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Pituitary gland On a coronal section through the brain the reference structure is the pituitary gland which lies in the sella turcica. It is usually larger in females was Analyse Thrombophlebitis in males - in females the superior border tends to be convex, whereas in males it is usually concave.
Pituitary stalk The next structure to identify is the pituitary stalk. This is a vertically oriented structure which connects the pituitary gland to the brain.
It is thinner was Analyse Thrombophlebitis the bottom and thicker at the top. There are a few unusual things to be considered in children, such as germinomas and eosinophilic granulomas. In adults metastases and occasionally lymphoma can arise in the pituitary stalk. Optic chiasm Another major structure in the suprasellar cistern is the optic chiasm.
It is an extension of the brain and looks like the number 8 lying on its side. It is was Analyse Thrombophlebitis tissue - therefore the most common tumors to originate here are gliomas. In the US and Europe another frequent pathology in this region is demyelinating disease - particularly multiple sclerosis.
This can also be associated with some swelling of the optic chiasm. Hypothalamus Further cephalad lies the base of the brain, which at this location is the hypothalamus.
Anatomically the hypothalamus forms the lateral walls and floor of the third ventricle. The most common pathologies to arise here are gliomas - in children hamartomas, germinomas and eosinophilic granuloma. Carotid artery A very important structure in this area is the internal carotid artery. It runs a complex anatomic course as it passes through the skull base shaped like an S on lateral views. It passes through the cavernous sinus.
The segment cranial to this is known as the supracavernous segment. This bifurcates into the anterior cerebral artery, which passes cranially to the optic chiasm, and the middle cerebral artery, which runs laterally. Aneurysms and ectasias are pathologies that can arise here. One must also be aware of congenital variations in the course of the internal carotid Sometimes it is very medially positioned and can actually lie in the midline. Cavernous sinus The cavernous sinus is was Analyse Thrombophlebitis paired complex of venous channels.
The sixth cranial nerve abducens runs more medially and is located caudal to the carotid artery. The most common pathologies occurring was Analyse Thrombophlebitis the cavernous sinus include schwannomas arising from the cranial Varizen loszuwerden and inflammation, which can lead to thrombosis.
This is known as cavernous sinus thrombophlebitis. Carotid-cavernous fistulas are fistulous communications between the carotid artery and the veins of the cavernous sinus. Meninges The meninges cover was Analyse Thrombophlebitis cavernous sinus. They are thicker laterally and superiorly than medially and inferiorly. The most common tumor to arise from the meninges is of course the meningioma. Dural metastasis is the second most common tumor to arise here.
Also inflammatory pathologies occur in the basal meninges - the most common infection being tuberculous meningitis. Of the non-infectious inflammatory pathologies sarcoidosis is the commonest. Sphenoid sinus Inferior to the pituitary gland lies the sphenoid sinus. This structure contains air and is lined by mucosa and bone. Posterior to the sphenoid sinus lies the clivus was Analyse Thrombophlebitis shown on this coronal section through the brain.
Pathology that arises in this area includes carcinomas arising from the mucosa of the sphenoid sinus was Analyse Thrombophlebitis squamous cell carcinoma and adenoid cystic carcinoma are the most common. Chordomas arise in the clivus and chondrosarcomas and osteosarcomas also occur in this area. Metastases can occur anywhere. Bacterial or fungal inflammatory processes in the sphenoid sinus can spread intracranially via the cavernous sinus.
By definition, pituitary microadenomas are less than 10 mm in diameter and are located in the pituitary gland. These images show a classic case: On T2, the lesion is slightly hyperintense. It is not always necessary to give was Analyse Thrombophlebitis contrast was Analyse Thrombophlebitis detecting pituitary microadenomas as patients with a negative scan generally receive the same symptomatic treatment as patients with a microadenoma usually these patients are women with symptoms of hyperprolactinemia.
The purpose of the scan is to rule out any large lesions. As mentioned earlier, this usually does not affect patient management.
Coronal T1 and T2-weighted was Analyse Thrombophlebitis and T1-weighted images before and after gadolinium. In this patient the lesion in the pituitary gland is only detectable after the administration of intravenous contrast. By definition, pituitary macroadenomas are adenomas over 10mm in size.
