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See-saw nystagmus: An unusual sign of brain-stem infarction
439
Journal of the neuro!ogical Sciences, 1974, 22 : 439~,43 t : Elsevier Scientific Publishing Company, Amsterdam
Printed in The Netherlands
See-saw Nystagmus" An Unusual Sign of Brain-Stem Infarction F.L. MASTAGLIA Department of Medicine, University of Western Australia," Neurological Service, Perth Medical Centre, Verdun Street, Shenton Park, Perth, W. Australia 6008 (Australia) (Received 14 January, 1974)
INTRODUCTION
Nystagmus is a common sign in patients with acute vascular disturbances in the brain-stem and is usually horizontal, vertical or rotary in type. Convergence-retraction nystagmus and dissociated nystagmus confined to the abducting eye are less common varieties encountered in some patients with vascular lesions involving the dorsal mid-brain and medial longitudinal fasciculus respectively. See-saw nystagmus is not usually regarded as a sign of brain-stem infarction but has been considered to indicate diencephalic dysfunction (Plum and Posner 1966; Daroff and Troost 1973) usually due to a neoplastic lesion in the anterior third ventricular region (Drachman 1966). The purpose of the present report is to describe a patient in whom see-saw nystagmus occurred transiently during the acute phase of lower brain-stem infarction and was associated with skew deviation of the eyes and rotary nystagmus. CASE REPORT (E.S., S.C.G.H. 36323) The patient was a 73-year-old female who was admitted to hospital 24 hr after the acute onset of vertigo, dysphagia, dysphonia, hiccough and ataxia of gait. At the time of admission she was conscious and alert and showed no impairment of higher cortical functions. The visual fields were full to confrontation. Coarse rotary nystagmus with an anti-clockwise fast component was present in the primary position and on vertical and left lateral gaze. There was no strabismus but she complained of diplopia on left lateral, vertical and downward gaze. There was a left Homer's syndrome. There was impaired appreciation of light touch over the left ophthalmic nerve territory and of pain and thermal sensation over the whole of the left side of the face. Pain and thermal sensation were also depressed over the right side of the face, particularly in the ophthalmic and maxillary nerve territories. Left corneal sensation was depressed. Other signs included left trigeminal motor paresis, mild left lower motor neurone facial paresis, left palatal palsy, marked dysphonia and dysphagia with inability to cope with pharyngeal secretions, mild left hemiparesis with left-sided dysmetria, dysdiadochokinesis and intention tremor, bilateral extensor plantar responses, depressed pain and thermal sensation over the right limbs and the right side of the trunk, and truncal dysequilibrium. She was normotensive (B.P. 150/90 mm Hg) and no evidence of long-standing pre-existing hypertension was found on examination of the cardiovascular system. The carotid and radial pulses were equal in volume with no disparity in blood pressures between the two arms. No bruits were audible over the supraclavicular fossae, neck or cranium.
440
F.L. MASTAGLIA
L
,©
i
f N.
i
-N
Fig. 1. Diagrammatic representation of the skew deviation Iposition l) and of the movements of the eyes constituting see-saw nystagmus in the case reported. Heparin and dextran infusions were commenced soon after admission to hospital. On the second hospital day the ocular signs had changed. Skew deviation was now present, the right eye being elevated above and the left eye depressed below the horizontal meridian by approximately 15° . In addition, typical see-saw nystagmus was present, the right eye elevating and intorting, the left eye depressing and extorting in synchrony {Fig. 1), each cycle lasting approximately 1 sec before the eyes had returned to their resting skewed position. The two phases of both the vertical and the torsional components were of approximately equal speed. The cycle recurred approximately once every second The see-saw movements were not present continuously but could be brought on by attempted upward gaze. They were not influenced by changes in position of the head. On the third hospital day the ocular axes had returned to normal and see-sawing was no longer present but coarse rotary nystagmus was again present in the primary position and on left lateral, upward and downward gaze. Diplopia was still present on upward, downward and left lateral gaze and failure of complete abduction of the left eye was now apparent. There was now only minimal weakness of the left limbs and the right plantar response was flexor in type. On the fourth hospital day the patient sustained an episode of prolonged myocardial ischemia with atrial tachycardia, hypotension (B.P. 90/50 mm Hg I and left ventricutar failure. Symmetrical pyramidal signs w e r e n o w present in the lower limbs but the eye signs remained unchanged. The patient remained in hospital for a period of 4½ months, during which there was a slow improvement in her neurological signs. Neither see-saw nystagmus nor skew deviation of the eyes was noted again during this period. Ophthalmic examination (Mr, G. Bougher) showed early bilateral lens opactties with a visual acuity of R.6/36, L.6/24 improving to R.6 7.5, L6/9 with refraction.
