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.

2,302 results found
Article

Dural sinus malformations

Dural sinus malformations (DSMs) are congenital vascular malformations characterized by massive dilatation of one or more dural venous sinuses. This condition is typically associated with arteriovenous shunts (DAVS). Sub types There are two types of DSMs DSM involving the confluence of sinuse...
Article

Dural sinus occlusive disease

Dural sinus occlusive disease (DSOD) is an infective form of dural sinus thrombosis (thrombophlebitis) commonly seen in the setting of acute otomastoiditis. It typically presents with: severe headaches high fevers sixth nerve palsy - due to involvement of Dorello's canal altered conscious st...
Article

Dural tail sign

The dural tail sign occurs as a result of thickening and enhancement of the dura and is most often seen adjacent to a meningioma. Initially, the sign was felt to be pathognomonic of meningiomas, however as experience grew, it has become increasingly noted to be present in many other conditions,...
Article

Dural venous sinuses

Dural venous sinuses are venous channels located intracranially between the two layers of dura mater (endosteal layer and meningeal layer). They can be conceptualised as trapped epidural veins. Unlike other veins in the body they run alone, not parallel to arteries. Furthermore, they are valvele...
Article

Dural venous sinus thrombosis

Dural venous sinus thrombosis is a subset of cerebral venous thrombosis, often coexisting with cortical or deep vein thrombosis, and presenting in similar fashions, depending mainly on which sinus is involved. As such, please refer to the cerebral venous thrombosis article for a general discuss...
Article

Dura mater

The dura mater, also known as the pachymeninx, is the tough outer layer of the meninges that surrounds the central nervous system and is pierced by the cranial nerves, the internal carotid arteries and the vertebral arteries.  Intracranially it is formed by two layers: outer endosteal layer, c...
Article

Duret hemorrhage

Duret hemorrhage is a small hemorrhage (or multiple hemorrhages) seen in the medulla or pons of patients who are rapidly herniating.  Pathology Raised supratentorial pressure causes the brainstem and mesial temporal lobes to be forced downwards through the tentorial hiatus. As a result of this...
Article

Dyke-Davidoff-Masson syndrome

Dyke-Davidoff-Masson syndrome (DDMS) is a condition characterized by hemicerebral atrophy/hypoplasia secondary to brain insult usually in fetal or early childhood period and is accompanied by ipsilateral compensatory osseous hypertrophy and contralateral hemiparesis. It is characterized by: th...
Article

Dynamic contrast enhanced (DCE) MR perfusion

Dynamic contrast-enhanced (DCE) MR perfusion, sometimes also referred to as permeability MRI, is one of the main MRI perfusion techniques which calculates perfusion parameters by evaluating T1 shortening induced by a gadolinium-based contrast bolus passing through tissue. The most commonly calcu...
Article

Dynamic susceptibility contrast (DSC) MR perfusion

Dynamic susceptibility contrast (DSC) MR perfusion is one of the most frequently used techniques for MRI perfusion, and relies on the susceptibility induced signal loss on T2* weighted sequences which results from a bolus of gadolinium-based contrast passing through a capillary bed.  The most co...
Article

Dysembryoplastic neuroepithelial tumor

Dysembryoplastic neuroepithelial tumors (DNET) are benign (WHO Grade I) slow growing glioneuronal tumors arising from either cortical or deep grey matter. The vast majority are centred in cortical grey matter, arise from secondary germinal layers, and are frequently associated with cortical dysp...
Article

Dysgenesis of the corpus callosum

Dysgenesis of the corpus callosum may be complete (agenesis) or partial and represents an in utero developmental anomaly. It can be divided into: primary agenesis: the corpus callosum never forms secondary dysgenesis: the corpus callosum forms normally and is subsequently destroyed Epidemiolo...
Article

Dysgerminoma

A dysgerminoma refers to a class of tumor with germ cell origin. This can refer to: CNS dysgerminoma ovarian dysgerminoma See also germ cell tumors
Article

