Interactive Transcript
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Although it's not as common as pharyngitis, tonsillitis,
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and dental infections,
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I did want to mention one additional inflammatory
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process that you should be aware of in the emergency
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evaluation of a patient. In this case, with ear pain.
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Now,
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this is a 73-year-old elderly gentleman
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who had diabetes.
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And what we see on these two images is the characteristic
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features of Malignant Otitis Externa
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or Necrotizing External Otitis.
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There will be different terms
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used for the same entity.
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What you see is the inflammatory process in the
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external auditory canal with some erosion
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of the walls of the external auditory canal.
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And then you also see some undercutting of
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the clivus on the right side on the CT scan.
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This patient had previously had irrigation of this
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right ear by the local MD and developed cranial
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neuropathies and additional sort of deep-seated
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skull pain. If we look on the MRI scan,
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it's really quite striking what's going on.
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Now note that this is an MRI scan in which we've applied
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fat suppression and giving gadolinium.
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What you see is the markedly narrowed external auditory
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canal with inflammatory changes on either
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side of the anterior and posterior border.
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We see the mastoid air cells are opacified and enhancing.
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Unfortunately,
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we also see the flow void of the internal carotid artery
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surrounded by enhancing inflammatory tissue.
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As this inflammatory process is extending to the
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skull base. These are the longest colli muscles.
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The right side shows enhancement.
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The left side is normal, not enhancing.
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So we have inflammation even in the pre
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vertebral musculature on the right side.
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We also notice the clivus.
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The clivus has fat within it and should show
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fat suppression as you see on the left side.
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On the right side, we have enhancement of this bone,
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the clivus.
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So enhancement of this clivus section right here,
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because the patient has skull base osteomyelitis.
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This inflammatory process extends into the
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parapharyngeal space of the nasopharynx. Here's
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the normal parapharyngeal space showing
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absence of enhancement.
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So this entity of Malignant Otitis Externa,
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which starts as an external otitis,
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basically a swimmer's ear, if you will,
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can go even so far as the skull base,
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with skull base osteomyelitis,
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vasculitis and cellulitis extending
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to the parapharyngeal space.
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The theory is that with the irrigation
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of the external ear, the pathogen,
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which in most cases is pseudomonas, gets driven into
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the fissures of santorini between the bony portion of
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the external auditory canal and the cartilaginous
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portion of the external auditory canal,
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are these things called the fissures of santorini,
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which extend inferiorly and medially
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into the parapharyngeal space.
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And so, the irrigation under pressure actually drives the
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pseudomonas into the skull base, leading to spread of
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the infection to the longest musculature, the clivus,
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the carotid artery and the parapharyngeal space.
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This is a deadly disease.
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It's not quite as deadly as what was in the pre
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antibiotic era where we said
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it had a 70% mortality rate.
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At this juncture, we're probably at about
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20% mortality rate, which is still very high.
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And the reason is because the patient, who's typically
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diabetic, has a hard time fighting
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off this pseudomonas infection.
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We are talking here about mastoiditis
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and middle ear cavity disease.
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I want to just mention one other factor, and that is
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that from the middle ear cavity and the mastoid air
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cells, you have the potential to spread to the jugular
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foramen the sigmoid sinus and the transverse sinus
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as one of the complications of otomastoiditis.
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In this case we see a thrombus in
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the transverse sinus of the brain.
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It's outlined by a little bit of contrast enhancement,
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and that may lead into the sigmoid sinus, and from there,
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into the jugular vein and potentially be another
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source of septic thromboemboli into
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the lung. From the middle ear cavity,
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you can also lead to meningitis by erosion of the
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tegmen tympani, extending to the meninges of the
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middle cranial fossa floor. And from there, we
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can also involve the cavernous sinus.
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So otomastoiditis has lots and lots of potential
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destructive complications.
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They include bony destruction with
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osteomyelitis at the skull base, you can have a
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subperiosteal abscess, which we've shown
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an example for in the oral orbits.
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You could have spread to the extraaxial space and
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meningitis and epidural abscess. You could have
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cranial nerve involvement as you have spread to the
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petrous apex, taking out the meckel's cave and the 6th
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cranial nerve in gradenigo syndrome. That's G-R-
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A-D-E-N-I-G-O. And then thrombosis of the venous sinuses.
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