DISCUSSION
Two types of nystagmus appeared during the course of this patient's illness. A jerk nystagmus of rotary type without disconjugation of the ocular axes was present 24 hr after the onset of the vascular disturbance and again on day 3 and persisted for several weeks thereafter. The ocular movements on day 2 of the illness were of a different type consisting of rhythmic vertical disconjugation with a superimposed conjugate torsional component and were considered to represent true see-saw nystagmus. See-saw nystagmus is an unusual form of ocular involuntary movement, only 29 cases having been reported in the literature to date (Maddox 19t4: Rucker 1946; Larsen 1957; Jensen 1959; Smith and Mark 1959; Mark, Smith and Kjetlberg 1960: Lourie 1963; Kinder and Howard 1963; Schurr 1963; Arnott 1964; Slatt and Nykiel 1964; Daroff 1965 ; Drachman 1966; Druckman. Ellis, Kleinfeld and Watdman 1966: Sogg and Bland 1966; Fein and Williams 1969; Schmidt and Kommerelt 1969; Arnott and Miller 1970: Regli, Gerber and Fisch 1971 : Garelli and Gherardini t972).
SEE-SAW NYSTAGMUS, UNUSUAL SIGN OF BRAIN-STEM INFARCTION
441
The underlying pathological process in these cases has been variable. Eleven cases have had craniopharyngiomas (Kinder and Howard 1963; Schurr 1963 ; Arnott 1964; Druckman et al. 1966), pituitary adenomas (Lourie 1963; Schurr 1963; Daroff 1965; Drachman 1966) or some other supra-sellar (Smith and Mark 1959) or chiasmal (Larsen 1957; Mark et al. 1960) tumour and the nystagmus was associated with bitemporal hemianopia and severe visual impairment. In 4 cases the nystagmus followed a head injury (Schmidt and Kommerell 1969; Arnott and Miller 1970) and was also associated with impaired visual acuity and bitemporal hemianopia suggesting chiasmal damage. Single cases have had syringomyelia and syringobulbia (Fein and Williams 1969), probable multiple sclerosis (Druckman et al. 1966), perinatal hypoxia with multiple congenital abnormalities (Druckman et al. 1966), and stereotactic surgery to the region of the zona incerta for Parkinson's disease (Garelli and Gherardini 1972). In 7 cases the nature of the underlying pathological process was not apparent; 2 of these cases had bitemporal hemianopia (Maddox 1914; Smith and Mark 1959) suggesting a chiasmal lesion and only 2 of the other 5 cases had normal visual acuity and visual fields. Three of the previously reported cases of see-saw nystagmus had ischaemic lesions in the brain-stem (Jensen 1959; Daroff 1965). In each of these cases, as in the present case, the see-saw nystagmus was noted in the acute phase of brain-stem infarction and was short-lived, having disappeared after 2~48 hr in 2 cases (Jensen 1959), while in the third case it persisted into the second week (Daroff 1965). Associated rotary nystagmus was noted in 2 of these 3 cases. In Jensen's first case the major involvement was of the left side of the medulla and a vertebral artery occlusion was postulated. Involvement of the oculomotor nucleus was also inferred on the basis of an ipsilateral medial rectus paresis. In the other 2 cases the localisation of the ischaemic lesions was less precise. A medial rectus paresis was also present in each of these cases and was considered to be indicative of mid-brain involvement. Skew deviation was not recorded in any of these cases. In the present case the clinical signs were those of a left lateral medullary syndrome with additional involvement of the left abducens and facial nerve nuclei, the trigeminal motor nucleus and the contralateral trigemino-thalamic pathway in the pons, and of the corticospinal pathways. There was no clinical evidence of chiasmal, diencephalic or mid-brain involvement. Although arteriographic studies were not carried out, a clinical diagnosis of intracranial thrombosis of the left vertebral