Dysmyelinating disorders

Dysmyelinating disorders are a subset of white matter disorders characterized by abnormal myelination 1. They include numerous inherited conditions that are characterized by a defective structure and function of the myelin sheath 2.  Terminology Dysmyelinating disorders are often thought of be...
Article

Early DWI reversal in ischemic stroke

Early DWI reversal in ischemic stroke (also referred to as diffusion lesion reversal) is encountered early in the course of ischemic infarction, most frequently in the setting of reperfusion within 3 to 6 hours of onset 1. DWI reversal is defined as the interval disappearance of the initially-v...
Article

Ears of the lynx sign

The ear of the lynx sign refers to abnormal T2/FLAIR cone shaped hypeintensity at the tip of the frontal horn of the lateral ventricles in the region of forceps minor which resembles the tufts of hair crowning the ears of a lynx. This sign is seen in hereditary spastic paraplegia (HSP) associate...
Article

Eastern equine encephalitis

Eastern equine encephalitis (EEE) is one of many viral encephalitides and results from infection with the eastern equine encephalitis virus. Clinical presentation Most patients have non-specific viral prodromal symptoms for approximately one week, including fevers, headache, nausea and vomitin...
Article

EBV associated smooth muscle tumor

Epstein-Barr virus-associated smooth muscle tumors (EBV-SMT) are rare and encountered in immunocompromised individuals. Epidemiology These tumors are generally exceedingly rare, and only seen with any frequency in the setting of immunosuppression, particularly in HIV/AIDS patients, but also po...
Article

EBV-positive diffuse large B-cell lymphoma, NOS

EBV-positive diffuse large B-cell lymphoma, NOS (not otherwise specified) is one of the immunodeficiency-associated CNS lymphomas, usually seen in elderly individuals. Unlike other EBV-associated CNS lymphomas, these individuals do not have a defined cause for immunosuppression. It is believed t...
Article

Eccentric target sign (cerebral toxoplasmosis)

The eccentric target sign is considered pathognomonic for cerebral toxoplasmosis. It is seen on postcontrast MRI/CT as a ring enhancing lesion with an eccentrically located enhancing mural nodule. It is believed that this mural nodule is an extension from the abscess wall itself with inflamed ve...
Article

Ecchordosis physaliphora

Ecchordosis physaliphora is a congenital benign hamartomatous lesion derived from notochord remnants, usually located in the retroclival prepontine region, but can be found anywhere from the skull base to the sacrum.  Terminology There has been some controversy as to whether intradural chordom...
Article

Ectopia lentis

Ectopia lentis refers to subluxation or dislocation of the lens of the eye secondary to dysfunction or disruption of zonular fibers.  Pathology Etiology trauma systemic and syndromic disorders Marfan syndrome typically upwards and out most common spontaneous cause 2 homocystinuria -  typ...
Article

Ectopic posterior pituitary

An ectopic posterior pituitary reflects a disruption of normal embryogenesis of the posterior pituitary and is one of the more common causes of pituitary dwarfism. Although it can be an isolated abnormality, numerous other congenital central nervous system malformations have been identified. Ep...
Article

Edinburgh criteria for lobar intracerebral hemorrhage associated with cerebral amyloid angiopathy

The Edinburgh criteria were proposed in 2018 in order to diagnose lobar intracerebral hemorrhage associated with cerebral amyloid angiopathy (CAA) 1. They can potentially be used to rule CAA-associated lobar hemorrhage either in or out, but require external validation in other patient population...
Article

Efface

Efface is a term frequently used by radiologists, most often in the context of CSF-containing spaces in the brain (sulci and ventricles). Unfortunately, it is often used incorrectly.  The word efface, in general English usage, means to cause something to fade or disappear 1,2. In the context o...
Article

Elevated prolactin (differential)

