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Recent Development of the Study on Clinical Significance of Abnormal Eye Movement
Auris' Nasus' Larynx (Tokyo) 12, 169-182 (1985)
RECENT DEVELOPMENT OF THE STUDY ON CLINICAL SIGNIFICANCE OF ABNORMAL EYE MOVEMENT Eiji SAKATA, M. D., Kazuhiro TERAMOTO, M. D., Kanji BABA, M. D., and Kyoko OHTSU, M. D. Neurotological Clinic, Saitama Medical School, Saitama, Japan
As a general trend, the diagnosis in medical clinics often depends on laboratory test results. Neurotological diagnosis, however, requires detailed neurological examinations on a patient by a neurotologist. Therefore, there are differing diagnostic skills among physicians, and there is a kind of "man-made flavor" in neurotological diagnostic procedure. In the present study, current development in the knowledge on the clinical diagnostic significance of pathological eye movement during the last 2-3 years is summarized. I) Acquired pendular wondering eye-movement. 2) Fixation jerks. 3) Spontaneous and transitory eyeball burst or seizure. 4) Vertical rebound nystagmus. 5) Optokinetic vertical ocular dysmetria. 6) Divergence nystagmus. 7) Counterolling, pure rotatory positioning nystagmus. 8) Inversion of optokinetic afternystagmus (OKAN). 9) Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN). 10) Treatment of congenital nystagmus. 11) Vertical spontaneous nystagmus to lower eyelid or so-called "downbeat nystagmus." 12) Downbeat nystagmus seen in bilateral labyrinthine dysfunction. The significance of bilateral vestibular lesion, or symmetric lesion in other is emphasized in the present report for reader's reference and criticism. Our experience on the clinical significance of the abnormal eye movement was reported. It is our wish that accumulation of data on important cases along with the results of experimental studies directly connected with clinical medicine may contribute to the progress of our neurotology in the right direction as "neurology of the posterior fossa." FINDINGS OF PATHOLOGICAL EYE MOVEMENT
1) Acquired pendular wondering eye-movement
This is a pendular eye movement of the horizontal (Fig. la) and vertical (Fig. Received for publication January 30, 1985 169
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Fig. 1. Acquired pendular wondering eye-movement. Horizontal lead ENG-recording (a) and vertical one (b) are useful for the evaluation of this eye movement. A sign of cerebellar nuclei disease. A in figure shows a horizontal lead.
1b) planes, frequently occurring on various changes of the visual conditions, when the eyes are closed, or the opened state was changed to the closed state, naturally during alert consciousness (ASCHOFF, CONRAD, and KORNHUBER, 1974). This condition occurs in patients with intoxication by organic solvents, those who are taking anticonvulsants and those with cerebellar atrophy under the influence of certain drugs. When such eye movement was noted, important information may be obtained for further diagnostic processes with reference to the history of the present iIIness and other laboratory findings. 2) Fixation jerks This is not an object for eye-tracking test, but a spontaneous eye movement
RECENT DEVELOPMENT OF CLINICAL SIGNIFICANCE
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Fig. 3. Spontaneous and transitory eyeball burst or seizure. This phenomenon is frequently seen in patients with benign tumor of posterior fossa especially epidermoid and meningioma. The upper panel shows horizontal lead, and the lower panel shows vertical lead.
on forward fixation (Fig. 2). The eyeballs slowly shift to the right and left, along with fine jerking abnormal eye movement with nystagmoid slow and quick phase. A lateralized lesion gives rise to the quick phase only unilaterally. The bilateral occurrence of this movement would suggest the presence of midline or symmetric
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Fig. 4. Vertical rebound nystagmus. (a) is a rebound nystagmus directed to the lower eyelid appearing on a rapid shift from upward gaze to forward gaze. The upper panel A of the figure shows the horizontal lead and the lower panel B of the figure shows the vertical lead ENG-recording. We have also found out the occurrence of vertical rebound nystagmus directed to the upper eyelid on a quick shift from the lower gaze to the frontal gaze (b). The upper panel A of the figure shows the vertical lead and the lower panel B enlarged lead ENG-record.
lesions. In other words, the fixation oscillation which is considered as physiological movement has become coarse. These symptoms may also be seen in patients with cerebellar atrophy, space-taking lesion in the posterior fossa or cerebrovascular disease (SAKATA, 1971, 1980). The disturbance of the function of fastigial nuclei appears to have an important relationship with the occurrence of these symptoms.
RECENT DEVELOPMENT OF CLINICAL SIGNIFICANCE
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10·CAL ----- -- --
Fig. 5. Optokinetic vertical ocular dysmetria. Among the vertical rebound nystagmus, those directed towards the lower eyelid were found to show dysmetria as downward OKN as shown on the right side of the lower panel of the figure. This is seen in patients with midline lesion of the posterior fossa, especially in the rostral portion. In the upper pannel, the right OKN on the left and left OKN on the right. The lower panel shows the upper OKN on the left and lower OKN on the right.
