- Email: [email protected]
Upbeat Nystagmus Influenced by Posture: Report of Two Cases
Auris· Nasus· Larynx (Tokyo) 16, 215-221 (1990)
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE: REPORT OF TWO CASES Masahiro MIZUNO, M. D., Yasuhiro KUDO, M. D., and Masaaki YAMANE, M. D. Department of Otolaryngology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
Two cases of vertical gaze nystagmus, which were influenced by posture are reported. In both cases, upbeat nystagmus (UBN) on forward gaze in upright and supine positions changed to downbeat nystagmus (DBN) in prone position. Convergence had no influence on the vertical nystagmus. A CT scan revealed an atrophy of the anterior vermis of the cerebellum in the first case. The UBN of the second case was suspected to be associated with lesions in the brachium conjunctivum. The authors concluded that both UBN and DBN were not completely separate, but they could coexist in cases with certain lesions in the posterior cranial fossa. Upbeat nystagmus (UBN) on forward gaze was observed in patients with central vestibular diseases (DAROFF and TROOST, 1973; FISHER, GRESTY, CHAMBERS, and RUDGE, 1983) though not frequently. We report here two cases with UBN on forward gaze influenced by posture, changing to downbeat nystagmus (DBN). Although the exact mechanism of vertical nystagmus is still not clear, the authors assume that UBN and DBN can be generated by common causes in some cases. CASE REPORT
Case 1 A 41-year-old male with spinocerebellar degeneration was referred for evaluation of upbeat nystagmus. He first noticed an unsteady gait in 1983. Since then, he has suffered speech disturbance, tremors in his extremities, oscillopsia and writing disabilities which have progressed gradually. He has hearing impairment in his right ear since childhood and has consumed five bottles of beer daily until September 1984. He has no family history of mental or neurological Received for publication August 24, 1989 215
216
M. MIZUNO, Y. KUDO, and M. YAMANE
disorders. He was admitted to Tokyo Metropolitan Neurological Hospital in May 1985. Neurological examination revealed dysarthria, truncal and limb ataxia, tremors in his extremities mainly at rest, and vertical nystagmus. There was no significant decrease in power and sensation, and deep tendon reflexes were present. Coordination was disturbed and pathological reflexes (Rossolimo) were observed bilaterally. CSF, EEG, and blood vitamin B levels were within normal limits. On examination UBN was present on forward gaze (in primary position) and in all other fields of gaze in an upright position . UBN was also present in a supine position and augmented with an upward gaze. However, DBN was observed in the prone position, except with upward gaze (Fig. 1). Vertical upbeat nystagmus was present through Frenzel's glasses in a positional test with the head in supine, right lateral and left lateral positions, and with head-hanging, in right and left lateral positions. Positioning test from upright to head-hanging induced large-amplitude DBN. UBN was confirmed in the test from head-hanging to upright position. Eye movements, both in horizontal and vertical directions, were recorded by electronystagmograph (ENG). Saccadic eye movements, using 0.3 Hz, 30° amplitude stimuli, were within normal limits in a horizontal direction, and UBN was superimposed in a vertical direction. Smooth pursuit eye movements, using 0.3 Hz, 30° amplitude sinusoidal stimuli, were saccadic both in horizontal and vertical directions. Optokinetic nystagmus (OKN) was examined using Suzuki and Komatsuzaki's method (OKP test), with a constant acceleration of 40/S2 up to a maximum Fw
Up
V
On
I I
sitting ",-,,,,,,~ ~ ~'"
sUPine ~~~
/
,I
...
'~/'
_.
Fig. 1. Electronystagmographic recordings of vertical eye movements (Case 1). Upbeat nystagmus (UBN) is most prominent in supine position. Downbeat nystagmus (DBN) on forward gaze is seen in prone position. Up, upward gaze; Fw, forward gaze; Dn, downward gaze. Upper tracings in each position: time constant, 3.0 s; calibration, 10 0 /s. Lower tracing in each position: time constant, 0.03 s; calibration, 20°Is.
