Among several sources of error on the caloric test, the following which may have relevance to the diagnosis of canal paresis were discussed. First, with the alternate cold and hot caloric test one cannot detect canal paresis of one labyrinth unless the response obtained on that side is abnormally weak. Second, the majority of cases showing directional prepon-derance on the alternate cold and hot caloric test revealed spontaneous nystagmus in the spontaneous- and the evoked-nystagmus tests using electronystagmography. Thus the combination of these tests and the caloric test using the cold water irrigation alone may afford the diagnosis of canal paresis, because the influence of directional preponderance can be eliminated. Third, the use of Frenzel glasses and the eye opening in darkness are recommended as the condi-tions for observing and recording caloric nystagmus respectively. Furthermore, application of considerably intense caloric stimulation is recommended to avoid false positive interpretation of canal paresis.
Effects of ocular fixation on pendular rotation nystagmus in the upper brainstem, cerebellar and cere-bellopontine angle lesions were investigated in thirtyfour patients using a damped pendular rotation test (DPRT) apparatus. The DPRT was performed employing mental arithmetic in the dark or under ocular fixation. In upper brainstem tumors, the failure of visual suppression was observed in the DPRT as in lower brainstem tumors, which had already been reported, and nystagmus was evoked as is seen under darkness. In contrast to lower brainstem tumors in which the findings of perrotatory nystagmus as nystagmic rhythm, amplitude in the dark and auditory brainstem response (ABR) was abnormal, in upper brainstem tumors these were not pathological. In four of the five cerebellar tumors, mostly postoperative, failure of visual suppression on the DPRT was seen. In three of the four cases, the ABR was pathological and abnormal nystagmic findings on the DPRT under darkness were obtained. In spite of these findings of cerebellar tumors, further studies are needed to conclude that the cerebellum is responsible for the failure of visual suppression in cerebellar tumors. The effects of cerebellar lesions on the brainstem could best be judged from neurological and neurootological findings using the DPRT under darkness, ABR, together with optokinetic nystagmus and the eye tracking test. That the failure of visual suppressssion was seen on the DPRT in a case with small cerebellar infarction suggested the cerebellum is involved in the visual suppression.
In order to explain the role of the cerebellum in the vestibulo-ocular reflex, the transfer function (TF) of the oculomotor system was studied in 13 healthy male subjects and 17 patients with cerebellar disease. For this purpose, the following three tests were performed, that is, the eye tracking test (ETT) and the head oscillation tests in the dark and light in order to examine the opto-oculomotor, vestibulocer-vico-oculomotor and optovestibulocervico-oculomotor systems. The results obtained were as follows. A. Normal subjects. 1) As to the Bode plots of the TF of the opto-oculomotor system, the gain and phase were flat from 0.4 to 0.9 Hz. 2) As to the Bode plots of the TF of the vestibulocervico-oculomotor system, the gain lineary in-creased at a rate of 5db per decade in the frequency range from 0.2 to 4 Hz. 3) As to the Bode plots of the TF of the optovestibulocervico-oculomotor system, the gain and phase were flat from 0.3 to 4 Hz. B. Patients with cerebellar disease. 1) As to the Bode plots of the TF of the optooculomotor system, fourteen of the 17 patients showed normal patterns, two showed decrease in gain and one showed a shift of the break frequency toward low-frequency side. 2) As to the Bode plots of the TF of the vestibulocervico-oculomotor system, seven of the 17 patients showed normal patterns, two showed increase in gain and eight showed flatness in gain curve., 3) As to the Bode plots of the TF of the optovestibulocervico-oculomotor system, four of the 17 patients showed normal patterns, ten showed a shift of the break frequency toward low-frequency side and three showed decrease in gain. These results lead to the following conclusion. On the observation of the dynamic characteristics of the vestibulo-ocular system, the increase of the gain in wide frequency range was uncommon in patients with cerebellar disease.
This paper is concerned with the results of a survey of thousands of school children, who live in two districts that are geographically distant from each other and contract sharply in their environmental conditions, family history, and sports history. Our intention is to elucidate regional differences in the incidence and cause of motion sickness. The subjects were 861 pupils living in a secluded mountain area of Totsukawa Village, Nara Prefecture, and 6, 017 pupils in a large industrialized city of Amagasaki, Hyogo Prefecture. The incidence of any history of motion sickness was 69.5% in Totsukawa Village and 63.6 in Amagasaki City. Pupils suffering from habitual motion sickness accounted for 5.4% and 8.1%, respectively, of the subjects. The causes of motion sickness classified by various traffic facilities were as follows. Pupils whose motion sickness was due to cars and buses were as much as about four-fifths of those who had experienced this disorder. This rate was common to the two areas. Meanwhile, pupils whose sickness was due to other traffic facilities including trains, ships and airplanes were far fewer, particularly in Totsugawa Village, where few people have access to these vehicles.The overt difference in the incidence of motion sickness between the two areas was shown to depend on regional differences in environmental conditions accessibility to individual traffic facilities, and meaning not immediately clear the pupils health problems derived from or influenced by their physical activities, as well as on the susceptibility of individual pupils.
We routinely use the Cornell Medical Index (CMI) for vertiginous patients. The vertigo of the patients of types III and IV of CMI seemed to be caused by psychological problems and not by organic disease. The Manifest Anxiety Scale (MAS) and the Rosenzweig Picture Frustration Study (P-F Study) were used to analyse the vertigo of these patients in detail. These patients showed strong anxiety tendencies and lack of self-assertion. Thus, vertigo in these psychosomatic patients seemed to be caused by psychic unsteadiness due to lack of self-control.
The eye tracking test (E. T. T.) is usually evaluated in terms of the alternating wave pattern and the velocity or frequency of the eye movements. This way of testing has, however, ignored the mutual relationships among the amplitude, velocity and frequency of the wave. A triangular wave has been used to clarify these relationships. Ten normal persons were gathered randomly. No significant neurological defects were recognized in their histories. Their age ranged from 24 to 48. The sex ratio of male to female was 8 to 2. Binocular recordings were taken on all the 10 subjects on a D-C ENG in frequencies of 0.1, 0.3, 0.5, 0.8 and 1 Hz with amplitudes of 10°, 20°, 30°, 60°, and 90°. The velocity was calculated mannually from D-C ENG recording data. The results obtained are as follows. 1) The E. T. T. is influenced mostly by the frequency but not by the velocity or amplitude itself of the target. 2) Alternating wave patterns begin around 0.5-0.8Hz in which saccadic eye movement is supposed to be mixed in smooth pursuit eye movement.
Most cases of the Dandy-Walker syndrome (DWS) develop symptoms before the age of two. In this report, we present a rare case of DWS, the patient having been in good health until the age of 13 when she suddenly developed intracranial hypertension. A 13-year-old girl visited our clinic complaining of headache, vomiting and diplopia. Paralysis of the bilateral abducent nerves was present. CT examination demonstrated a large posterior fossa cyst communicating with the fourth ventricle, 'inverted Y' configuration, absence of cerebellar vermis and symmetrical enlargement of ventricular system. Angiography, pneumoventriculography and RI-ventriculography confirmed the diagnosis of DWS. An equilibrium test revealed direction-changing, opposing, vertical-positioning nystagmus with almost normal findings on the caloric test, OKP and ETT. We theorized that the cerebellar vermis takes part in the occurance of direction-changing, opposing, vertical-positioning nystagmus and that a slowlygrowing, expansive cyst of the posterior cranial fossa does not have important effects upon OKP, ETT or the occurance of cerebellar symptoms.