additional CNS abnormalities and, in particular, to evaluate the location of the posterior pituitary gland (Fig. 5.4). Ectopic posterior pituitary glands are associated with a high incidence of hormonal problems such as growth hormone deficiency, diabetes insipidus, hypothyroidism, and adrenal insufficiency. Prompt treatment can be life saving. Optic nerve hypoplasia, absence of the septum pellucidum and agenesis of the corpus callosum, is called septo-optic dysplasia or de Morsier’s syndrome (Fig. 5.5).

5.1.7 Treatment

There is currently no treatment to augment the axonal tissue in the optic nerve. Care must be taken to monitor for amblyopia, especially in cases with unilateral or asymmetric disease. Occlusion therapy can be instituted to maximize vision potential. Patients with posterior pituitary ectopia as well as any patient with severe hypoplasia regardless of the MRI finding should be evaluated by an endocrinologist for possible hormonal supplementation. A history of neonatal jaundice suggests hypothyroidism while neonatal hypoglycemia or seizures suggest panhypopituitarism. A T4 level should be obtained in infants with ONH to rule out neonatal hypothyroidism. Patients with ONH and diabetes insipidus have significant problems with thermal regulation and should be monitored carefully during febrile illnesses.

Fig. 5.5 Absent septum pellucidum and agenesis of the corpus callosum

5.2 Morning Glory Disc Anomaly

5.2.1 Overview/Clinical Significance

The morning glory disc anomaly (MGDA) is a rare congenital dysplasia of the optic nerve head, first named by Kindler in 1970 [13]. However, Handmann described six cases with similar appearance in 1929 [14]. Vision is typically worse than 20/200, and approximately 30% of eyes eventually suffer a retinal detachment. There is a weak association with basal encephalocele [15].

MGDA is an excavated disc anomaly along with optic nerve coloboma and peripapillary staphyloma. However, MGDA is thought to arise from a different embryologic defect than these other entities.

The clinical appearance, as set forward by Kindler, involves a funnel-shaped optic nerve head with a dot of white tissue in the center. The retinal vessels are numerous, thin and straightened, and the origin is hidden. An elevated annulus of gray–black pigmented tissue surrounds the nerve (Fig. 5.6).

5.2.3  Genetics

MGDA is usually unilateral, and there have been no reported cases of familial inheritance.

The embryologic origin of the MGDA has been discussed by a number of authors, and there is some confusion in the nomenclature [16, 17]. Pollock draws a distinction between MGDA, optic nerve coloboma, and peripapillary staphyloma [18] (Table 5.2). He believes the primary defect in MGDA is a dilated junction between the optic stalk and optic vesicle. Invagination of the optic cup and formation and closure of the fetal fissure proceed normally, except for the cone-shaped extension of the optic cup lumen into the distal optic stalk. Therefore, the optic nerve head develops at the base of the excavation, instead of in the plane of the retina. The neurosensory retina and RPE arise from the inner and outer layers of the optic cup and line the excavation without a colobomatous defect. The retinal vessels are then obscured as they exit the optic nerve head by a glial remnant of the hyaloid system that fails to regress in the narrow confines of the excavation (Fig. 5.7). Because the retinal vessels arise in a plane posterior to the retina and may have bifurcated before reaching the edge of the defect, they appear more numerous. Contractile fibers can be present in the surrounding tissue, and the opening can be observed to widen and narrow.

Fig. 5.6  Morning glory disc. Note wide excavated disc with vessels disappearing into the grayish glial tissue covering the surface

5.2.5  Natural History

The MGDA is a stable malformation of the optic nerve. It is usually unilateral but can be bilateral and asymmetric. Visual potential is difficult to assess by appearance; therefore, amblyopia maybe superimposed thereby contributing to some or all of the visual loss. Amblyopia therapy may be necessary to maintain useful vision in some patients. A number of patients will develop retinal detachment in the eye with MGDA.