[Music] all right can you guys see my main presentation again looks good all right thanks again okay so now um let me check that there's some questions and we'll move on to uh talk about some tumors here all right so what are some ways to differentiate a new tumor enhancement and radiation necrosis post resection with radiation yeah so that that's um you know something people are actively working on there are some more advanced sequences such as perfusion imaging where um you know changes in perfusion can help to differentiate these um some of the work that i did in the past was trying to use machine learning tools to try to differentiate this but there's not a great method to do it with certainty many times what ends up happening is if it's a gbm for instance and there's new enhancement if the patient's doing well and there's not a lot of mass effect we usually don't rush in to take this to take that lesion out sometimes for clinical trials it will require a biopsy of the material to see if it's more consistent with tumor versus radiation but those are you know kind of the clinical way it plays out um you know pseudo progression is something else to think about it's basically where patients are treated but then they develop new contrast enhancement in the cavity the patient i'm following with the same thing and you know he's doing very well clinically so we're just following him with surveillance imaging you know every two to four months but that's a great question and things people are actively working on uh do you ever find narcissistic processing foam or toxic to also hybrid enhancement absolutely so lymphoma toxo these are all um ring enhancing lesions for toxo it's usually multiple and there are some blood tests that you can send for toxo for lymphoma you could have ophthalmology do a slit lamp experiment you could do lumbar punctures to send for cytology so these are some adjuncts if all those fell a biopsy is usually indicated or in the case we start first neurocystic psychosis you could do a resection potentially okay so in a patient in an ongoing um radiation therapy for gbm how do you differentiate lesion is improving odoration causes further damage yeah so that's that's again um one of the things we mentioned um it's very hard to know so short answer is there are some adjuncts but you end up just following the patient clinically and if whatever it is if it's tumor recurrence or if it's radiation necrosis if it's exerting mass effect you may consider going into resected okay could you please show too effective ms and how to differentiate it from gbm uh you know i'd say there's not a great way let me see i think i had one two effective uh yeah so you could argue two effective ms's here not a great way for ms you could do other tests um individual evolved potentials sending off csf so there's a few adjuncts and again you know a lot of these ring enhancing lesions look the same it's going to depend a lot on the clinical history and other testing to differentiate them and ultimately sometimes pathology you know there have been cases where you know we don't think it's lymphoma we get in there it is lymphoma and we simply stop which is important because lymphoma is usually very treatable um by medicine or radiation okay and then in terms of mri ring enhancing lesions how can you differentiate an infarct from a ring lesion of a cortical venous thrombosis so that's interesting question so i think for subacute bleeds i'm sorry subacute infarcts um you see ring enhancement usually cortical venous thrombosis you will see um more of a territory that is affected and sometimes there could be blood products inside that basically in venous thrombosis the there's venus hypertension such that there could be bleeds that occur under pressure so that's probably how i would indirectly do it but again not not a clear-cut differentiation okay let's jump ahead a little bit so um really another key thing is extra axial versus intra-axial so is the tumor coming from the outside pushing in on the brain or is it starting from the brain itself that could also change your operative approach in many cases if it's extra axial like a large meningioma i usually will do a much larger craniotomy or opening in order to really be able to get around it if it's something deep in the brain of course you can think about what part of the brain you're in but sometimes you know once you're in you can kind of suction and work inside the lesion you don't need such a such a large opening so a very good distinction this applies for when you're looking at pictures of spinal cord tumors and elsewhere okay so this lesion a little hard to say just on these pictures alone but this is an extra axial lesion this is a meningioma so this arises from the coverings of the meninges of the brain it pushes onto the brain but does not usually invade it sometimes if you notice t2 signal or edema that suggests that there are tumor cells that are invading the brain or affecting and this patient underwent a i believe a bicoronal incision to remove this lesion this is a this is a specific type of meningioma that we call parafalci and these can be interesting because it's very important to figure out the relationship with the superior sagittal sinus so depending on several factors like the patient's age you may resect this lesion but at the time of surgery see if it's invading the sagittal sinus you may choose to actually leave some of that tissue and later can follow this with imaging depending on its its grade and potentially do radiation therapy if someone were to ask you what part of the sinus is safer to sacrifice if you had to is it the anterior third the middle third or the posterior third my answer would be it's safer to sacrifice the anterior third so that's something that you may be asked in the future okay this lesion is a little bit different this is an intra-axial lesion and