3)
Spontaneous and transitory eyeball burst or seizure This phenomenon is frequently seen in patients with benign tumor of posterior fossa, especially epidermoid and meningioma. (Fig. 3) This appears to be similar to a seizure in EEG during epileptic attacks (SAKATA, ITOH, OTSU, and KANAZAWA, 1982). On appearance of such phenomena, the patient simultaneously complained of a severe oscillopsia. When such findings were noted, examinations should be carried out, on suspicion of epidermoid and meningioma or even A VM in the posterior fossa. The upper panel shows horizontal lead, and the lower panel shows vertical lead. 4)
Vertical rebound nystagmus In recent years, attention has been focussed on the relationship between
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Fig. 6. Divergence nystagmus. The upper panel A of the figure shows the monocular horizontal lead ENG of the right eye, middle panel B shows the corresponding lead of the left eye and the lower panel C shows the vertical lead (a). The CT-scan in this patient, furthermore, revealed a low density area in a region slightly lateral from the central pons (b).
cerebellar disturbance and abnormal eye movement, and discussions have been repeated. It is widely known, for example, that horizontal rebound nystagmus or contrast nystagmus seen on horizontal gaze accompanies cerebellar lesion (OLZECHOWSKI, 1927; COGAN, 1954). We have found out, however, that vertical rebound nystagmus may also occur during vertical gaze (OHTSU, 1984; LESSER, SMITH, and LEBENSON, 1971). This is a rebound nystagmus directed to the lower eyelid appearing on a rapid shift from upward gaze to forward gaze. (Fig. 4a). The upper panel A of the Fig. 4 shows the horizontal lead and the lower panel B of the figure shows the vertical lead ENGrecording. We have also found out the occurrence of vertical rebound nystagmus directed to the upper eyelid on a quick shift from the lower gaze to the forward gaze. The upper panel A of the figure shows the vertical lead and the lower panel B the vertical enlarged lead ENG-record (Fig. 4b). The former was seen in patients with lesions located in the rostral portion in the midline lesion of the posterior fossa, whereas the latter was seen in those with lesions located in the caudal portion.
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Fig. 7. Counterolling, pure rotatory positioning nystagmus. Positioning nystagmus with latent period, accompanied by severe vertigo along with nystagmus, with subsequent fatigability has been thought to be seen in patients with partial lesions of the inner ear especially otolith lesion (a). Since we have started to utilize CT-scanner, however, such nystagmus has been noted in II patients, all of whom had cerebellar vermis infarction (b).
5)
Optokinetic vertical ocular dysmetria As was described in 4), among the patients with horizontal rebound nysragmus, patterns with downward outsliding from the baseline may be encountered in optokinetic nystagmus test, because of the dysmetria of OKN, as shown in the upper panel, the right OKN on the left and left OKN on the right (Fig. 5). The lower panel of the figure shows the upper OKN on the left and lower OKN on the right. Among the vertical rebound nystagmus, those directed towards the
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Fig. 8. Inversion of optokinetic after-nystagmus (OKAN). The figure shows an example in a patient with typical basilar artery insufficiency. As seen in the upper panel, induction of OKN on the right side produced OKAN on the left. As seen in the lower panel, induction of OKN on the left produced OKAN on the right. Such phenomenon was seen in patients with bilateral peripheral vestibular or central vestibular lesion.
lower eyelid were found to show dysmetria on downward OKN as shown on the right side of the lower panel of the figure. This is seen in patients with midline lesion of the posterior fossa, especially in the rostral portion (OHTSU, 1984). 6)
Divergence nystagmus
Convergence nystagmus is one of the representative disconjugated nystagmus, frequently seen in patients with pinealoma and those with tumor of the posterior part of the third ventricle. Its pathophysiological picture has been established as that caused by a lesion in the pretectal area of the midbrain. On the contrary, however, such divergence nystagmus is seen only in rare patients, and only a few reports are available (BENDER and SAVITSKEY, 1940). Only 1 autopsy case is found to the author's knowledge. In a patient with cardiac disease recently seen, diplopia and equilibrium disorder suddenly appeared, along with a marked divergence nystagmus, which was recorded on ENG. The upper panel A of the figure shows the monocular horizontal lead ENG of the right eye, middle panel B shows the corresponding lead of the left eye and the lower panel C shows the vertical lead ENG-record (Fig. 6a). The CT-scan in this patient, furthermore, revealed a low density area in a region slightly lateral from the midline pons (Fig. 6b). From the history of the patient, an intimate causal relationship is assumed between divergence nystagmus and CT-scan findings.
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Fig. 9. Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN). The nystagmus of jerking type is directed to the upper eyelid, with hereditary and familial mode of occurrence. The left upward OKN is directed downward despite the presence of original upward nystagmus indicating a complete inversion. The downward OKN shows no reaction, recorded unchanged from the spontaneous nystagmus directed upward.
