脳幹の形態計測学的試み—橋上部での計測法の開発と応用

MORPHOMETRY OF THE BRAINSTEM WITH TRANSVERSE SECTION OF THE UPPER PONS

　抄録　脳幹の大きさを定量的に評価する方法として，橋上部（青斑核のレベル）の水平断断面での計測法を開発した。ホルマリン固定剖検脳の大脳および小脳をはずして脳幹のみとし，橋の中脳および延髄との境界部で切断した後，4枚の水平断切片を作り，その吻側より2枚目の切片の吻側面を計測対象とし，橋全体の断面積値および内側毛帯の腹側を境として脳幹被蓋と底部に分けてそれぞれの断面積値を計測した。非神経疾患の23例（年齢16-77歳）では，全断面積値（被蓋＋底部）は562±85mm²，被蓋断面積値は136±19mm²と症例間の差が多少認められたが，全断面積値に占める被蓋断面積値の割合は24.4±2.3％と各例が近似の値を示し，正常の脳幹の形態を表わすに有効な指標となると考えられた。また上記の断面の全体および被蓋の前後径値を計測し，全前後径値に占める被蓋前後径値の割合を求めると35.1±3.4％となり，肉眼観察時にきわめて簡便に利用しうる方法であった。本計測法をパラフィン包埋染色標本に応用した結果，OPCAの症例や点頭てんかんを示した小児発達障害例で被蓋断面積値が小さいことが明らかとなった。

The authors developed new method of morphc-metry in the brainstem, which used transverse section of the upper pons.

After fixation with formalin, the brainstem was separated from the cerebrum and the cerebellum. Both junctions of midbrain-pons and pons- medulla were cut and then the pons was holizontally sepa-rated into four slices, The oral surface of the second slice from oral side, in which the central portion of the locus ceruleus is located, was mea-sured with computed digitizer after enlarging the picture.

The authors measured the total size of the slice in the pots (TetalS), the tegmentum size (TegS), the total length (TotalL), the tegmentumlength (TegL) and so on. The tegmentum was separated from the base along the ventral line of the medial leminiscus.

In the study of 23 control cases (16 to 77 year old, 13 male and 10 female, all were Japanese), TotalS (563±85mm) and TegS (136±19mm) ran-ged to some extent, while the percentage of the tegmentum size to the total size (TegS/TotalSx 100: %TegS) distributed in narrow range (24.4± 2.3%), which was considered to be an appropriate index to reveal normal structure of the upper pons. The percentage of the tegmentum length to the total length (%TegL) was also an appropriate and a simple index. Using this method to staind preparation, it was confirmed that the tegmen-tum size of such cases with olivopontocerebellar atrophy or infantile spasms were significantly small.