artery with possible extension to the lower basilar artery was made. See-saw nystagmus is not seen in typical cases of the lateral medullary syndrome and is not part of the usual clinical syndromes which result from occlusion of the basilar artery or of its branches. The transient nature of the see-sawing in the present case and in 2 of the previously reported cases suggests that without careful serial examination of patients during the acute stages of brain-stem infarction this sign could be missed and may be commoner than is suspected. Skew deviation of the eyes may occur with a variety of pathological processes at different levels of the brain-stem and has been reported previously in the lateral medullary syndrome (Silverski61d 1966). It is most characteristic of acute lesions in the vicinity of the brachium pontis ipsilateral to the depressed eye (Smith, David
442
F.L. MASTAGL1A
and Klintworth 1964). In the present case the skew deviation is likely to have resulted from ischaemic damage to the left side of the pons. The association of skew deviation with see-saw nystagrnus has been noted previously (Plum and Posner 1966: Garetli and Gherardini 1972) and is of interest as it suggests a common or closely-related anatomical and functional basis for these two abnormalities of ocular posture and motility. See-saw nystagmus could be looked upon as a composite of rhythmic skewing with superimposed torsional nystagmus. The patho-physiological basis for see-saw nystagmus is not known. In view of the frequent association with impaired visual acuity and visual field defects, it has been postulated that the nystagmus may be ocular in origin (Lourie 1963 : Slatt and Nykiet 1964; Plum and Posner 1966) and due to a disturbance of the normal tonic influence of the macula on visual fixation. However. the occurrence of see-saw nystagmus in subjects with normal vision (Daroff 1965: Sogg and Bland 1966: Fein and Williams 1969) indicates that visual impairment is not essential. A number of cases have had abnormal vestibular function in addition to visual impairment (Jensen 1959: Smith and Mark 1959: Slatt and Nykiel 1964: Drachman 1966: Druckman el al. t966), and it has been suggested that a combination of functional abnormalities in visual and vestibular pathways may be necessary to produce see-saw nystagmus ~Drachman 1966). Although see-saw nystagmus has not been produced experimentally, the individual components of the movement viz. rhythmic skewing and ocular torsion have been produced by stimulation of certain areas in the brain-stem and diencephalon. Rhythmic biphasic skewing has been produced in the rabbit by electrical stimulation of the bulbar vestibular area lateral and posterior to the area from which horizontal nystagmus is evoked (Montandon and Monnier 19641. Torsional eye movements which occur physiologically on head-tilting and which are considered to originate in the utricle and saccule (Miller 1962), have been produced in the cat by electrical stimulation of the zona incerta and interstitial nucleus of Cajal (Hyde and Toczek 1962). A combination of vertical and rotary nystagrnus not too dissimilar from see-saw nystagmus has been produced in cats by the injection of Carbachol into the third ventricle (Szekely and Spiegel 1963), and presumably resulted from stimulation of the same areas. In the present case there was both a visual defect and a vestibular disturbance and the possibility of minor ischaemic damage to diencephalic structures cannot be absolutely excluded in view of the lack of pathological data. Nevertheless. it is felt that the see-saw nystagmus probably resulted from damage to ponto-medullary vestibular areas. ACKNOWLEDGEMENTS The author is grateful to Mr. H. Upenieks who prepared the illustration and to Miss L. Samuels for secretarial assistance. SUMMARY