Elevated prolactin can be due to a number of causes, including elevated production/secretion as well as reduced inhibition.  Prolactin is controlled by numerous homeostatic mechanisms, with tonic secretion of prolactin inhibitory hormone (dopamine) by the hypothalamus having a dominant effect 1...
Article

Eloquent cortex

Eloquent cortex is a term that refers to specific brain areas that directly controls function, thus damage to this areas generally produces major focal neurological deficits. Examples of eloquent cortex are:  primary motor cortex (precentral gyrus) primary somatosensory cortex (postcentral gyr...
Article

Embryonal tumors with multilayered rosettes (ETMR)

Embryonal tumors with multilayered rosettes (ETMR) are rare small round blue cell tumor of the central nervous system and are one of the most aggressive brain tumors usually encountered in children.  Terminology Previously embryonal tumors with multilayered rosettes (ETMR) were known as embryo...
Article

Emergency CT head (mnemonic)

A useful mnemonic which is used to read an emergency head CT scan is: Blood Can Be Very Bad Mnemonic Using a systematic approach will help to ensure that significant neuropathology will not be missed. B: blood look for epidural hematoma, subdural hematoma, intraparenchymal hemorrhage, intra...
Article

Empty delta sign

The empty delta sign is a CT sign of dural venous sinus thrombosis of the superior sagittal sinus, where contrast outlines a triangular filling defect, which represents thrombus. It is only described with CECT-scan or MRI, not with NECT nor non-contrast MRI. An equivalent appearance can be note...
Article

Empty light bulb sign in brain death

In brain death, on HMPAO-Tc99m imaging there is absent or reduced flow in the internal carotid arteries and increased flow within the external carotid arteries. This leads to absent uptake in the brain with subsequent increased perfusion in the nasal region. This appearance has been called the e...
Article

Empty sella

An empty sella, also known as an empty pituitary fossa, is a relatively common incidental finding and posed more of a diagnostic problem before modern cross-sectional imaging. In addition to being incidental, a well-established association with benign intracranial hypertension is also recognised...
Article

Empty thecal sac sign

The empty thecal sac sign or empty sac sign is when the thecal sac appears empty on MRI of the lumbar spine, best seen on T2-weighted images. If the empty thecal sac sign is present, a diagnosis of adhesive arachnoiditis can be made.​ Radiographic features MRI There is usually no gadolinium c...
Article

Empyema

Empyemas are purulent inflammatory collections within a body cavity. They are similar to abscesses, which arise within parenchymal tissue rather than occupying a pre-existing anatomical space. Terminology Colloquially, the term empyema is used to refer to thoracic empyemas but there are variou...
Article

Encephalitis due to herpesvirus family

Although sporadic viral encephalitis is most commonly due to herpes simplex virus 1 (HSV-1) the extended herpesvirus family consists of many other viruses many of which can also infect the central nervous system. Encephalitis due to herpesvirus family include 1:   herpes simplex virus 1 (HSV-1)...
Article

Encephalitis lethargica

Encephalitis lethargica, also known as von Economo encephalitis, is a rare disease of unknown etiology that affects the midbrain and basal ganglia.  Clinical presentation Symptoms are initially that of pharyngitis followed by lethargy, extrapyramidal movements (parkinsonism and dyskinesias), n...
Article

Encephalocele

Encephalocele, also known as meningoencephalocele, is a form of neural tube defect and a type of cephalocele where brain tissue and overlying meninges herniate out through a defect in the cranium.  Terminology It should be distinguished from cranial meningocele in which the lesion contains onl...
Article

Encephalocraniocutaneous lipomatosis

Encephalocraniocutaneous lipomatosis (ECCL), also known as Haberland syndrome, is a rare congenital neurocutaneous syndrome characterized by unilateral lipomas of the cranium, face, and neck, ipsilateral lipodermoids of the eye, and ipsilateral brain anomalies. The clinical features of ECCL ove...
Article

Encephalomalacia

Encephalomalacia is term given to describe softening or loss of brain parenchyma with or without surrounding gliosis, as a late manifestation of injury.  Clinical presentation asymptomatic  serve as a focus of seizure Pathology Encephalomalacia is the end result of liquefactive necrosis of ...
Article

