Auris·Nasus·Larynx (Tokyo) 19, 83-94 (1992)
A VISUAL SUPPRESSION TEST USING POSTROTATORY NYSTAGMUS Kazuhiro TERAMOTO, M.D. Department of Neurotology, Saitama Medical School, Moroyama-cho, Saitama, Japan
The visual suppression test is one method for examining the function of visual fixation and visual influence on vestibular nystagmus. In this study the visual suppression test using post-rotatory nystagmus was investigated in 65 normal subjects and 142 clinical cases with cerebellar lesions. In 65 normal subjects the mean ± standard deviation of visual suppression of the slow phase velocity on post-rotatory nystagmus was 69 ± 11%. As to the stimulation for visual suppression test, the post-rotatory method using rotatory stimulation is milder than caloric stimulation. This method is far simpler to analyze than the visual suppression test using pendular rotatory nystagmus and other vestibula-ocular reflex tests. In the 142 patients with cerebellar lesions, reduced or abolished visual suppression on postrotatory nystagmus was seen in 89 patients with radiologically confirmed disturbances in the vestibula-cerebellum. And this method could identify the lesion side in the cerebellum. These results showed a correlation between the visual suppression test using post-rotatory nystagmus and one using caloric nystagmus in 65 normal subjects and 142 clinical cases with cerebellar lesions. It has been well known that vestibular nystagmus elicited by either caloric stimulation or rotatory stimulation is inhibited by the visual state, and that the visual suppression test is a very useful method for examining the influence of the visual state on vestibular nystagmus. In 1974 TAKEMORI and COHEN (1974a, b) defined the visual suppression test using the slow phase velocity of caloric nystagmus. This method is useful for quantitative analysis of the visual influence on vestibular nystagmus. However, there are some difficulties in testing visual suppression, because caloric nystagmus is such a strong stimulation of the inner ear for patients that are afraid of vertigo. On the other hand, since the use of torsion balance enabled the administration of frequently repeated stimuli (MACH, 1990), many studies have evaluated vesReceived for publication
December 10, 1990 83
84
K. TERAMOTO
tibular function with the pendular rotatory acceleration test (KOENIG, ALLUM, and 1978). As the intensity of the stimulus constantly changes in the pendular rotation test, it is very difficult to identify the lesion side using the stimulus of pendular rotation. The purpose of this paper is to evaluate post-rotatory stimuli for testing visual suppression. DICHGANS,
METHODS
A target for visual fixation was put on the forehead of the subject as in Fig. 1. The distance from patient's eyes to the fixating point was about 50 em. A rotation chair was accelerated at 0.3°/sec2 • The room light was turned off and the subjects were requested to close their eyes. The rotatory velocity was increased to a maximum of 90°/sec and then maintained at that speed for 1 min. After that the chair was suddenly stopped and the subjects were requested to open their eyes in the darkness. After 5 sec in the darkness, the room light was turned on and the subjects were requested to fix their eyes on the target for 5 sec. The time lag between the light switching on and the room light accurately turning on was controlled to within 1 sec. Then the room light was turned off again and the room was made dark until the disappearance of the first phase of the post-rotatory nystagmus. Eye movements were .recorded by an electronystagmograph (ENG) using silver plate electrodes. The time constant for eye movement recording was 3 sec,
Fig. 1. A target for visual fixation was put on the forehead of the subject. The distance from patient's eyes to the fixating point (white arrow) was about 50cm.
VISUAL SUPPRESSION TEST
85
Visual suppression(%)
A-b XIOO A
R
c dark
~
dark
Fig. 2. Measurement of visual suppression. Eye movement is differentiated to obtain velocity measurements and clipped to display the slow phase velocity. Upper R shows a recording of the slow phase velocity during visual suppression test using post-rotatory nystagmus, schematically, and lower C shows the one using caloric stimulation. The mean slow phase velocity curve for 5 sec without visual fixation on the target (area A) was measured, and the mean slow phase velocity curve with visual fixation on the target was measured (area b). The areas of A and b were measured using a precision linear planimeter.
and for eye velocity recording it was 0.03 sec. Eye movements were differentiated to obtain velocity measurements and clipped to display the slow phase velocity. Visual suppression tests using both post-rotatory nystagmus and caloric stimulation are shown schematically in Fig. 2. The upper R shows the recording of a visual suppression test using post-rotatory nystagmus. The lower C shows the one using caloric stimulation. Visual suppression test using caloric stimulation was performed according to the TAKEMORI and COHEN 1974 (1974a, b) method. The first phase of the post-rotatory nystagmus was used for the measurement of visual suppression test using post-rotatory nystagmus. The mean slow phase velocity curve was drawn for the gradually decelerated first phase of the slow phase velocity recording of the post-rotatory nystagmus using a flexible curve ruler. And also the mean slow phase velocity curve was drawn for the recording during visual fixation on the target using a flexible curve ruler. The mean slow phase velocity curve for 5 sec without visual fixation on the target (area A) was measured, and the mean slow phase velocity curve with visual fixation on the target was measured (area b). The areas of A and b were measured using a precision linear planimeter. Visual suppression on post-rotatory nystagmus was calculated as follows: Visual suppression (%) =
A;;b
X 100.
