Persisting Embryonal Infundibular Recess in Morning Glory Syndrome: Clinical Report of a Novel Association

Discussion

MGDA is a sporadic condition, but it has been previously described as an isolated finding in a mother and child.⁹ Our patients were initially referred for pituitary MR imaging due to growth hormone deficiency, revealing a PEIR. The pituitary stalk was apparently duplicated on coronal images because of its tubular morphology and direct communication with the third ventricle. This finding should be carefully evaluated to avoid a potential misdiagnosis of other pituitary stalk malformative conditions, such as duplication.² The anomalous infundibulum perforation, in the absence of meningoencephaloceles, was clearly defined by high-resolution volumetric T2-weighted sequences (CISS and driven equilibrium in our cases). To the best of our knowledge, among reported MGDA cases in the literature, none had associated PEIR.

Among the possible midline abnormalities reported in MGS, there is the craniopharyngeal canal, not present in our patients.¹⁰ It represents a rare, well-corticated midline channel of the sphenoid body that develops from the sellar floor to the nasopharynx. Its origin has been hypothesized from incomplete closure of the Rathke pouch, the precursor of the adenohypophysis. This entity can be variably associated with encephalocele and hypopituitarism, most likely due to ectopic adenohypophysis and even tumors (gliomas, dermoids, teratomas, craniopharyngiomas, or adenomas).¹¹

Both of our patients had chiasmatic abnormalities with thickening and inferior drooping. On the basis of our experience and the lack of progression on follow-up imaging, we agree with Doneda et al¹² on the dysplastic and not neoplastic nature of the chiasmal thickening. In our second patient, in the absence of sellar floor defects, chiasmatic prolapse was related to ipsilateral sphenoidal hypoplasia, which could be considered the less severe form of a sphenoid malformative spectrum ending with a meningoencephalocele.

While corpus callosum partial agenesis has already been described in MGS,² global thickening, as observed in the second case, though in the absence of dysmorphisms or psychomotor delay, has never been reported.

Intracranial vascular abnormalities in MGS, not necessarily ipsilateral to the optic disc anomaly, could be due to the close relationship of the ICA and optic vesicle development during the fourth week of gestation.^1,4,12 Arterial involvement, most commonly affecting the anterior circulation, ranges from mild hypoplasia to focal stenosis or complete agenesis and progressive Moyamoya syndrome.^3,13 Arterial alterations in our patients were not associated with cerebrovascular reserve impairment. While it is not possible to completely exclude Moyamoya syndrome without more prolonged monitoring, we believe a nonprogressive arterial dysplasia is a more probable diagnosis. We recommend PWI in addition to MRA and follow-up for MGS-associated vasculopathy evaluation.