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.

36 results found
Article

Eagle syndrome

Eagle syndrome refers to symptomatic elongation of the styloid process or calcified stylohyoid ligament 1-2. It is often bilateral. In most cases, the cause is unknown; however, the condition is sometimes associated with disorders causing heterotopic calcification such as abnormal calcium/phosph...
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Ectodermal dysplasia

Ectodermal dysplasia (ED) refers to a heterogeneous group of genetic disorders that cause abnormal ectoderm development. The effect is a non-progressive defect in the development of two or more tissues derived from embryonic ectoderm.  Epidemiology ED is rare with an estimated prevalence of 1:...
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Ectopia lentis

Ectopia lentis refers to subluxation or dislocation of the lens of the eye secondary to dysfunction or disruption of zonular fibres.  Pathology Aetiology trauma systemic and syndromic disorders Marfan syndrome typically upwards and out most common spontaneous cause 2 homocystinuria -  ty...
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Ectopic thyroid

An ectopic thyroid gland is one which is located in a location other than the normal position anterior to the laryngeal cartilages. During embryological development, the thyroid gland migrates down from the foramen caecum at the posterior aspect of the tongue to its permanent location. This nor...
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Endolymph

Endolymph is a one of two type of cochlear fluids, the other being perilymph. It is located in the scala media of the cochlea. It is secreted by the stria vascularis (colloquially called 'battery of the cochlea') on the outer wall of the scala media. It has a high level of potassium (K+) and g...
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Endolymphatic sac tumour

Endolymphatic sac tumours (ELST) are very rare, locally invasive tumours of endolymphatic sac. Early detection of these tumours is critical, because early surgical intervention may prevent further hearing loss. Endolymphatic sac tumours do not metastasize but are highly locally aggressive.  Epi...
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Endophthalmitis

Endophthalmitis is a potentially sight-threatening condition that involves intraocular inflammation of any cause. It is either infectious or noninfectious in aetiology, but in clinical practice, intraocular infections are the commonest.  Clinical presentation Eye pain and discomfort are common...
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Enlarged extraocular muscles (differential)

There is a short list of causes for enlarged extraocular muscles: thyroid associated orbitopathy lymphoma orbital pseudotumour sarcoidosis metastases amyloidosis (very rare) 2
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Enophthalmos

Enophthalmos refers to the posterior displacement of the globe in the orbit. It implies that the globe itself is normal and is caused by either one or a combination of 1: structural alterations in the bony orbit orbital fat atrophy retraction Specific causes include 2: orbital blowout fract...
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Epiglottis

The epiglottis is a leaf-shaped fibrocartilaginous structure that forms part of the supraglottic larynx and defines the division of the hypopharynx from the larynx.  Gross anatomy The epiglottis projects posterosuperiorly from its stem-like base, which is attached to the thyroid cartilage. It ...
Article

Epiglottitis

Epiglottitis is a life-threatening condition caused by inflammation of the epiglottis and aryepiglottic folds 1,  which can lead to acute airway obstruction. Hence, treatment should be urgent and performed by appropriately trained individuals, e.g. instrumentation of the trachea should be perfor...
Article

Epignathus

Epignathus is a term given to a very rare form of teratoid tumour that arises from the oropharyngeal region. Epidemiology There may be a slight female predilection ref. The estimated incidence is ~ 1 in 35,000 to 200,000 births. Clinical presentation The tumour classically presents in utero ...
Article

Epistaxis

Epistaxis (nosebleed) is very common and has a broad differential diagnosis in clinical practice. In clinical practice, anterior epistaxis are mainly located in Kiesselbach's plexus and posterior epistaxis (5% of all epistaxis) in Woodruff's plexus. Epidemiology Epistaxis is very common, with ...
Article

Ethmocephaly

Ethmocephaly refers to a rare type of midline cranio-facial anomaly that is characterised by the presence of extreme hypotelorism, arrhinia and a midline proboscis.  Pathology Associations holoprosencephaly 1-2: particularly alobar holoprosencephaly See also cebocephaly
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Ethmoidal air cells

The ethmoidal air cells (or less commonly, the ethmoidal sinuses) form one of the four pairs of paranasal sinuses. They are located within the single, midline ethmoid bone. They are present at birth, and they develop rapidly from 0-4-year-old; they further mature from 8-12-year-old during pubert...
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Ethmoid bone

The ethmoid bone is a single midline facial bone that separates the nasal cavity from the brain and is located at the roof of the nose and between the two orbits. It is a cubical shape and is relatively lightweight because of its spongy construction. It contributes to the anterior cranial fossa....
Article