K. TERAMOTO
86
SUBJECTS
Sixty-five normal adults and 142 clinical cases with cerebellar lesions were examined for visual suppression test using post-rotatory nystagmus in this study. RESULTS
Normal subjects
Sixty-five subjects without vertigo (males 30, females 35) were examined. Visual suppression of the slow phase velocity examined by post-rotatory nystagmus varied from 51 to 84%. The mean value and standard deviation of visual suppression was 69± 11% (Fig. 3).
eye
R
11
slow
movement
phase
B
A
velocity
L
dark
1~ec
dark
light dark 1~ec
Fig. 3. Normal visual suppression. Visual suppression of a normal subject is shown. The left side of this figure (A) shows the recording of a visual suppression test using post-rotatory nystagmus. The upper part of the left side shows the recording after rotation to the right (R), and the lower one shows after rotation to the left (L). The right side of this figure (B) shows a visual suppression test using caloric stimulation. The upper part of the right side shows the recording of the right ear irrigation with cold water, and the lower one was caused by left ear irrigation. These are the same in Figs. 4, 5, and 6. Visual suppression of the slow phase velocity was 73% by rotation to the right, 78% by rotation to the left, 67% by right ear irrigation, and 63% by left ear irrigation.
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87
Pathological subjects with cerebellar lesions
Visual suppression on post-rotatory nystagmus and caloric stimulation were investigated in 142 clinical cases of cerebellar lesions. The clinical diagnoses were mainly based on the medical history, neurotological examinations, and neurological examinations and were confirmed by radiological examinations, which included mainly CT-scanning, magnetic resonance imaging (MRI), and angiography. Visual suppression of the slow phase velocity in 65 normal subjects varied from 51 to 84%. Then, visual suppression of less than 40% was defined as reduced or abolished visual suppression, and that from 50 to 80% was defined as normal visual suppression. The results of visual suppression test on post-rotatory nystagmus and the clinical diagnoses are shown in Table 1. Cerebellar atrophy (91 cases), caused by Table 1 (A)
Results of visual suppression using post-rotatory nystagmus and clinical diagnoses. Reaction of visual suppression (V.S.) using post-rotatory nystagmus
Cerebellar atrophy (91 cases) Vascular lesion No affection to vestibulo-cerebellum ( 13 cases) Involving vestibulo-cerebellum ( 19 cases) Spinocerebellar degeneration ( 10 cases) (cerebellar type) Cerebellar hemorrhage ( 5 cases) Cerebellar tumor (2 cases) Arterio-venous malformation (I case) Cerebellitis ( I case) Total (B)
Normal V.S.
Reduced or abolished V.S.
40
51
13 0 0
0 19 10
0 0 0 0
5 2
53 cases
89 cases
Cerebellar lesions and the direction of reduced or abolished visual suppression of post-rotatory nystagmus. Reduced or abolished visual suppression Ipsilateral nystagmus
Cerebellar atrophy (51 cases) Cerebellar infarction ( 19 cases) Spinocerebellar degeneration (cerebellar type) ( 10 cases) Cerebellar hemorrhage ( 5 cases) Cerebellar tumor (2 cases) Cerebellitis ( 1 case) Arterio-venous malformation ( 1 case)
Contralateral nystagmus
Bilateral nystagmus 51 10
9
10
2
2
88
K. TERAMOTO
pesticide intoxication and organic solvent intoxication, was distinguished clinically to evaluate this visual suppression from spinocerebellar degeneration ( 10 cases) caused by chronic alcoholism and late cortical cerebellar atrophy (LCCA). Normal visual suppression in cerebellar lesions. Visual suppression on postrotatory nystagmus was found to be normal in 53 patients with cerebellar disease. Ninety-one patients had also radiologically confirmed diffuse atrophic changes throughout the cerebellum. However, 40 of these 91 patients showed normal range of visual suppression. This discrepancy in the ratio of visual suppression in the cerebellar atrophy group may be due to the property of the disease, or the extent of histologic or functional involvement of the cerebellum. It was especially noteworthy that, among these 53 patients, 13 that had cerebellar infarction were radiologically confirmed to have no associated lesions of the vestibulo-cerebellum. A typical case is presented in Fig. 4. Oblique nystagmus to the lower eyelid was observed with gazing to both the right and left sides, at positional nystagmus test and positioning nystagmus test. The CT-scan findings showed a lesion in the left superior cerebellar peduncle that did not affect the vestibulo-cerebellum. The visual suppression on post-rotatory nystagmus was normal in this case. Cases with reduced or abolished visual suppression. Eighty-nine patients with cerebellar lesions showed reduced or abolished visual suppression on post-rotatory nystagmus. The clinical diagnoses and visual suppression on post-rotatory nystagmus are shown in Table 1. Seventy-five patients that were radiologically confirmed to have bilateral lesions of the vestibulo-cerebellum or diffuse and severe lesions involving the vestibulo-cerebellum showed bilateral reduced or abolished visual suppression on post-rotatory nystagmus (Table lB). An illustrative case