See-saw nystagmus is an unusual form of ocular involuntary movement which is not usually regarded as a sign of brain-stem ischacmia but has been more commonly
SEE-SAW NYSTAGMUS, UNUSUAL SIGN OF BRAIN-STEM INFARCTION
443
associated with tumours in the region of the optic chiasm and diencephalon. The patient described in the present report demonstrated typical see-saw nystagmus in the acute phase after ponto-medullary infarction with associated skew deviation of the eyes and rotary nystagmus. The possible patho-physio[ogical mechanisms involved in the production of see-saw nystagmus are discussed and the relationship between see-saw nystagmus ~nd skew deviation is considered. REFERENCES AgNorr, E. J. (1964) Vertical see-saw nystagmus, Trans. ophthal. Soc. U.K., 84: 251-257. ARNOTT, E. J. AND S. J. H. MILLER (1970) See-saw nystagmus, Trans. ophthal. Soc. U.K., 90: 491~,96. DAROVF, R. B. (1965)See-saw nystagmus, Neurology (Minneap.), 15:874-877. DAROFF, R. B. AND B. T. TROOST (1973) Upbeat nystagmus, J. ,4met. reed. Ass., 225: 312. DRACHMAN, D. A. (1966) See-saw nystagmus, J. Neuro/. Neurosurg. Psychiat., 29: 356-361. DRUCKMAN, R., P. ELLIS, J. KLEINFELD AND M. WALDMAN (1966) See-saw nystagmus, Arch. Optha/., 76 : 668-675. FEIN, J. M., AND R. D. B. WILLIAMS (1969) See-saw nystagmus, J. Neuro/. Neurosurg. Psychiat., 32: 202-207. GARELL1, F. F. AND G. GHERARDINI (1972) Rapporti tra il nistagmo "see-saw" e lo strabismo verticale "sghembo" (skew deviation). Descrizione di un caso, Riv. NeuroL, 42: 137--162. HYDE, J. E. AND S. TOCZEK 0962) Functional relation of interstitial nucleus to rotatory movements evoked from zona incerta stimulation, J. Neurophysiol., 25: 455-466. JENSEN, O. A. (1959) See-saw nystagmus, Brit. J. Ophthal., 43: 225-259. KINDER, R. S. L. AND G. M. HOWARD (1963) See-saw nystagmus, ,4met. J. Dis. ChiM., 106: 331-332. LARSEN, V. (1957) Et tilfaelde af vippenystagmus, Ugeskr. Lceg., 119: 947-950. LOURIE, H. (1963) See-saw nystagmus, Arch. Neurol. (Chic.), 9: 531-533. MADDOX, E. E. (1914) See-saw nystagmus with bitemporal hemianopia, Proc. roy. Soc. Med., 7: 12-13. MARK, V. H., J. L. SMmJ AND R. D. KJELLBER6 (1960) Suprasellar epidermoid tumour: A case report with the presenting complaint of see-saw nystagmus, Neurology (Minneap.), 10: 81-83. MILLER, E. G. (1962) Counterrolling of the human eyes produced by head tilt with respect to gravity, ,4cta oto-laryng. (Stockh.), 54: 479-501. MONTANDON P. AND M. MONNIER (1964) Correlations of the diencephalic nystagmogenic area with the bulbo-vestibular nystagmogenic area, Brain, 87: 673-690. PLUM, F. AND J. B. POSNER (1966) Diagnosis of Stupor and Coma, Davis, Philadelphia, Pa., p. 30. REC3LI, F., N. GERBER AND U. FISCH (1971) Der see-saw-Nystagmus, Nervenarzt, 42: 316-319. RUCKER, C. W. (1946) See-saw nystagmus associated with choroiditis and positive neutralization test for toxoplasma, Arch. Ophthal., 35: 301-302. SC~MIDT, D. AND G. KOMMERELL(1969) See-saw nystagmus with bitemporal hemianopia following head injury, Albrecht v. Graefes Arch. Ophthal., 178:349 366. SCHURR, P. H. (1963) See-saw nystagmus, Proc. roy. Soc. Med., 56: 808- 810. SILFVERSKIOLD, B. P. (1966) Skew deviation in Wallenberg's syndrome, ,4cta neuro/, scand., 41 : 381-386. SEAI'X, B. and F. NYKIEL (1964) See-saw nystagmus, ,4met. J. Ophthal., 58: 1016-1021. SMITH, J. L. AND V. H. MARK (1959) See-saw nystagmus with supra-sellar epidermoid turnout, Arch. Ophtha/., 62: 28(~283. SMrrH, J. L., N. J. DAVIDAND G. KLINTWORTH(1964) Skew deviation, Neurology (Minneap.), 14: 96-105. SOGG, R. L. AND R. BLAND (1966) See-saw nystagmus. Quoted by R. Druckman et a/. (1966). SZEKELV, E. G. AND E. A. SPIEGEL (1963) Vertical nystagmus induced by the injection of stimulating substances in the striatum, third or lateral ventricle, Neurology (Minneap.), 13" 306-314.
