Monday, August 31, 2009

Causes of Pituitary Hyperplasia

The pituitary can enlarge physiologically under the following conditions:
  • Hypothyroidism
  • Pregnancy
  • Lactation
Look for a sellar mass that is not separate from the pituitary. In contrast to pituitary adenoma, there is no remodeling of the sella. When in doubt, dynamic contrast-enhanced MRI can resolve the issue. Pituitary hyperplasia will enhance uniformly, while pituitary tumors will have an enhancement pattern different from the rest of the gland.

Sunday, August 30, 2009

Torus Mandibularis and Palatinus

Torus mandibularis is an exostosis of the lingual surface of the mandible above the myohyoid line and opposite the bicuspids. They are bilateral in 80% of cases.

When located along the maxilla, the exostoses are referred to torus palatinus (shown).


Malin Cesarz, MD and Per-Lennart Westesson, MD, PhD, DDS. University of Rochester Medical Center. Neuroradiology Case of the Week: Case 200.

Saturday, August 29, 2009

Multicentric Reticulohistiocytosis

Multicentric reticulohistiocytosis is a rare systemic disorder characterized by cutanenus and mucous nodules and chronic polyarthritis seen most commonly in patients 40 to 50 years of age.

Radiographs reveal marginal erosions principally at the distal interphalangeal joints of the hands that spread centrally. Nodules and cysts are commonly seen at the insertions of the extensor tendons of the fingers.

Differential considerations include:
  • Psoriatic arthritis: Asymmetric distribution, periosteal new bone formation, intraarticular ankylosis, and early involvement of the sacroiliac joints are seen in psoriatic arthritis, but are not typical of multicentric reticulohistiocytosis.
  • Rheumatoid arthritis: Periarticular osteoporosis, thinning of the articular cartilage, and sparing of the distal interphalangeal joints are seen in rheumatoid arthritis, but not typical of multicentric reticulohistiocytosis.
  • Erosive osteoarthritis: Also affects the distal interphalangeal joints of the hands, but the erosions are typically in the central part of the articular surface (gull wing appearance).
  • Gout: Also has skin nodules, but the they are asymmetrically distributed in the periarticular soft tissues, in contrast to the cysts and nodules commonly seen at the insertions of the extensor tendons of the fingers in multicentric reticulohistiocytosis. Erosions in gout occur at or near joints with the typical "over-hanging margins."


Scutellari PN, Orzincolo C, Trotta F. Case report 375: Multicentric reticulohistiocytosis. Skeletal Radiol. 1986;15(5):394-7.

Friday, August 28, 2009

Contents of the Internal Auditory Canal

  • 7.Up = Cranial nerve 7 ("7-up, coke down")
  • BB = The Bill bar
  • Coke = Cochlear nerve ("7-up, coke down")
  • IVN = Inferior vestibular nerve
  • SVN = Superior vestibular nerve
  • TC = Transverse crest

Thursday, August 27, 2009

Central Nervous System Lipomas

Intracranial lipomas are not true tumors, but rather congenital malformations. They are uncommon lesions that tend to involve midline structures, such as the case shown here, which is a lipoma of the tuber cinereum.

80% of central nervous system lipomas are supratentorial, with up to 50% of these occurring at the interhemispheric fissure, 20% suprasellar, and 15% in the pineal region. The 20% that are infratentorial involve the cerebellopontine angle, jugular foramen, and foramen magnum.

On CT, they demonstrate fat attenuation, may have calcifications, and do not enhance. They're hyperintense on T1-weighted (A) images and drop out on fat suppressed images (D). On standard spin echo T2 images, they're hypointense with chemical shift artifact. On fast spin echo T2 images, they are iso- to hyperintense (B) and intermediate signal on proton density images. These lesions do not enhance.


Saleem SN, Said AH, Lee DH. Lesions of the hypothalamus: MR imaging diagnostic features. Radiographics. 2007 Jul-Aug;27(4):1087-108.

