Non-neoplastic Vascular Malformations – Vascular Malformations

00:00 Let’s move to ones that are a little nastier in terms of their clinical ability to cause problems. And that’s the non-neoplastic vascular malformations.

00:10 They’re also present at birth. They do not go through the rapid proliferative phase of a hemangioma. And they don’t involute. They stay. They grow with the patient. And about a third of them are found on the head and neck. And they’re thought to result when there’s an interruption at a particular stage of development of the blood vessel so that you don’t get to the final stage of the blood vessel. There are in a sense primitive blood vessels.

00:40 And the type of malformation depends on the stage at which this development – morphogenesis – this development is interrupted.

00:50 And here you can see in a couple of cartoons exactly what they look like. First of all, you can see that the AVM actually is a direct connection between the artery and the vein.

01:00 It bypasses the capillaries and it bypasses the arterioles. So there’s no resistance in there. As you remember, the resistance is in the arterioles. So a lot of blood can shunt through these. Often they have a number of side vessels connected to them. There’s a lot of blood going through that system. This is a high-flow system. And they can actually enlarge. And as you see in the two cartoons on the right, you can actually see they bulge and they can be quite irritating because they’re not just flat and only cosmetic, like the hemangioma.

01:39 It’s of course, as I said, an abnormal connection between the arteries and veins. It bypasses the capillary system. It can appear at any location. Most are asymptomatic but some can cause intense pain, bleeding or can become infected and torn. They dilate with time and become larger. And the worst ones are, of course, the ones in the brain where they can bleed.

02:06 A secondary type of AV malformation is the cavernoma. And here you see instead of there being a direct connection between the artery and the vein, rather there’s a connection to a whole clump of abnormal primitive blood vessels. And in a sense, the cavernoma is fed by both the artery and the vein. And when these are also in the brain, they can bleed and cause quite a lot of trouble.

02:34 The AV malformations have been classified by two pediatric specialists in this area: Spetzler and Martin. And they have a grading system where you get points for a certain number of things which I’ll talk about in a moment. And the higher you score, the worse is the prognosis and the more likely that you’re going to have real clinical problems with these.

02:56 So you can see you get various points for the size of the AVM. The larger the AVM, the nastier it is.

03:03 The so-called eloquence of adjacent brain, in other words, is this in the brain area that controls motor – arm or leg motion? Is it in an area that controls speech? Or is it in a silent area? If it’s in a silent or so-called no-eloquent area, it’s much more benign than of course if it potentially affects speech or muscle contraction.

03:28 If the venous drainage is only very superficial, that’s okay. But if there’s a deep component it’s much worse because getting them out may require sacrificing more brain tissue.

03:38 I show you this just to show you that they can be relatively not so bad or they can be really nasty.

03:46 When they’re in the brain – and here we’ll talk a little bit about the nasty ones – they can bleed. And the bleed most commonly presents clinically as a subarachnoid or an intracerebral bleed.

04:01 There can be scarring following a bleed. And that leads to seizures. There can be a mass effect. That is if there’s enough bleeding into it, it can actually cause the brain to shift and this can be potentially fatal.

04:14 There can be progressive neurological deficits, paralysis, inability to speak. And 7% of these patients also have aneurysms that can rupture. So this is not something that you’re happy about when it occurs in your child.

04:31 The diagnosis is made, again, usually not invasively although occasionally angiography is needed. The CT scan almost always picks that up and I’ll show you an example in a moment.

04:44 If you're not totally satisfied with the imaging CT, MRI will give you a more detailed image.

04:50 And particularly if neurosurgical intervention is planned, often the neurosurgeons want both a CT angiogram to show the blood vessels feeding it and also an MRI to show exquisitely the anatomy. And you can also, of course, occasionally do MRI angiography if you’re not satisfied with the CT angiography image or if the patient is allergic to the angiographic dye.

05:15 And finally sometimes you actually have to put a catheter in the carotid and thread it up into the brain and actually make a cerebral angiogram. But these days mostly the non-invasives are adequate.

05:26 And here we see an example. This is a cerebral AVM. You can see it’s circled in green.

05:34 And then on the right-hand side, you can actually see a CT angiogram. The tangled abnormal blood vessels.

05:42 And usually there’s an attempt to destroy these. One way is operating and actually cutting them out. More frequently these days, the radiologists do it. They go up and they put a catheter in the artery that’s feeding one of these. And then they embolise material that clots off these abnormal blood vessels. And then they involute. It’s a very sophisticated radiologic procedure. But it avoids surgery on the brain.