7)
Counterolling, pure rotatory positioning nystagmus Positioning nystagmus with latent period, accompanied by severe vertigo along with nystagmus, with subsequent fatigability has been thought to be seen in patients with partial lesions of the inner ear especially of otolith lesion. We agree with this and have constantly emphasized the significance of this phenomenon in clinical diagnosis (SAKATA, 1963; TAKAHASHI, OHTSU, and SAKATA, 1985). Since we have started to utilize CT-scanner, however, such nystagmus has been noted in 11 patients, all of whom had cerebellar vermis infarction (Fig. 7a, b). Attention should be focussed on such association. As to such association between such nystagmus and CT findings, simple coincidence would not have been excluded in case such combination is seen only in 1 or 2 patients, but its occurrence in as many as 11 patients might suggest a causal role of cerebellar vermis lesions. This might be explained by the incomplete inhibition by cerebellar flocculo-nodular lobe or vestibulocerebellum to the vestibulo-oculomotor system. 8) Inversion of optokinetic after-nystagmus (OKAN) OKAN is an after-discharge of the vestibulo-oculomotor system seen after the elimination of OKN stimulus. This phenomenon is important since this makes it possible to detect the balance of right-left side difference of the fine vestibulo-oculomotor system function which cannot be detected by other methods (SAKATA, 1980). As to the occurrence of this phenomenon, however, individual
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Fig. 10. Treatment of congenital nystagmus. We have recently demonstrated the disappearance of such nystagmus on a slow intravenous injection of 2 ml 2 %lidocaine solution diluted with 20% glucose solution along with a transient improvement of the visual acuity. In this figure, A shows the beginning of the injection and B the end of the injection. Almost complete disappearance of nystagmus is noted.
difference is noted, presenting difficult problems on its actual performance such as the setting of the examination room and apparatus, so that this method has not yet been widely used. Many abnormal findings, however, can be concluded as definitely pathological. One is the inversion phenomenon. The figure shows an example in a patient with typical basilar artery insufficiency. As seen in the upper panel, induction of OKN on the right side produced OKAN on the left. As seen in the lower panel, induction of OKN on the left produced OKAN on the right (Fig. 8). Such phenomenon was seen in patients with bilateral peripheral vestibular or central vestibular lesion in more than 100 patients in our clinic. 9)
Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN) Most of the congenital spontaneous nystagmus are horizontal; however, there are occasional rotatory and rarely vertical ones. A lot of diagnostic evidences of congenital nystagmus have been presented. The inversion of optokinetic nystagmus is one of the important evidences. As to the congenital vertical nystagmus, however, the response of optokinetic nystagmus has remained unknown since the cases are rare. While several cases have been reported, no OKN has been described nor record of OKN was presented even if it was referred. In a very few cases, only vague descriptions of "no reaction" are available. Figure 9 is the ENG-record in a patient with congenital vertical spontaneous
RECENT DEVELOPMENT OF CLINICAL SIGNIFICANCE
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Fig. 11. Vertical spontaneous nystagmus to lower eyelid or so-called "downbeat nystagmus." There are at least two different lesions involved. The downbeat nystagmus in the upper panel of the figure indicates a pontine lesion and the one in the lower panel, a cerebellar lesion.
nystagmus recently examined. The nystagmus of jerking type is directed to the upper eyelid, with hereditary and familial mode of occurrence (lWASHITA, NAKAZAWA, OHTSU, and SAKATA, 1984). The OKN which is shown in the upward left of the Fig. 9, is directed downward despite the presence of original upward nystagmus. This indicates a complete inversion of the OKN. The downward OKN shows no reaction, recorded unchanged in spite of the presence of the spontaneous nystagmus directed upward. 10)
Treatment of congenital nystagmus
In patients with congenital nystagmus, visual disturbance occurs due to eye oscillation and strabismus appears because the gaze is directed to the object at the neutral point of the nystagmus, with consequent scoliosis, presenting with serious problems. Attention of the ophthalmologists all over the world is directed to the treatment of this disease but no satisfactory method is yet available. We have recently demonstrated the disappearance of such nystagmus along
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with a transient improvement of the visual acuity as a result of a slow intravenous injection of 2 ml 2 % lidocaine solution diluted with 20 % glucose solution (NAKAZAWA, im Druck). In this figure, A shows the beginning of the injection and B the end of the injection (Fig. 10). Almost complete disappearance of nystagmus is noted. By repeating the injection 2-3 times a week for 6 months, nystagmus persistently disappeared and favorable visual results were obtained in 10 patients. 11)