is presented in Fig. 5. Nystagmus was observed with gazing to both the right and left sides. Directional changing upward beating positional nystagmus and vertical positioning nystagmus were observed. The MRI findings showed diffuse and severe atrophic changes throughout the cerebellum, including lesions in the vestibulo-cerebellum. Visual suppression test using postrotatory nystagmus showed bilateral abolished visual suppression of the slow phase velocity. Unilateral reduced or abolished visual suppression on post-rotatory nystagmus. In 14 patients whose radiological examinations confirmed unilateral lesions in the vestibulo-cerebellum, unilateral reduced or abolished visual suppression on postrotatory nystagmus was seen. The correlation between the lesion side and the direction of visual suppression on post-rotatory nystagmus is summarized in Table lB. These results showed that visual suppression of post-rotatory nystagmus to the lesion side was reduced or abolished in most cases. An illustrative case is presented in Fig. 6. Spontaneous nystagmus to the right
VISUAL SUPPRESSION TEST
slow
phase
velocity
A
89
B
1".~1.,.~, ..1 I~ '
200/SEC _c dark """"jkJ1!!1PI._d""a"rk~-------------~~-dark_."!!hg!!hl'"tLd;;-;;a"'rk-
1
:ec
Fig. 4. (A) Cerebellar hemorrhage of the left superior cerebellar peduncle. Visual suppression of the slow phase velocity was within the normal range, 78% by rotation to the right, 68% by rotation to the left, 74% by right ear irrigation, and 77% by left ear irrigation. (B) CT-scan. The CT-scan findings show a lesion of the left superior cerebellar peduncle. The white arrow shows a hemorrhage of the left superior cerebellar peduncle.
was observed in the right and primary eye positions. The CT -scan showed a lesion in the left vestibu)o-cerebellum. The visual suppression test on post-rotatory nystagmus showed reduced visual suppression to the left side, which was the lesion side. DISCUSSION
Visual suppression is a method for examining the function of visual conditions.
90
(A)
R
K. TERAMOTO
eye
movement
slow phase
l
A
B
velocity
!"
+.
~ ,
nzo·tsec
1
I
DARK
Fig. 5. (A) A case with bilaterally abolished visual suppression. Visual suppression of the slow phase velocity was O% by rotation to the right, O% by the rotation to the left, 0% by right ear irrigation, and O% by left ear irrigation. (B) MRI (TI-weighted image). The MRI (Tlweighted image) showed diffuse and severe atrophic changes throughout the cerebellum.
VISUAL SUPPRESSION TEST
91
(A)
R
L
.1sec
DARK
LIGHT
DARK
1lSEC
Fig. 6. (A) A case of unilaterally reduced visual suppression. Visual suppression of the slow phase velocity was 8% by rotation to the right, 75% by rotation to the left, 10% by right ear irrigation, and 77% by left ear irrigation. The lesion was confirmed on the same side as the direction of the quick phase of the post-rotatory nystagmus: the left. (B) CT-scan. The white arrow shows an infarction of the left vestibulo-cerebellum.
92
K. TERAMOTO
The visual condition is important for maintaining equilibrium. It is well known that the vestibular nystagmus elicited by either caloric or rotatory stimulation is influenced by visual conditions. The visual suppression test is widely used to diagnose lesions of the flocculus, nodulus, pons, and lower parietal lobe. In 1976 HART used the ocular fixation index, which affected some of the parameters of nystagmus. He demonstrated the enhancement of caloric nystagmus by ocular fixation in cerebellar diseases. In 1970 CoATS reported the failure of fixation suppression of caloric nystagmus. He demonstrated the failure of fixation suppression in patients with brainstem tumors and spinocerebellar degeneration. But in 1974 TAKEMORI and CoHEN reported the visual suppression test using the slow phase velocity of caloric nystagmus. This method is useful for quantitative analysis of visual conditions on vestibular nystagmus and for diagnostic evaluation. In 1976 SAKATA reported the caloric-eye tracking pattern test using visual fixation. This method is useful for making a differential diagnosis between peripheral and central vertigo. And ever since BARANY ( 1907) introduced the clinical usefulness of the rotatory test for vestibular evaluation, there has been a great deal of interest in the development and improvement of acceleration techniques. On the other hand, since MACH reported in 1900, that the use of torsion balance enabled the administration of frequently repeated stimuli, many studies have evaluated vestibular function by the pendular rotatory acceleration test. An interaction between visual and vestibular reflexes has been demonstrated since OHM first described it in 1926. In 1978 KOENIG et a/. quantified the visual-vestibular interaction upon nystagmus slow phase velocity using the pendular rotatory test. And ToUPET, MENGUY, and TEYSSON made studies on ocular fixation using the pendular rotatory test in 1977. However, when the pendular rotatory technique is used, the intensity of the stimulus constantly changes and the direction of the stimulus constantly mixes. Therefore, an evaluation of visual suppression using this technique would be rather complicated. And furthermore, concerning the correlation between the disturbed direction of pendular rotatory nystagmus and the laterality of the lesion, the direction of the stimulus constantly mixes and the intensity of the stimulus constantly changes, so it may be difficult to identify the side of cerebellar lesions when visual suppression with pendular rotatory nystagmus is used. Compared with the visual suppression test using pendular rotatory nystagmus, post-rotatory nystagmus can always be elicited toward one direction, therefore the visual suppression test using post-rotatory nystagmus is easier to analyze. Without using computer analysis, the results can be obtained by simple inspection. The stimulation is milder in the visual suppression test using post-rotatory
