Tullio, Hennebert and other absurd eponyms

If vertigo patients make you vomit, this post is nothing for you.

It is always exciting to watch medicine develop new concepts. While Neurology is certainly full of examples with new diseases, acro- and eponyms popping up everywhere, HEENT people seem to be more conservative, perhaps because they are busy operating and healing people. Superior canal dehiscence syndrome is a very young disease that  probably owes it’s discovery more to highres CT than to puzzled (neuro-)otologists. But now that we have learned how to deal with it, even the posterior canal can erode and be operated on, so perhaps a thorough neurootologic exam and neurophysiological investigations are in order when your patient tells weird stories (as SCDS-patients seem to do).

We discuss an example we pulled out of our ER recently which then went on to surgery and successfully had his superior canal plugged (not before a repeated workup in a specialized vertigo clinic) and who now is symptom free.

References

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Testing otolith function

Vestibulologists (?) have an arsenal of clinical and neurophysiological tests that no ordinary mortal is supposed to understand. But  for emergency neurologists some of their tricks are actually quite useful. Starting from the question what this weird bucket is for, we discuss the physiology of the otolith organs utriculus and sacculus.

Sacculus

  • Lateral head thrust test
  • cVEMPs

Utriculus

We note how to use the laterality of the deviation of the subjective visual vertical to distinguish between peripheral/vestibular nuclear and other brainstem lesions. We also discuss the pathophysiology of the SVV over time after vestibular neuritis.

All things BPPV

I just wrote up our local SOP BPPV and used the opportunity to collect all current and fancy information of the last 2 years, trying to judge whether they help at all. Apart from the fact that most of the research has been done in Korea and Italy, I found some further interesting things and joined them in a Prezi (in German, though).

Feel free to use that.

The neurootological examination of dizzy patients

We do have many dizzy patients to work up in the ER. Nowadays with the HINTS or INFARCT scheme, life has become much easier if you have to distinguish between vestibular neuritis and central vertigo (stroke and migraine mostly) in an acute vestibular syndrome. But if they are only dizzy, you have to invest more work. In today’s session we concentrated on the neurophysiology of extraocular eye movements, the various categories and how to examine them.
From a physiological viewpoint you have to distinguish the following EOM categories:
  • Voluntary and involuntary (e.g. the correcting saccade of a nystagmus) saccades
  • VOR movements
  • Smooth pursuit
  • Optokinetic reflex
Here are the basic exam steps for a dizzy patient:
  • Spontaneous nystagmus (using Frenzel glasses or the penlight cover test)
  • Gaze directions: check gaze in all 9 directions at about 30-45° for diplopia and bulbar misalignment
  • Check for gaze evoked nystagmus in the same step
  • Head shaking nystagmus (quickly oscillate move the head between left 45° to right 45° with about 2 cycles per second)
  • Vergence movements (move the fixated pen from 60 to 10cm before the nose)
  • Saccadic eye movements: preferably use diagonal saccades between two pens
  • Smooth pursuit: estimate the speed at which the patient can still keep up with a moving pen, horizontally and vertically, compare sides
  • Horizontal VOR: use the head thrust maneuver (Halmagyi)
  • VOR cancellation: the easiest is to have the patient follow your finger with his head rather than the eyes, can also use a rotating chair
  • Dynamic visual acuity: have the patient read some text while moving his head rhythmically between left and right
  • Positional nystagmus: Dix-Hallpike, head roll test and head hanging test
  • Tragus test: occlude the ear and press on the tragus
  • Romberg’s and Unterberger’s test
  • Complete neuro examination including testing for extremity ataxia
I never use the drum roll because it does not properly test the optokinetic reflex (which is a non-foveal process).

Brainstem anatomy, ocular tilt reaction and the subjective visual vertical

I found a few people that didn’t know the 4m4s-rule! So we did that once more. While declinating the various brainstem strokes we had on our ward today, we also spoke about the various ways that vestibular disturbances can be found, what the ocular tilt reaction is and how the subjective visual vertical works. To be honest, while I still marvel at the possibility to measure it with a simple bucket contraption (here is how they build them in Pittsburgh and here is how you can even throw your Iphone into the bucket), I find it exceedingly difficult to interpret the test – it should be less affected by peripheral than central disorders (with thresholds around 8-10°), but would you really forgo an MRI if the SVV is only 6° deviated?