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE Fig. 2. Optokinetic nystagmus test (OKP test after SUZUKI and KOMATSUZAKI (1962)) of Case 1. Optokinetic nystagmus (OKN) is markedly reduced and in downward direction only spontaneous UBN is recorded. Bottom tracing, optokinetic stimuli; H, horizontal ; Y, vertical; R, OKN toward right; L, OKN toward left; U,OKN upward; D, OKN downward.
217
.ii4iMlMlli.," Wi. ltd ltll4llUiliUillliilllJ .. ,i44IiIClIWI!_,. . . i4UW.......
H
,I
~~~~ ~ R
V
L
~JJ\J~\t~ ~
Fig. 3. CT scan of Case 1. Showing an atrophy of anterior vermis (right). is seen in the region of pons (left).
No atrophy
velocity of 1600/s , then with a deceleration of _ 40/S2 to a standstill. Nystagmus was recorded with the chart feeding speed of 1 mmls (SUZUKI and KOMATSUZAKI, 1962). OKN was markedly disrupted in both horizontal and vertical directions. In a downward direction, only spontaneous UBN was recognized (Fig. 2). No caloric nystagmus could be induced by cold water irrigation of the external auditory canal, although ocular counterrolling reflexes were present. A CT scan
218
M. MIZUNO, Y. KUDO, and M. YAMANE
revealed atrophy in the upper vermis (Fig. 3).
Case 2 A 44-year-old female with multiple sclerosis, first visited the Department of Otolaryngology, the University of Tokyo Hospital, on June I, 1987. She was referred from the neurology department for evaluation of nystagmus. She was admitted to another hospital because of nausea, vomiting, and loss of appetite. She had experienced oscillopsia, numbness in the extremities, and unsteadiness for the previous 2 months. Horizontal nystagmus to right, limb ataxia, truncal ataxia, and sensory disturbances were found during admission. CSF showed slight pleocytosis (dominantly lymphocytes) and normal protein concentration (15 mg/dl). Symptoms other than oscillopsia gradually subsided, without the use of steroids. On May 9, visual field deficit of her right eye (upper medial quadrant) suddenly appeared, which was diagnosed as retrobulbar neuritis. She has no family history of neurological disorders. When she was seen at our outpatient clinic, neurological findings were visual field deficit of her right eye, mild cerebellar ataxia in her left upper limb, and vertical nystagmus on gaze. UBN in primary position was present in upright and supine positions, and DBN was observed in the prone position (Fig. 4). Both saccadic and smooth pursuit movements on a horizontal plane were normal; however, on a vertical plane, saccadic eye movements showed superimposed UBN, and smooth pursuit eye movements were saccadic. Optokinetic nystagmus in a horizontal direction was almost within normal limits. Caloric nystagmus were induced normally bilaterally and suppressed by visual fixation. Although neurological findings indicated cerebellar lesion, no remarkable change was demonstrated in MRI. V
UpG
sitting~'T-,~~.
prone
Fig. 4. Electronystagmographic recordings of vertical eye movements (Case 2). UBN on forward gaze in sitting position, and DBN on forward gaze in prone position.
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE
219
Therefore, a small lesion in brachium conjunctivum was suspected to be responsible for her symptoms. When reviewed one year later, DBN on forward gaze was observed in upright, supine, and prone positions with persistent oscillopsia. DISCUSSION
Vertical nystagmus on forward gaze (in primary position), upbeat nystagmus (UBN), and downbeat nystagmus (DBN), are considered to be important neurological signs indicating lesions of the central vestibular systems in the posterior cranial fossa (FISHER et al., 1983; COGAN, 1968). In the present two cases, primary position UBN, in upright and supine positions, was influenced by posture, changing to DBN in the prone position. In one case, DBN was observed in every position one year later. UBN is reported to alter its nature and even to become DBN as a result of various causes. FISHER et al. (1983) reported 11 cases of UBN. In their first case, they found that UBN was inverted to DBN in the prone position. Cox, CORBETT, THOMPSON, and LENNARSON (1981), TABUCHI, TANIGUCHI, and AMATSU (1983), and BABA, SAKATA, NAKAZAWA, ITo, and OHZU (1986) reported cases with UBN in which convergence converted the nystagmus to DBN. HASEGAWA, KOWA, TAZAKI, and TOKUMASU (1987) reported a case of multiple sclerosis with UBN in exacerbation and DBN in remission. Therefore, both UBN and DBN are considered to be generated by common lesions in the posterior cranial fossa (GILMAN, BALOH, and TOMIYASU, 1977). DAROFF and TROOST (1973) classified UBN into two types: coarse, largeamplitude UBN increasing in intensity on upward gaze, and small-amplitude UBN increasing in intensity on downward gaze. They suggested that the former is associated with lesions in the anterior vermis, and the latter, with lesions in the lower brain stem. Since that study, the followings have been proposed to be responsible for UBN: i) ponto-mesencephalic junction (TROOST, MARTINEZ, ABEL, and HEROS, 1980), ii) ponto-medullary junction or medulla (FISHER et al., 1983; GILMAN et al., 1977; SCHATZ, SCHLEZINGER, and BERRY, 1975), iii) anterior vermis of the cerebellum (FISHER et al., 1983), and iv) brachium conjunctivum (FISHER et aI., 1983; NAKADA and REMLER, 1981). On the other hand, DBN is considered to be caused by lesions in i) the cerebellum (COGAN, 1968), especially archicerebellum (ZEE, FRIENDLICH, and RoBINSON, 1974; BALOH and SPOONER, 1981; CHAMBERS, ELL, and GRESTY, 1983; HALMAGYI, RUDGE, GRESTY, and SANDERS, 1983) and/or ii) the lower brain stem and high cervical region (COGAN, 1968; ZEE et al., 1974). In the present series, in Case 1 an atrophy occurred in the region of the anterior vermis, as demonstrated by CT scan. UBN in Case 2 was suspected to be associated with lesions in the brachium conjunctivum.
220
M. MIZUNO, Y. KUDO, and M. YAMANE
The mechanism of UBN has still not been clarified. GILMAN et al. (1977) suggested that UBN could be produced by a pursuit defect in downward direction similar to DBN caused by a pursuit defect in upward direction (as proposed by ZEE at al. (1974». This hypothesis seems unlikely in present series. It does not explain the fact that the direction of vertical nystagmus in both cases of the present series was inverted, influenced by posture. NAKADA and REMLER (1981) concluded that UBN, similar to DBN (BALOH and SPOONER, 1981), is a type of central vestibular nystagmus resulting from an imbalance of vertical vestibulo-ocular reflex activity. Other authors have ascribed UBN to convergence related (Cox et al., 1981) or otolith related (FISHER et al., 1983) components. Although vertical nystagmus behind Frenzel's glasses (non-gaze nystagmus) is frequently influenced by posture, gaze nystagmus rarely seems to be. However, both UBN (FISHER et al., 1983; BABA et al., 1986; HASEGAWA et al., 1987; KATTAH, KOLSKY, GUY, and O'DOHERTY, 1983; YOSHIMOTO and YABE, 1984) and DBN (FISHER et al., 1983; COGAN, 1968; BALOH et al., 1981; CHAMBERS et al., 1983; GRESTY, BARRATT, RUDGE, and PAGE, 1986) were reported to be influenced by posture. MATSUO and COHEN (1984) demonstrated that vertical optokinetic nystagmus in monkeys is also influenced by posture. Convergence is another factor which could have influences on vertical nystagmus. Both UBN (FISHER et aI., 1983; Cox et al., 1981; T ABUCHI et al., 1983; BABA et al., 1986; HASEGAWA et al., 1987) and DBN (CHAMBERS et al., 1983; HALMAGYI et al., 1983; LAVIN, TRACCIS, DELL'OSSO, ABEL, and ELLENBERGER, 1983) are reported to be influenced by convergence. LAVIN et al. (1983) reported a case of DBN which was improved through use of base-out prisms. However, in both cases of the present series, UBN was not influenced by convergence. In conclusion, the authors have concluded that vertical gaze nystagmus, both UBN and DBN, may be generated by common lesions in the vermis of the cerebellum and brain stem. They also believe that the direction of vertical gaze nystagmus can be altered by the effect of posture, presumably influenced by the activity of otolith-ocular reflexes. The authors wish to express their appreciation to Ms. H. Miyazaki for her help in the preparation of this manuscript.