when we give contrast which you can tell lighting up here in the sinus this tumor does not light up so this is what we would call a low-grade tumor however it is seen very clearly on a flare image here's a pretty sizable uh tumor here it's contrast enhancing this was taken out through a right frontal approach and you can see it originated from the ventricle um most high-grade like things like glioblastoma many people have traced um having origins in the ventricle it's thought that there are some stem cells that are in that area potentially that can give rise to these tumors so this again just showing you how contrast enhancement usually suggests a more virulent or higher grade tumor this actually turned out to be a very unusual tumor called an atrt a typical territoried rhabdoid this was in a 23 year old male usually you see them more commonly in young children but but a very very aggressive lesion this patient unfortunately despite a good resection passed away a few months later from recurrence of this solution okay here's a few more pictures um this is a patient i believe in the 70s who presented with speech issues so you can see this is located on the left side a little hard to tell just from these axial images but very close to his language areas you can see it has some on the head ct what we've learned you know a little bit bright areas so blood products contrast enhancement on the mri you see the sagittal sinus lining up it's got edema around it and it's effacing the ventricle so this was a case of uh we did a resection to remove the lesion case of metastatic melanoma melanoma is one that's known to be a little more hemorrhagic among the types of lesions that that metastasize other very common metastases just one based on numbers is lung so lung meds are most common breast melanoma gi i'd say those are some very common ones i'd like to show a few examples of different pathologies based on location so one location is the cerebellum pontine angle so we have your cerebellum the pons it's kind of the angle that it makes and there's a lot of different pathologies here one is a schwannoma which is a um you know along the vestibular nerve most commonly cranial nerve people refer to that as an acoustic neuroma those patients usually present with a combination of vertigo hearing loss and tinnitus so you can see this lesion is um right in the cp angle tracking out along the nerve reasons for surgery would be if they're compressing on the brainstem as they grow another example more commonly than aneurysm is an arachnoid cyst a meningioma and epidermoid i'd say those four are um very common in this area some other hints and then they give this pneumonic here same some other hints meningiomas will grow in a way that will narrow the internal auditory canal where schwannomas will actually sculpt out and expand the opening and sculpt out the bone further meningiomas i'll show another example where they have a dural tail they originate from the covering on the brain and therefore you can see a dural tail epidermoids show diffusion restrictions so that's a very nice way if you look at that sequence there's restriction that's a good way of telling you what jimmy you're dealing with here's some other examples acoustic neuroma or what we call vestibular schwannoma here's a dural tail suggesting more meningioma these arrows show some other examples of dural towels here here's an example of diffusion restriction you can see this bright area suggesting that the germline so again the combination of different sequences and just knowledge of some of these these features can be very helpful intraventricular tumors or another class of lesions go over based on location this is a choroid plexus probably a choriplexus papilloma these can be very bloody cases and usually you have to find really a main feeding vessel to really get control of this these are very commonly associated with hydrocephalus some people think it's because the tumor produces fluid other times it could be obstructing the normal flow of food this is a lesion the pathology came back as a central neurocytoma there are other similarly shaped lesions um such as subappendable nodules or subpoenal giant cell astrocytomas segas so really a host of lesions that are found in the ventricle sometimes with very large ventricles and smaller lesions than this you could approach them endoscopically meaning coming with a camera through the csf and ventricle other times you cannot sorry i'm gonna have to just pause just for one moment if that's all right hello it is i'm just a little presentation can i call back shortly all right thanks so much okay i'm sorry guys um so now we're going to take a look at the posterior fossa so the differential diagnosis here um varies based on the age of the patient so for adults by far the most common lesion is a metastatic lesion so really the top three things in your diagnosis should be metastasis for anyone who comes in an adult with a posterior fossa lesion like this this was a gentleman very heavy smoker in his 50s i believe who came in with balance issues and you can imagine with compression of this fourth ventricle you know his developed hydrocephalus also um in coordination which um you know makes sense that this affects the cerebellum so this patient had a reception um and again showing this more just to show that metastasis is really the top of the differential so for adults the second most common lesion is a hemangioblastoma this is actually a low-grade lesion they come in kind of two different flavors the more common one is this one where there's a very bright nodule which is your vascular lesion and it produces a cyst fluid and you know with surgery this can be a cure for the patient if this neural nodule is removed really you do not have to go after the walls of the cyst once the nodule is removed the cis fluid doesn't get produced and you could really