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The association of congenital optic nerve head anomalies, especially of the morning glory disc variety, with moyamoya disease is well recognised and has been described in a number of patients.1–4 To the best of our knowledge, the occurrence of a congenital third nerve palsy with moyamoya disease and a congenital optic nerve head anomaly has not been reported. We describe a patient who demonstrated the ipsilateral occurrence of these three congenital abnormalities, strengthening the association of congenital optic nerve and carotid abnormalities and suggesting a common underlying aetiology.
A 3 year old boy was examined because of left sided exotropia and blepharoptosis. His birth, developmental, and medical histories were unremarkable. Visual acuity was 20/25 right eye and 20/200 left eye. There was a near total ptosis of the left upper eyelid. There was a large exotropia and a small hypotropia of the left eye that he was unable to adduct, elevate, or infraduct. His right pupil reacted briskly to light, but the left pupil was dilated and sluggishly reactive to light. A left relative afferent pupillary defect was present. Fundus examination disclosed an anomalous left optic disc and peripapillary area, with what appeared to be an enlarged scleral opening and a staphylomatous defect around the optic papilla (fig 1). The rest of the retina was normal. The right fundus was normal.
A magnetic resonance imaging scan and magnetic resonance angiogram of the brain revealed an absence 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 (fig 2).
This patient has an optic nerve head malformation that appears to be most compatible with a peripapillary staphyloma or a variant of a morning glory disc anomaly (MGDA). MGDA is one of the cavitary optic disc malformations comprising a congenital, funnel-shaped excavation of the posterior peripapillary sclera that incorporates the optic disc. In addition to the anomalous retinal vasculature that distinguishes the MGDA from other excavated optic disc anomalies such as optic disc coloboma, the association of morning glory disc with carotid circulation anomalies, especially moyamoya disease has been reported.1–5 Moyamoya disease is a rare cerebrovascular disorder characterised by stenosis or occlusion of the distal internal carotid arteries. Progressive brain ischaemia triggers formation of a collateral vascular network in the basal ganglia region referred to as moyamoya (Japanese word for “cloud of smoke”) vessels. The most common clinical features are transient ischaemic attacks and stroke in children, and intracranial haemorrhage in adults. Our patient appears to have an extreme form of this condition with total absence of the left internal carotid artery and collateral vessel formation typical of moyamoya disease.
Congenital third nerve palsy was once thought not to be associated with other neurological abnormalities. More recent studies have however revealed a high incidence of associated neurological deficits such as hemiparesis, seizures, hemianopia, and hydrocephalus.5 An association of congenital third nerve palsy with MGDA or peripapillary staphyloma has not been reported to the best of our knowledge. The third nerve palsy in the present case may be due to an ischaemic brainstem event or a developmental defect affecting the left third nerve nucleus.
The constellation of abnormalities in our patient confirms the association of moyamoya vessels with optic nerve head malformations such as MGDA or peripapillary staphyloma, and the possible neurological complications of this malformation complex, as evidenced by the third nerve palsy in this case. It is possible that an intracranial vascular dysgenesis may underlie some cases of the morning glory disc anomaly. We strongly recommend magnetic resonance angiography in conjunction with magnetic resonance imaging to identify carotid vascular anomalies in patients with MGDA or peripapillary staphylomas, especially in the presence of other neurological signs such as a congenital third nerve palsy.