Eustachian tube

The Eustachian tube is the channel through which the tympanic cavity communicates with the nasopharynx. It is approximately 36 mm in length and is directed downward, forward, and medially, forming an angle of about 45 degrees with the sagittal plane and one of 30 to 40 degrees with the horizonta...
Article

Eustachian tube dysfunction

Eustachian tube dysfunction (ETD) is considered by many to be the underlying cause of chronic otomastoiditis, although both the exact pathogenesis and role of ETD in chronic middle ear infections is unclear. Epidemiology ETD is estimated to be present in ~1% of the adult population. Pathology...
Article

External auditory canal atresia

External auditory canal atresia (EACA) is characterised 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 auditory canal cholesteatoma

External auditory canal cholesteatomas are an uncommon locations for cholesteatomas, which are usually in the middle ear or petrous apex.  When they occur lateral to the tympanic membrane, they are referred to as external auditory canal cholesteatomas.   Epidemiology The external acoustic cana...
Article

External auditory canal exostoses

Exostosis of the external auditory canal (also known as surfer's ear), is a benign bony overgrowth of the bony external auditory canal brought about by exposure to cold wind and water combined. Radiographic features broad-based or more focal circumferential bony overgrowth of the osseous exter...
Article

External auditory canal osteoma

External auditory canal osteoma is a rare focal pedunculated bony overgrowth of the osseous external auditory canal. Radiographic features solitary pedunculated bony overgrowth of the external auditory canal usually at the bony cartilaginous junction unilateral large lesions may be associate...
Article

External carotid artery

The external carotid artery (ECA) is one of the two terminal branches of the common carotid artery. The other terminal branch is the internal carotid (ICA), which is somewhat larger than the ECA. Summary origin: bifurcation of the common carotid artery course: under the submandibular gland an...
Article

External ear

The external ear comprises the auricle (or pinna), the external auditory meatus, and the tympanum (eardrum). The pinna concentrates and amplifies sound waves and funnels them through the outer acoustic pore into the external auditory meatus, which carries them to the tympanic membrane. Gross an...
Article

External jugular vein

The external jugular vein (EJV) drains the head, face and part of the pectoral region. Gross anatomy Origin and course The posterior division of the retromandibular vein and posterior auricular vein unite to form the external jugular vein at the angle of the mandible. It courses inferiorly in...
Article

Extraconal orbital compartment

The extraconal orbital compartment or extraconal space is the space within the orbit outside the musculofascial cone. The base of which is anterior and is formed by the orbital septum that surrounds the equator of the globe. The external sides are formed by the bones of the orbit and their perio...
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 paediatrics  lacrimial gland lesions dacry...
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 tumours, most often occurring in the head and neck, ...
Article

Extramedullary plasmacytoma

Extramedullary plasmacytoma (EMP) is an uncommon plasma cell tumour that is composed of monoclonal plasma cells arranged in clusters or sheets. The rate of progression to multiple myeloma (MM) varies from 10% to 30%. Epidemiology EMP occurs most commonly during the fourth through to seventh de...
Article

Extramural air cell

An extramural air cell is one that is not contained within its named parent bone. So, the infraorbital ethmoidal air cells that lie within the maxilla rather than the ethmoidal bone are an example of extramural air cells.
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

Extra-ocular muscles

The extra-ocular muscles are the six muscles that insert onto the eye and hence control eye movements: superior rectus: elevation superior oblique: intorsion medial rectus: adduction lateral rectus: abduction inferior oblique: extorsion inferior rectus: depression Associated pathology op...
Article

Extrinsic muscles of the tongue

The extrinsic muscles of the tongue are a group of 4 muscles of the tongue. They all arise outside the tongue, which is in comparison to the intrinsic muscles of the tongue which are entirely within the tongue with no external attachments. They act to alter the position of the tongue where as th...
Article

Extrinsic muscles of the tongue (mnemonic)

 The extrinsic muscles of the tongue can be remembered with the following mnemonic: Paris St Germain's Hour Mnemonics Paris St. Germain's Hour P: palatoglossus S: styloglossus G: genioglossus H: hyoglossus
Article

Exudative retinitis

Exudative retinitis (also known as retinal telangiectasis or Coats disease) is a rare congenital disease affecting the eyes and is a cause of leukocoria. Epidemiology The exact aetiology is unknown and the disease is a non hereditary disorder.  It occurs predominantly in young males, with the ...
Article

Eye movements

Eye movements are a complex set of movements of the globe that are performed by the extra-ocular muscles that are grouped by the muscles that perform particular movements: ocular adductors ocular abductors ocular elevators ocular depressors ocular internal rotators ocular external rotators

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