Vertical spontaneous nystagmus to lower eyelid or so-called "downbeat nystagmus" Marked downbeat nystagmus indicating midline lesions in the posterior fossa has gradually received widespread attention not only in neurotology, but also in neurology, neurosurgery and neurophthalmology, with active discussions. As to the pathophysiological explanations, however, much confusion is noted, because the discussions are based on a pre-occupied concept on the presence of an identical lesion for all the pathological phenomena. There are at least two different lesions involved (SAKATA, 1980). One is a lesion mainly in the pons giving rise to paretic eye movement. The speed of both slow and fast phases of the nystagmus are decreased with low frequency, giving a specific pattern. Another lesion is in the caudal part of the cerebellum or "Innere Abteilung des Kleinhirnstiels" (IAK), giving rise to holding tremor with high frequency oscillation of a specific pattern. The downbeat nystagmus in the upper
RECENT DEVELOPMENT OF CLINICAL SIGNIFICANCE
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panel of the figure indicates a pontine lesion and the one in the lower panel a cerebellar lesion (Fig. 11). 12) Downbeat nystagmus seen in bilateral labyrinthine dysfunction Downbeat nystagmus is seen with simultaneous dysfunction of the bilateral vestibular system. Such lesion is therefore frequently seen in the brainstem and cerebellum where the bilateral vestibular systems are located close to each other or forming network, especially in the presence of midline or symmetric lesions. When such nystagmus was clinically noted, the presence of midline lesions in the posterior fossa should be at first suspected. Occurrence of vertical nystagmus was reported on caloric test by simultaneous stimulation of both ears, and appearance of vertical eye deviation was pointed out in cats on electrical stimulation of bilaterally paired semicircular canal. For the treatment of labyrinthine vertigo and cochlear tinnitus, we have injected a local anesthetic, 4 % lidocaine, into the middle ear cavity to improve the symptoms, over the past 10 years. Occurrence of downbeat nystagmus over a period of several hours was confirmed and recorded in many patients on such occasion (ITOH, OHTSU, YAMASHITA, and SAKATA, im Druck). The upper panel of Fig. 12 is the horizontal lead ENG-recording and the lower panel, vertical lead ENG. This is not due to the cupular deviation caused by the endolymphatic flow, and is also different from eye deviation caused by bilateral electric stimulation of animal's semicircular canal nerve. The confirmation of the nystagmus in human under conditions close to the clinical setup should more contribute to the medicine. REFERENCES ASCHOFF, J. C., CONRAD, B., and KORNHUBER, H. H.: Acquired pendular nystagmus with oscillopsia in multiple sclerosisia sign of cerebellar nuclei disease. J. Neurol. Neurosurg. Psychia. 37: 570-577, 1974. BENDER, M. B., and SAVITSKEY, N.: Paralysis of divergence. Arch. Ophthal. 23: 1046-1051, 1940. CooAN, D. G.: Ocular dysmetria, flutter-like oscillations of the eyes and opsoclonus. Arch. Ophthal. 52: 318-328, 1954. ITOH, Y., OHTSU, K., YAMASHITA, H., and SAKATA, E.: Wird der vertikale Spontannystagmus infolge der Innenohrdys funktion hervorgerufen? Aus der Erfahrung der beidohrigen Lidocaininfusion in die PaukenhOhle beim Menschen. (im Druck) IWASHITA, N., NAKAZAWA, H., OHTSU, K., and SAKATA, E.: A case of congenital vertical nystagmus with inversion of vertical optokinetic reaction. Equilibrium Res. 43: 71-82, 1984. LESSER, P. L., SMITH, J. L., and LEBENSON, D. S.: Vertical ocular dysmetria. Am. J. Ophthal. 76: 208-211, 1971. NAKAZAWA, H.: Die Behandlung des kongenitalen Nystagmus mit der intravenosen Infusion von 2% Lidocain-und 20% Glucose-Losung. (im Druck) OHTSU, K.: Vertical ocular dysmetria. Vertical rebound nystagmus and optokinetic vertical ocular dysmetria. Auris-Nasus-Larynx (Tokyo) 11: 91-100,1984. OLZECHOWSKI, K.: De I'ataxie dysmetrique des yeux. Remarques sur I'ataxie des yeux dite
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182
myoclonique (Opsoc1onie, Opsoc1onus) J. Psychol. Neurol. 35: 1-13, 1927. SAKATA, E.: Das neurootologische Studium iiber die Liision des Kleinhirnwurms. Equilibrium Res. Suppl. 1: 30-46, 1971. SAKATA, E.: Lageschwindel vom gutartigen paroxysmalen Typ als senile Krankheit. Geront. Geriat. 7: 349-364, 1963. SAKATA, E.: Leitfaden der klinischen Neurootologie, S. 73-75, Ishiyaku-Verlag, Tokio, 1980. SAKATA, E., ITOH, A., OHTSU, K., and KANAzAWA, C.: Diagnosis of out-patients with brain benign tumor, especially meningioma. Equilibrium Res. 41: 120-127, 1982. TAKAHASHI, K., OHTSU, K., and SAKATA, E.: Counterolling, pure rotatory positioning nystagmus caused by cerebellar vermis lesion. Pract. Otol. Kyoto 78: 2729-2736, 1985
Request reprints from:
