Hypoglossal artery = not always present. Sometimes, can have a small emissary vein that runs through here that can protrude into the cerebellomedullary cistern and mimic a nerve sheath tumor. |~|/files/powerpoints_images/node267549/Slide7.JPG|~|563|~|422|~|0
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Hypoglossal artery = not always present. Sometimes, can have a small ...
2 parts separated by the jugular spur.: (a) Pars nervosa = anteromedial; (b) Pars vascularis (also known as pars venosa) = posterolateral. Pars nervosa: glossopharyngeal nerve, inferior petrosal sinus - runs along petrooccipital fissure. Pars vascularis: vagus and spinal accessory nerve. Jugular bulb: confluence b/w sigmoid sinus and internal jugular vein|~|/files/powerpoints_images/node267549/Slide8.JPG|~|563|~|422|~|0
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2 parts separated by the jugular spur.: (a) Pars nervosa = anteromedi...
Foramen Spinosum V3 recurrent = mandibular branch. Emissary veins in Foramen Spinosum and Foramen Ovale connect cavernous sinus with pterygoid plexus of veins = path for nasaopharyngeal tumors. Foramen of vesalius - inconstant. Anterior and medial to foramen ovale. |~|/files/powerpoints_images/node267549/Slide9.JPG|~|563|~|422|~|0
Pterygopalatine Fossa = conduit for spread of tumor and infection.|~|/files/powerpoints_images/node267549/Slide12.JPG|~|563|~|422|~|0
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Pterygopalatine Fossa = conduit for spread of tumor and infection.
Pterygopalatine Fossa – foramen rotundum = connection with Meckel’s cave, cavernous sinus, since we have mentioned it a few times now and because it contains a lot of key elements: Cavernous sinus. V2- lateral wall of Cavernous sinus - then to foramen rotundum. V1- lateral wall of cavernous sinus - then to superior orbital fissure, along with Cranial nerves III, IV, VI.|~|/files/powerpoints_images/node267549/Slide13.JPG|~|563|~|422|~|0
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Pterygopalatine Fossa – foramen rotundum = connection with Meckel...
(a) Chordomas like the clivus. (b) Chondrosarcomas like the cartilaginous endplates- petrooccipital suture. (c) Glomus tumors like the jugular bulb, middle ear, carotid body. (d) Meningiomas: most common (20% of all brain tumors). But most = cerebral convexity, along and lateral to the falx. 10% clivus; 20% sphenoid ridge. (e) Schwannomas almost always develop from sensory nerves. Because the olfactory and optic nerves do not have a Schwann cell layer, they do not develop these tumors. The most common intracranial schwannoma = acoustic neuroma- it develops from the vestibular nerve. Bilateral acoustic neuromas = pathogomonic for NF2. (90% of the time, schwannomas are solitary). The second most common intracranial schwannomas develop from the trigeminal nerve. Trigeminal schwannomas usually arise from the root or ganglion and occupy the middle fossa and, sometimes, the posterior fossa. Schwannomas of the other cranial nerves are rare. |~|/files/powerpoints_images/node267549/Slide16.JPG|~|563|~|422|~|0
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(a) Chordomas like the clivus. (b) Chondrosarcomas like the cartilagi...
T1 post contrast MR showing extraaxial lesion arising from the middle cranial fossa. Heterogeneous enhancement. Low signal areas = flow voids or calcifications. Coronal = involvement with skull base. Mass effect on temporal lobe.|~|/files/powerpoints_images/node267549/Slide17.JPG|~|563|~|422|~|0
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T1 post contrast MR showing extraaxial lesion arising from the middle...
(a) Chondrosarcomas can occur anywhere in the skeletal system. Often = preexisting cartilaginous lesion like previously benign osteochondroma. In skull base = usually at cartilage endplates. E.g. petrooccipital suture. (b) Clinical: Most commonly, patients are diagnosed with chondrosarcomas during the third or fourth decade of life. Males are affected more often than females. Chondrosarcomas can be divided into classic, mesenchymal, and dedifferentiated tumors. (c) Mesenchymal, Dedifferentiated = high grade. Classic low grade = like chordoma. (d) Differential diagnosis: Chordoma- usually has marked bone destruction, midline (clivus); Chondrosarcoma = significant soft tissue component, little bone destruction, arcs/nodules of calcification, eccentric locations- often centered in framen lacerum.|~|/files/powerpoints_images/node267549/Slide19.JPG|~|563|~|422|~|0
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(a) Chondrosarcomas can occur anywhere in the skeletal system. Often...
