Morning Glory Disc Anomaly and Moyamoya Vessels

The morning glory disc anomaly comprises a congenital excavation of the peripapillary fundus, enlargement of the optic disc, anomalous peripapillary glial tissue, and a complex pattern of retinovascular anomalies.¹ Unlike other optic disc anomalies, the morning glory disc anomaly is consistently associated with a profound retinal vascular dysgenesis. We describe a patient who had signs of middle cerebral artery occlusion and moyamoya vessels ipsilateral to a morning glory disc anomaly.

A 5-year-old Asian boy was evaluated for decreased vision in the left eye of unknown duration. His birth, developmental, and medical histories were unremarkable. Visual acuity was 20/25 OD and 20/100 OS. A left relative afferent pupillary defect was present. Funduscopic examination in the left eye (Figure 1) revealed a morning glory disc anomaly, a persistent hyaloid artery, and a chronic macular hole accompanied by rhegmatogenous retinal detachment limited to the posterior pole.

A magnetic resonance imaging scan and magnetic resonance angiogram of the brain disclosed narrowing of the left intracranial carotid artery and its bifurcation into middle and anterior cerebral arteries. The lenticulostriate arteries were increased in size, consistent with moyamoya vessels (Figure 2).

Moyamoya disease is a rare cerebrovascular disorder of unknown etiology characterized by progressive bilateral stenosis or occlusion of the distal internal carotid arteries.² The stenosis can progress to involve the proximal anterior and middle cerebral arteries. Progressive brain ischemia triggers formation of a collateral vascular network in the basal ganglia region referred to as moyamoya vessels. The disorder is more common in Asians, and the name moyamoya derives from the Japanese term for "puff of smoke," which describes the angiographic appearance of the abnormal vessels. The most common clinical features are transient ischemic attacks and stroke in children but intracranial hemorrhage in adults. The natural history of unilateral moyamoya vessels is unknown, and the prognosis depends on the condition of the circle of Willis and its ability to provide blood from the unaffected side.

Moyamoya is usually an idiopathic disorder, or is sometimes acquired in the setting of cranial irradiation or atherosclerosis. However, moyamoya vessels can be associated with underlying congenital conditions such as neurofibromatosis, tuberous sclerosis, sickle cell anemia, Down syndrome, saccular aneurysms, and arteriovenous malformation.² Our patient had none of these disorders.

Anomalous retinal vasculature is one of several features that distinguish the morning glory disc anomaly from other excavated optic disc anomalies such as optic disc coloboma and peripapillary staphyloma.¹ With rare exceptions, the central retinal vasculature is ophthalmoscopically absent in the morning glory disc anomaly. The major retinal vessels curve abruptly as they emerge from the periphery of the optic disc, then run an abnormally straight course over the peripapillary retina. The vessels appear to be increased in number, and it may be difficult to distinguish arterioles from venules. Arteriovenous communications frequently interconnect the major retinal vessels, producing a rosette or arcade appearance on fluorescein angiography. The anatomical basis of this anomalous retinovascular system is speculative, since all histopathological descriptions have lacked clinical confirmation.

The association of morning glory disc anomaly with intracranial vascular anomalies is probably underrecognized, since carotid angiography is rarely performed in these individuals. Hanson et al³ described a 9-year-old girl with a morning glory disc anomaly in whom carotid angiography disclosed multiple branch occlusions of the ipsilateral middle cerebral arteries associated with moyamoya vessels in the region of the basal ganglia. A second patient with a morning glory disc anomaly had a history of multiple facial hemangiomas. Carotid angiography disclosed occlusion of the ipsilateral internal carotid artery at its origin with reconstitution intracranially via an enlarged branch of the right internal maxillary artery.

Our patient confirms the association of moyamoya vessels with the morning glory disc anomaly and strengthens the argument that an intracranial vascular dysgenesis may underlie at least some cases of the morning glory disc anomaly. Magnetic resonance angiography is a noninvasive screening technique that is widely available. We advocate its use in conjunction with routine magnetic resonance imaging to identify and further define the prevalence of intracranial vascular anomalies of the carotid system in patients with anomalous optic discs of the morning glory variety.

Reprints: Grant T. Liu, MD, Hospital of the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19104.