This study aimed to clarify the interpretation of positional nystagmus (PN) by looking at the current criteria for significance of PN, comparison of PN in symptomatic patients with normative data, prevalence of PN among participants with balance problems and assessing if PN may be associated with other abnormalities. These issues are important as although the BSA recommended procedure for static positional testing exists, there is still vagueness in terms of the criteria for the tests’ interpretation. Ninety participants reporting imbalance or vertigo took part in this study. Subjects with BPPV or those that were unable to perform the test as described in the BSA recommended procedure were excluded from this study. The authors suggested that the BSA threshold criterion for the horizontal nystagmus should be decreased from 6°/s to 3°/s. They suggested that decreasing this criterion would significantly increase ‘true-positive’ results while still keeping the ‘false-positive’ results below 5%. The criterion for the vertical upbeat positional nystagmus was suggested at 7°/s, however authors indicated that this was only approximate and that these results must be validated further. Additionally, the researchers pointed out that significant downbeat nystagmus under the above criterion is less prevalent than the upbeat one which indicates that the threshold for the downbeat nystagmus should be reconsidered. Additionally, the presence of PN was not significantly associated with other vestibular tests which is in accordance with previous research concerning this subject. In addition to the very interesting results presented in this paper, I also found it a good literature review of the subject. 

The interpretation of static positional nystagmus in a balance clinic.
Jeffery H, Hopkins M, Anderson R, Patel V, Rogers J.
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Joanna Lemanska

De Montfort University, Leicester, UK.

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