BTW: A very short table exemplifying the “use” of the SVV is found in the wonderful article “A bucket of vestibular function”, written by the Brandt/Strupp/Dieterich clan.

Which side is affected in lateral canal BPPV?

From the rate of vertigo talks you can probably infer that either I must be very interested In or very insecure with vertigo. In fact, both is true.

So here is today’s problem: assume we know how to recognize horizontal canal BPPV and how to differentiate it from the other forms. Then there is still the difficulty in determining the affected side, because often enough it is not evident at all (this is not just my experience).

More concretely, we have a 56 yo saleswoman that wome up with extremely disabling vertigo. The world started spinning (horizontally, she says) when she turned over in bed to her alarm clock and she is not able to move since then, vomiting profusely on the slighest head turn. We managed to throw her around through our basic screening maneuvers – Dix-Hallpike and head-roll-test (also known as Paganini-McLure), where she showed purely horizontal decrescendo nystagmus towards the underlying ear on turning to either side – this is geotropic nystagmus. There is slightly more vertigo on turning to the left äs compared to right, but the nystagmus is pretty much the same.

Many maneuvers have been proposed for this situation and there is even some basic data about test theoretic properties of some of them. From this evidence I suggest the following successive tests (which actually can be performed during the screening phase).

  • History: which side is worse to turn to when supine? About 56% of patients can determine that and they usually are right.
  • Pseudospontaneous nystagmus: 56,2% have a spontaneous nystagmus when sitting straight, which – in the canalolithiasis situation – will abate eventually and is due to the purported angle of about 20-30° the lateral canal has wrt the horizontal plane (frontal arm is higher up than the other).
  • Lying down = supine nystagmus: in the so called Asprella diagnostic maneuver (which I love as a screening method for positional vertigo) you just move your patient quickly to the supine position, holding the head straight and record eye movements. In most of positional vertigos some nystagmus will come up and depending on the form of nystagmus you perform other maneuvers. Well, in this position about 75% (!) of lateral canal BPPV patients have some nystagmus and you can use the direction of nystagmus to determine the affected side (see table below).
  • Nystagmus intensity during the head-roll-test: due to some of Ewald’s laws (in fact, the second), nystagmus should be worse on the affected side in canalolithiasis. This happens to be the case in about 81% in the above mentioned article.
  • Bow-and-lean-test: when you bow the head of the sitting patient over the 30° angle the affected lateral canal has wrt the horizontal plane you should be able to evoke a the bow- or bending-nystagmus in about 59%. When leaning back a similar nystagmus can be observed (this is actually the pseudospontaneous nystagmus mentioned above). Both happens in only 40%.
  • Head-shaking nystagmus: any proper vertigo workup should include the screening for head shaking effects. The nystagmus evoked can be due to several reasons, but in lateral canal BPPV it produces a nystagmus in 62,5%.

Performing all of these maneuvers and then integrating the results with the table below, you should get the affected side right most of the time. Yet, if your treatment maneuver is then not effective, you should try the other side at least once, before starting a workup for other etiologies (central positional vertigo) as well.

 

Geotropic

R

L

Apogeotropic

R

L

Vertigo worse when supine
and turning to

the affected side

R

L

the unaffected side

L

R

Pseudospontaneous nystagmus towards

the unaffected side

L

R

the affected side

R

L

Lying down (supine) nystagmus towards

the unaffected side

L

R

the affected side

R

L

Nystagmus worse during head roll test towards

the affected side

R

L

the unaffected side

L

R

Bowing nystagmus
towards

the affected side

R

L

the unaffected side

L

R

Leaning nystagmus
towards

the unaffected side

L

R

the affected side

R

L

Head shaking nystagmus towards

the unaffected side

L

R

the affected side

R

L