REFERENCES BABA, K., SAKATA, E., NAKAZAWA, H., ITO, N., and OHZU, K.: Primary position spontaneous vertical nystagmus: Pathophysiology and review of the literature. Pract. Otol. (Kyoto) 79: 193-212, 1986 (in Japanese). BALOH, R. W., and SPOONER, J. W.: Downbeat nystagmus: A type of central vestibular nystagmus. Neurology 31: 304-310, 1981.
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE
221
CHAMBERS, B. R., ELL, J. J., and GRESTY, M. A.: Case of downbeat nystagmus influenced by otolith stimulation. Ann. Neurol. 13: 205-207, 1983. COGAN, D. G.: Down-beat nystagmus. Arch. Ophthalmol. 80: 757-768,1968. Cox, T. A., CORBETT, J. J., THOMPSON, H. S., and LENNARSON, L.: Upbeat nystagmus changing to downbeat nystagmus with convergence. Neurology 31: 891-892, 1981. DAROFF, R. B., and TROOST, B. T.: Upbeat nystagmus. JAMA 225: 312, 1973. FISHER, A., GRESTY, M., CHAMBERS, B., and RUDGE, P.: Primary position upbeating nystagmus: A variety of central positional nystagmus. Brain 106: 949-964, 1983. GILMAN, N., BALOH, R. W., and TOMIYASU, U.: Primary position upbeat nystagmus: A clinicopathologic study. Neurology 27: 294-298, 1977. GRESTY, M., BARRATT, H., RUDGE, P., and PAGE, N.: Analysis of downbeat nystagmus: Otolith vs. semicircular canal influences. Arch. Neurol. 43: 52-55, 1986. HALMAGYI, G. M., RUDGE, P., GRESTY, M. A., and SANDERS, M. D.: Downbeating Nystagmus: A review of 62 cases. Arch. Neurol. 40: 777-784, 1983. HASEGAWA, K., KOWA, H., TAZAKI, Y., and TOKuMAsu, K.: Directional change of vertical nystagmus in a case with multiple sclerosis. C/in. Neurol. 27: 1103-1107,1987 (in Japanese). KATTAH, J. C., KOLSKY, M. P., GUY, J., and O'DOHERTY, D.: Primary position vertical nystagmus and cerebellar ataxia. Arch. Neurol. 40: 310-314, 1983. LAVIN, P. J. M., TRACCIS, S., DELL'OSSO, L. F., ABEL, L. A., and ELLENBERGER, C., Jr.: Downbeat nystagmus with a pseudocycloid waveform: Improvement with Base-out prisms. Ann. Neurol. 13: 621-624, 1983. MATSUO, V., and COHEN, B.: Vertical optokinetic nystagmus and vestibular nystagmus in the monkey: Up-down asymmetry and effects of gravity. Exp. Brain Res. 53: 197-216, 1984. NAKADA, T., and REMLER, M. P.: Primary position Upbeat nystagmus: Another central vestibular nystagmus? J. C/in. Neuro-Ophthalmol. 1: 185-189,1981. SCHATZ, N. J., SCHLEZINGER, N. S., and BERRY, R. G.: Vertical up-beat nystagmus on downward gaze: A clinical pathologic correlation. Neurology 25: 380, 1975. SUZUKI, J., and KOMATSUZAKI, A.: Clinical application of optokinetic nystagmus-optokinetic pattern test. Acta Otolaryngol. 54: 49-55, 1962. TABUCHI, T., TANIGUCHI, S., and AMATSU, M.: Upbeat nystagmus. Otolaryngology (Tokyo) 55: 681-690, 1983 (in Japanese). TROOST, B. T., MARTINEZ, J., ABEL, L. A., and HEROS, R. C.: Upbeat nystagmus and internuclear ophthalmoplegia with brain stem glioma. Arch. Neurol. 37: 453-456, 1980. YOSHIMOTO, Y., and YABE, Y.: A case of spinocerebellar degeneration with primary position upbeat nystagmus. Otolaryngology (Tokyo) 56: 373-380, 1984 (in Japanese). ZEE, D. S., FRIENDLICH, A. R., and ROBINSON, D. A.: The mechanism of downbeat nystagmus. Arch. Neurol. 30: 227-237, 1974.
