鈍力に因る上膊神經叢根硬膜内離脱の發生機轉に關する研究

The Mechanism of Intradural Laceration of the Brachial Plexus Roots by Blunt Force

緒言

　鈍力に因る外傷性上膊神經叢麻痺の發生機轉に就いては種々の説がある。古は骨骼による神經叢の壓挫，即ち鎖骨，第1肋骨又は鎖骨，頸椎横突起間に於ける神經叢の壓挫等が原因と考えられていたが近來上膊神經叢の過伸展が有力な原因と見做される様になつた。又叢部に於ける出血，瘢痕絞扼等の結果起る二次的障碍も重視されている。

　上膊神經叢麻痺に於ける損傷部位は一般に神經叢部にあると考えられていたが，Bardenheuor （1909），和田（1914），　Reichle （1920），　Schallow　（1930），　Sehneck　（1930）氏等は損傷部位が椎間孔又は脊髓の極く近くにあることを思わせる臨牀所見或は手術所見を記載している。然るにFrazier ＆ Skillern （1921），岩原，森田（1939）氏等は鈍力に因る上膊神經叢麻痺の患者に椎弓切除術を施して上膊神經叢根が硬膜内で損傷されていることを確認した。以來上膊神經叢根硬膜内離脱は鈍力に因る上膊神經叢麻痺の重要な原因と見做されるに至つたが，その發生機轉に就いてに未だ詳かにされていない。

　私は新鮮な胎兒又は新産兒屍體を用いて實驗を行い，自家臨床例と比較檢討して，その發生機轉こ關して聊か知見を碍たので？に論述する。

The mechanism of intradural laceration of the spinal root by blunt force is not still clarified. Therefore this time, I studied on this point by using thirty-five fresh foetal cadavers and obtain-ed the following results.

I found that the laceration of the intradural spinal root occurred in forcible pulling of the upper extremities in various directions and at the same time bending the neck excessively in the oppsite direction.

Without exception, the laceration of the spinal root was found at the proximal part of the spi-nal root fibers, but no injury was found in the spinal cord,

The in jured spinal roots were divided in follow- ing three kinds: 1) complete-laceration, 2) partial laceration & 3) over-stretching without laceration.

In cases in which the roots were partly lacerated, the lacerations were always found only in the upper spinal root fibers. Among the cases in whi-ch complete lacerations occurred, small holes were found on the wall of the dura.

By pulling the arms of the foetus upward, I found that the eighth cervical and the first tho-racic roots were completely or partly lacerated, while pulling the arms in other directions, for-ward, downward & outward, the cervical roots. from the sixth to the eighth, were most frequen-ty lacerated.

In addition to the intradural spinal root leaera-tion, I found in many cascs rupture of the trun cus cranialis just at the margin of the scalenus anterior muscle.

As the result of these studies and by our clinicsl experiences, I conclude that the paralysis of the brachial plexus due to intradural lacerations of the spinal roots is caused by forcible pulling of the upper extrermiies and bending the neck in the opposite direction. Traction causes the spinal root fibers to over-stretch and the laceration occurs at the proximal portion of the spinal root, which is the point of least resistance, and there the root ers change their direction.