Endolymphatic sac tumor

Endolymphatic sac tumors are very rare, locally invasive tumors of endolymphatic sac. Early detection of these tumors is critical, because early surgical intervention may prevent further hearing loss. Endolymphatic sac tumors do not metastasize but are highly locally aggressive.  Epidemiology ...
Article

Enlarged posterior fossa 'CSF' space

An enlarged posterior fossa 'CSF' space posterior to the cerebellum has a number of differentials that include: mega cisterna magna epidermoid cyst arachnoid cyst Careful attention to the cerebellum needs to paid as also to be considered are: cerebellar atrophy Dandy-Walker malformations ...
Article

Enlarged sella turcica (differential)

Enlargement of sella turcica can be seen in situations including the following: empty sella syndrome slight globular enlargement of the sella with no erosion, destruction or posterior displacement of dorsum sellae intracranial hypertension enlargement with erosion of anterior cortex of dorsu...
Article

En plaque meningioma

En plaque meningiomas refer to a specific meningioma macroscopic appearance characterized by diffuse and extensive dural involvement, usually with extracranial extension into calvarium, orbit, and soft tissues. These tumors are thought to have a collar-like or sheet-like growth along the dura ma...
Article

Enterovirus 71

Enterovirus 71 is one of the viruses that causes hand-foot-and-mouth disease in children. It is an enterovirus, one of the picornaviruses. Infection with enterovirus 71 predominantly results in a vesicular rash of the hands and feet that follows a prodrome of symptoms including fever, vomiting ...
Article

Enterovirus rhomboencephalitis

Enterovirus rhomboencephalitis is the most common neurological complication of enterovirus infection 1. Clinical presentation Enterovirus rhomboencephalitis causes acute and severe neurologic disorders such as ataxia, nystagmus, oculomotor palsies, or bulbar palsy. In some cases, neurologic af...
Article

Entorhinal cortex

The entorhinal cortex (Brodmann area 28) is located in the mesial temporal lobe and acts as the interface between the hippocampus and the neocortex. It has been considered part of the hippocampal formation (along with Ammon’s horn, subiculum and presubiculum), but is difficult to precisely local...
Article

Eosinophilia myalgia syndrome

Eosinophilia myalgia syndrome (EMS) is a fatal neurological condition caused by ingestion of improperly manufactured L-tryptophan.  Impurities and/or metabolites that block histamine degradation result in peripheral blood eosinophilia and myalgia.   In the brain, cortical and basal ganglia atro...
Article

Ependymal cells

Ependymal cells are one of the four main types of glial cells, and themselves encompass three types of cells 1:  ependymocytes: line the ventricles of the brain and central canal of the spinal cord tanycytes: line the floor of the third ventricle choroidal epithelial cells: line the surface o...
Article

Ependymal cyst

Ependymal cysts are rare benign neuroepithelial cysts lined by ependymal cells. Most are small and asymptomatic and only cause symptoms if large. On imaging, these cysts are essentially indistinguishable from other intraventricular simple cysts (e.g. intraventricular arachnoid cysts). Epidemio...
Article

Ependymal rosettes (ependymoma)

Ependymal rosettes correspond to a histologic architectural pattern that very characteristic of ependymomas, as tumor cells form structures similar to the lining of normal ventricles. They are characterized by a halo or spoke-wheel arrangement of tumor cells surrounding an empty central tubule l...
Article

Ependymitis granularis

Ependymitis granularis sounds far more worrying than it actually is. The term refers to symmetrical foci of periventricular high T2 and FLAIR signal hyperintensity anterior and lateral to the frontal horns. It is just an anatomical variant, usually small, less than 1 cm, and have a triangular mo...
Article