Wednesday, August 26, 2009


Gangliogliomas are the most common mixed glioneural tumors of the CNS and most commonly present with seizures. About 40% occur in the temporal lobe, followed by the parietal (30%) and frontal (20%) lobes. They can also be found in the anterior third ventricle, cerebellum, spinal cord, and optic nerves.


On CT, they may be hypo (40%) mixed cystic and nodular (30%), isodense (15%), or hyperdense (15%). Mass effect is variable, and there is generally no edema. Up to 50% have calcifications and about 50% demonstrate faint enhancement.

They are hypo- to isointense on T1-weighted images. Solid enhancing components are usually seen (A and B). Calcifications will be hyperintense to gray matter. The solid and cystic parts will be high signal on T2-weighted images (C). No significant peritumoral edema is seen (FLAIR, D).


The glial portion of a ganglioglioma defines its aggressiveness, and degeneration of the glial component may lead to an anaplastic ganglioglioma.

A desmoplastic infantile ganglioglioma (DIG) is a variant of ganglioglioma that is usually seen in the first 2 years of life. Like the regular ganglioglioma, it is a low-grade tumor with good prognosis. As opposed to the standard ganglioglioma, however, DIGs are more commonly seen in the frontal and parietal lobes. Imaging features may be identical to pilocytic astrocytomas: A large cyst with a peripheral (cortical) enhancing nodule. Some may also have a calcified rim.


Neuroradiology: The Requisites. Second ed. pp 136-138.

Tuesday, August 25, 2009

Wandering Spleen

A wandering spleen is one that is found in a location other than the left upper quadrant. This wandering ability may be due to congenital absence of the ligaments that tether the spleen in place, with the lienorenal ligament being the most important. Hormonally induced laxity of ligaments (e.g., during pregnancy) can also allow the spleen to wander off.

Patients may be asymptomatic, present with chronic abdominal pain (presumably from recurrent torsion), or acute abdominal pain. The dreaded complication of wandering spleen is torsion around its vessels, resulting in infarction.


Romero JR, Barksdale EM Jr. Wandering spleen: a rare cause of abdominal pain. Pediatr Emerg Care. 2003 Dec;19(6):412-4

Monday, August 24, 2009

Right Upper Quadrant Abdominal Calcifications in a Neonate

Differential diagnosis for right right upper quadrant abdominal calcifications in a neonate include:
  • TORCH infections
  • Meconium peritonitis
  • Fetal gallstones
  • Neuroblastoma metastasis
  • Infarction
  • Hepatoblastoma
  • Regressing hemangioma
  • Hemangioma
  • Hamartoma
  • Teratoma
  • Ruptured hydrometrocolpos
  • Calcified thrombus in portal vein or inferior vena cava

Sunday, August 23, 2009

Circumcaval Ureter

A circumcaval ureter in one that develops normally, but, due to the anomalous development of the inferior vena cava, ends up travelling posterior to the inferior vena cava and then travels around the medial border anteriorly to partially encircle the inferior vena cava. Patients may be asymptomatic or present with symptoms of ureteral obstruction.

The normal infrarenal inferior vena cava derives from the supracardinal vein, which is posterior to the ureter. A circumcaval inferior vena cava derives from the subcardinal or postcardinal veins, which are anterior to the ureter.

This should be differentiated from the normal oblique impression from the crossing iliac vessels, which occurs at the level of L5 or S1. Adenopathy, retroperitoneal fibrosis, or pelvic lipomatosis may also be considered in the differential.

A circumcaval ureter can be associated with horseshoe kidney, Turner syndrome, and double vena cava.


Lautin EM, Haramati N, Frager D, Friedman AC, Gold K, Kurtz A, Self J. CT diagnosis of circumcaval ureter. AJR Am J Roentgenol. 1988 Mar;150(3):591-4.

Saturday, August 22, 2009

Anatomy of the Temporomandibular Joint

The mandibular condyle is centered on the glenoid fossa when the mouth is closed. When the mouth is open, the condyle moves anteriorly under the center of the articular eminence.

