Commentary: Is There an “Acquired Idiopathic Head-Shaking Nystagmus?”: A Discussion of Mechanisms and Clinical Implications Based on a Case Report

We read the article by Filippopulos and his colleagues with great interest (1). This report described a patient with recurrent episodes of vertigo prompted by fast head movement (1). The vertigo was accompanied by a severe right-beating head-shaking nystagmus (HSN) with an increased time constant of 60 s. Despite scrutinized neurotologic and radiologic evaluation, there was no evidence of peripheral or central vestibulopathy, except prominent HSN. The patient had no prior history or subsequent development of any associated symptoms during the 6 years of follow-up, which may exclude the diagnosis of vestibular migraine, Meniere's disease, or vestibular paroxysmia. The authors insisted that this patient represents a distinct clinical entity with an unstable velocity storage mechanism (VSM), thereby assigning a new disorder termed “acquired idiopathic head-shaking nystagmus” (aiHSN).

As the authors noted, we previously reported a group of patients with recurrent spontaneous vertigo with interictal HSN (BRV-HSN) in the absence of peripheral vestibulopathy as was documented by caloric, head-impulse, or rotatory chair tests. Even though we could not assess HSN in those patients with BRV-HSN during the attacks, the only difference between the BRV-HSN and aiHSN appears to be the absent HSN between the attacks in aiHSN. Given the (1) increased time constants of the HSN and rotatory nystagmus, (2) emergence of the HSN even with a short duration of head-shaking, and (3) good responses to baclofen, we proposed that unstable and asymmetric VSM may be the cause for vertigo and BRV-HSN (2). Apparently, the characteristics of HSN observed in the patient reported by Filippopulos et al. (1) do not seem to differ from those observed in our patients with BRV-HSN. Thus, the BRV-HSN and aiHSN may lie on the same spectral line due to a common pathomechanism (unstable and asymmetric VSM), rather than distinct disease entities. In addition, the clinical presentation does not escape from the umbrella term of BRV.

Statements

Summary

Keywords

vertigo, nystagmus, benign recurrent vertigo, head-shaking nystagmus, dizziness

Citation

Lee S-U and Kim J-S (2022) Commentary: Is There an “Acquired Idiopathic Head-Shaking Nystagmus?”: A Discussion of Mechanisms and Clinical Implications Based on a Case Report. Front. Neurol. 13:955081. doi: 10.3389/fneur.2022.955081

Received

28 May 2022

Accepted

03 June 2022

Published

22 June 2022

Volume

13 - 2022

Edited by

Sun-Young Oh, Jeonbuk National University, South Korea

Reviewed by

Michael C. Schubert, Johns Hopkins University, United States

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Copyright

© 2022 Lee and Kim.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Ji-Soo Kim jisookim@snu.ac.kr

This article was submitted to Neuro-Otology, a section of the journal Frontiers in Neurology

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