Hidemitsu Isago

Utricular and Saccular Volumetry in Human Temporal Bones

Using serially sectioned human temporal bones, endolymphatic volumes of utriculus and sacculus were measured with the aid of a computer. The mean of the utricular volume was 8.187 mm3, and the saccular volume, 2.096 mm3. The former was 3.9 X the latter. The surface area of the macula utriculi was 3.271 mm2, and the macula sacculi was 2.188 mm2. The former was 1.5 X the latter. The study using pathologic temporal bones (Menieres disease, otosclerosis, and otitis media chronica) showed that the utricular volume could indeed increase, and the saccular membrane was found to be more fragile than the utricular membrane in those diseased conditions.

A Case of Periodic Alternating Nystagmus: With a Special Reference to the Efficacy of Baclofen Treatment

A case of periodic alternating nystagmus (PAN), probably of congenital type, was reported. A 25-year-old woman, who has been suffering from cerebral palsy, was referred to our clinic for the consultation of a peculiar nystagmus and intermittent oscillopsia. Electronystagmographic examination revealed that the horizontal nystagmus on straight ahead gaze in the light continuously changed its direction alternately about 110 sec in right direction and about 90 sec in left direction with about 5 sec of an interlude, during which no nystagmus was observed, between each span. Electronystagmographic recording also illustrated that the amplitude and slow phase eye velocity of PAN first increase and then decrease in each span. Since other various kind of examination including neuroradiological examination revealed no special abnormality except for the signs of cerebral palsy, congenital PAN was suspected in this case. Although previous report indicated that baclofen dose not control congenital PAN in contrast to that of acquired type, we tried baclofen in this case. Baclofen reduced the strength of the nystagmus remarkably and patient also recognized the considerable improvement of her oscillopsia. We are of the opinion that the baclofen may improve the strength of congenital PAN and oscillopsia as well as those of acquired type PAN.

Vestibular-Visual Conflict Sickness in the Squirrel Monkey

When combined vestibular and visual (optokinetic) stimuli were given to squirrel monkeys in a direction and phase mismatching sinusoidal mode (in yaw plane), five of six monkeys exhibited actual emesis during three repeated exposures on separate trial days. Two animals vomited on two trial days and three animals, on one day. The incidence took place in 38.9% of the total trial days. When the identical vestibular and visual stimuli were given individually, the effect was negligible, thus confirming each stimulus magnitude was not stressful enough to produce emesis when used separately.

The Effect of Amphetamine on Head and Eye Movements Following Vestibular Stimulation in Squirrel Monkeys

The effect of a single dose intra-muscular injection of amphetamine sulfate on head and eye movements evoked by vestibular stimulation was investigated in squirrel monkeys. Doses injected were 0.5, 0.4, 0.3, 0.2 mg/kg, and control no injections. Amphetamine did not change the gain of vestibular evoked head and eye movements, but prolonged time constant (in function of dose) showing greater effect in eye movements. More than 0.3 mg/kg was found to be a proper dose for this species to maintain an appropriate constant alertness level for vestibular studies.

Effect of amphetamine on optokinetically evoked head and eye movements in the squirrel monkey.

The effect of amphetamine sulfate injection on head and eye movements evoked by optokinetic stimulus was studied in squirrel monkeys. No change was found in the gain of optokinetic-oculomotor and optokinetic-caputomotor functions, even after the maximum dose (0.5 mg/kg) of amphetamine. Also, no change in eye-head coordination was found. However, amphetamine facilitated the frequency of head nystagmus, whereas that of eye nystagmus did not change. When the poststimulus responses were studied in the dark, both nystagmoid head movement and optokinetic after eye nystagmus showed first phase and second phase. A different effect was found in the duration of these two phases suggesting the existence of distinct generators. Moreover, the synchronized onsets of head and eye nystagmus in both phases, and synchronized occurrence of quick phases indicated the existence of shared neural circuitry between head and eye movements.

Tympanosclerosis and Concentric Lamellated Bodies in Middle Ear

In a case of bilateral tympanosclerosis, in addition to the tympanosclerotic changes, the round (or ovoid) concentric lamellated bodies in the right tympanic cavity (epitympanum and mesotympanum) and mastoid cavity were found. The pathogenesis of tympanosclerosis was discussed in conjunction with those concentric lamellated bodies including its relationship with Pacinian body or middle ear corpuscle.

Upbeating Nystagmus Resulting from Anticonvulsant Intoxication

A rare case of upbeating nystagmus, which occurred under the condition of a loss of visual fixation, due to anticonvulsant intoxication is reported. This patient, a 29 year old male, suffered from grand mal epilepsy for about 12 years, and he had been treated with anticonvulsive drugs. Although a neurological evaluation by a neurosurgeon could suggest the presence of a vague cerebellar sign, neuro-otological evaluation disclosed diverse abnormal findings which clearly demonstrated the presence of dysfunction in the cerebellar system, especially of the verminal and flocculonodular lobe lesion. This may indicate that the anticonvulsive drug affected the vermis and flocculonodular lobe much more than the hemisphere of cerebellum, or that the cerebellar system sign in verminal and flocculonodular lobe lesion and its connection is detected more easily than the hemispheric lesion with the aid of a neuro-otological examination. It was presumed that the upbeating nystagmus in this case was elicited from the lesion of the anterior vermis of the cerebellum and/or its connections. Usefulness and sensitivity of the neuro-otological examination in the field of dysequilibrium of central disorder as well as peripheral vestibular disorder is emphasized.

Examinations of elderly patients with vertigo and/or dizziness.

Equilibrium examinations were performed in 133 patients over 60 years of age who complained of vertigo and/or dizziness.1. The incidence of vertigo or dizziness due to central nervous system lesions (central disorders) increased with age, while that of peripheral vestibular lesions (peripheral disorders) fell with age.2. Elderly patients with peripheral disorders had a incidence of abnormal caloric response (36.6%) compared with those with central disorders.3. The eye tracking test of patients with central disorders indicated that smooth pursuit eye movement tended to be more difficult.4. Nystagmus tests showed abnormal nystagmus in those with cerebellar and brain stem lesions.