Abstract
Purpose:
Spasmus nutans is a type of nystagmus that has been known for years to be benign, while recent studies have shown that it sometimes reveals serious neurological or retinal disease. We tested the hypothesis that spasmus nutans is most often not benign and idiopathic. We performed a retrospective, observational study to better understand the conditions associated with spasmus nutans-type nystagmus, as well as the incidence of these conditions.
Methods:
Children referred to the neuro-ophthalmology clinic between November 1, 2009 and November 1, 2014, for a spasmus nutans and having benefitted from a systematic work-up were retrospectively reviewed. Spasmus nutans was defined as a pendular nystagmus with a high beating frequency (>5Hz), a small amplitude and a phase dissociation between the two eyes. It could be intermittent, horizontal, vertical, torsional or multidirectional and dissociated to the extent of being purely monocular. It could be associated with head tilt or head nodding. The work-up included neuro-ophthalmological examination with dilated fundus, recording of the nystagmus (video, eye tracking with a child-friendly dedicated infrared photo-reflectometry eye tracker, Ober Consulting®, Poland, when possible) cerebral imaging (MRI-scan) and electroretinography (Metrovision®, France). Cases with incomplete investigations, cases with already known diagnosis and also incidentally presenting a spasmus nutans and cases with obvious associated photophobia at the first visit were excluded. The combination of these data allowed us to classify each case in one of three groups of categories of spasmus nutans (revealing a neurological disease, revealing a retinal disease, or idiopathic) and to compare their relative proportions.
Results:
Thirty-two children (19 males) were included. The nystagmus had been noticed at a median age of 5 months. In 53% of cases (n=17), it led to the diagnosis of another condition. Most often a neurological disease was diagnosed (34%, n=11) such as chiasmal gliomas (22%, n=7), while 13% (n=4) of the children exhibited a retinal dysfunction. In 47% (n=15) of cases, spasmus nutans was considered benign idiopathic.
Conclusions:
In this study, spasmus nutans-type nystagmus was, in the majority of cases, the revealing symptom of another disease, often severe, and not a benign clinical entity. A systematic work-up should be considered in any case of a child who presents with spasmus nutans.