Ependymocytes

Ependymocytes are one of the three types of ependymal cells, which in turn are one of the four principles types of glial cells, and are found lining the ventricular system of the brain and the central canal of the spinal cord 1.  They do not form a water-tight barrier between the cerebrospinal ...
Article

Ependymoma

Ependymomas represent a relatively broad group of glial tumors most often arising from the lining the ventricles of the brain or the central canal of the spinal cord. They account for ~5% of all neuroepithelial neoplasms, ~10% of all pediatric brain tumors and up to 33% of brain tumors occurring...
Article

Ependymoma RELA fusion-positive

Ependymoma RELA fusion-positive is a recently accepted molecular variant of ependymoma, only recognised in the 2016 update to the WHO classification of CNS tumors. They are the most common type of supratentorial ependymoma in children, and not found in the posterior fossa or spinal cord.  Epide...
Article

Ependymoma vs astrocytoma of the spinal cord

A number of factors are useful when differentiating between spinal cord ependymoma and spinal cord astrocytoma.  Ependymoma child or adult more central in location bone remodelling is common low T1 signal well-defined enhancement syrinx is more common hemorrhage is more common Astrocyto...
Article

Epidermoid cyst

The term epidermoid cyst can refer to a: epidermal inclusion cyst intracranial epidermoid cyst splenic epidermoid cyst spinal epidermoid cyst testicular epidermoid cyst
Article

Epidural angiolipoma

Epidural angiolipomas are rare benign tumors composed of mature adipocytes and abnormal vessels.  Epidemiology Epidural angiolipomas are more frequently encountered in women, and typically in middle age (40-50 years of age) 1.  Clinical presentation In keeping with the slow growth of these t...
Article

Epidural blood patch

Epidural blood patch is a treatment option for patients with craniospinal hypotension or post lumbar puncture headaches. The procedure can be done blind or under fluoroscopic or CT guidance, and is performed predominantly by radiologists and anesthesiologists.  Indications craniospinal hypoten...
Article

Epidural empyema

Epidural empyema refers to a collection within the epidural space either within the cranium or the spinal cord. Epidemiology Epidural empyemas are rare overall but together with subdural empyema account for around 20-33% of all intracranial infections. They can present in any age group and hav...
Article

Epidural ligaments

The epidural ligaments, also known as meningovertebral ligaments, are variably thick bands of connective tissue located within the spinal epidural space attaching the outer surface of the theca to the inner borders of the spinal canal (vertebrae and ligaments).  They are somewhat variable in nu...
Article

Epidural lipomatosis

Epidural lipomatosis refers to an excessive accumulation of fat within the spinal epidural space resulting in compression of the thecal sac. In severe cases, compression may be symptomatic. The lumbar region is most frequently affected. Epidemiology The demographics of affected individuals ref...
Article

Epilepsy

Epilepsy is a common neurological disorder that has a varied presentation and requires two or more unprovoked seizures at least 24 hours apart for diagnosis. MRI is the modality of choice for epilepsy, most often investigating for an underlying cause, especially in adults.  Epidemiology Epilep...
Article

Epilepsy protocol (MRI)

MRI protocol for epilepsy is a group of MRI sequences put together to improve sensitivity and specificity in identifying possible structural abnormalities that underlie seizure disorders (e.g. mesial temporal sclerosis and malformation of cortical development). MRI is the imaging procedure of ch...
Article

Epiphora

Epiphora represents excessive tearing of the eye and is a common clinical presentation to ophthalmological practice. It is most frequently due to an obstruction of the nasolacrimal drainage apparatus. Less commonly, overproduction of tears may be responsible. 
Article

Epithalamus

The epithalamus is a dorsal posterior segment of the diencephalon which includes the habenula, stria medullar is, pineal gland and posterior commissure. Its function is the connection between the limbic system to other parts of the brain.
Article

Epithelial membrane antigen (EMA)

Epithelial membrane antigen (EMA) is a commonly used target for immunohistochemisty, found on the surface of many epithelial cells and thus present in a wide variety of tumors. It also is sometimes seen within the cytoplasm of cells (e.g. perinuclear dot in ependymomas). 
Article