Dr. E. Sakata, Neurotological Clinic, Saitama Medical School, Moroyama, lruma, Saitama 350-04, Japan
RECENT DEVELOPMENT OF THE STUDY ON CLINICAL SIGNIFICANCE OF ABNORMAL EYE MOVEMENT Eiji SAKATA, M. D., Kazuhiro TERAMOTO, M. D., Kanji BABA, M. D., and Kyoko OHTSU, M. D. Neurotological Clinic, Saitama Medical School, Saitama, Japan
As a general trend, the diagnosis in medical clinics often depends on laboratory test results. Neurotological diagnosis, however, requires detailed neurological examinations on a patient by a neurotologist. Therefore, there are differing diagnostic skills among physicians, and there is a kind of "man-made flavor" in neurotological diagnostic procedure. In the present study, current development in the knowledge on the clinical diagnostic significance of pathological eye movement during the last 2-3 years is summarized. I) Acquired pendular wondering eye-movement. 2) Fixation jerks. 3) Spontaneous and transitory eyeball burst or seizure. 4) Vertical rebound nystagmus. 5) Optokinetic vertical ocular dysmetria. 6) Divergence nystagmus. 7) Counterolling, pure rotatory positioning nystagmus. 8) Inversion of optokinetic afternystagmus (OKAN). 9) Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN). 10) Treatment of congenital nystagmus. 11) Vertical spontaneous nystagmus to lower eyelid or so-called "downbeat nystagmus." 12) Downbeat nystagmus seen in bilateral labyrinthine dysfunction. The significance of bilateral vestibular lesion, or symmetric lesion in other is emphasized in the present report for reader's reference and criticism. Our experience on the clinical significance of the abnormal eye movement was reported. It is our wish that accumulation of data on important cases along with the results of experimental studies directly connected with clinical medicine may contribute to the progress of our neurotology in the right direction as "neurology of the posterior fossa." FINDINGS OF PATHOLOGICAL EYE MOVEMENT
1) Acquired pendular wondering eye-movement
This is a pendular eye movement of the horizontal (Fig. la) and vertical (Fig. Received for publication January 30, 1985 169
E. SAKATA et al.
170
(a)
:...L ..
(b)
_.. RT-LATERAL GAZE ..
FORWARD GAZE
LT -LATERAL GAZE
B
• ___,..,'ui."
H
0( • •
lO'CAL 2sec
Fig. 1. Acquired pendular wondering eye-movement. Horizontal lead ENG-recording (a) and vertical one (b) are useful for the evaluation of this eye movement. A sign of cerebellar nuclei disease. A in figure shows a horizontal lead.
1b) planes, frequently occurring on various changes of the visual conditions, when the eyes are closed, or the opened state was changed to the closed state, naturally during alert consciousness (ASCHOFF, CONRAD, and KORNHUBER, 1974). This condition occurs in patients with intoxication by organic solvents, those who are taking anticonvulsants and those with cerebellar atrophy under the influence of certain drugs. When such eye movement was noted, important information may be obtained for further diagnostic processes with reference to the history of the present iIIness and other laboratory findings. 2) Fixation jerks This is not an object for eye-tracking test, but a spontaneous eye movement
RECENT DEVELOPMENT OF CLINICAL SIGNIFICANCE
171
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Fig. 2. Fixation jerks. This is not an object for eye-tracking test, but a spontaneous eye movement on forward fixation. A sign of cerebellar nuclei disease. I l i ' . ' . ; f , ' , i ' i i . , ; I ' T -.... ~~
10° CAL
2 sec
Fig. 3. Spontaneous and transitory eyeball burst or seizure. This phenomenon is frequently seen in patients with benign tumor of posterior fossa especially epidermoid and meningioma. The upper panel shows horizontal lead, and the lower panel shows vertical lead.
on forward fixation (Fig. 2). The eyeballs slowly shift to the right and left, along with fine jerking abnormal eye movement with nystagmoid slow and quick phase. A lateralized lesion gives rise to the quick phase only unilaterally. The bilateral occurrence of this movement would suggest the presence of midline or symmetric
172
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Fig. 4. Vertical rebound nystagmus. (a) is a rebound nystagmus directed to the lower eyelid appearing on a rapid shift from upward gaze to forward gaze. The upper panel A of the figure shows the horizontal lead and the lower panel B of the figure shows the vertical lead ENG-recording. We have also found out the occurrence of vertical rebound nystagmus directed to the upper eyelid on a quick shift from the lower gaze to the frontal gaze (b). The upper panel A of the figure shows the vertical lead and the lower panel B enlarged lead ENG-record.
lesions. In other words, the fixation oscillation which is considered as physiological movement has become coarse. These symptoms may also be seen in patients with cerebellar atrophy, space-taking lesion in the posterior fossa or cerebrovascular disease (SAKATA, 1971, 1980). The disturbance of the function of fastigial nuclei appears to have an important relationship with the occurrence of these symptoms.