help a patient with this one this is a more solid appearing one so this one is cystic less common is a solid appearing hemangioblastoma these can be very difficult to take out surgically they're almost like an avm they're very highly vascular in this patient we got an angiogram and ended up embolizing about a third of this lesion and again very similar presentation of hydrocephalus and in coordination so things like finger to nose was off so in children a completely different differential some of the most common ones are jpa so juvenile pylocytic astrocytoma shown here similar to hemangioblastoma has a mural nodule and then a cystic component to it very common is medulloblastoma this arises from the roof of the fourth ventricle and then ependymoma some people call these plastic tumors in that they actually take up this the shape of the ventricle and sometimes will go out those foramina that we discussed early on foramen of lushka for instance and could involve some of the lower cranial nerves so again you know something i think it's useful to know for uh differentials when dealing with tumors in different locations here's another uh location this is a tumor in the brain stem now in the past these were called dipgs diffuse infiltrating ponte glioma some of the wh criteria has changed and usually these are called diffuse midline gliomas you have a characteristic histone mutation unfortunately these tumors are somewhat difficult to treat you know these tumors are usually lower grade but they intermingle with many of the normal um neurons in the brain stem such that if you were to do a surgery you would have really unacceptable amount of collateral damage so these are not usually resected more frequently though they're biopsied so this patient underwent the right frontal biopsy where we pass the needle down from the top of the head all the way down which is you know always a little bit disconcerting but we've got a good sample of tissue and based on that we're able to identify some gene mutations to enroll her in clinical trial really the cornerstone for this at this time is radiation treatment but it's definitely an area of active research okay let me just take a quick look at some questions here uh can you expand on why interior one-third of spirit sagittal sinus sacrifice is preferred so um you know anytime you're sacrificing a sinus you know shouldn't be done um for no reason uh but if you had to um if the first third is a little bit safer and that a lot of the major bridging veins are found more posteriorly especially in the middle and posterior portions you can actually see how you know even in this picture we have to be looking at it's much more diminutive in the entry apart not as many large veins and as you get further back and enlarges so i think part of it is just a natural anatomy the way the bridging veins come in and a little bit less eloquent area in the front here so again you know you never want to take the sinus you know lightly but if you ever had to you get away with it a little more in the anterior portion so if you have a mid geometry you're really trying to go for a cure but i think i think surveillance and radiation is a very good alternative okay why is okay so that's we answered the second question here and then diffusion weighting imaging is helpful to differentiate which ring-enhancing lesions i would say lymphoma infection gbm these are all things that actually will could be ring enhancing and then could diffusion restrict so [Music] you know even though you have an extra sequence still not the most specific metastatic melanoma could that be confused with an oligodendroglioma due to hemorrhage and calcification yeah i think so that's a good point and that oligos are usually um kind of the gray white interface um yeah absolutely i think that's um you know with surgery you'll be able to get um tissue and i think either one probably you know prompt you to do surgery so yeah that's a good point okay so a few more tumor cases so this is an example of some lesion in the cellar region so it's this kind of area in the sphenoid bone so here we have some pituitary tumors we have a microadenoma you can see very nicely the pituitary stock in the midline here and then macroadenoma which we see in a coronal and sagittal view so really i think it's worth just briefly discussing some of the indications for surgery for pituitary tumors really in my mind i cancelled patients that there are two reasons to do surgery for pituitary gland tumors one is if the tumor is secretory meaning if it will secrete different hormones a simple blood test can can look for these of course prolactin is one that you want to check right off the bat because that's something that can be treated with medicine rather than surgery and some of the other common hormones you do a full panel on so if those hormones are elevated that could have deleterious effects on the body such that surgery could potentially cure the patient if you get all the adenoma out second thing which applies a little bit more to macroadenomas which are just defined as larger pituitary tumors if it's pushing on the optic chiasm or the optic apparatus so you can only almost make out here a little bit the left-sided optic chiasm but this tumor is definitely touching it and it seems to be compressing the right side this is a patient who had rights who had visual field deficits and was offered surgery for that reason so really two reasons one if it's a secreting tumor that could lead to endocrine dysfunction where there's too much of a certain hormone or and or if it's pushing on the optic nerve causing vision to climb of course you want to have the patient see my ophthalmologist to do an objective test of it [Music] hey everyone ryan rad here from neurosurgery training.org if you like that video subscribe and donate to keep our content available for medical students across the world