Journal of the neuro!ogical Sciences, 1974, 22 : 439~,43 t : Elsevier Scientific Publishing Company, Amsterdam
Printed in The Netherlands
See-saw Nystagmus" An Unusual Sign of Brain-Stem Infarction F.L. MASTAGLIA Department of Medicine, University of Western Australia," Neurological Service, Perth Medical Centre, Verdun Street, Shenton Park, Perth, W. Australia 6008 (Australia) (Received 14 January, 1974)
INTRODUCTION
Nystagmus is a common sign in patients with acute vascular disturbances in the brain-stem and is usually horizontal, vertical or rotary in type. Convergence-retraction nystagmus and dissociated nystagmus confined to the abducting eye are less common varieties encountered in some patients with vascular lesions involving the dorsal mid-brain and medial longitudinal fasciculus respectively. See-saw nystagmus is not usually regarded as a sign of brain-stem infarction but has been considered to indicate diencephalic dysfunction (Plum and Posner 1966; Daroff and Troost 1973) usually due to a neoplastic lesion in the anterior third ventricular region (Drachman 1966). The purpose of the present report is to describe a patient in whom see-saw nystagmus occurred transiently during the acute phase of lower brain-stem infarction and was associated with skew deviation of the eyes and rotary nystagmus. CASE REPORT (E.S., S.C.G.H. 36323) The patient was a 73-year-old female who was admitted to hospital 24 hr after the acute onset of vertigo, dysphagia, dysphonia, hiccough and ataxia of gait. At the time of admission she was conscious and alert and showed no impairment of higher cortical functions. The visual fields were full to confrontation. Coarse rotary nystagmus with an anti-clockwise fast component was present in the primary position and on vertical and left lateral gaze. There was no strabismus but she complained of diplopia on left lateral, vertical and downward gaze. There was a left Homer's syndrome. There was impaired appreciation of light touch over the left ophthalmic nerve territory and of pain and thermal sensation over the whole of the left side of the face. Pain and thermal sensation were also depressed over the right side of the face, particularly in the ophthalmic and maxillary nerve territories. Left corneal sensation was depressed. Other signs included left trigeminal motor paresis, mild left lower motor neurone facial paresis, left palatal palsy, marked dysphonia and dysphagia with inability to cope with pharyngeal secretions, mild left hemiparesis with left-sided dysmetria, dysdiadochokinesis and intention tremor, bilateral extensor plantar responses, depressed pain and thermal sensation over the right limbs and the right side of the trunk, and truncal dysequilibrium. She was normotensive (B.P. 150/90 mm Hg) and no evidence of long-standing pre-existing hypertension was found on examination of the cardiovascular system. The carotid and radial pulses were equal in volume with no disparity in blood pressures between the two arms. No bruits were audible over the supraclavicular fossae, neck or cranium.
440
F.L. MASTAGLIA
L
,©
i
f N.
i
-N
Fig. 1. Diagrammatic representation of the skew deviation Iposition l) and of the movements of the eyes constituting see-saw nystagmus in the case reported. Heparin and dextran infusions were commenced soon after admission to hospital. On the second hospital day the ocular signs had changed. Skew deviation was now present, the right eye being elevated above and the left eye depressed below the horizontal meridian by approximately 15° . In addition, typical see-saw nystagmus was present, the right eye elevating and intorting, the left eye depressing and extorting in synchrony {Fig. 1), each cycle lasting approximately 1 sec before the eyes had returned to their resting skewed position. The two phases of both the vertical and the torsional components were of approximately equal speed. The cycle recurred approximately once every second The see-saw movements were not present continuously but could be brought on by attempted upward gaze. They were not influenced by changes in position of the head. On the third hospital day the ocular axes had returned to normal and see-sawing was no longer present but coarse rotary nystagmus was again present in the primary position and on left lateral, upward and downward gaze. Diplopia was still present on upward, downward and left lateral gaze and failure of complete abduction of the left eye was now apparent. There was now only minimal weakness of the left limbs and the right plantar response was flexor in type. On the fourth hospital day the patient sustained an episode of prolonged myocardial ischemia with atrial tachycardia, hypotension (B.P. 90/50 mm Hg I and left ventricutar failure. Symmetrical pyramidal signs w e r e n o w present in the lower limbs but the eye signs remained unchanged. The patient remained in hospital for a period of 4½ months, during which there was a slow improvement in her neurological signs. Neither see-saw nystagmus nor skew deviation of the eyes was noted again during this period. Ophthalmic examination (Mr, G. Bougher) showed early bilateral lens opactties with a visual acuity of R.6/36, L.6/24 improving to R.6 7.5, L6/9 with refraction.