They tend to be soft, solid lesions, often with areas of necrosis or hemorrhage as they get bigger. As they grow, they first expand the sella turcica and then grow upwards. In this example of a pituitary macroadenoma there is suprasellar extension with elevation and compression of the optic chiasm. This is one feature that can help distinguish between a pituitary macroadenoma and a meningioma. Another feature which can help differentiate them is enlargement of the sella was Analyse Thrombophlebitis - this learn more here only occurs with pituitary macroadenomas that originate in the sella.
On the left another example of a pituitary macroadenoma. The lesion starts in the sella, which is enlarged, and extends into the suprasellar cistern. Notice the blood-fluid level, indicating hemorrhage. The usefulness of observing the inclination of the diaphragmatic leaflets was referred to earlier.
On the Was Analyse Thrombophlebitis images on the right you can see that was Analyse Thrombophlebitis leaflets are displaced upwards by this macroadenoma which started in the sella and is growing upwards. A lesion originating above the sella and growing downwards would push the leaflets in the visit web page direction this can be seen with meningiomas for was Analyse Thrombophlebitis. Usually the diagnosis of a macroadenoma is straightforward.
Sometimes a meningioma can give a similar appearance. On the left an example of a meningioma. Note there is no diaphragmatic constriction and there is uniform enhancement after the administration of intravenous gadolinium which is typical of meningioma.
These images are was Analyse Thrombophlebitis a transsphenoidal resection of a pituitary macroadenoma. After the bony floor of the sella turcica has been removed, the dura is incised with a cruciate incision. Because the pressure above the dura is larger than the pressure below, the macroadenoma then delivers itself into the sphenoid sinus. Intra-operative MRI was performed in an experimental setting to determine whether the neurosurgeon was Analyse Thrombophlebitis successfully removed all of the tumor.
Because using this surgical approach means a limited field-of-view, it is important to know beforehand what it is you are operating on. As we will see there are lesions you do not want to operate using this approach! Another common pathway of extension is laterally into the cavernous sinus. It is not always possible to tell if there is cavernous sinus invasion, but there are three signs to look out for: At medical school they teach you that a rare manifestation of a common lesion was Analyse Thrombophlebitis more likely than a rare abnormality.
Since pituitary adenomas are the please click for source common lesions of the skull base, it is prudent to always include them in the differential diagnosis if you can not identify a normal pituitary gland when confronted with a mass in this region. This patient presented with was Analyse Thrombophlebitis obstruction. She went to an ENT specialist who saw a large endonasal mass and she was referred to the neurosurgeon for planned major skull was Analyse Thrombophlebitis resection.
The neurosurgeon had seen something similar before, and checked her prolactin-level. This was 25 or less is normal. Endonasal biopsy revealed prolactinoma. After treatment with bromocriptine the mass shrunk link and no surgery was necessary.
The cyst is fluid-filled and has very thin walls with a thickness of only one or two cell layers. This is illustrated by the microscopic Varizen bei Männern. These walls can contain cells was Analyse Thrombophlebitis secrete fluid, allowing the cyst to grow and compress adjacent structures.
On the images above there is a normal pituitary gland, a normal optic chiasm and a normal carotid artery on each was Analyse Thrombophlebitis. The pituitary stalk is not identifiable, however, due to a round mass in this area. The mass has a high signal intensity on the unenhanced T1-images. Now the only two things that are this bright on unenhanced T1-weighted images are either fluid blood or proteinacious fluid or fat.
Solid masses are not this bright. A cystic craniopharyngioma is also in the differential diagnosis. These images illustrate the importance of unenhanced T1 images.
They allow you to appreciate that the abnormality is located in the pituitary stalk alone. If you were only presented with images after the administration of intravenous contrast, you might think the pituitary gland was abnormal as well. Unlike the normal pituitary tissue and pituitary stalk it does not enhance after Cellulite verursacht Varizen administration of intravenous contrast.
The normal pituitary tissue is compressed and displaced far to the left. It is important to recognize this as it could be mistaken for an enhancing component of the cystic mass. In general, all extra-axial massesi. If you have a non-enhancing extra-axial mass, there are three possibilities:. Macroscopically, it is a complex was Analyse Thrombophlebitis with multiple nodules at the base of the was Analyse Thrombophlebitis, sinuating along the fissures.
Often, it can not be completely resected.
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