Popliteal Nerves & Trauma
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In terms of the nerves,
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you're gonna be getting a lecture on nerve entrapment by Dr.
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Flsa at the end of the course.
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So I'll just show you a few selected examples.
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Uh, here's the anatomy of the nerves,
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the sciatic bifurcating into the tibial and perineal nerves.
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This bifurcation generally occurs well above the knee joint.
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In fact, it can be very far proximal
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and can occur even up at the level of the hip joint.
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This is a patient with enlarged nerves.
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This is a sciatic just before bifurcation,
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and this was a patient with charcoal Marie tooth, which is,
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uh, uh, well-known, uh, condition that is associated
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with enlargement.
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The vesicular architecture looks perfect in this case.
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The signal of the nerve is not abnormal.
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Uh, but we can see just how, how big it is.
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We can see some of the smaller saphenous, uh, nerve uh,
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components, even some
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of the small tiny sural nerve components, uh,
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in this particular, uh, patient.
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So you'll see nerve enlargement.
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This unfortunate patient had a sarcoma, uh,
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and had to, uh, undergo surgery as well
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as radiation therapy.
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Uh, we have a lot of postoperative scarring,
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but notice what's happened now to the nerve,
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which is markedly irregular looking.
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A lot of perineural fibrosis, uh, sles
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still relatively preserved,
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but an enlarged, uh, fibrotic, uh, nerve, uh, related to,
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uh, radiation, uh, neuritis.
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This interestingly does not enhance with the contrast,
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which can help you to distinguish it from recurrent tumor.
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Something that we use a lot when we do our
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brachial plexus imaging.
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Brady already talked about trauma.
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Again, the significant associations of this
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with posterolateral corner injuries as well as
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with proximal tibial fibular, joint dislocations,
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and even fractures of the head, uh, of the fibula.
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So anytime you're seeing a lateral injury, it, uh, is, uh,
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important that you look at the, uh, peroneal nerve,
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a typical neurogenic tumor showing a tail sign
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and the speckled appearance, uh, internally, which is, uh,
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well known I think to all of you.
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And this was a interesting case of a neurofibromatosis
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with a very extensive plexiform neurofibroma.
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But what was interesting in this case was
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that it had invaded into the joint.
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So we don't generally see intraarticular neurofibromatosis,
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uh, but in this case, we had encasement of all
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of the neurovascular structures, extension into some
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of the musculature, as well as an intraarticular component.
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Uh, from this, uh, from this, uh, neurofibroma.
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This was benign. It was not a neuros sarcoma in this, uh,
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particular, uh, example, just a plexiform, uh, neurofibroma.
Donald Resnick, MD
Professor Emeritus, Department of Radiology
University of California, San Diego
Mini N. Pathria, MD, FRCP(C)
Division Chief, Musculoskeletal Imaging
University of California San Diego
Eric Y. Chang, MD
Adjunct Professor, Radiology
University of California, San Diego
Brady K. Huang, MD
Clinical Professor of Radiology
UC San Diego Medical Center
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