Optic nerve hypoplasia with intracranial arachnoid cyst

Background. The frequent association between optic nerve hypoplasia (ONH) and other central nervous system abnormalities has been widely reported in the literature. Occasional reference has been made to arachnoid cyst as one of the associated findings. Method: The charts and neuroradiologic findings of the 40 patients with ONH seen in our department as well as the Visually Impaired Program during the past 8 years were reviewed. Results. An intracranial arachnoid cyst was present in 5 of the 40 patients (12.5%) with ONH and visual impairment. These patients' clinical and neuroradiologic findings are reported here. Conclusion: The presence of an intracranial arachnoid cyst in a patient with hypoplastic optic nerves could occur as a coincidental association between these lesions. Alternatively, a common mechanism could give rise to both abnormalities. Three such possibilities-including damage to the developing visual pathway by the arachnoid cyst, absence of an axonal guidance molecule similar to netrin-1 identified in the mouse, or a common genetic mutation involving the myocillin gene causing both abnormalities-are considered.