RECENT DEVELOPMENT OF CLINICAL SIGNIFICANCE
173
10·CAL ----- -- --
Fig. 5. Optokinetic vertical ocular dysmetria. Among the vertical rebound nystagmus, those directed towards the lower eyelid were found to show dysmetria as downward OKN as shown on the right side of the lower panel of the figure. This is seen in patients with midline lesion of the posterior fossa, especially in the rostral portion. In the upper pannel, the right OKN on the left and left OKN on the right. The lower panel shows the upper OKN on the left and lower OKN on the right.
3)
Spontaneous and transitory eyeball burst or seizure This phenomenon is frequently seen in patients with benign tumor of posterior fossa, especially epidermoid and meningioma. (Fig. 3) This appears to be similar to a seizure in EEG during epileptic attacks (SAKATA, ITOH, OTSU, and KANAZAWA, 1982). On appearance of such phenomena, the patient simultaneously complained of a severe oscillopsia. When such findings were noted, examinations should be carried out, on suspicion of epidermoid and meningioma or even A VM in the posterior fossa. The upper panel shows horizontal lead, and the lower panel shows vertical lead. 4)
Vertical rebound nystagmus In recent years, attention has been focussed on the relationship between
E. SAKATA et al.
174
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Fig. 6. Divergence nystagmus. The upper panel A of the figure shows the monocular horizontal lead ENG of the right eye, middle panel B shows the corresponding lead of the left eye and the lower panel C shows the vertical lead (a). The CT-scan in this patient, furthermore, revealed a low density area in a region slightly lateral from the central pons (b).
cerebellar disturbance and abnormal eye movement, and discussions have been repeated. It is widely known, for example, that horizontal rebound nystagmus or contrast nystagmus seen on horizontal gaze accompanies cerebellar lesion (OLZECHOWSKI, 1927; COGAN, 1954). We have found out, however, that vertical rebound nystagmus may also occur during vertical gaze (OHTSU, 1984; LESSER, SMITH, and LEBENSON, 1971). This is a rebound nystagmus directed to the lower eyelid appearing on a rapid shift from upward gaze to forward gaze. (Fig. 4a). The upper panel A of the Fig. 4 shows the horizontal lead and the lower panel B of the figure shows the vertical lead ENGrecording. We have also found out the occurrence of vertical rebound nystagmus directed to the upper eyelid on a quick shift from the lower gaze to the forward gaze. The upper panel A of the figure shows the vertical lead and the lower panel B the vertical enlarged lead ENG-record (Fig. 4b). The former was seen in patients with lesions located in the rostral portion in the midline lesion of the posterior fossa, whereas the latter was seen in those with lesions located in the caudal portion.
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5)
Optokinetic vertical ocular dysmetria As was described in 4), among the patients with horizontal rebound nysragmus, patterns with downward outsliding from the baseline may be encountered in optokinetic nystagmus test, because of the dysmetria of OKN, as shown in the upper panel, the right OKN on the left and left OKN on the right (Fig. 5). The lower panel of the figure shows the upper OKN on the left and lower OKN on the right. Among the vertical rebound nystagmus, those directed towards the
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Fig. 8. Inversion of optokinetic after-nystagmus (OKAN). The figure shows an example in a patient with typical basilar artery insufficiency. As seen in the upper panel, induction of OKN on the right side produced OKAN on the left. As seen in the lower panel, induction of OKN on the left produced OKAN on the right. Such phenomenon was seen in patients with bilateral peripheral vestibular or central vestibular lesion.
lower eyelid were found to show dysmetria on downward OKN as shown on the right side of the lower panel of the figure. This is seen in patients with midline lesion of the posterior fossa, especially in the rostral portion (OHTSU, 1984). 6)
Divergence nystagmus
Convergence nystagmus is one of the representative disconjugated nystagmus, frequently seen in patients with pinealoma and those with tumor of the posterior part of the third ventricle. Its pathophysiological picture has been established as that caused by a lesion in the pretectal area of the midbrain. On the contrary, however, such divergence nystagmus is seen only in rare patients, and only a few reports are available (BENDER and SAVITSKEY, 1940). Only 1 autopsy case is found to the author's knowledge. In a patient with cardiac disease recently seen, diplopia and equilibrium disorder suddenly appeared, along with a marked divergence nystagmus, which was recorded on ENG. The upper panel A of the figure shows the monocular horizontal lead ENG of the right eye, middle panel B shows the corresponding lead of the left eye and the lower panel C shows the vertical lead ENG-record (Fig. 6a). The CT-scan in this patient, furthermore, revealed a low density area in a region slightly lateral from the midline pons (Fig. 6b). From the history of the patient, an intimate causal relationship is assumed between divergence nystagmus and CT-scan findings.