VISUAL SUPPRESSION TEST
93
nystagmus than in caloric stimulation. Thus this method can easily be performed on patients with motion sickness, patients who are afraid of vertigo, elderly persons, and children. In 1975 TAKEMORI reported visual suppression of calorically induced vestibular nystagmus in cerebellar lesions of rhesus monkeys. A reduced or loss of visual suppression was seen in a unilateral flocculus lesion, and bilateral loss of visual suppression was seen in bilateral flocculus lesions. Nodulus lesions and lesions of the dentate nucleus showed a loss of visual suppression in certain period. Lesions of the uvula, vermis, paraflocculus, cerebellar cortex, or the fastigial or interpositus nuclei had no observed effect on visual suppression. In our 142 patients with cerebellar lesions, 91 patients with cerebellar atrophy had radiologically confirmed diffuse atrophic changes throughout the cerebellum. However, 40 of these 91 patients showed normal range of visual suppression. This discrepancy in the cerebellar atrophy group may be due to the property of the disease, or the extent of histologic or functional involvement of the cerebellum. Reduced or abolished visual suppression examined by post-rotatory nystagmus was seen in 89 patients that had radiologically confirmed disturbances of the vestibulo-cerebellum. In these 89 cases, 75 patients that were radiologically confirmed to have bilateral lesions in the vestibulo-cerebellum or diffuse and severe lesions throughout the cerebellum showed reduced or abolished visual suppression of post-rotatory nystagmus bilaterally. And 12 cases who had radiologically confirmed unilateral lesions in the vestibulo-cerebellum showed reduced or abolished visual suppression on post-rotatory nystagmus directed to the lesion side. The lesion side of the cerebellum could be diagnosed by the visual suppression test using post-rotatory nystagmus. It was considered that a lesion of the vestibulocerebellum existed in the ipsilateral direction of the quick phase of the post-rotatory nystagmus. These results showed a correlation between visual suppression using postrotatory nystagmus and caloric nystagmus in 65 normal subjects and 142 clinical cases with cerebellar lesions. However, post-rotatory nystagmus is weaker than caloric nystagmus, so measurement of the ratio of visual suppression should be done more carefully. CONCLUSION A visual suppression test using a post-rotatory nystagmus gives a far milder stimulation than caloric stimulation. In 142 patients with cerebellar lesions, a correlation of the results of visual suppression of the slow phase velocity using post-rotatory nystagmus and caloric stimulation was found. Therefore, it may be better to use rotatory stimulation to evoke vestibular nystagmus than to use caloric stimulation for a visual suppression test.
K. TERAMOTO
94
This paper is respectfully dedicated to Prof. E. Sakata, M.D. The author especially thanks Prof. S. Takemori, M.D. and K. Ohtsu, Ph.D., and the entire staff of the Department of Neurotology, Saitama Medical School. REFERENCES BARANY, R.: Physiologie und Pathologie des Bogengangsapparatus beim Menschen, Deuticke, Leipzig & Wien, 1907. COATS, A. C.: Central electronystagmographic abnormalities. Arch. Otolaryngol. 92: 43-53, 1970. HART, C. W.: Ocular fixation of the caloric test. Laryngoscope 77: 2103-2114, 1976. KoENIG, E., ALLUM, J. H. J., and DICHGANS, J.: Visual-vestibular interaction upon nystagmus slow phase velocity in man. Acta Otolaryngol. (Stockh.) 85: 397-410, 1978. MACH, E.: Die Analyse der Empfindungen, 2nd ed., Gustav-Fisher, Jena, 1900. OHM, J.: Uber den Einftuss des Sehens auf den vestibuliiren Drehnystagmus und Nachnystagmus. Z. Hals Nasen Ohreheilkd. 16: 521-540, 1926. SAKATA, E.: Caloric-eye tracking pattern test: 1. Visual suppression and the possibility of simplified differential diagnosis between peripheral and central vertigo. Ann. ORL 85: 261-267, 1976. TAKEMORI, S.: Visual suppression of vestibular nystagmus after cerebellar lesions. Ann. Otolaryngol. 84: 318-326, 1975. TAKEMORI, S., and COHEN, B.: Visual suppression of vestibular nystagmus in rhesus monkeys. Brain Res. 72: 203-212, 1974a. TAKEMORI, S., and COHEN, B.: Loss of visual suppression of vestibular nystagmus after flocculus lesions. Brain Res. 72: 213-224, 1974b. ToUPET, M., MENGUY, C., and TEYSSON, M.: Test de fixation dculaire au cours de Ia stimulation vestibulaire pendulaire. Ann. Otolaryngol. Chir. Cervicofac. 94: 301-308, 1977.
