Items tagged “refs”

2,938 results found
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Nutmeg liver

A nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of hepatic venous congestion. When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner. This results in a mottled pattern of contrast enhancement in the a...
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Oculomotor nerve palsy

Oculomotor nerve palsies, or third nerve palsies, result in weakness of the muscles supplied by the oculomotor nerve, namely the superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris muscles. Terminology If the pupil is normal sized and reactive to...
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Odontogenic myxoma

Odontogenic myxomas are rare tumors that involve the mandible or maxilla and account for 3-6% of odontogenic tumors 2. Epidemiology Typically seen in the 2nd to 3rd decades of life (slightly earlier than ameloblastomas). They are usually not painful. Pathology Arises from mesenchymal odontog...
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Odontoma

Odontomas are one of the most common mandibular lesions encountered and the most common odontogenic tumors of the mandible. They account for up to two-thirds of all such tumors; the next most common are ameloblastomas, making up the majority of the remaining one-third. Epidemiology They can oc...
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Olfactory nerve

The olfactory nerve is the first (CN I) cranial nerve (TA: nervus olfactorius or nervus cranialis I) and is responsible for conveying the sense of smell from the nasal cavity to the brain. Along with the optic nerve, it is actually a peripheral extension of the central nervous system.  Summary ...
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Middle ear ossicles

There are three tiny articulating bones in the middle ear known as ossicles (from lateral to medial): malleus incus stapes Their role is to mechanically amplify the vibrations of the tympanic membrane and transmit them to the cochlea where they can be interpreted as sound. They are located i...
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Otomastoiditis

Otomastoiditis, or more simply inflammation of the mastoid air cells, can be divided into two distinct entities: acute otomastoiditis: usually due to bacterial infection chronic otomastoiditis: usually due to Eustachian tube dysfunction
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Posterior cerebral artery (PCA) infarct

Posterior cerebral artery (PCA) infarcts arise, as the name says, from occlusion of the posterior cerebral artery. It is a type of posterior circulation infarction. Epidemiology Posterior cerebral artery strokes are believed to comprise approximately 5-10% of ischemic strokes 6. Clinical pres...
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Avascular necrosis causes (mnemonic)

Mnemonics for the causes of avascular necrosis (AVN) or more correctly osteonecrosis: STARS PLASTIC RAGS ASEPTIC Mnemonics STARS Most common causes: S: steroids, SLE T: trauma (e.g. femoral neck fracture, hip dislocation, scaphoid fracture, slipped capital femoral epiphysis 2) A: alcoho...
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Patellar tendon rupture

Patellar tendon rupture is one of the extensor mechanism of the knee injuries and occurs almost invariably at either the patellar or tibial insertion of the patellar tendon, when in the setting of trauma, and is often associated with a small avulsion fracture. Most commonly, it is at the superi...
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Persistent primitive trigeminal artery

Persistent primitive trigeminal artery (PPTA) is one of the persistent carotid-vertebrobasilar anastomoses. It is present in 0.1-0.6% of cerebral angiograms and is usually unilateral. In utero, the trigeminal artery supplies the basilar artery before the development of the posterior communicati...
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Pine cone bladder

A pine cone bladder or Christmas tree bladder is a cystographic appearance in which the bladder is elongated and pointed with a thickened, trabeculated wall. It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesion...
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Pituitary stalk

The pituitary stalk, also known as the infundibulum or infundibular stalk, is largely outside the blood brain barrier like the rest of the pituitary and therefore normally enhances following the administration of gadolinium. It gradually tapers inferiorly, and superiorly is spread by the infundi...
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Pituitary stalk abnormal enhancement (differential)

Abnormal nodular enhancement of the pituitary stalk can be seen in a number of entities. Differential diagnosis tumors germinoma craniopharyngioma hypothalamic glioma pituitary lymphoma pituicytoma granular cell tumor of the pituitary (pituitary choristoma) pilocytic astrocytoma of the...
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Pneumatized dorsum sella

Pneumatization of the dorsum sella is not uncommon, but needs to be remembered as an unusual site of sinus disease, which otherwise may be mistaken for intracranial of pituitary disease.
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Portal hypertensive gastroenterocolopathy

Portal hypertensive gastroenterocolopathy is a finding in portal hypertension, whereby chronic portal venous congestion leads to dilatation and ectasia of the submucosal vessels of the stomach (portal hypertensive gastropathy), small bowel (portal hypertensive enteropathy) and/or large bowel (po...
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Pregnancy-related osteonecrosis

Pregnancy-related osteonecrosis, also known as pregnancy-related avascular necrosis, is a common cause of femoral head osteonecrosis. Since the femoral head is deficient in blood supply, it is particularly vulnerable to osteonecrosis. Pathology The pathophysiology is thought to be due to venou...
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Pulmonary edema grading

One pulmonary edema grading based on chest radiograph appearances and pulmonary capillary wedge pressure (PCWP) is as follows: grade 0: normal chest radiograph, PCWP 8-12 mmHg grade 1: shows evidence of upper lobe diversion on a chest radiograph, PCWP 13-18 mmHg grade 2: shows interstitial ed...
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Quadriceps tendon

The quadriceps tendon is a thick tendon extending to the patella made up of contributions from all four quadriceps muscles. It classically has a trilaminar structure: superficial layer: rectus femoris middle layer: vastus medialis, vastus lateralis deep layer: vastus intermedius It continues...
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Racing car sign (callosal dysgenesis)

The racing car sign refers to widely spaced lateral ventricles due to agenesis of the corpus callosum with intervening Probst bundles. Appearances on axial MRI or CT are reminiscent of a Formula One car seen from above, with the tyres represented by the widely-spaced frontal horns, and the dilat...