椎骨動脈周囲神経組織刺激時の瞳孔反応と自律神経の変化—Powers症候群の解析に関連して

Effects of Stimulation of the Vertebral Nerve Around the Proximal Vertebral Artery on Pupil and the Autonomic Nervous System : A contribution to Pathophysiology of Powers' Intermittent Vertebral Artery Compression Syndrome

　Powers症候群（椎骨動脈間歌的圧迫症候群）の病態に椎骨神経が如何に関わり合っているのかについて，猫20匹を用いて検索した。一側椎骨神経の低電圧電気刺激およびKイオンの局所適用は，刺激強度依存性に，刺激側の散瞳を起こし，より強い刺激では両側性の散瞳と昇圧反応を示した。鎖骨下動脈近位部の動脈周囲組織の低電圧刺激でも上述のような散瞳を示したが，鎖骨下動脈遠位部や肋頸動脈，肩甲頸動脈，内胸動脈では上述の瞳孔反応は全く示さなかった。椎骨神経の電気刺激により，刺激側の頸部交感神経幹から刺激強度依存性の交感神経遠心性活動の興奮が認められ，上部胸髄側角に位置する毛様体脊髄中枢から短潜時の誘発電位が認められ，また，副交感神経線維を含有する短毛様体神経においては抑制効果が認められた。これらの結果から，椎骨神経刺激時の散瞳反応には交感神経の興奮と副交感神経の抑制が関与していることが確認された。そしてこの中枢機序として，①椎骨神経に混在する感覚線維を介する毛様体脊髄中枢の興奮，②体性交感神経反射の関与，③視床下部の交感ならびに副交感神経中枢の関与などが複雑に関連していることが推論され，Powes症候群の症例に潜在する複雑な自律神経系の病態生理を説明する基礎的資料をなすものと考察した。

In order to elucidate the pathophysiology involved in Powers' intermittent vertebral artery compression syndrome, the author investigated sym-pathetic and parasympathetic changes produced by stimulation of nerves around the proximal vertebral artery (the vertebral nerve) in anesthetized and immobilized cats. These changes were observed mainly through pupillary changes, pulse and blood pressure, evoked potentials in the lateral horn of theupper thoracic cord (centrum ciliospinale), in the cervical sympathetic trunk, and in the short ciliary nerve. Electrical stimulation of vertebral nerve and local application of K ion around the vertebral artery produced stimulus-dependent ipsilateral mydriasis ; when stimulation of higher strength was applied pronounced ipsilateral and mild contralate-ral mydriasis and hypertension occurred. Electrical stimulation of perivascular tissue around the sub-clavian artery proximal to origin of the vertebral artery showed ipsilateral mydriasis ; while on stim-ulating the distal subclavian, the costcervical, the omocervical and the internal thoracic arteries did not show any pupillary response. Neuronal dis-charges in the lateral horn of upper thoracic cord and in the cervical sympathetic trunk showed stimu-lus-dependent increases on stimulating the verte-bral nerve ; while, inhibitory responses were obser-ved in the short ciliary nerve formed by parasympa-thetic nerve fibers.

From the data available, it seems likely that the stimulation of periarterial neural structure of the vertebral artery produced sympathetic excitatory as well as parasympathetic inhibitory neuronal discharges simultaneously may probably be derived from the integrating autonomic center in the hynnthalamils.