Fenestrated optic nerve in craniopharyngioma.

Sir,

Fenestrated optic nerve (nervus opticus fissus) has been described de novo or in association with ruptured aneurysms of the anterior circulation. Five mechanisms have been described- a penetrating embryonic artery with aneurysm,[12] stream of blood splitting optic nerve during SAH subsequently allowing ingrowth of aneurysm,[3] aggressive unruptured aneurysm,[4] osseous trabeculae[5] (developmental) and de novo.[67]

This 10-year-old child was diagnosed to have sellar, suprasellar craniopharyngioma and was operated with right fronto-temporal craniotomy and excision. There was a tumor bulging from the sella lifting the chiasm and the optic nerves. Following intratumoral decompressionthe left optic nerve was found to be split with the medial portion of left optic nerve thinner than the lateral with a distinct arachnoid layer [Figure 1]. The chiasm was thinned out due to chronic compression by the tumor. There were no arterial loops/aneurysms or osseousbridges separating the two roots.

Figure 1

Subfrontal view showing bilateral optic nerves with split in left optic nerve and openedcapsule of craniopharyngioma

To the best of our knowledge, this is the first reported case in the literature of a craniopharyngioma associated with a split optic nerve.