The disc has anterior (A) and posterior (P) bands. The thinner central portion is called the intermediate zone (iz). The posterior band is normally located directly on top of the condyle (C) when the mouth is closed. The intermediate zone should be between the condyle and the closest portion of the temporal bone in any mouth position. The disc is low signal on all MR sequences, but you may be able to see intermediate signal centrally in the anterior and posterior bands.

The posterior aspect of the disc attaches to the bilaminar zone, collagen fibers that pull the disc back when it moves forward.


Helms CA, et al. Musculoskeletal MRI. Second edition. pp 172-173.

Friday, August 21, 2009

Tendons without Sheaths

Some notable examples of sheathless tendons:
  • Achilles: Surrounded by peritenos around 2/3 of its diameter, predominantly posteriorly. A dilated vein posterior to the Achilles tendon can mimic peritendinitis.
  • The distal biceps tendon:
  • Supraspinatus tendon:
  • Patellar tendon:
  • Proximal gastrocnemius tendon:
  • Semimembranous tendon:

Thursday, August 20, 2009

Foramen Cecum

The foramen cecum is a small hole anterior to the crista galli along the midline. It carries an emissary vein from the nasal mucosa to the superior sagittal sinus. It becomes important in infections of the nasal cavity and danger triangle of the face, which can spread to the meninges via the foramen cecum.

Wednesday, August 19, 2009

High Signal in Tendons

High signal may be seen in normal tendons:
  • Quadriceps and distal triceps tendons: Longitudinal striations with intermediate signal
  • Midsubstance of Achilles tendon: Thought to represent the apposition of the soleus and gastrocnemius tendons.
  • At osseous insertions, where tendon fibers fan out
  • Magic angle artifact (~55 degrees)
Abnormalities associated with high signal in tendons:
  • Myxoid degeneration (often coexist with partial tears)
  • Partial or complete tear
  • Xanthoma
  • Gout
  • Tumor


Helms et al. Musculoskeletal MRI. Second edition. p 51.

Monday, August 17, 2009

Focal Cortical Dysplasia

Focal cortical dysplasia (FCD) is a type of malformation caused by abnormalities of cortical development and one of the most common causes of intractable epilepsy in children. Other malformations of cortical development include pachygyria, polymicrogyria, and hemimegalencephaly, all of which, unlike focal cortical dysplasia, are associated with diffuse abnormal gyration.

Histopathological Subtypes

Two types of focal cortical dysplasia have been described based on histopathology. Type I demonstrates dyslamination of the cortical layer on pathology, without dysmporphic neurons or balloon cells. Type IA FCD demonstrates dyslamination (architectural abnormalities), with or without neuronal ectopia. Type IB demonstrates dyslamination plus giant or immature neurons. Patients with type I FCD may or may not have epilepsy. Some may have learning or other cognitive disorders. Patients with Type I FCD who have epilepsy, tend to do better following resection.

Type II (Taylor type) FCD has the dyslamination of type I plus dysmorphic neurons, without or with balloon cells. Type IIA FCD does not have balloon cells, while type IIB does. Balloon cells are large cells that can't decide whether they're neurons or astrocytes. They can be seen in tuberous sclerosis, leading some people to hypothesize that type IIB FCD is a forme fruste of tuberous sclerosis


MRI findings can be subtle. It is unclear whether type I FCD can be detected on MRI. In addition, not all type II FCDs are detectable on MRI. Findings on MRI may include
  • Focal areas of increased cortical thickness
  • Blurring of the gray-white junction
  • Increased signal on T2-weighted, PD, or FLAIR images (more likely in balloon cell FCD)
  • Extension of cortical tissue with increased signal from the surface to the ventricle (transmantle dysplasia)


  • Palmini A, Najm I, Avanzini G, Babb T, Guerrini R, Foldvary-Schaefer N, Jackson G, Lüders HO, Prayson R, Spreafico R, Vinters HV. Terminology and classification of the cortical dysplasias. Neurology. 2004 Mar 23;62(6 Suppl 3):S2-8.
  • Rastogi S, Lee C, Salamon N. Neuroimaging in pediatric epilepsy: a multimodality approach. Radiographics. 2008 Jul-Aug;28(4):1079-95.