Sagittal T1-weighted MR image shows a large, hypointense soft-tissue mass that arises from the distal clivus with anterior extension into the nasopharynx (arrows) and extradural extension into the posterior fossa (arrowhead).|~|/files/powerpoints_images/node267549/Slide20.JPG|~|563|~|422|~|0
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Sagittal T1-weighted MR image shows a large, hypointense soft-tissue ...
CT to assess degree of bone involvement. MRI to evaluate extension of tumor.CT Findings:The most characteristic appearance of intracranial chordoma is of a centrally located homogeneous soft tissue mass arising from the clivus and causing adjacent bone destruction. Calcification is common but variable. Areas of low attenuation within the soft tissue mass occasionally are found on CT, representing the myxoid and gelatinous material found on pathologic examination. CT reliably demonstrates petrous apex involvement and lysis of the skull base foramina.|~|/files/powerpoints_images/node267549/Slide21.JPG|~|563|~|422|~|0
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CT to assess degree of bone involvement. MRI to evaluate extension o...
Contrast enhanced T1 spin echo image. Chordoma of the upper part of the clivus with posterior extension into the pontine cistern. Chordomas = benign tumor but has significant problems b/c of location, local invasion, recurrence. Origin: Notochord = early fetal axial skeleton. Gets surrounded by cartilage. Cartilage ossifies and notochord = squeezed out into intervertebral regions = nucleus pulposus of intervertebral disks. Can get remnants then, along any position of the neural axis- turn into chordomas.Location: read slide. Rare. <0.2% of all intracranial tumors.CN deficits: HA, dysphagia, facial pain, facial paresis, visual loss, hearing loss, and ataxia. CT to assess degree of bone involvement. MRI to evaluate extension of tumor. CT Findings:The most characteristic appearance of intracranial chordoma is of a centrally located homogeneous soft tissue mass arising from the clivus and causing adjacent bone destruction. Calcification is common but variable. Areas of low attenuation within the soft tissue mass occasionally are found on CT, representing the myxoid and gelatinous material found on pathologic examination. CT reliably demonstrates petrous apex involvement and lysis of the skull base foramina. MRI Findings: Mass originating from midline with extension primarily in the anteroposterior axis rather than laterally. Well delineated. Expands bone in the early stage = indicator that it arises from bone, not from adjacent tructures. Post gad = lobulated area, heterogeneous on T1 and T2 b/c of mucinous and gelatinous contents. |~|/files/powerpoints_images/node267549/Slide22.JPG|~|563|~|422|~|0
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Contrast enhanced T1 spin echo image. Chordoma of the upper part of ...
CT imaging demonstrates the extent of bony destruction (white and black arrows) by the tumor. The normal jugular foramen on the left (arrow head) is shown for comparison. |~|/files/powerpoints_images/node267549/Slide23.JPG|~|563|~|422|~|0
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CT imaging demonstrates the extent of bony destruction (white and bla...
Salt and pepper: multiple low signal intensity areas = flow voids in tumor. When large: erode bone.|~|/files/powerpoints_images/node267549/Slide24.JPG|~|563|~|422|~|0
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Salt and pepper: multiple low signal intensity areas = flow voids in ...
Glomus tumors arise from chemoreceptor cells.These tumors are slow-growing hypervascular tumors that usually occur in the temporal bone. Location: read slide- check other places for them b/c = multiple. E.g. Carotid bodyPatients usually present with gradual hearing loss, unilateral pulsatile tinnitus, and lower cranial nerve palsies. Approximately 1-3% of gangliogliomas produce catecholamines, so can get arrythmia, BP fluctuation. May be locally invasive but rarely metastasize.|~|/files/powerpoints_images/node267549/Slide25.JPG|~|563|~|422|~|0
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Glomus tumors arise from chemoreceptor cells.These tumors are slow-gr...
Brief Description