nuclei

The vestibular nuclei are a group of four small special sensory nuclei in the lower pons and upper medulla for the vestibular nerve component of the vestibulocochlear nerve. They are part of the extensive cranial nerve nuclei within the brainstem. Gross Anatomy There four nuclei are located ad...

Vestibular schwannoma

Vestibular schwannomas, also known as acoustic neuromas, are relatively common tumors that arise from the vestibulocochlear nerve (CN VIII) and represent ~80% of cerebellopontine angle (CPA) masses. Bilateral vestibular schwannomas are strongly suggestive of neurofibromatosis type 2 (NF2). On i...

Vestibulocochlear nerve

The vestibulocochlear nerve (CN VIII) is the eighth cranial nerve and has two roles: innervation to the cochlea for hearing innervation to the vestibule for acceleration and balance senses Gross anatomy Nuclei There are two special sensory cochlear nuclei and four special sensory vestibular...

Vidian nerve

Vidian nerve, also known as the nerve of the pterygoid canal or nerve of the Vidian canal, is so named because of the canal in which it travels: the Vidian canal. It is formed by the confluence of two nerves: greater superfical petrosal nerve (from the geniculate ganglion of the facial nerve) ...

Viking helmet appearance

The Viking helmet appearance refers to the morphology of the lateral ventricles in the coronal plane in patients with dysgenesis of the corpus callosum. The cingulate gyrus is everted into narrowed and elongated frontal horns. An alternative name is moose head appearance. Other names include st...

Viral encephalitides

Viral encephalitides are the result of brain parenchymal infection by a number of different viruses, many of which have similar presentations and imaging features. Specific diagnosis often requires PCR. For viral infection of the meninges, please refer to the general article on viral meningiti...

Viral meningitis

Viral meningitides correspond to a relatively common and self-limited type of CNS infection clinically diagnosed based on the cerebrospinal fluid analysis and proportionally more frequent in young children than adults. Enteroviruses represent nowadays the most common cause of viral meningitis fo...

Visual agnosia

Visual agnosia is a special type of agnosia where patients are unable to recognize objects despite having knowledge about them and being able to visually perceive them. It typically occurs when there is damage to the ventral occipitotemporal pathway, such as in posterior cerebral atrophy (Benso...

Visual hallucinations

Visual hallucinations are relatively uncommon, and can be due to a variety of 'organic' brain diseases, affecting a variety of regions of the brain. The use of the term organic here is by convention, and should not be taken to imply absence of brain dysfunction in psychiatric illness. Clini...

Visual pathway deficits

Visual pathway or visual field deficits are defects in visual space determined by the location of a lesion in the neurological visual pathway from eye to brain cortex. Understanding of the visual system is paramount 1: retina or optic nerve anopia or central scotoma (ipsilateral) optic chiasm...

Visual system

The visual system or the optic pathway transmits visual information from the retina within the eyes to the primary visual cortex of the occipital lobe as well as the pretectal nuclei and superior colliculi of the midbrain. Gross anatomy Below the visual pathway is described from distal to prox...

Vitamin B1

Vitamin B1 (thiamine) is a water-soluble vitamin, that is part of the vitamin B complex, and is an important coenzyme for two reactions in the citric acid cycle (Kreb cycle). It therefore is vital for cellular ATP production, particularly in the central nervous system. Terminology Thiamine is ...

Vitamin B12 deficiency

Vitamin B12 deficiency, also known as hypovitaminosis B12 or hypocobalaminemia, is not uncommon, with potentially serious sequelae if not adequately treated. Clinical presentation Vitamin B12 deficiency results in a reduction of two metabolic pathways 3: conversion of L-methylmalonyl coenzym...

Vitamin B3

Vitamin B3 (niacin or nicotinic acid) is a water-soluble vitamin, part of the vitamin B complex, that is an important part of the coenzyme nicotinamide adenine dinucleotide (NAD+) which is involved in many reactions of cellular metabolism. Related pathology pellagra is the clinical syndrome of...

Vitamin B5 deficiency

Vitamin B5 deficiency, also known as hypovitaminosis B5, is extremely rare. Pantothenic acid (vitamin B5) is needed for the formation of coenzyme A, itself essential for the synthesis of acetylcholine and melatonin. Pantothenic acid is also required for normal functioning of the tricarboxylic ac...

Vitamin B6 deficiency

Vitamin B6 deficiency (also known as hypovitaminosis B6) is rare, as the B6 vitamers are present in many commonly-consumed foodstuffs. It is most commonly seen in the context of chronic ethanol excess, although many other risk factors are known. In children, deficiency may manifest as seizures. ...

Vitamin B6 excess

Vitamin B6 excess (hypervitaminosis B6) is caused by excessive consumption of supplemental pyridoxine, which is used as a therapeutic agent for several conditions. Epidemiology This hypervitaminosis is almost exclusively seen in those taking pyridoxine as prescription medication, it remains i...

Vitamin B9

Vitamin B9 (folate or folic acid) is a water-soluble vitamin, part of the vitamin B complex, vital for the synthesis of several amino acids, the purines adenosine and guanine and the pyrimidine thymine (three of the four nucleotide bases and hence critical for the synthesis of nucleic acids). T...

Volcano sign (meningioma)

Volcano sign refers to the appearance of classical meningioma that resembels the appearance of volcano (viewed in cross-section MRI, parallel to dural attachment) in which there is triangular hyperostosis at the base of the meningioma (mountain) with the tumor being the cloud around it. The intr...

Voltage gated potassium channel (VGKC) antibody encephalitis

Voltage-gated potassium channel (VGKC) antibody encephalitis is autoimmune encephalitis with antibodies against the voltage-gated potassium channel. It is one of the most common forms of autoimmune limbic encephalitis in the absence of primary extra-CNS tumors. Autoimmune VGKC encephalitis can b...

Von Hippel-Lindau disease

Von Hippel-Lindau (vHL) disease is characterized by the development of numerous benign and malignant tumors in different organs (at least 40 types 1) due to mutations in the VHL tumor suppressor gene on chromosome 3. Epidemiology The disease is rare with an estimated prevalence of 1:35,000-50,...

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