下垂体腺腫に伴ったシーソー眼振の1症例

A Case of Pituitary Adenoma Presenting Seesaw Nystagmus

　はじめに

　シーソー眼振は左右の眼球が回旋しながら交互に上下に動く異常な眼球運動で，障害部位としてはCajal間質核などが想定されているが未だ不明の点が多い。今回，下垂体腺腫症例にみられたシーソー眼振を経験したので報告し，その発症メカニズムについて考察を加えた。

Seesaw nystagmus (SSN) is a relatively uncom-mon oculomotor disorder characterized by alternat-ing elevation and intorsion of one eye with depres-sion and extorsion of the other eye.

A 42-year-old man presented with a large pitui-tary adenoma with bitemporal hemianopia. He complained of poor vision in his left eye. Pendular SSN was seen. The tumor was removed with the trans-sphenoidal approach. Six months after the operation, SSN had disappeared. It is assumed that secondary involvement of central otolithic/ves-tibular pathways at the diencephalic-mesencephalic junction is involved in SSN. This is possibly due to a vascular insufficiency to the interstitial nucleus of Cajal.