Name

Gliome du nerf optique associé au "Morning Glory Syndrome" : une terminologie qui prête à confusion ?

Morning Glory Disc Anomaly (MGDA) is a rare, mostly unilateral, ophthalmic disease with a severe visual loss due to a funnel-shaped excavation of a markedly enlarged optic disc opening. It is usually discovered upon systematic eye exam in young infants with strabismus or low visual acuity. Since it may be associated with other intracranial abnormalities such as midline developmental or vascular malformations, a cerebral MRI under general anesthesia is highly recommended. In some cases, radiologists report concurrent enlargements of the ipsilateral optic nerve or chiasm, termed « low grade glioma », a terminology that, albeit hypothetical, often leads to repeated neurologist consults and serial MRI follow up. The aim of this observational study was to assess the frequency of these optic nerve or chiasm thickenings in patients with MGDA and to report their evolution over time.

All patients with MGDA who received cerebral MRI at the Fondation Rothschild were retrospectively searched for in the clinical and radiological records of the computerized database, using the Query Software. We collected the clinical parameters (age at first MRI, gender, most recent measure of visual acuity of the affected eye, serous retinal detachment occurrence, syndromic association), along with the radiological features (report of « optic pathway glioma », evolution when MRI follow-up was available, report of associated intracranial abnormalities).

From January 2011 to November 2019, a total of 24 patients (15 females and 9 males) with MGDA were given a cerebral MRI. Median age at first MRI was 3 years. The average best corrected visual acuity was 0.38 logMAR (n=10); in the other patients, visual acuity was either not available (n=6), limited to hand movements or counting fingers or light perception (n=4), or reduced to no light perception (n=3). Most cases were unilateral (n=21/24), and no syndromic association was found. Retinal detachment was found in eight patients (33.3%) and one patient showed evidence for peripapillary schisis. Eight patients (33.3%) had MRI evidence for optic pathway glioma, the localization of the enlargement being intra-orbital (n=7), at the apex (n=5), intra-cranial (n=7) or in the chiasm (n=7). In the three patients for whom an MRI follow-up was available, no evolutive thickening was observed over time. Interestingly, two patients were addressed to an onco-ophthalmologic reference center for specific advice, and in one case of MGDA with atypical grade II glioma lesion and no light perception the patient was even proposed an ipsilateral optic nerve section. No patient showed associated radiologic intracranial abnormalities.

Only five cases of « low grade glioma » or optic nerve enlargement in patients with MGDA have been described so far in the literature (1,2). Serial MRI scans, that were available for three of them, revealed no growth at follow-up (2).

This retrospective cohort seems to comfort the idea that MGDA is frequently associated with an ipsilateral enlargement of the optic nerve and/or of the chiasm that is non-evolutive, an argument that challenges the usefulness of serial MRI scans follow-up.