In positional (episodic) dizziness, these rules shift. Emergency physicians must learn some of the details about nystagmus as it can really help us to make a confident diagnosis.

The presence/absence of nystagmus, but more important, its quality, is very helpful in making a specific diagnosis in dizzy patients.

—Jonathan Edlow, MD
Boston

Response

Jonathan, thank you for submitting your thoughts. I will certainly defer to your expertise on this topic and appreciate the work you have done to improve our understanding of headache and other serious neurological diseases.

Honestly, I don’t think, fortunately for me, we are that far apart on our thinking.

My statement, “Nystagmus is an unreliable sign and does not differentiate serious neurological disease from other causes of dizziness,” was made in reference to the article by Chase et al, which stated, “Nystagmus was only present in one-third of those with stroke and in one-fifth without stroke.”3 Thus, nystagmus is an unreliable sign with respect to ruling in or ruling out stroke, particularly when, as you noted, many emergency physicians only document its presence or absence.

This is much akin to the ECG analogy you provided: “‘the presence of ECG changes is unreliable’ for diagnosing an acute coronary syndrome.” Although I agree completely that all ECG changes are not created equal, I do think that ECGs are unreliable for diagnosing ACS. ECGs alone, their specific abnormalities, and the presence or absence of those abnormalities are unreliable in exclusively ruling in or ruling out ACS. Thus, they are an important part of the evaluation but could never be used in isolation for risk stratification.

My intent was to draw a bright line between reliability and usefulness. It appears we agree on two things for certain: “the mere presence of any kind of nystagmus does not help to differentiate peripheral from central causes of the acute vestibular syndrome,” and that, when present, the quality of nystagmus does have utility, particularly when a detailed assessment can be performed, as you have adeptly outlined in your letter.

Thank you for the instruction and valuable input.

—Kevin M. Klauer, DO, EJD, FACEP

Medical Editor-in-Chief, ACEP Now

References

1. Redekop GJ. Extracranial carotid and vertebral artery dissection: a review. Can J Neurol Sci. 2008;35:146-152.
2. Merwick Á, Werring D. Posterior circulation ischaemic stroke. BMJ. 2014;348:g3175
3. Chase M, Joyce NR, Carney E, et al. ED patients with vertigo: can we identify clinical factors associated with acute stroke? Am J Emerg Med. 2012;30:587.