| Transcript |
Today I'm going to be talking to you about something that's very interesting which is Tullio phenomenon and the Hennebert sign, and these come to ENT, primarily, because they are the symptoms of superior semicircular canal dehiscence and normally that's an ENT thing. However, it can come to ophthalmology and especially neuro-ophthalmology because patients with these symptoms- the Tullio and the Hennebert's- actually have eye symptoms, even though it's an ear problem. The eye symptoms with the Tulio phenomenon are that sound induces oscillopsia because it causes the nystagmus, and if they stick their finger in their ear, or they do something to change the pressure in their ear, it causes the oscillopsia. So the symptom is oscillopsia, and "opsia" means "see" and "oscillo" means "to move, to oscillate," and the sign that is associated with oscillopsiais nystagmus. So, nystagmus is the sign and oscillopsia is the symptom. And so when we have nystagmus we're really trying to figure out if it's peripheral or central nystagmus, and in another video you can see the differences between the peripheral and central vestibular nystagmus. So when we say peripheral we're talking about the vestibular system, which is the balance part of your ear, not the hearing part of your ear. However, when they go to ENT, they're gonna check their ear. They're gonna have audiogram to look for the hearing loss, and they're gonna be asking about hearing loss and tinnitus, the ringing in the ear, and so normally when you have an acute vertigo with acute hearing loss and acute symptoms that are positional, those are the symptoms that suggest the problem is peripheral and those patients all end up with ENT. However, if it's chronic, non-positional, and there's no hearing loss and no tinnitus, that's more likely to be central, but there's going to be overlap between these two, and one of the things that's interesting about these two complaints is their eye complaints because their eyes jumping oscillopsia and so the neuro-ophthalmologist role in this is to hear the symptom, generate the sign, and look for the nystagmus. So, in the semicircular canals, as you know, they're not really oriented in the pitch, yaw, and, roll plane because some of these canals have to do double duty, and so the horizontal canal can produce horizontal nystagmus, but usually the superior canal and the posterior canal have different nystagmus way for us that are multifactorial so if we see purely down beat or purely upbeat nystagmus that's going to be very hard to generate out of your superior or posterior semicircular canal. And, likewise, if it's purely torsional, like the rotary nystagmus we see in the Wallenberg syndrome, for example, from the PICA infarct in the brainstem, that's going to be a torsional rotary nystagmus. So, purely torsional or purely vertical nystagmus suggests central. In the Tullio phenomenon it's normally a mixed type of nystagmus, so it can be vertical with some torsional component because it's a superior semicircular canal dehiscence, and, so under normal conditions, as you know, when the stapes is holding the membrane we have the two windows, the oval window and the round window, and when those sound wave comes it kind of goes all the way around the bend and then the pressure has to be felt on the opposite window. So, the membrane vibrates, the fluid goes around, the hair cells deform, and then the pressure is dissipated out the other window. So the oval and the round window are the windows that are the normal membranes, but if you have this extra window-a third window or a false window- created by a dehiscence in the bone in the superior semicircular canal, that superior semicircular canal dehiscence will cause the fluid to move inside the canal, when it's not supposed to because you've got this extra window- a false window, a third window, if you will- that's allowing the pressure wave to be dissipated out that canal and that canal will feel that as rotational movement of your head and that will generate oscillopsia and nystagmus. So, Tulio phenomenon the sound makes my eyes jump. Also the patients might have autophony- they hear their eyes moving, or they move their jaw or their mouth and they feel like their eye is moving, or they stick their ear, their finger in their ear, and the eye starts jumping. These are symptoms of something wrong with the window. Either the window is leaking, that's a perilymph fistula, so the fluid is leaking out of the window, or you have a false window, a third window, and that is called the superior semicircular canal dehiscence. The reason you need to know about it at this juncture is because they often have seen Neurology, and they've often had an MRI, and the MRI scan is not that good for looking for superior semicircular canal dehiscence. We need a CT scan to look right at the temporal bone, and thin sections, 0.5 millimeter to 0.6, something like that, millimeter cuts the secede the dehiscence. And once they identify that they can fix it by closing it, and that requires surgery. So, two very strange, crazy sounding complaints, "my eyes jump when I hear loud noises," or "my eyes jump when I have a pressure change in my ear" either by "sticking the finger in the ear" or doing something to change the pressure- those are very specific symptoms that should lead you to superior semicircular canal dehiscence." |