DISCUSSION
Two types of nystagmus appeared during the course of this patient's illness. A jerk nystagmus of rotary type without disconjugation of the ocular axes was present 24 hr after the onset of the vascular disturbance and again on day 3 and persisted for several weeks thereafter. The ocular movements on day 2 of the illness were of a different type consisting of rhythmic vertical disconjugation with a superimposed conjugate torsional component and were considered to represent true see-saw nystagmus. See-saw nystagmus is an unusual form of ocular involuntary movement, only 29 cases having been reported in the literature to date (Maddox 19t4: Rucker 1946; Larsen 1957; Jensen 1959; Smith and Mark 1959; Mark, Smith and Kjetlberg 1960: Lourie 1963; Kinder and Howard 1963; Schurr 1963; Arnott 1964; Slatt and Nykiel 1964; Daroff 1965 ; Drachman 1966; Druckman. Ellis, Kleinfeld and Watdman 1966: Sogg and Bland 1966; Fein and Williams 1969; Schmidt and Kommerelt 1969; Arnott and Miller 1970: Regli, Gerber and Fisch 1971 : Garelli and Gherardini t972).
SEE-SAW NYSTAGMUS, UNUSUAL SIGN OF BRAIN-STEM INFARCTION
441
The underlying pathological process in these cases has been variable. Eleven cases have had craniopharyngiomas (Kinder and Howard 1963; Schurr 1963 ; Arnott 1964; Druckman et al. 1966), pituitary adenomas (Lourie 1963; Schurr 1963; Daroff 1965; Drachman 1966) or some other supra-sellar (Smith and Mark 1959) or chiasmal (Larsen 1957; Mark et al. 1960) tumour and the nystagmus was associated with bitemporal hemianopia and severe visual impairment. In 4 cases the nystagmus followed a head injury (Schmidt and Kommerell 1969; Arnott and Miller 1970) and was also associated with impaired visual acuity and bitemporal hemianopia suggesting chiasmal damage. Single cases have had syringomyelia and syringobulbia (Fein and Williams 1969), probable multiple sclerosis (Druckman et al. 1966), perinatal hypoxia with multiple congenital abnormalities (Druckman et al. 1966), and stereotactic surgery to the region of the zona incerta for Parkinson's disease (Garelli and Gherardini 1972). In 7 cases the nature of the underlying pathological process was not apparent; 2 of these cases had bitemporal hemianopia (Maddox 1914; Smith and Mark 1959) suggesting a chiasmal lesion and only 2 of the other 5 cases had normal visual acuity and visual fields. Three of the previously reported cases of see-saw nystagmus had ischaemic lesions in the brain-stem (Jensen 1959; Daroff 1965). In each of these cases, as in the present case, the see-saw nystagmus was noted in the acute phase of brain-stem infarction and was short-lived, having disappeared after 2~48 hr in 2 cases (Jensen 1959), while in the third case it persisted into the second week (Daroff 1965). Associated rotary nystagmus was noted in 2 of these 3 cases. In Jensen's first case the major involvement was of the left side of the medulla and a vertebral artery occlusion was postulated. Involvement of the oculomotor nucleus was also inferred on the basis of an ipsilateral medial rectus paresis. In the other 2 cases the localisation of the ischaemic lesions was less precise. A medial rectus paresis was also present in each of these cases and was considered to be indicative of mid-brain involvement. Skew deviation was not recorded in any of these cases. In the present case the clinical signs were those of a left lateral medullary syndrome with additional involvement of the left abducens and facial nerve nuclei, the trigeminal motor nucleus and the contralateral trigemino-thalamic pathway in the pons, and of the corticospinal pathways. There was no clinical evidence of chiasmal, diencephalic or mid-brain involvement. Although arteriographic studies were not carried out, a clinical diagnosis of intracranial thrombosis of the left vertebral