垂直性one-and-a-half症候群とseesaw眼振を認めた視床中脳梗塞の1症例

A Case Presenting Vertical One-and-a-half Syndrome and Seesaw Nystagmus due to Thalamo-mesencephalic Infarction

要旨　症例は58歳女性の脳梗塞例。上方注視麻痺と右眼の下方注視麻痺，さらにseesaw眼振（SSN）を示した。MRIではrostral interstitial nucleus of the medial longitudinal fasciculus（riMLF）とCajal間質核を含む右視床中脳梗塞を認めた。上方注視麻痺がより強く出現し，下方注視は不全麻痺であったことより，垂直性one-and-a-half 症候群の病巣は riMLFの背外側が尾内側より強く障害されたと考えられた。つまり一側のriMLFから両側に投射する上方注視の遠心線維が障害されるとともに，同側の下直筋を支配する線維と対側の滑車神経核に向かう線維が障害されたと考えられた。またriMLFの近傍にあるCajal間質核の障害によりSSNが同時に出現したと考えられた。

A 58-year-old woman presented conjugate upgaze palsy and monocular paresis of downward gaze in the ipsilateral eye（vertical one-and-a-half syndrome; VOHS）as well as seesaw nystagmus（SSN）. Vertical oculocephalic response and conjugate horizontal gaze were preserved. Magnetic resonance imaging revealed a right thalamo-mesencephalic infarction including the rostral interstitial nucleus of the medial longitudinal fasciculus（riMLF）and the interstitial nucleus of Cajal. On the 22nd hospital day SSN was disappeared, and then on the 32nd day VOHS was improved. The lesions of VOHS may have affected the efferent tracts of riMLF and the descending fibres to the ipsilateral subnucleus of the inferior rectus and contralateral subnucleus of the superior oblique. Furthermore, it was assumed that SSN was caused simultaneously by a lesion in the interstitial nucleus of Cajal existing in the adjacent area of riMLF.