Sensation of the nasal mucosa. Physiological and neuro-histological study

Abstract

Aiming to resolve the problem on sensation of the nasal mucosa, the anterior part of the inferior turbinate was stimulated with rectangular pulse generated from an electrostimulator, and the subjective threshold of intensity (volt) and the objective observation with GSR were measured in normal, sinusitis, atrophic rhinitis, hypertrophic rhinitis etc.A silver-wire of 0. 4mm in diameter, the end of which was covered by a cotton-ball soaked with normal saline solution, was used as an electrode, and a silver-plate of 55×100mm was applied to the wrist as the indifferent pole.Sensation of prick, pain or touch were produced by electric stimulation.The threshold in simple atrophic rhinitis was the lowest, and that in hypertrophic rhinitis was the highest: the thicker the turbinate, the higher was the threshold.Neuro-histological changes were investigated by means of Bielschowsky-Suzuki's silver impregnation at the same time.The mucosa was innervated abundantly by considerable fine nerve-fibers of myelinated and fine whose myeline-sheath were lost which were ramifying in plexiform. Most of them terminated freely in every layer of the mucose, but some in terminal bodies were seen only in the vascular layer.Normal density of nerve-endings was confirmed in normal cases and simple atrophic rhinitis. Rather low density was seen in hypertrophic rhinitis but was normal in turbinal hypertrophy due to cavernous tissues.The density in genuine atrophihic rhinitis varies according to the grade of pathologic process.Sensory nerve-endings were preserved well in the turbinal tissue of simple chronic inflammation, but lessened or absent in that of degenerative and destructive inflammation, and higher threshold in the latter was obtained. Such findings were confirmed in Wegener's granulomatosis.Generally, nerve-fibers show more resistance than other tissues against these pathologic process.In cases of nerve-injury due to invasion of tumors, the threshold rose abnormally high, and revealed at times insensitivity.It is concluded that threshold-shift depends on the distance between the electrode and nerveendings, the grade of pathologic changes of nerve-fibers, and on mucosa such as epithelial metaplasia and fibrosis.