Request reprints to:
Dr. K. Teramoto, Department of Neurotology, Saitama Medical School, 38 Morohongo, Moroyama-cho, Iruma-gun, Saitama 35D-04, Japan
A VISUAL SUPPRESSION TEST USING POSTROTATORY NYSTAGMUS Kazuhiro TERAMOTO, M.D. Department of Neurotology, Saitama Medical School, Moroyama-cho, Saitama, Japan
The visual suppression test is one method for examining the function of visual fixation and visual influence on vestibular nystagmus. In this study the visual suppression test using post-rotatory nystagmus was investigated in 65 normal subjects and 142 clinical cases with cerebellar lesions. In 65 normal subjects the mean ± standard deviation of visual suppression of the slow phase velocity on post-rotatory nystagmus was 69 ± 11%. As to the stimulation for visual suppression test, the post-rotatory method using rotatory stimulation is milder than caloric stimulation. This method is far simpler to analyze than the visual suppression test using pendular rotatory nystagmus and other vestibula-ocular reflex tests. In the 142 patients with cerebellar lesions, reduced or abolished visual suppression on postrotatory nystagmus was seen in 89 patients with radiologically confirmed disturbances in the vestibula-cerebellum. And this method could identify the lesion side in the cerebellum. These results showed a correlation between the visual suppression test using post-rotatory nystagmus and one using caloric nystagmus in 65 normal subjects and 142 clinical cases with cerebellar lesions. It has been well known that vestibular nystagmus elicited by either caloric stimulation or rotatory stimulation is inhibited by the visual state, and that the visual suppression test is a very useful method for examining the influence of the visual state on vestibular nystagmus. In 1974 TAKEMORI and COHEN (1974a, b) defined the visual suppression test using the slow phase velocity of caloric nystagmus. This method is useful for quantitative analysis of the visual influence on vestibular nystagmus. However, there are some difficulties in testing visual suppression, because caloric nystagmus is such a strong stimulation of the inner ear for patients that are afraid of vertigo. On the other hand, since the use of torsion balance enabled the administration of frequently repeated stimuli (MACH, 1990), many studies have evaluated vesReceived for publication
December 10, 1990 83
84
K. TERAMOTO
tibular function with the pendular rotatory acceleration test (KOENIG, ALLUM, and 1978). As the intensity of the stimulus constantly changes in the pendular rotation test, it is very difficult to identify the lesion side using the stimulus of pendular rotation. The purpose of this paper is to evaluate post-rotatory stimuli for testing visual suppression. DICHGANS,
METHODS
A target for visual fixation was put on the forehead of the subject as in Fig. 1. The distance from patient's eyes to the fixating point was about 50 em. A rotation chair was accelerated at 0.3°/sec2 • The room light was turned off and the subjects were requested to close their eyes. The rotatory velocity was increased to a maximum of 90°/sec and then maintained at that speed for 1 min. After that the chair was suddenly stopped and the subjects were requested to open their eyes in the darkness. After 5 sec in the darkness, the room light was turned on and the subjects were requested to fix their eyes on the target for 5 sec. The time lag between the light switching on and the room light accurately turning on was controlled to within 1 sec. Then the room light was turned off again and the room was made dark until the disappearance of the first phase of the post-rotatory nystagmus. Eye movements were .recorded by an electronystagmograph (ENG) using silver plate electrodes. The time constant for eye movement recording was 3 sec,
Fig. 1. A target for visual fixation was put on the forehead of the subject. The distance from patient's eyes to the fixating point (white arrow) was about 50cm.
VISUAL SUPPRESSION TEST
85
Visual suppression(%)
A-b XIOO A
R
c dark
~
dark
Fig. 2. Measurement of visual suppression. Eye movement is differentiated to obtain velocity measurements and clipped to display the slow phase velocity. Upper R shows a recording of the slow phase velocity during visual suppression test using post-rotatory nystagmus, schematically, and lower C shows the one using caloric stimulation. The mean slow phase velocity curve for 5 sec without visual fixation on the target (area A) was measured, and the mean slow phase velocity curve with visual fixation on the target was measured (area b). The areas of A and b were measured using a precision linear planimeter.
and for eye velocity recording it was 0.03 sec. Eye movements were differentiated to obtain velocity measurements and clipped to display the slow phase velocity. Visual suppression tests using both post-rotatory nystagmus and caloric stimulation are shown schematically in Fig. 2. The upper R shows the recording of a visual suppression test using post-rotatory nystagmus. The lower C shows the one using caloric stimulation. Visual suppression test using caloric stimulation was performed according to the TAKEMORI and COHEN 1974 (1974a, b) method. The first phase of the post-rotatory nystagmus was used for the measurement of visual suppression test using post-rotatory nystagmus. The mean slow phase velocity curve was drawn for the gradually decelerated first phase of the slow phase velocity recording of the post-rotatory nystagmus using a flexible curve ruler. And also the mean slow phase velocity curve was drawn for the recording during visual fixation on the target using a flexible curve ruler. The mean slow phase velocity curve for 5 sec without visual fixation on the target (area A) was measured, and the mean slow phase velocity curve with visual fixation on the target was measured (area b). The areas of A and b were measured using a precision linear planimeter. Visual suppression on post-rotatory nystagmus was calculated as follows: Visual suppression (%) =
A;;b
X 100.