Request reprints to:
Dr. M. Mizuno, Department of Otolaryngology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE: REPORT OF TWO CASES Masahiro MIZUNO, M. D., Yasuhiro KUDO, M. D., and Masaaki YAMANE, M. D. Department of Otolaryngology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
Two cases of vertical gaze nystagmus, which were influenced by posture are reported. In both cases, upbeat nystagmus (UBN) on forward gaze in upright and supine positions changed to downbeat nystagmus (DBN) in prone position. Convergence had no influence on the vertical nystagmus. A CT scan revealed an atrophy of the anterior vermis of the cerebellum in the first case. The UBN of the second case was suspected to be associated with lesions in the brachium conjunctivum. The authors concluded that both UBN and DBN were not completely separate, but they could coexist in cases with certain lesions in the posterior cranial fossa. Upbeat nystagmus (UBN) on forward gaze was observed in patients with central vestibular diseases (DAROFF and TROOST, 1973; FISHER, GRESTY, CHAMBERS, and RUDGE, 1983) though not frequently. We report here two cases with UBN on forward gaze influenced by posture, changing to downbeat nystagmus (DBN). Although the exact mechanism of vertical nystagmus is still not clear, the authors assume that UBN and DBN can be generated by common causes in some cases. CASE REPORT
Case 1 A 41-year-old male with spinocerebellar degeneration was referred for evaluation of upbeat nystagmus. He first noticed an unsteady gait in 1983. Since then, he has suffered speech disturbance, tremors in his extremities, oscillopsia and writing disabilities which have progressed gradually. He has hearing impairment in his right ear since childhood and has consumed five bottles of beer daily until September 1984. He has no family history of mental or neurological Received for publication August 24, 1989 215
216
M. MIZUNO, Y. KUDO, and M. YAMANE
disorders. He was admitted to Tokyo Metropolitan Neurological Hospital in May 1985. Neurological examination revealed dysarthria, truncal and limb ataxia, tremors in his extremities mainly at rest, and vertical nystagmus. There was no significant decrease in power and sensation, and deep tendon reflexes were present. Coordination was disturbed and pathological reflexes (Rossolimo) were observed bilaterally. CSF, EEG, and blood vitamin B levels were within normal limits. On examination UBN was present on forward gaze (in primary position) and in all other fields of gaze in an upright position . UBN was also present in a supine position and augmented with an upward gaze. However, DBN was observed in the prone position, except with upward gaze (Fig. 1). Vertical upbeat nystagmus was present through Frenzel's glasses in a positional test with the head in supine, right lateral and left lateral positions, and with head-hanging, in right and left lateral positions. Positioning test from upright to head-hanging induced large-amplitude DBN. UBN was confirmed in the test from head-hanging to upright position. Eye movements, both in horizontal and vertical directions, were recorded by electronystagmograph (ENG). Saccadic eye movements, using 0.3 Hz, 30° amplitude stimuli, were within normal limits in a horizontal direction, and UBN was superimposed in a vertical direction. Smooth pursuit eye movements, using 0.3 Hz, 30° amplitude sinusoidal stimuli, were saccadic both in horizontal and vertical directions. Optokinetic nystagmus (OKN) was examined using Suzuki and Komatsuzaki's method (OKP test), with a constant acceleration of 40/S2 up to a maximum Fw
Up
V
On
I I
sitting ",-,,,,,,~ ~ ~'"
sUPine ~~~
/
,I
...
'~/'
_.
Fig. 1. Electronystagmographic recordings of vertical eye movements (Case 1). Upbeat nystagmus (UBN) is most prominent in supine position. Downbeat nystagmus (DBN) on forward gaze is seen in prone position. Up, upward gaze; Fw, forward gaze; Dn, downward gaze. Upper tracings in each position: time constant, 3.0 s; calibration, 10 0 /s. Lower tracing in each position: time constant, 0.03 s; calibration, 20°Is.
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE Fig. 2. Optokinetic nystagmus test (OKP test after SUZUKI and KOMATSUZAKI (1962)) of Case 1. Optokinetic nystagmus (OKN) is markedly reduced and in downward direction only spontaneous UBN is recorded. Bottom tracing, optokinetic stimuli; H, horizontal ; Y, vertical; R, OKN toward right; L, OKN toward left; U,OKN upward; D, OKN downward.