Laryngoceles result from elongation and dilatation of the laryngeal saccules, and often form due to benign or malignant obstruction of the neck of the saccule.

Laryngoceles are divided into internal and external based on their course. An internal laryngocele extends superiorly along the paraglottic space and is confined by the thyrohyoid membrane. An external laryngocele extends through the thyrohyoid membrane into the soft tissues of the neck. Since an external laryngocele also has an internal component, some people call it a mixed laryngocele.

Sunday, August 16, 2009

En-Plaque Meningioma

An en plaque meningioma is a meningioma that grows as a film over the dura without poking into the adjacent brain or spinal cord. Like standard meningiomas, it can cause hyperostosis; however, hyperostosis caused by an en plaque meningioma is more pronounced.

The case shown here actually ended up being a dural lymphoma that was mimicking an en plaque meningioma. Tuberculosis can also have a similar appearance. There is also a report of neurosarcoidosis mimicking en-plaque meningioma.


  • Ozek E, Iplkcioglu AC, Erdal M. Intradural extramedullary tuberculoma mimicking en plaque meningioma. Neurol India. 2009 Mar-Apr;57(2):211-2.
  • Osenbach RK, Blumenkopf B, Ramirez H Jr, Gutierrez J. Meningeal neurosarcoidosis mimicking convexity en-plaque meningioma. Surg Neurol. 1986 Oct;26(4):387-90.

Saturday, August 15, 2009

Cystic Brain Masses

Differential Diagnosis:
  • Non-Neoplastic
    • Exactly follows CSF signal: Enlarged perivascular space, encephalomalacia, porencephalic cyst, neuroglial cyst.
    • Infection: Neurocysticercosis, abscess
    • Resolving hematoma: May have peripheral enhancement in the subacute phase
    • Multiple sclerosis
    • Epidermoid/dermoid cyst
  • Neoplastic
    • Ganglioglioma: Well-circumscribed cystic lesion with nodule and minimal edema.
    • DNET: Look for "bubbly" appearance on MRI
    • Pleomorphic Xanthoastrocytoma: Look for a cortically based nodule
    • Pilocytic astrocytoma: Well-circumscribed cystic lesion with nodule and minimal edema. Most commonly seen in children and in the cerebellum.
    • Hemangioblastoma: Posterior fossa mass.
    • Glioblastoma multiforme
    • Metastases
    • Cystic meningioma
    • Ependymoma

Friday, August 14, 2009

Laryngeal Ventricle and Saccule, and Laryngocele

The laryngeal saccule, also known as an appendix of the laryngeal ventricle, is a sac that arises from the superior border of the laryngeal ventricle and is bounded medially by the false vocal folds and laterally by the thyreoepiglotticus muscle and the thyroid cartilage.

The surface of the saccules contains up to 70 mucous glands. The squeezing action of the thyreoepiglotticus muscle releases the contents of the saccules into the ventricle.

Laryngoceles are abnormal cystic dilatations of the laryngeal saccules. Internal laryngoceles are within the larynx and do not cross the thyrohyoid membrane. External laryngoceles penetrate the thyrohyoid membrane.


Koeller KK, Alamo L, Adair CF, Smirniotopoulos JG. Congenital cystic masses of the neck: radiologic-pathologic correlation. Radiographics. 1999 Jan-Feb;19(1):121-46.

Wednesday, August 12, 2009

Hyperintense Subarachnoid Space on FLAIR

Increased FLAIR signal may be seen in the subarachnoid space in conditions other than subarachnoid hemorrhage. Differential diagnosis:
  • Acute subarachnoid hemorrhage
  • Meningitis
  • Susceptibility artifact
  • High levels of inspired oxygen (e.g., in sedated kids)
  • Meningeal metastases
  • Leaky blood-brain barrier from cerebritis, PRES
  • Delayed gadolinium clearance in renal failure
  • Acute infarction (thought to be related to slow flow)
  • Ruptured dermoid Cyst
  • Moyamoya

Enhancement Patterns of Primary CNS Lymphoma

Primary CNS lymphoma demonstrates different enhancement patterns depending on the immune status of the patient. In immunocompetent patients, there is strong, homogeneous enhancement. In immunocompromised patients, on the other hand, there is peripheral enhancement with central necrosis, although homogeneous enhancement may also be seen.