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Fig. 9. Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN). The nystagmus of jerking type is directed to the upper eyelid, with hereditary and familial mode of occurrence. The left upward OKN is directed downward despite the presence of original upward nystagmus indicating a complete inversion. The downward OKN shows no reaction, recorded unchanged from the spontaneous nystagmus directed upward.
7)
Counterolling, pure rotatory positioning nystagmus Positioning nystagmus with latent period, accompanied by severe vertigo along with nystagmus, with subsequent fatigability has been thought to be seen in patients with partial lesions of the inner ear especially of otolith lesion. We agree with this and have constantly emphasized the significance of this phenomenon in clinical diagnosis (SAKATA, 1963; TAKAHASHI, OHTSU, and SAKATA, 1985). Since we have started to utilize CT-scanner, however, such nystagmus has been noted in 11 patients, all of whom had cerebellar vermis infarction (Fig. 7a, b). Attention should be focussed on such association. As to such association between such nystagmus and CT findings, simple coincidence would not have been excluded in case such combination is seen only in 1 or 2 patients, but its occurrence in as many as 11 patients might suggest a causal role of cerebellar vermis lesions. This might be explained by the incomplete inhibition by cerebellar flocculo-nodular lobe or vestibulocerebellum to the vestibulo-oculomotor system. 8) Inversion of optokinetic after-nystagmus (OKAN) OKAN is an after-discharge of the vestibulo-oculomotor system seen after the elimination of OKN stimulus. This phenomenon is important since this makes it possible to detect the balance of right-left side difference of the fine vestibulo-oculomotor system function which cannot be detected by other methods (SAKATA, 1980). As to the occurrence of this phenomenon, however, individual
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difference is noted, presenting difficult problems on its actual performance such as the setting of the examination room and apparatus, so that this method has not yet been widely used. Many abnormal findings, however, can be concluded as definitely pathological. One is the inversion phenomenon. The figure shows an example in a patient with typical basilar artery insufficiency. As seen in the upper panel, induction of OKN on the right side produced OKAN on the left. As seen in the lower panel, induction of OKN on the left produced OKAN on the right (Fig. 8). Such phenomenon was seen in patients with bilateral peripheral vestibular or central vestibular lesion in more than 100 patients in our clinic. 9)
Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN) Most of the congenital spontaneous nystagmus are horizontal; however, there are occasional rotatory and rarely vertical ones. A lot of diagnostic evidences of congenital nystagmus have been presented. The inversion of optokinetic nystagmus is one of the important evidences. As to the congenital vertical nystagmus, however, the response of optokinetic nystagmus has remained unknown since the cases are rare. While several cases have been reported, no OKN has been described nor record of OKN was presented even if it was referred. In a very few cases, only vague descriptions of "no reaction" are available. Figure 9 is the ENG-record in a patient with congenital vertical spontaneous
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nystagmus recently examined. The nystagmus of jerking type is directed to the upper eyelid, with hereditary and familial mode of occurrence (lWASHITA, NAKAZAWA, OHTSU, and SAKATA, 1984). The OKN which is shown in the upward left of the Fig. 9, is directed downward despite the presence of original upward nystagmus. This indicates a complete inversion of the OKN. The downward OKN shows no reaction, recorded unchanged in spite of the presence of the spontaneous nystagmus directed upward. 10)
Treatment of congenital nystagmus
In patients with congenital nystagmus, visual disturbance occurs due to eye oscillation and strabismus appears because the gaze is directed to the object at the neutral point of the nystagmus, with consequent scoliosis, presenting with serious problems. Attention of the ophthalmologists all over the world is directed to the treatment of this disease but no satisfactory method is yet available. We have recently demonstrated the disappearance of such nystagmus along
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with a transient improvement of the visual acuity as a result of a slow intravenous injection of 2 ml 2 % lidocaine solution diluted with 20 % glucose solution (NAKAZAWA, im Druck). In this figure, A shows the beginning of the injection and B the end of the injection (Fig. 10). Almost complete disappearance of nystagmus is noted. By repeating the injection 2-3 times a week for 6 months, nystagmus persistently disappeared and favorable visual results were obtained in 10 patients. 11)