217
.ii4iMlMlli.," Wi. ltd ltll4llUiliUillliilllJ .. ,i44IiIClIWI!_,. . . i4UW.......
H
,I
~~~~ ~ R
V
L
~JJ\J~\t~ ~
Fig. 3. CT scan of Case 1. Showing an atrophy of anterior vermis (right). is seen in the region of pons (left).
No atrophy
velocity of 1600/s , then with a deceleration of _ 40/S2 to a standstill. Nystagmus was recorded with the chart feeding speed of 1 mmls (SUZUKI and KOMATSUZAKI, 1962). OKN was markedly disrupted in both horizontal and vertical directions. In a downward direction, only spontaneous UBN was recognized (Fig. 2). No caloric nystagmus could be induced by cold water irrigation of the external auditory canal, although ocular counterrolling reflexes were present. A CT scan
218
M. MIZUNO, Y. KUDO, and M. YAMANE
revealed atrophy in the upper vermis (Fig. 3).
Case 2 A 44-year-old female with multiple sclerosis, first visited the Department of Otolaryngology, the University of Tokyo Hospital, on June I, 1987. She was referred from the neurology department for evaluation of nystagmus. She was admitted to another hospital because of nausea, vomiting, and loss of appetite. She had experienced oscillopsia, numbness in the extremities, and unsteadiness for the previous 2 months. Horizontal nystagmus to right, limb ataxia, truncal ataxia, and sensory disturbances were found during admission. CSF showed slight pleocytosis (dominantly lymphocytes) and normal protein concentration (15 mg/dl). Symptoms other than oscillopsia gradually subsided, without the use of steroids. On May 9, visual field deficit of her right eye (upper medial quadrant) suddenly appeared, which was diagnosed as retrobulbar neuritis. She has no family history of neurological disorders. When she was seen at our outpatient clinic, neurological findings were visual field deficit of her right eye, mild cerebellar ataxia in her left upper limb, and vertical nystagmus on gaze. UBN in primary position was present in upright and supine positions, and DBN was observed in the prone position (Fig. 4). Both saccadic and smooth pursuit movements on a horizontal plane were normal; however, on a vertical plane, saccadic eye movements showed superimposed UBN, and smooth pursuit eye movements were saccadic. Optokinetic nystagmus in a horizontal direction was almost within normal limits. Caloric nystagmus were induced normally bilaterally and suppressed by visual fixation. Although neurological findings indicated cerebellar lesion, no remarkable change was demonstrated in MRI. V
UpG
sitting~'T-,~~.
prone
Fig. 4. Electronystagmographic recordings of vertical eye movements (Case 2). UBN on forward gaze in sitting position, and DBN on forward gaze in prone position.
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE
219
Therefore, a small lesion in brachium conjunctivum was suspected to be responsible for her symptoms. When reviewed one year later, DBN on forward gaze was observed in upright, supine, and prone positions with persistent oscillopsia. DISCUSSION
Vertical nystagmus on forward gaze (in primary position), upbeat nystagmus (UBN), and downbeat nystagmus (DBN), are considered to be important neurological signs indicating lesions of the central vestibular systems in the posterior cranial fossa (FISHER et al., 1983; COGAN, 1968). In the present two cases, primary position UBN, in upright and supine positions, was influenced by posture, changing to DBN in the prone position. In one case, DBN was observed in every position one year later. UBN is reported to alter its nature and even to become DBN as a result of various causes. FISHER et al. (1983) reported 11 cases of UBN. In their first case, they found that UBN was inverted to DBN in the prone position. Cox, CORBETT, THOMPSON, and LENNARSON (1981), TABUCHI, TANIGUCHI, and AMATSU (1983), and BABA, SAKATA, NAKAZAWA, ITo, and OHZU (1986) reported cases with UBN in which convergence converted the nystagmus to DBN. HASEGAWA, KOWA, TAZAKI, and