Tuesday, August 11, 2009

Calcific Tendinitis of the Longus Colli Muscle

Calcific tendinitis of the longus colli muscle, also known as acute retropharyngeal calcific tendinitis and calcific prevertebral tendinitis, is an inflammatory/granulomatous response to deposition of calcium hydroxyapatite crystals in the tendons of the longus colli muscle.

Calcifications may be seen on radiographs, but the preferred imaging modality is contrast-enhanced CT. On CT, amorphous calcifications are seen in the superior fibers of the longus colli muscle tendons (at the C1–C2 level). Small retropharyngeal effusions and edema of the adjacent prevertebral soft tissues may also be seen. Enhancement around the effusion should shift the diagnosis towards an abscess. Adenopathy and bone destruction, likewise, should suggest alternative diagnoses.

MRI will show the edema, but is not as great with the calcifications. At least one case of localized marrow signal inflammatory has been reported.

Patients may present with debilitating symptoms that are unrelated to the degree of calcification seen on CT. Conservative management with NSAIDs is generally all that is needed, and symptoms resolve within a few weeks.

The patient in the case shown here presented with throat and neck pain for 2 days. She was unable to straighten her neck from the neutral position and had pain on turning her head and swallowing liquids or solids. She reported no fever, chills, or weight loss.

The images show (A) A small calcification anterior to the C4 vertebral body on the radiograph (arrow). (B) The amorphous calcification is better evaluated on the CT (arrow). Sagittal STIR (C) and coronal T2-weighted (D) images show edema anterior to the longus colli muscle.


  • Offiah CE and Hall E. Acute calcific tendinitis of the longus colli muscle: spectrum of CT appearances and anatomical correlation. Br J Radiol. 2009 Jun;82(978):e117-21.
  • Mihmanli I, Karaarslan E, Kanberoglu K. Inflammation of vertebral bone associated with acute calcific tendonitis of the longus colli muscle. Neuroradiology 2001;43:1098–101

Monday, August 10, 2009

Pellegrini-Stieda Disease

Pellegrini-Stieda Disease is post-traumatic ossification in or near the medial collateral ligament near the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femoral condyle).


Hunter TB, et al. Musculoskeletal Eponyms: Who Are Those Guys? RadioGraphics. 2000(20); 819-836.

Sunday, August 9, 2009

Dysembryoplastic Neuroepithelial Tumor (DNET)

Dysembryoplastic neuroepithelial tumors (DNETs) are benign lesions found in young people with a history of partial, drug-resistant seizures without progressive neurologic deficit (either no neurologic deficit or stable deficit).

DNETs most commonly occur in the temporal lobe (>50%), followed by the frontal lobe (~30%). There are also reports of DNETs along the septum pellucidum.

DNETs are cortically located and usually wedge-shaped and may scallop the inner table of the skull. They demonstrate low signal on T1-weighted images (A) and high signal on T2-weighted images (B). The typical appearance is described as "bubbly" (multinodular or septated).

There may be a bright rim on FLAIR (D), but no surrounding edema or mass effect is seen. Hemorrhage is uncommon (See GRE, image C), but when it does occur, mass effect and edema may be present. Less than 1/3 enhance. About 1/3 demonstrate calcifications. The case shown here does not enhance (E and F).

Differential considerations include Taylor dysplasia, neuroepithelial cyst, and pleomorphic xanthoastrocytoma.


  • Fernandez C et al. The usefulness of MR imaging in the diagnosis of dysembryoplastic neuroepithelial tumor in children: a study of 14 cases. AJNR Am J Neuroradiol. 24(5):829-34, 2003.
  • The Requisites: Neuroradiology. Second edition, p 139.