artery with possible extension to the lower basilar artery was made. See-saw nystagmus is not seen in typical cases of the lateral medullary syndrome and is not part of the usual clinical syndromes which result from occlusion of the basilar artery or of its branches. The transient nature of the see-sawing in the present case and in 2 of the previously reported cases suggests that without careful serial examination of patients during the acute stages of brain-stem infarction this sign could be missed and may be commoner than is suspected. Skew deviation of the eyes may occur with a variety of pathological processes at different levels of the brain-stem and has been reported previously in the lateral medullary syndrome (Silverski61d 1966). It is most characteristic of acute lesions in the vicinity of the brachium pontis ipsilateral to the depressed eye (Smith, David
442
F.L. MASTAGL1A
and Klintworth 1964). In the present case the skew deviation is likely to have resulted from ischaemic damage to the left side of the pons. The association of skew deviation with see-saw nystagrnus has been noted previously (Plum and Posner 1966: Garetli and Gherardini 1972) and is of interest as it suggests a common or closely-related anatomical and functional basis for these two abnormalities of ocular posture and motility. See-saw nystagmus could be looked upon as a composite of rhythmic skewing with superimposed torsional nystagmus. The patho-physiological basis for see-saw nystagmus is not known. In view of the frequent association with impaired visual acuity and visual field defects, it has been postulated that the nystagmus may be ocular in origin (Lourie 1963 : Slatt and Nykiet 1964; Plum and Posner 1966) and due to a disturbance of the normal tonic influence of the macula on visual fixation. However. the occurrence of see-saw nystagmus in subjects with normal vision (Daroff 1965: Sogg and Bland 1966: Fein and Williams 1969) indicates that visual impairment is not essential. A number of cases have had abnormal vestibular function in addition to visual impairment (Jensen 1959: Smith and Mark 1959: Slatt and Nykiel 1964: Drachman 1966: Druckman el al. t966), and it has been suggested that a combination of functional abnormalities in visual and vestibular pathways may be necessary to produce see-saw nystagmus ~Drachman 1966). Although see-saw nystagmus has not been produced experimentally, the individual components of the movement viz. rhythmic skewing and ocular torsion have been produced by stimulation of certain areas in the brain-stem and diencephalon. Rhythmic biphasic skewing has been produced in the rabbit by electrical stimulation of the bulbar vestibular area lateral and posterior to the area from which horizontal nystagmus is evoked (Montandon and Monnier 19641. Torsional eye movements which occur physiologically on head-tilting and which are considered to originate in the utricle and saccule (Miller 1962), have been produced in the cat by electrical stimulation of the zona incerta and interstitial nucleus of Cajal (Hyde and Toczek 1962). A combination of vertical and rotary nystagrnus not too dissimilar from see-saw nystagmus has been produced in cats by the injection of Carbachol into the third ventricle (Szekely and Spiegel 1963), and presumably resulted from stimulation of the same areas. In the present case there was both a visual defect and a vestibular disturbance and the possibility of minor ischaemic damage to diencephalic structures cannot be absolutely excluded in view of the lack of pathological data. Nevertheless. it is felt that the see-saw nystagmus probably resulted from damage to ponto-medullary vestibular areas. ACKNOWLEDGEMENTS The author is grateful to Mr. H. Upenieks who prepared the illustration and to Miss L. Samuels for secretarial assistance. SUMMARY