K. TERAMOTO
86
SUBJECTS
Sixty-five normal adults and 142 clinical cases with cerebellar lesions were examined for visual suppression test using post-rotatory nystagmus in this study. RESULTS
Normal subjects
Sixty-five subjects without vertigo (males 30, females 35) were examined. Visual suppression of the slow phase velocity examined by post-rotatory nystagmus varied from 51 to 84%. The mean value and standard deviation of visual suppression was 69± 11% (Fig. 3).
eye
R
11
slow
movement
phase
B
A
velocity
L
dark
1~ec
dark
light dark 1~ec
Fig. 3. Normal visual suppression. Visual suppression of a normal subject is shown. The left side of this figure (A) shows the recording of a visual suppression test using post-rotatory nystagmus. The upper part of the left side shows the recording after rotation to the right (R), and the lower one shows after rotation to the left (L). The right side of this figure (B) shows a visual suppression test using caloric stimulation. The upper part of the right side shows the recording of the right ear irrigation with cold water, and the lower one was caused by left ear irrigation. These are the same in Figs. 4, 5, and 6. Visual suppression of the slow phase velocity was 73% by rotation to the right, 78% by rotation to the left, 67% by right ear irrigation, and 63% by left ear irrigation.
VISUAL SUPPRESSION TEST
87
Pathological subjects with cerebellar lesions
Visual suppression on post-rotatory nystagmus and caloric stimulation were investigated in 142 clinical cases of cerebellar lesions. The clinical diagnoses were mainly based on the medical history, neurotological examinations, and neurological examinations and were confirmed by radiological examinations, which included mainly CT-scanning, magnetic resonance imaging (MRI), and angiography. Visual suppression of the slow phase velocity in 65 normal subjects varied from 51 to 84%. Then, visual suppression of less than 40% was defined as reduced or abolished visual suppression, and that from 50 to 80% was defined as normal visual suppression. The results of visual suppression test on post-rotatory nystagmus and the clinical diagnoses are shown in Table 1. Cerebellar atrophy (91 cases), caused by Table 1 (A)
Results of visual suppression using post-rotatory nystagmus and clinical diagnoses. Reaction of visual suppression (V.S.) using post-rotatory nystagmus
Cerebellar atrophy (91 cases) Vascular lesion No affection to vestibulo-cerebellum ( 13 cases) Involving vestibulo-cerebellum ( 19 cases) Spinocerebellar degeneration ( 10 cases) (cerebellar type) Cerebellar hemorrhage ( 5 cases) Cerebellar tumor (2 cases) Arterio-venous malformation (I case) Cerebellitis ( I case) Total (B)
Normal V.S.
Reduced or abolished V.S.
40
51
13 0 0
0 19 10
0 0 0 0
5 2
53 cases
89 cases
Cerebellar lesions and the direction of reduced or abolished visual suppression of post-rotatory nystagmus. Reduced or abolished visual suppression Ipsilateral nystagmus
Cerebellar atrophy (51 cases) Cerebellar infarction ( 19 cases) Spinocerebellar degeneration (cerebellar type) ( 10 cases) Cerebellar hemorrhage ( 5 cases) Cerebellar tumor (2 cases) Cerebellitis ( 1 case) Arterio-venous malformation ( 1 case)
Contralateral nystagmus
Bilateral nystagmus 51 10
9
10
2
2
88
K. TERAMOTO
pesticide intoxication and organic solvent intoxication, was distinguished clinically to evaluate this visual suppression from spinocerebellar degeneration ( 10 cases) caused by chronic alcoholism and late cortical cerebellar atrophy (LCCA). Normal visual suppression in cerebellar lesions. Visual suppression on postrotatory nystagmus was found to be normal in 53 patients with cerebellar disease. Ninety-one patients had also radiologically confirmed diffuse atrophic changes throughout the cerebellum. However, 40 of these 91 patients showed normal range of visual suppression. This discrepancy in the ratio of visual suppression in the cerebellar atrophy group may be due to the property of the disease, or the extent of histologic or functional involvement of the cerebellum. It was especially noteworthy that, among these 53 patients, 13 that had cerebellar infarction were radiologically confirmed to have no associated lesions of the vestibulo-cerebellum. A typical case is presented in Fig. 4. Oblique nystagmus to the lower eyelid was observed with gazing to both the right and left sides, at positional nystagmus test and positioning nystagmus test. The CT-scan findings showed a lesion in the left superior cerebellar peduncle that did not affect the vestibulo-cerebellum. The visual suppression on post-rotatory nystagmus was normal in this case. Cases with reduced or abolished visual suppression. Eighty-nine patients with cerebellar lesions showed reduced or abolished visual suppression on post-rotatory nystagmus. The clinical diagnoses and visual suppression on post-rotatory nystagmus are shown in Table 1. Seventy-five patients that were radiologically confirmed to have bilateral lesions of the vestibulo-cerebellum or diffuse and severe lesions involving the vestibulo-cerebellum showed bilateral reduced or abolished visual suppression on post-rotatory nystagmus (Table lB). An illustrative case is presented in Fig. 5. Nystagmus was observed with gazing to both the right and left sides. Directional