Epithelioid glioblastoma

Epithelioid glioblastoma is a variant of glioblastoma (along with gliosarcoma and giant cell glioblastoma) only recently added to the WHO classification of CNS tumors as part of the 2016 update 1.  Terminology Whether or not epithelioid glioblastomas are distinct from rhabdoid glioblastomas is...
Article

Epstein-Barr virus encephalitis

Epstein-Barr virus (EBV) encephalitis is an uncommon manifestation of EBV infection and an uncommon causative organism of encephalitis in general. Epidemiology Most reported cases have been in children, although adults can rarely be affected 5. Clinical presentation Primary EBV infection is ...
Article

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell, non-familial multisystemic granulomatosis, with widespread manifestations and of highly variable severity. The most common presenting symptom is bone pain. Epidemiology Erdheim-Chester disease is a rare, non-inherited disease of midd...
Article

État criblé

État criblé, also known as status cribrosum, is a term that describes the diffusely widened perivascular spaces (Virchow-Robin spaces) in the basal ganglia, especially in the corpus striatum on MRI. It is usually symmetrical, with the perivascular spaces showing CSF signal and without diffusion ...
Article

État lacunaire

État lacunaire is a term describing the presence of multiple lacunar infarcts, which are ischemic strokes due to occlusion of penetrating cerebral arterioles, especially in the basal ganglia. The term has been strongly described as a pathological substrate for a multi-infarct vascular dementia 4...
Article

Ethylene glycol toxicity

Ethylene glycol toxicity is a type of toxic leukoencephalopathy. Ethylene glycol, best known as a component of antifreeze, has been ingested both deliberately and accidentally, resulting in neurotoxicity and renal failure. Clinical presentation A delay is present between ingestion and developm...
Article

Evans' index

The Evans' index is the ratio of maximum width of the frontal horns of the lateral ventricles and maximal internal diameter of skull at the same level employed in axial CT and MRI images. This ratio varies with the age and sex. It is useful as a marker of ventricular volume and thus has been pr...
Article

Exencephaly

Exencephaly is a lethal congenital fetal brain developmental anomaly (neural tube defect) considered to be a precursor to anencephaly in the acrania-exencephaly-anencephaly sequence. Pathology It is characterized by calvarial absence and loss of fetal brain tissue to variable degrees and is co...
Article

External auditory canal atresia

External auditory canal atresia (EACA) is characterized by complete or incomplete bony atresia of the external auditory canal (EAC) and, especially when seen in the setting of an associated syndrome, a dysplastic auricle and an abnormal middle ear cavity. Epidemiology The incidence is 1 in 10,...
Article

External capsule

The external capsule is a series of white matter tracts in the brain situated between the putamen and claustrum. It is composed of claustrocortical fibers dorsally and the combined mass of the uncinate fasciculus and inferior frontal occipital fasciculus ventrally.  Relationships The putamen s...
Article

External petrosal nerve

The external petrosal nerve is one of the three branches from the geniculate ganglion. It carries sympathetic fibers to the middle meningeal artery.
Article

External ventricular drain

External ventricular drains (EVDs) are a common neurosurgical procedure used to monitor and treat raised intracranial pressure in the acute setting.  Treatment and prognosis Complications infection EVD malfunction EVD malposition intracranial hemorrhage (e.g. subdural, intraventricular) s...
Article

Extra-axial

Extra-axial is a descriptive term to denote lesions that are external to the brain parenchyma, in contrast to intra-axial which describes lesions within the brain substance.  Radiographic features Often it is trivially easy to distinguish an intra-axial from an extra-axial mass. In many cases,...
Article

Extra-axial collection (summary)

This is a basic article for medical students and other non-radiologists Extra-axial collections are collections of fluid within the skull, but outside the brain parenchyma. They may be comprised of CSF, blood or pus and may exist in the extradural, subdural or subarachnoid space.  Reference ar...
Article