Saturday, August 8, 2009

Danger Space

The danger space of the neck is a potential space directly posterior to the retropharyngeal space and anterior to the vertebral bodies. Its danger lies in its ability to allow the spread of retropharyngeal infections into the mediastinum. The retropharyngeal space communicates with the danger space via the fascial trap door at around the T3 level.

Friday, August 7, 2009

Stenosing Tenosynovitis

Stenosing tenosynovitis refers to the adhesion of the tendon to its tendon sheath. MRI and ultrasound may show loculated tendon sheath fluid. Ultrasound may show fixation of the tendon and sheath.

De Quervain disease is a stenosing tenosynovitis of the first dorsal wrist compartment. The extensor pollicis brevis tendons is most commonly involved, but the abductor pollicis longus tendon can also be involved.

Patients with os trigonum syndrome commonly have stenosing tenosynovitis of the flexor hallucis longus tendon.

Thursday, August 6, 2009

Special Names of the Ethmoid Air Cells

Agger nasi cells are the most anterior ethmoid air cells and are located within the lacrimal bone. They are located anterior, lateral, and inferior to the frontoethmoidal recess and anterior and above the attachement of the middle turbinate.

Haller cells refer to ethmoid air cells that are located along the inferolateral margin of the orbit and protrude into the maxillary sinus. If they get too big, they can block the drainage pathway of the maxillary sinus.

Ethmoidal bulla refers to the largest ethmoid air cell, located above and behind the infundibulum and hiatus semilunaris. If it gets too big, it can block the drainage pathway of the maxillary sinus and result in the infundibular pattern of sinus disease.

Onodi (sphenoethmoid) cells are the posteriormost ethmoidal air cells that pneumatize into the sphenoid bone superior to the sphenoid sinus. The image shows a left Onodi cell (white arrows) above the left spenoid sinus (pink arrow). The right sphenoid sinus is indicated by the blue arrow. They can be intimately associated with the optic nerve (most common, green arrow) and internal carotid artery (less common). The anterior clinoid process may be pneumatized via Onodi cells (not so in this case). Onodi cells are important in sinus surgery. In a transsphenoidal approach, an Onodi cell can be entered under, resulting in damage the optic nerve or internal carotid artery.


Kantarci M, Karasen RM, Alper F, Onbas O, Okur A, Karaman A. Remarkable anatomic variations in paranasal sinus region and their clinical importance. Eur J Radiol. 2004 Jun;50(3):296-302.

Wednesday, August 5, 2009

Neoplasms Associated with the Neurocutaneous Syndromes

Neurofibromatosis 1
  • Low-grade optic nerve pilocytic glioma
  • Increased risk of multicentric gliomas
  • Neurofibrosarcomas (malignant degeneration of neurofibromas).
  • Leukemia, lymphoma
  • Medullary thyroid carcinoma
  • Pheochromocytoma
  • Melanoma
  • Wilms tumor
Neurofibromatosis 2: MISME (Multiple Inherited Schwannomas, Meningioma, and Ependymoma)
  • Schwannomas: CN 8 > CN V > spinal canal
  • Spinal ependymomas
  • Meningiomas
von Hippel-Lindau
  • Hemangioblastomas: Cerebellum > Retina > Brainstem
  • Renal cell carcinoma (more commonly bilateral and smaller than sporadic form)
  • Pheochromocytoma
  • Angiomas: leptomeninges and skin of the face
Tuberous Sclerosis
  • Angiomyolipomas
  • Subependymal nodules may degenerate to subependymal giant-cell astrocytomas (SEGA)
  • Cardiac rhabdomyomas

Tuesday, August 4, 2009

Foramen Rotundum and the Vidian Canal

The vidan canal (blue) and foramen rotundum (red) are openings in the greater wing of the sphenoid that connect the pterygopalatine fossa to the middle cranial fossa.