changing upward beating positional nystagmus and vertical positioning nystagmus were observed. The MRI findings showed diffuse and severe atrophic changes throughout the cerebellum, including lesions in the vestibulo-cerebellum. Visual suppression test using postrotatory nystagmus showed bilateral abolished visual suppression of the slow phase velocity. Unilateral reduced or abolished visual suppression on post-rotatory nystagmus. In 14 patients whose radiological examinations confirmed unilateral lesions in the vestibulo-cerebellum, unilateral reduced or abolished visual suppression on postrotatory nystagmus was seen. The correlation between the lesion side and the direction of visual suppression on post-rotatory nystagmus is summarized in Table lB. These results showed that visual suppression of post-rotatory nystagmus to the lesion side was reduced or abolished in most cases. An illustrative case is presented in Fig. 6. Spontaneous nystagmus to the right
VISUAL SUPPRESSION TEST
slow
phase
velocity
A
89
B
1".~1.,.~, ..1 I~ '
200/SEC _c dark """"jkJ1!!1PI._d""a"rk~-------------~~-dark_."!!hg!!hl'"tLd;;-;;a"'rk-
1
:ec
Fig. 4. (A) Cerebellar hemorrhage of the left superior cerebellar peduncle. Visual suppression of the slow phase velocity was within the normal range, 78% by rotation to the right, 68% by rotation to the left, 74% by right ear irrigation, and 77% by left ear irrigation. (B) CT-scan. The CT-scan findings show a lesion of the left superior cerebellar peduncle. The white arrow shows a hemorrhage of the left superior cerebellar peduncle.
was observed in the right and primary eye positions. The CT -scan showed a lesion in the left vestibu)o-cerebellum. The visual suppression test on post-rotatory nystagmus showed reduced visual suppression to the left side, which was the lesion side. DISCUSSION
Visual suppression is a method for examining the function of visual conditions.
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Fig. 5. (A) A case with bilaterally abolished visual suppression. Visual suppression of the slow phase velocity was O% by rotation to the right, O% by the rotation to the left, 0% by right ear irrigation, and O% by left ear irrigation. (B) MRI (TI-weighted image). The MRI (Tlweighted image) showed diffuse and severe atrophic changes throughout the cerebellum.
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Fig. 6. (A) A case of unilaterally reduced visual suppression. Visual suppression of the slow phase velocity was 8% by rotation to the right, 75% by rotation to the left, 10% by right ear irrigation, and 77% by left ear irrigation. The lesion was confirmed on the same side as the direction of the quick phase of the post-rotatory nystagmus: the left. (B) CT-scan. The white arrow shows an infarction of the left vestibulo-cerebellum.
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The visual condition is important for maintaining equilibrium. It is well known that the vestibular nystagmus elicited by either caloric or rotatory stimulation is influenced by visual conditions. The visual suppression test is widely used to diagnose lesions of the flocculus, nodulus, pons, and lower parietal lobe. In 1976 HART used the ocular fixation index, which affected some of the parameters of nystagmus. He demonstrated the enhancement of caloric nystagmus by ocular fixation in cerebellar diseases. In 1970 CoATS reported the failure of fixation suppression of caloric nystagmus. He demonstrated the failure of fixation suppression in patients with brainstem tumors and spinocerebellar degeneration. But in 1974 TAKEMORI and CoHEN reported the visual suppression test using the slow phase velocity of caloric nystagmus. This method is useful for quantitative analysis of visual conditions on vestibular nystagmus and for diagnostic evaluation. In 1976 SAKATA reported the caloric-eye tracking pattern test using visual fixation. This method is useful for making a differential diagnosis between peripheral and central vertigo. And ever since BARANY ( 1907) introduced the clinical usefulness of the rotatory test for vestibular evaluation, there has been a great deal of interest in the development and improvement of acceleration techniques. On the other hand, since MACH reported in 1900, that the use of torsion balance enabled the administration of frequently repeated stimuli, many studies have evaluated vestibular function by the pendular rotatory acceleration test. An interaction between visual and vestibular reflexes has been demonstrated since OHM first described it in 1926. In 1978 KOENIG et a/. quantified the visual-vestibular interaction upon nystagmus slow phase velocity using the pendular rotatory test. And ToUPET, MENGUY, and TEYSSON made studies on ocular fixation using the pendular rotatory test in 1977. However, when the pendular rotatory technique is used, the intensity of the stimulus constantly changes and the direction of the stimulus constantly mixes. Therefore, an evaluation of visual suppression using this technique would be rather complicated. And furthermore, concerning the correlation between the disturbed direction of pendular rotatory nystagmus and the laterality of the lesion, the direction of the stimulus constantly mixes and the intensity of the stimulus constantly changes, so it may be difficult to identify the side of cerebellar lesions when visual suppression with pendular rotatory nystagmus is used. Compared with the visual suppression test using pendular rotatory nystagmus, post-rotatory nystagmus can always be elicited toward one direction, therefore the visual suppression test using post-rotatory nystagmus is easier to analyze. Without using computer analysis, the results can be obtained by simple inspection. The stimulation is milder in the visual suppression test using post-rotatory
