Toshiharu Sasano

Experimental Study of Nystagmus Induced by Injecting Various Solutions into the Middle Ear Cavity

Injecting of various solutions into the middle ear cavity of cats and rabbits provoked certain characteristic types of nystagmus which resembled caloric nystagmus or clinical cases of peripheral vestibular disorders. Solutions with different degrees of specific gravity, osmotic effect and ion composition were used in this study. Direction-changing positional nystagmus, irritative nystagmus, and paralytic nystagmus were elicited according to the physical or chemical properties of each solution. Histological findings showed mild changes in the perilymphatic space and/or in the endolymphatic space in the period with some characteristic types of nystagmus. Infiltration of the substances into the inner ear fluids from the middle ear cavity via a round window membrane were probably responsible for these types of nystagmus.

Importance of Cervical Muscles in Galvanic Body Sway Test

Retro-auricular galvanic stimulation in Rombergs posture elicits body sway which consists of an initial response (IR) and a deviation response (DR). Generally, anodal stimulation of the right side elicits IR to the left and DR to the right. We measured the deviation response (VDR) in various conditions in normal subjects. There was no significant difference between mean VDR in the standing posture weighted on the left foot (0.49 +/- 0.17 cm) and on the right foot (0.39 +/- 0.20 cm). Stimulation in the squatting posture also elicited IR to the left and DR to the right. Stimulation of the right side produced DR backward and to the right in the condition of the head facing to the right, and forward and to the right in the condition of the head facing to the left. The same body sway response as the after galvanic stimulation was also induced by non-galvanic maneuvers like inclining the head or moving the finger. Anodal stimulation in the sitting posture elicited slight but apparent head inclination to the stimulated side. These results suggest that cervical muscles play an important role in the galvanic body sway test (GBST), viz. IR and DR seemed to be secondarily produced by changes in the muscular tension of the neck.

A Case Of Delayed Endolymphatic Hydrops

A 30-year-old male with delayed endolymphatic hydrops was given a sac operation. An intradural portion of the endolymphatic sac was resected and the epithelial surface was examined under a scanning electron microscope. The epithelium showed fibrous degeneration and disappearance of the epithelial cells. Pathogenesis of degeneration of the endolymphatic sac is discussed.