Morning Glory anomaly

From EyeWiki



Disease Entity

Morning Glory Disc Anomaly

Disease

Morning glory anomaly is a rare congenital malformation of the optic nerve.[1] It is named for its resemblance to the morning glory flower.[2] When it is associated with systemic signs and symptoms, it is known as morning glory syndrome.

Etiology

The embryonic origins of morning glory anomaly is not clear but is hypothesized to be either due to a defect in fetal fissure closure or a primary mesenchymal abnormality.[1]

Risk Factors

Morning glory anomaly is more common in females and more rare in African-Americans.[3]

Systemic Associations

The morning glory disc anomaly can be seen with transsphenoidal basal encephalocele. In the basal encephalocele, a congenitally malformed outpouching of the meninges, often containing the optic chiasm and hypothalamus, protrudes through a defect in the sphenoid bone.[3] Children with this structural defect often have dysmorphic features, including a wide head, flat nose, hypertelorism and a midline notch in the upper lip.[3] Many patients with transsphenoidal encephalocele also have callosal agenesis, leading to dilation of the lateral ventricles.[4]

Morning glory disc anomaly is also associated with cerebrovascular anomalies, including hypoplasia of the cerebral arteries and Moyamoya.[3] Other reported associations include with the PHACE syndrome (posterior fossa malformation, large facial hemangioma, arterial anomalies, cardiac anomalies, eye anomalies) and neurofibromatosis 2.[3] 

Diagnosis

Symptoms

Visual acuity can vary from normal 20/20 to very poor(20/200 to count fingers) depending on the extent of optic nerve anomaly. Patients often have visual field defects, commonly enlarged blind spots.[2][3] However, amblyopia may be a contributing factor to the poor vision in unilateral cases. Patients are also often initially referred for leukocoria or strabismus.[2]

VF Morning Glory.jpg

Clinical Diagnosis

The optic nerve appears large and funneled.[3] There is a conical excavation of the dysplastic optic disc and the surrounding posterior pole, filled with glial tissue.[2] An increased number of straight retinal vessels arise from the disc margin and peripapillary pigmentation can also been seen.[2] The term “macular capture” is used when the macula is involved in the excavation.[3] Contractions of the optic nerve have also been described and is attributed to the presence of myofibroblasts in the papillae.[2] Due to unilateral involvement in most cases, an afferent pupillary defect can be noted.[2]

Morning glory.jpg

OCT morning glory.jpg

Differential diagnosis

Optic nerve coloboma: Optic nerve colobomas will typically appear as a white excavation involving the inferior portion and extending to the choroid and retina.[2] Optic nerve colobomas also lack the central glial tuft and peripapillary pigmentation seen in morning glory disc anomalies.[3] It is important to differentiate from a morning glory disc anomaly because optic nerve colobomas can be associated with systemic syndromes such as CHARGE (coloboma of the eye, heart defects, choanal atresia, growth retardation, genitourinary abnormalities and ear abnormalities).[2]

Peripapillary staphyloma: Peripapillary staphyloma is another excavation of the optic disc where the optic disc is seen at the bottom of the excavation.[3] It can be differentiated from morning glory disc anomaly by the lack of central glial tuft and normal retinal vasculature.[3]

Management

There is no treatment for morning glory disc anomaly. However it is important to optimize visual acuity to prevent amblyopia.[2] Dilated fundus exams should be done to detect serous retinal detachments that tend to originate in the peripapillary area and extends to the posterior pole.[3] Brain imaging (MRI, MRA and/or CTA) should be done to rule out CNS involvement, including basal encephalocele, Moyamoya and other structural or vascular abnormalities.[2] Surgical correction of the transsphenoidal basal encephalocele can be extremely difficult or even contraindicated due to the vital structures that may be found in the herniation, included the optic chiasm, the hypothalamus, and the anterior cerebral artery.[3]

References

  1. 1.0 1.1 Cennamo, G et al. 2009. Evaluation of Morning Glory Syndrome with Spectral Optical Coherence Tomography and Echography. Ophthalmology. 117:6, p1269–1273
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Lee, BJ and Traboulsi, EI. 2008. Update on the Morning Glory Disc Anomaly. Ophthalmic Genetics 29:2, p47-52
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Brodsky, M.C. 2010. Congenital Optic Disc Anomalies in Pediatric Neuro-ophthalmology. 2nd ed. New York: Springer
  4. Brodsky, MC. 1994. Congenital Disc Anomalies. Survey of Ophthalmology 39:2, p89-112