Regarding the article “The Pupillary (Hippus) Nystagmus”: A Possible Clinical Hallmark to Support the Diagnosis of Vestibular Migraine
Pupillary nystagmus, defined as the cyclic dilation and contraction of the pupil in the presence of constant light, has been recognised for many years.
In this study, the authors sought to determine the incidence of pupillary nystagmus in patients with vestibular migraine, thereby obtaining objective data for the diagnosis of this very common condition.
The diagnosis of vestibular migraine is essentially clinical (Consensus document of the Bárány Society and the International Headache Society), with additional diagnostic tests to be used to rule out other conditions considered in the differential diagnosis, which makes this new test even more useful in patients who do not meet all the established diagnostic criteria.
In this retrospective study, the presence of pupillary nystagmus was investigated in a group of 30 patients diagnosed with vestibular migraine and compared with the same assessment in a group of 50 patients with vertigo of non-migraine origin.
Of the patients with vestibular migraine, only two did not present with pupillary nystagmus. In the group of 50 patients without vestibular migraine, three had pupillary nystagmus and 47 did not exhibit this sign. Analysis of these findings yields a test with a sensitivity of 0.93% and a specificity of 0.94%.
The authors suggest that the presence of pupillary nystagmus is an objective sign (even during the intercritical period) which should be used to supplement the international criteria for the diagnosis of vestibular migraine.
This study is limited by the small sample size and the heterogeneity of the control group. Further studies are required, involving a larger number of patients and a more detailed characterisation of those involved, as well as a more accurate assessment of pupillary nystagmus (through an ophthalmological examination).
Text by Teresa Matos
