Vestibular case quiz

[Harriet Hill]

Hey there! I have a couple of questions about the vestibular case quiz.

1. For question 1, the pt’s symptoms are reported as general imbalance with all mobility, and especially quick turns. I selected unilateral vestibular hypofunction, because there was no report of horizontal oscillopsia indicating a dramatically reduced dynamic visual acuity, which is what I would expect to see with bilateral hypofunction. I’m wondering what in this question would help me clarify how to choose between bilateral and unilateral for this patient. Is it just that he is complaining of imbalance with all mobility vs. just pivoting or turning to one side? My answer of unilateral hypofunction influenced my answers for the rest of this quiz, so my score was pretty poor!

2. For question 9, I am wondering what the justification is between predicting the pt will score 23/30 vs. a 28/30 in 4 weeks. I think I may have just not spent enough time on the wording of the answer (if he scored *AT LEAST* 23/30 within a month, that also encompasses the possibility of scoring 28/30 and would be more likely than saying he would score at least a 28/30 in one month since this score is higher). But I just wanted to make sure I wasn’t missing anything beyond the wording of the question. I am seeing the MDC for vestibular disorders for the FGA is 6 points, and my thought process was in about four weeks he should be showing some detectable change as one of the articles we read said individuals with bilateral hypofunction could show significant improvements in about 5 weeks. I am I still thinking along the right lines here?

[Chrissy Durrough Lugge]

Hi Harriet!

Thanks for these questions! I’ll do my best to help!

1. The key here is that the patient is describing his dizziness as only imbalance. Someone with a unilateral vestibular hypofunction would likely experience imbalance AND dizziness (vertigo, lightheadedness, etc.) with head turns due to the asymmetry in left/right vestibular function. Similarly, we would expect a sensation of dizziness with BPPV (though this would likely be positional and not necessarily affect balance with all mobility) and central vestibular dysfunction. People with bilateral hypofunction often experience imbalance without dizziness. Another hint here is that the patient had a severe bacterial infection recently – and ototoxicity is a common cause of bilateral vestibular hypofunction.

2. This question is getting at the relatively slow progress expected with bilateral hypofunction (compared to unilateral hypofunction). The 2022 CPG recommends dosing balance exercises at 6-9 weeks minimum for bilateral hypofunction. It isn’t likely the patient will improve his FGA to 28/30 within one month. The MDC of 6 points is a great metric for goals and a reasonable goal for this patient would be meeting or exceeding the MDC to score >=27/30 within 2-3 months.

Hope this helps! 🙂

Chrissy

[Harriet Hill]

Yes! This does help a lot. I haven’t looked at the actual CPG yet, saving that for closer to the exam date. So knowing that, the answer makes lots of sense. My only remaining question is just some clarification on the dizziness symptom with unilateral hypofunction. If someone had vestibular neuritis, I believe I would expect them to have vertigo for days-weeks. Once the acute stage had resolved, I would expect them to be left with some residual oscillopsia and imbalance, but the vertigo/dizziness should have resolved. Sounds like I don’t quite have it right though. For reference, I also did the medbridge vestibular courses, so I am going off of what I learned there as well. Let me know what your thoughts are! Thank you so much!

[Chrissy Durrough Lugge]

I think you’re on the right track! Someone with unilateral vestibular neuritis would likely have acute vertigo for days-weeks. Then, they would likely only have symptoms when performing head turns that might be marked by visual blurring due to impaired VOR/retinal slip. I guess this visual blurring could fit with the definition of oscillopsia, but I tend to think of oscillopsia is the apparent moving/jumping/bouncing of the world around us. (https://www.dizzyandvertigo.com/what-is-oscillopsia-and-how-is-oscillopsia-treated/)

Someone with bilateral hypofunction would have a more classical experience of oscillopsia, as well as imbalance with all mobility. Imbalance will be worse with head/body turns – but more impaired overall than someone with unilateral hypofunction.

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