See-saw nystagmus is an unusual form of ocular involuntary movement which is not usually regarded as a sign of brain-stem ischacmia but has been more commonly
SEE-SAW NYSTAGMUS, UNUSUAL SIGN OF BRAIN-STEM INFARCTION
443
associated with tumours in the region of the optic chiasm and diencephalon. The patient described in the present report demonstrated typical see-saw nystagmus in the acute phase after ponto-medullary infarction with associated skew deviation of the eyes and rotary nystagmus. The possible patho-physio[ogical mechanisms involved in the production of see-saw nystagmus are discussed and the relationship between see-saw nystagmus ~nd skew deviation is considered. REFERENCES AgNorr, E. J. (1964) Vertical see-saw nystagmus, Trans. ophthal. Soc. U.K., 84: 251-257. ARNOTT, E. J. AND S. J. H. MILLER (1970) See-saw nystagmus, Trans. ophthal. Soc. U.K., 90: 491~,96. DAROVF, R. B. (1965)See-saw nystagmus, Neurology (Minneap.), 15:874-877. DAROFF, R. B. AND B. T. TROOST (1973) Upbeat nystagmus, J. ,4met. reed. Ass., 225: 312. DRACHMAN, D. A. (1966) See-saw nystagmus, J. Neuro/. Neurosurg. Psychiat., 29: 356-361. DRUCKMAN, R., P. ELLIS, J. KLEINFELD AND M. WALDMAN (1966) See-saw nystagmus, Arch. Optha/., 76 : 668-675. FEIN, J. M., AND R. D. B. WILLIAMS (1969) See-saw nystagmus, J. Neuro/. Neurosurg. Psychiat., 32: 202-207. GARELL1, F. F. AND G. GHERARDINI (1972) Rapporti tra il nistagmo "see-saw" e lo strabismo verticale "sghembo" (skew deviation). Descrizione di un caso, Riv. NeuroL, 42: 137--162. HYDE, J. E. AND S. TOCZEK 0962) Functional relation of interstitial nucleus to rotatory movements evoked from zona incerta stimulation, J. Neurophysiol., 25: 455-466. JENSEN, O. A. (1959) See-saw nystagmus, Brit. J. Ophthal., 43: 225-259. KINDER, R. S. L. AND G. M. HOWARD (1963) See-saw nystagmus, ,4met. J. Dis. ChiM., 106: 331-332. LARSEN, V. (1957) Et tilfaelde af vippenystagmus, Ugeskr. Lceg., 119: 947-950. LOURIE, H. (1963) See-saw nystagmus, Arch. Neurol. (Chic.), 9: 531-533. MADDOX, E. E. (1914) See-saw nystagmus with bitemporal hemianopia, Proc. roy. Soc. Med., 7: 12-13. MARK, V. H., J. L. SMmJ AND R. D. KJELLBER6 (1960) Suprasellar epidermoid tumour: A case report with the presenting complaint of see-saw nystagmus, Neurology (Minneap.), 10: 81-83. MILLER, E. G. (1962) Counterrolling of the human eyes produced by head tilt with respect to gravity, ,4cta oto-laryng. (Stockh.), 54: 479-501. MONTANDON P. AND M. MONNIER (1964) Correlations of the diencephalic nystagmogenic area with the bulbo-vestibular nystagmogenic area, Brain, 87: 673-690. PLUM, F. AND J. B. POSNER (1966) Diagnosis of Stupor and Coma, Davis, Philadelphia, Pa., p. 30. REC3LI, F., N. GERBER AND U. FISCH (1971) Der see-saw-Nystagmus, Nervenarzt, 42: 316-319. RUCKER, C. W. (1946) See-saw nystagmus associated with choroiditis and positive neutralization test for toxoplasma, Arch. Ophthal., 35: 301-302. SC~MIDT, D. AND G. KOMMERELL(1969) See-saw nystagmus with bitemporal hemianopia following head injury, Albrecht v. Graefes Arch. Ophthal., 178:349 366. SCHURR, P. H. (1963) See-saw nystagmus, Proc. roy. Soc. Med., 56: 808- 810. SILFVERSKIOLD, B. P. (1966) Skew deviation in Wallenberg's syndrome, ,4cta neuro/, scand., 41 : 381-386. SEAI'X, B. and F. NYKIEL (1964) See-saw nystagmus, ,4met. J. Ophthal., 58: 1016-1021. SMITH, J. L. AND V. H. MARK (1959) See-saw nystagmus with supra-sellar epidermoid turnout, Arch. Ophtha/., 62: 28(~283. SMrrH, J. L., N. J. DAVIDAND G. KLINTWORTH(1964) Skew deviation, Neurology (Minneap.), 14: 96-105. SOGG, R. L. AND R. BLAND (1966) See-saw nystagmus. Quoted by R. Druckman et a/. (1966). SZEKELV, E. G. AND E. A. SPIEGEL (1963) Vertical nystagmus induced by the injection of stimulating substances in the striatum, third or lateral ventricle, Neurology (Minneap.), 13" 306-314.