The V2 nerve passes through the foramen rotundum, while the vidian nerve passes through the vidian canal. The vidian nerve is formed by greater superficial and deep petrosal nerves and contains sensory fibers from cranial nerve 7, which supply the soft palate.

Monday, August 3, 2009

Pterygopalatine Fossa

The pterygopalatine fossa (PPF) is a groove between the maxillary bone anteriorly and the pterygoid process posteriorly. Its anteromedial border is the perpendicular plate of the palatine bone.

The pterygopalatine fossa is an important pathway for the spread of neoplastic and infectious processes.
  • Laterally: The PPF (red) communicates with the masticator space via the pterygomaxillary fissure (yellow).
  • Anteriorly: The PPF communicates with the orbit via the inferior orbital fissure.
  • Medially: The PPF communicates with the posterior nasal fossa via the sphenopalatine foramen (purple).
  • Posteriorly and superiorly: The PPF communicates with the Meckel cave and cavernous sinus via the foramen rotundum (green).
  • Posteriorly and inferiorly: The PPF communicates with the middle cranial fossa via the vidian canal (orange).
  • Inferiorly: The PPF communicates with the palate via the greater and lesser palatine foramina.
A tumor that characteristically spreads via the PPF is the juvenile angiofibroma. This tumor may originate in the posterolateral wall of the nasal cavity, where it reaches the PPF through the sphenopalatine foramen. From there, the tumor spreads through the pterygomaxillary fissure into the infratemporal fossa (the part of the masticator space below the level of the zygomatic arch).

The PPF contains the pterygopalatine ganglion, the descending palatine artery (branch of the maxillary artery), V2, and the nerve of the pterygoid canal.

Masses of the PPF include,
  • Juvenile angiofibroma
  • Invasive tumors
  • Meningioma of sphenoid wing or nasal fossa
  • Metastasis
  • Fracture of pterygoid plates


Sunday, August 2, 2009

Tarlov Cyst

Tarlov (perineurial) cysts are outpouchings of the arachnoid and, unlike meningeal cysts, at least part of their wall contains nerve fibers. CSF flows into the space between the endoneurium (extension of the pia mater) and perineurium (extension of the arachnoid mater) under pulsation, and gets trapped via a ball-valve phenomenon. They are most commonly found at the sacral (S2 and S3) nerve roots, where they can be associated with bone erosion, and can rarely cause sciatica.

Differential considerations include meningocele, arachnoid cyst, neurofibroma, and dural ectasia.


  • IM Tarlov, Spinal perineural and meningeal cysts. J Neurol Neurosurg Psychiatry 33 (1970), pp. 833–843.
  • Neuroradiology: The Requisites. Second edition. pp806-807.

Saturday, August 1, 2009

Submandibular Gland Sialolithiasis

Calculous disease of the submandibular gland is four times more common than that of the parotid gland. About 70% of submandibular gland calculi are radiopaque.

It is thought that the higher pH and viscosity of the submandibular gland secretions, and the fact that the saliva has to travel uphill to get excreted contribute to the higher incidence of sialolithiasis in the submandibular gland .

The workup for suspected calculous disease of salivary glands (painful glands worsened by chewing) begins with radiographs. If a radiopaque calculus is not found, then CT may be obtained. MR sialography (analogous to MRCP) is >90% accurate for the detection of sialolithiasis.

Sialadenitis is inflammation of the gland and is often associated with ductal ectasia (sialectasis) and most often caused by sialolithiasis. Microabscesses may be seen with sialectasis and/or sialadenitis. Sialodochitis is the inflammation of the ductal system.

Sialadenitis with sialodochitis without other systemic symptoms is referred to as Sjögren type I (also known as Mikulicz disease). When sialadenitis with sialodochitis are associated with a collagen vascular disease, it's referred to as Sjögren type II.

Because people with Sjögren disease are ten times more likely to develop lymphoma, make sure to look closely at the rest of the neck for lymph nodes. The lymphoma may also develop in the salivary glands themselves, so look closely at the glands for signs of lymphoma.


Neuroradiology: The Requisites. Second edition. pp 700-703.