Aberrant pyramidal tract—Sudan III染色による検討

ABERRANT PYRAMIDAL TRACT: A STUDY WITH SUDAN III STAIN

　抄録　標準的脂肪染色法であるSudan IIIを用いて橋脳内側毛帯内のaberrant pyramidal tractを6症例で検討した。4例は破壊性病変による錐体路の二次変性をきたしたもの，他は錐体路を冒した変性疾患の2症例である。Aberrant pyramidal tractの変性は前4例で両側性，あるいは橋底部の錐体路変性と同側に認められた。一方，後2例ではこのtractは確認されなかった。Aberrant pyramidal tractは最近の神経解剖の教科書には記載されていないが，その生理的役割を知るためにMRIでも注目すべき部位と考えられる。

The aberrant pyramidal tracts in the pontine medial lemnisci were studied, using standard Sudan AI stain, in six cases of chronic pyramidal tract degeneration. Three of the six cases had bilateral or unilateral cerebral destructive lesions, one cervical hematomyelia with rare retrograde pyramidal tract degeneration, one classical amyo-trophic lateral sclerosis, and one atypical motor neuron disease with striatonigral degeneration.

Except for the latter two cases the aberrant pyramidal tract degeneration was confirmed bila-terally or on the side ipsilateral to the pyramidal tract degeneration in the pontine base. This de-generation could also be found, on careful ex-amination, with other stains, i. e., H & E, Luxol fast blue-periodic acid Schiff and modified Biel-schowsky. Significant change was not observed in the medullary medial lemniscus in any case.

The different results observed in the aberrant pyramical tract between the destructive and de-generative disorders might be pathogenetically important. Reservation, however, may be required since the number of the cases of degenerative disorders in this study was limited. A possible factor for this difference is the survival length which might have erased degradation products altogether. Another factor is the sensitivity of Sudan RI in comparison with the Marchi's method which might demonstrate more subtle evidence of degeneration but with its intrinsic capricious staining characteristics.

The physiological role of the aberrant pyrami-dal tract, which has been neglected in the recent textbooks of neuroanatomy, may become of clinical interest with high-quality MRI in cases such as isolated cranial motor nerve palsy without con-comitant paralysis of the extremities.