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nystagmus than in caloric stimulation. Thus this method can easily be performed on patients with motion sickness, patients who are afraid of vertigo, elderly persons, and children. In 1975 TAKEMORI reported visual suppression of calorically induced vestibular nystagmus in cerebellar lesions of rhesus monkeys. A reduced or loss of visual suppression was seen in a unilateral flocculus lesion, and bilateral loss of visual suppression was seen in bilateral flocculus lesions. Nodulus lesions and lesions of the dentate nucleus showed a loss of visual suppression in certain period. Lesions of the uvula, vermis, paraflocculus, cerebellar cortex, or the fastigial or interpositus nuclei had no observed effect on visual suppression. In our 142 patients with cerebellar lesions, 91 patients with cerebellar atrophy had radiologically confirmed diffuse atrophic changes throughout the cerebellum. However, 40 of these 91 patients showed normal range of visual suppression. This discrepancy in the cerebellar atrophy group may be due to the property of the disease, or the extent of histologic or functional involvement of the cerebellum. Reduced or abolished visual suppression examined by post-rotatory nystagmus was seen in 89 patients that had radiologically confirmed disturbances of the vestibulo-cerebellum. In these 89 cases, 75 patients that were radiologically confirmed to have bilateral lesions in the vestibulo-cerebellum or diffuse and severe lesions throughout the cerebellum showed reduced or abolished visual suppression of post-rotatory nystagmus bilaterally. And 12 cases who had radiologically confirmed unilateral lesions in the vestibulo-cerebellum showed reduced or abolished visual suppression on post-rotatory nystagmus directed to the lesion side. The lesion side of the cerebellum could be diagnosed by the visual suppression test using post-rotatory nystagmus. It was considered that a lesion of the vestibulocerebellum existed in the ipsilateral direction of the quick phase of the post-rotatory nystagmus. These results showed a correlation between visual suppression using postrotatory nystagmus and caloric nystagmus in 65 normal subjects and 142 clinical cases with cerebellar lesions. However, post-rotatory nystagmus is weaker than caloric nystagmus, so measurement of the ratio of visual suppression should be done more carefully. CONCLUSION A visual suppression test using a post-rotatory nystagmus gives a far milder stimulation than caloric stimulation. In 142 patients with cerebellar lesions, a correlation of the results of visual suppression of the slow phase velocity using post-rotatory nystagmus and caloric stimulation was found. Therefore, it may be better to use rotatory stimulation to evoke vestibular nystagmus than to use caloric stimulation for a visual suppression test.
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This paper is respectfully dedicated to Prof. E. Sakata, M.D. The author especially thanks Prof. S. Takemori, M.D. and K. Ohtsu, Ph.D., and the entire staff of the Department of Neurotology, Saitama Medical School. REFERENCES BARANY, R.: Physiologie und Pathologie des Bogengangsapparatus beim Menschen, Deuticke, Leipzig & Wien, 1907. COATS, A. C.: Central electronystagmographic abnormalities. Arch. Otolaryngol. 92: 43-53, 1970. HART, C. W.: Ocular fixation of the caloric test. Laryngoscope 77: 2103-2114, 1976. KoENIG, E., ALLUM, J. H. J., and DICHGANS, J.: Visual-vestibular interaction upon nystagmus slow phase velocity in man. Acta Otolaryngol. (Stockh.) 85: 397-410, 1978. MACH, E.: Die Analyse der Empfindungen, 2nd ed., Gustav-Fisher, Jena, 1900. OHM, J.: Uber den Einftuss des Sehens auf den vestibuliiren Drehnystagmus und Nachnystagmus. Z. Hals Nasen Ohreheilkd. 16: 521-540, 1926. SAKATA, E.: Caloric-eye tracking pattern test: 1. Visual suppression and the possibility of simplified differential diagnosis between peripheral and central vertigo. Ann. ORL 85: 261-267, 1976. TAKEMORI, S.: Visual suppression of vestibular nystagmus after cerebellar lesions. Ann. Otolaryngol. 84: 318-326, 1975. TAKEMORI, S., and COHEN, B.: Visual suppression of vestibular nystagmus in rhesus monkeys. Brain Res. 72: 203-212, 1974a. TAKEMORI, S., and COHEN, B.: Loss of visual suppression of vestibular nystagmus after flocculus lesions. Brain Res. 72: 213-224, 1974b. ToUPET, M., MENGUY, C., and TEYSSON, M.: Test de fixation dculaire au cours de Ia stimulation vestibulaire pendulaire. Ann. Otolaryngol. Chir. Cervicofac. 94: 301-308, 1977.
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Dr. K. Teramoto, Department of Neurotology, Saitama Medical School, 38 Morohongo, Moroyama-cho, Iruma-gun, Saitama 35D-04, Japan