TOKUMASU (1987) reported a case of multiple sclerosis with UBN in exacerbation and DBN in remission. Therefore, both UBN and DBN are considered to be generated by common lesions in the posterior cranial fossa (GILMAN, BALOH, and TOMIYASU, 1977). DAROFF and TROOST (1973) classified UBN into two types: coarse, largeamplitude UBN increasing in intensity on upward gaze, and small-amplitude UBN increasing in intensity on downward gaze. They suggested that the former is associated with lesions in the anterior vermis, and the latter, with lesions in the lower brain stem. Since that study, the followings have been proposed to be responsible for UBN: i) ponto-mesencephalic junction (TROOST, MARTINEZ, ABEL, and HEROS, 1980), ii) ponto-medullary junction or medulla (FISHER et al., 1983; GILMAN et al., 1977; SCHATZ, SCHLEZINGER, and BERRY, 1975), iii) anterior vermis of the cerebellum (FISHER et al., 1983), and iv) brachium conjunctivum (FISHER et aI., 1983; NAKADA and REMLER, 1981). On the other hand, DBN is considered to be caused by lesions in i) the cerebellum (COGAN, 1968), especially archicerebellum (ZEE, FRIENDLICH, and RoBINSON, 1974; BALOH and SPOONER, 1981; CHAMBERS, ELL, and GRESTY, 1983; HALMAGYI, RUDGE, GRESTY, and SANDERS, 1983) and/or ii) the lower brain stem and high cervical region (COGAN, 1968; ZEE et al., 1974). In the present series, in Case 1 an atrophy occurred in the region of the anterior vermis, as demonstrated by CT scan. UBN in Case 2 was suspected to be associated with lesions in the brachium conjunctivum.
220
M. MIZUNO, Y. KUDO, and M. YAMANE
The mechanism of UBN has still not been clarified. GILMAN et al. (1977) suggested that UBN could be produced by a pursuit defect in downward direction similar to DBN caused by a pursuit defect in upward direction (as proposed by ZEE at al. (1974». This hypothesis seems unlikely in present series. It does not explain the fact that the direction of vertical nystagmus in both cases of the present series was inverted, influenced by posture. NAKADA and REMLER (1981) concluded that UBN, similar to DBN (BALOH and SPOONER, 1981), is a type of central vestibular nystagmus resulting from an imbalance of vertical vestibulo-ocular reflex activity. Other authors have ascribed UBN to convergence related (Cox et al., 1981) or otolith related (FISHER et al., 1983) components. Although vertical nystagmus behind Frenzel's glasses (non-gaze nystagmus) is frequently influenced by posture, gaze nystagmus rarely seems to be. However, both UBN (FISHER et al., 1983; BABA et al., 1986; HASEGAWA et al., 1987; KATTAH, KOLSKY, GUY, and O'DOHERTY, 1983; YOSHIMOTO and YABE, 1984) and DBN (FISHER et al., 1983; COGAN, 1968; BALOH et al., 1981; CHAMBERS et al., 1983; GRESTY, BARRATT, RUDGE, and PAGE, 1986) were reported to be influenced by posture. MATSUO and COHEN (1984) demonstrated that vertical optokinetic nystagmus in monkeys is also influenced by posture. Convergence is another factor which could have influences on vertical nystagmus. Both UBN (FISHER et aI., 1983; Cox et al., 1981; T ABUCHI et al., 1983; BABA et al., 1986; HASEGAWA et al., 1987) and DBN (CHAMBERS et al., 1983; HALMAGYI et al., 1983; LAVIN, TRACCIS, DELL'OSSO, ABEL, and ELLENBERGER, 1983) are reported to be influenced by convergence. LAVIN et al. (1983) reported a case of DBN which was improved through use of base-out prisms. However, in both cases of the present series, UBN was not influenced by convergence. In conclusion, the authors have concluded that vertical gaze nystagmus, both UBN and DBN, may be generated by common lesions in the vermis of the cerebellum and brain stem. They also believe that the direction of vertical gaze nystagmus can be altered by the effect of posture, presumably influenced by the activity of otolith-ocular reflexes. The authors wish to express their appreciation to Ms. H. Miyazaki for her help in the preparation of this manuscript.