Extra-axial masses (differential)

Extra-axial masses of the intracranial compartment have a wide range of differentials, ranging from benign developmental cysts to malignant tumors.  Differential diagnosis neoplasms chordoma choroid plexus papilloma/carcinoma cranial nerve schwannoma meninges meningioma solitary fibrous ...
Article

Extraconal orbital lesions

Extraconal orbital lesions include lesions which arise from structures within the extraconal orbital space and those extending from adjacent structures into the orbits. Differential diagnosis Intraorbital lesions dermoid cyst: most common lesion in pediatrics  lacrimial gland lesions dacryo...
Article

Extracranial brain herniation

Extracranial brain herniation refers to herniation of brain tissue external to the calvaria through a skull bone defect, which may be post-traumatic or post-surgical. Unlike encephaloceles, brain herniation is not surrounded by the meninges.  The herniated brain tissue requires surgical reducti...
Article

Extracranial meningioma

Extracranial meningiomas, also known as primary extradural meningiomas or ectopic meningioma, are a rare location-specific type of meningioma that arise outside the dural covering of the brain and spinal cord. They are essentially extracranial tumors, most often occurring in the head and neck, m...
Article

Extradural hematoma vs subdural hematoma

Differentiating extradural (EDH) from subdural (SDH) hemorrhage in the head is usually straightforward, but occasionally it can be challenging. SDHs are more common and there are a few distinguishing features which are usually reliable. Pathology History and mechanism of injury Extradural hem...
Article

Extradural hemorrhage

Extradural hematoma (EDH), also known as an epidural hematoma, is a collection of blood that forms between the inner surface of the skull and outer layer of the dura, which is called the endosteal layer. They are usually associated with a history of head trauma and frequently associated skull fr...
Article

Extradural hemorrhage (summary)

This is a basic article for medical students and other non-radiologists Extradural hemorrhages (EDH) represent collections of blood in the extradural (epidural) space. The hemorrhage sits between the skull superficially and the dura which overlies the brain parenchyma. Reference article This ...
Article

Extradural hemorrhage (venous)

Venous extradural hemorrhages are a relatively uncommon subtype of extradural hemorrhages, differing from arterial extradural hemorrhages not only in etiology, but also location and prognosis.  They occur as a result of damage to the dural venous sinuses and often result in the displacement of ...
Article

Extradural neural axis compartment

Extradural neural axis compartment (EDNAC) exists from the tip of the coccyx all the way to the back of the globe, and yet it is relatively unknown as a concept. It is bounded externally by the periosteum of the vertebrae and sacrum inferiorly and the skull superiorly, and the visceral layer of ...
Article

Extradural space

The extradural (epidural) space is a potential space between the cranial bones and the endosteal layer of the dura mater, which is otherwise adherent to the cranial bone.  Gross anatomy The extradural space is a potential space inside the cranial vault and is not normally appreciable unless th...
Article

Extraneural spread of intracranial neoplasm

Extraneural spread of primary intracranial neoplasm is distinctly uncommon, occurring far less frequently than CSF spread.  The most frequent neoplasms to do so, in decreasing order of frequency, are: glioblastoma (GBM) meningioma medulloblastoma
Article

Extraocular muscle involvement in thyroid associated orbitopathy (mnemonic)

A mnemonic to remember the order in which extraocular muscles are involved in thyroid-associated orbitopathy (TAO) is: I'M SLOw Mnemonic I: inferior rectus M: medial rectus S: superior rectus L: lateral rectus O: obliques There is some debate about this however. Some claim superior rectu...
Article

Extraocular muscle nerve supply (mnemonic)

A mnemonic to remember the nerve supply to the extraocular muscles: LR6SO4O3 (mock 'chemical formula') Mnemonic The letters represent the extraocular muscles and numbers represent their respective cranial nerve supply: LR6: lateral rectus, innervated by the 6th (abducens) nerve  SO4: superi...

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.