Vertical spontaneous nystagmus to lower eyelid or so-called "downbeat nystagmus" Marked downbeat nystagmus indicating midline lesions in the posterior fossa has gradually received widespread attention not only in neurotology, but also in neurology, neurosurgery and neurophthalmology, with active discussions. As to the pathophysiological explanations, however, much confusion is noted, because the discussions are based on a pre-occupied concept on the presence of an identical lesion for all the pathological phenomena. There are at least two different lesions involved (SAKATA, 1980). One is a lesion mainly in the pons giving rise to paretic eye movement. The speed of both slow and fast phases of the nystagmus are decreased with low frequency, giving a specific pattern. Another lesion is in the caudal part of the cerebellum or "Innere Abteilung des Kleinhirnstiels" (IAK), giving rise to holding tremor with high frequency oscillation of a specific pattern. The downbeat nystagmus in the upper
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panel of the figure indicates a pontine lesion and the one in the lower panel a cerebellar lesion (Fig. 11). 12) Downbeat nystagmus seen in bilateral labyrinthine dysfunction Downbeat nystagmus is seen with simultaneous dysfunction of the bilateral vestibular system. Such lesion is therefore frequently seen in the brainstem and cerebellum where the bilateral vestibular systems are located close to each other or forming network, especially in the presence of midline or symmetric lesions. When such nystagmus was clinically noted, the presence of midline lesions in the posterior fossa should be at first suspected. Occurrence of vertical nystagmus was reported on caloric test by simultaneous stimulation of both ears, and appearance of vertical eye deviation was pointed out in cats on electrical stimulation of bilaterally paired semicircular canal. For the treatment of labyrinthine vertigo and cochlear tinnitus, we have injected a local anesthetic, 4 % lidocaine, into the middle ear cavity to improve the symptoms, over the past 10 years. Occurrence of downbeat nystagmus over a period of several hours was confirmed and recorded in many patients on such occasion (ITOH, OHTSU, YAMASHITA, and SAKATA, im Druck). The upper panel of Fig. 12 is the horizontal lead ENG-recording and the lower panel, vertical lead ENG. This is not due to the cupular deviation caused by the endolymphatic flow, and is also different from eye deviation caused by bilateral electric stimulation of animal's semicircular canal nerve. The confirmation of the nystagmus in human under conditions close to the clinical setup should more contribute to the medicine. REFERENCES ASCHOFF, J. C., CONRAD, B., and KORNHUBER, H. H.: Acquired pendular nystagmus with oscillopsia in multiple sclerosisia sign of cerebellar nuclei disease. J. Neurol. Neurosurg. Psychia. 37: 570-577, 1974. BENDER, M. B., and SAVITSKEY, N.: Paralysis of divergence. Arch. Ophthal. 23: 1046-1051, 1940. CooAN, D. G.: Ocular dysmetria, flutter-like oscillations of the eyes and opsoclonus. Arch. Ophthal. 52: 318-328, 1954. ITOH, Y., OHTSU, K., YAMASHITA, H., and SAKATA, E.: Wird der vertikale Spontannystagmus infolge der Innenohrdys funktion hervorgerufen? Aus der Erfahrung der beidohrigen Lidocaininfusion in die PaukenhOhle beim Menschen. (im Druck) IWASHITA, N., NAKAZAWA, H., OHTSU, K., and SAKATA, E.: A case of congenital vertical nystagmus with inversion of vertical optokinetic reaction. Equilibrium Res. 43: 71-82, 1984. LESSER, P. L., SMITH, J. L., and LEBENSON, D. S.: Vertical ocular dysmetria. Am. J. Ophthal. 76: 208-211, 1971. NAKAZAWA, H.: Die Behandlung des kongenitalen Nystagmus mit der intravenosen Infusion von 2% Lidocain-und 20% Glucose-Losung. (im Druck) OHTSU, K.: Vertical ocular dysmetria. Vertical rebound nystagmus and optokinetic vertical ocular dysmetria. Auris-Nasus-Larynx (Tokyo) 11: 91-100,1984. OLZECHOWSKI, K.: De I'ataxie dysmetrique des yeux. Remarques sur I'ataxie des yeux dite
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myoclonique (Opsoc1onie, Opsoc1onus) J. Psychol. Neurol. 35: 1-13, 1927. SAKATA, E.: Das neurootologische Studium iiber die Liision des Kleinhirnwurms. Equilibrium Res. Suppl. 1: 30-46, 1971. SAKATA, E.: Lageschwindel vom gutartigen paroxysmalen Typ als senile Krankheit. Geront. Geriat. 7: 349-364, 1963. SAKATA, E.: Leitfaden der klinischen Neurootologie, S. 73-75, Ishiyaku-Verlag, Tokio, 1980. SAKATA, E., ITOH, A., OHTSU, K., and KANAzAWA, C.: Diagnosis of out-patients with brain benign tumor, especially meningioma. Equilibrium Res. 41: 120-127, 1982. TAKAHASHI, K., OHTSU, K., and SAKATA, E.: Counterolling, pure rotatory positioning nystagmus caused by cerebellar vermis lesion. Pract. Otol. Kyoto 78: 2729-2736, 1985
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Dr. E. Sakata, Neurotological Clinic, Saitama Medical School, Moroyama, lruma, Saitama 350-04, Japan