REFERENCES BABA, K., SAKATA, E., NAKAZAWA, H., ITO, N., and OHZU, K.: Primary position spontaneous vertical nystagmus: Pathophysiology and review of the literature. Pract. Otol. (Kyoto) 79: 193-212, 1986 (in Japanese). BALOH, R. W., and SPOONER, J. W.: Downbeat nystagmus: A type of central vestibular nystagmus. Neurology 31: 304-310, 1981.
UPBEAT NYSTAGMUS INFLUENCED BY POSTURE
221
CHAMBERS, B. R., ELL, J. J., and GRESTY, M. A.: Case of downbeat nystagmus influenced by otolith stimulation. Ann. Neurol. 13: 205-207, 1983. COGAN, D. G.: Down-beat nystagmus. Arch. Ophthalmol. 80: 757-768,1968. Cox, T. A., CORBETT, J. J., THOMPSON, H. S., and LENNARSON, L.: Upbeat nystagmus changing to downbeat nystagmus with convergence. Neurology 31: 891-892, 1981. DAROFF, R. B., and TROOST, B. T.: Upbeat nystagmus. JAMA 225: 312, 1973. FISHER, A., GRESTY, M., CHAMBERS, B., and RUDGE, P.: Primary position upbeating nystagmus: A variety of central positional nystagmus. Brain 106: 949-964, 1983. GILMAN, N., BALOH, R. W., and TOMIYASU, U.: Primary position upbeat nystagmus: A clinicopathologic study. Neurology 27: 294-298, 1977. GRESTY, M., BARRATT, H., RUDGE, P., and PAGE, N.: Analysis of downbeat nystagmus: Otolith vs. semicircular canal influences. Arch. Neurol. 43: 52-55, 1986. HALMAGYI, G. M., RUDGE, P., GRESTY, M. A., and SANDERS, M. D.: Downbeating Nystagmus: A review of 62 cases. Arch. Neurol. 40: 777-784, 1983. HASEGAWA, K., KOWA, H., TAZAKI, Y., and TOKuMAsu, K.: Directional change of vertical nystagmus in a case with multiple sclerosis. C/in. Neurol. 27: 1103-1107,1987 (in Japanese). KATTAH, J. C., KOLSKY, M. P., GUY, J., and O'DOHERTY, D.: Primary position vertical nystagmus and cerebellar ataxia. Arch. Neurol. 40: 310-314, 1983. LAVIN, P. J. M., TRACCIS, S., DELL'OSSO, L. F., ABEL, L. A., and ELLENBERGER, C., Jr.: Downbeat nystagmus with a pseudocycloid waveform: Improvement with Base-out prisms. Ann. Neurol. 13: 621-624, 1983. MATSUO, V., and COHEN, B.: Vertical optokinetic nystagmus and vestibular nystagmus in the monkey: Up-down asymmetry and effects of gravity. Exp. Brain Res. 53: 197-216, 1984. NAKADA, T., and REMLER, M. P.: Primary position Upbeat nystagmus: Another central vestibular nystagmus? J. C/in. Neuro-Ophthalmol. 1: 185-189,1981. SCHATZ, N. J., SCHLEZINGER, N. S., and BERRY, R. G.: Vertical up-beat nystagmus on downward gaze: A clinical pathologic correlation. Neurology 25: 380, 1975. SUZUKI, J., and KOMATSUZAKI, A.: Clinical application of optokinetic nystagmus-optokinetic pattern test. Acta Otolaryngol. 54: 49-55, 1962. TABUCHI, T., TANIGUCHI, S., and AMATSU, M.: Upbeat nystagmus. Otolaryngology (Tokyo) 55: 681-690, 1983 (in Japanese). TROOST, B. T., MARTINEZ, J., ABEL, L. A., and HEROS, R. C.: Upbeat nystagmus and internuclear ophthalmoplegia with brain stem glioma. Arch. Neurol. 37: 453-456, 1980. YOSHIMOTO, Y., and YABE, Y.: A case of spinocerebellar degeneration with primary position upbeat nystagmus. Otolaryngology (Tokyo) 56: 373-380, 1984 (in Japanese). ZEE, D. S., FRIENDLICH, A. R., and ROBINSON, D. A.: The mechanism of downbeat nystagmus. Arch. Neurol. 30: 227-237, 1974.
Request reprints to:
Dr. M. Mizuno, Department of Otolaryngology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan