The effect of brain stem lesions on vasomotor nerves and the smooth muscle of the cerebral arteries--a morphological study.

Abstract

A morphological study was performed on the nerve fibers and the smooth muscle of the cerebral arteries in human brains with hypertensive intracerebral hematomas. In addition, an experimental study was also performed on dogs. Immediately after autopsy, the nerve fibers on the Willis circle and its main branches in five patients with hypertensive intracerebral hematomas were examined with Falck and Hillarp's fluorescent method and with Koelle's thiocholine method. The smooth muscle of the main cerebral arteries from ten brains with intracerebral hematomas, which had been preserved in 10% formalin, was studied with histochemical examinations. Bilateral hypothalamic lesions were made experimentally in 16 dogs, and the nerve fibers and the smooth muscle of the main cerebral arteries were examined by the histochemical method and with an electron-microscope. No adrenergic fibers were seen with the fluorescent method in any of the five patients. The cholinergic nerve fibers on the same arteries were observed with the thiocholine method. Examinations for cholinergic nerve fibers of arteries from the affected cerebral hemispheres of two patients did not show any enzymatic activity, while it was shown to be present in the intact hemisphere. Ten brains showed degeneration of the smooth muscle cells in the tunica media. Animal studies showed a decrease of the adrenergic and cholinergic nerve fibers from experimental hypothalamic injuries. The degeneration of the nerve fibers was observed with electron-microscopic examinations. Thus our findings in this study suggest that brain stem damage leads to the degeneration of the smooth muscle together with the adrenergic and cholinergic nerve fibers of the cerebral artery.