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Show ]. CJjn. Neuro-ophthalmol. 1: 5-8, 1981. Periodic Alternating Skew Deviation JAMES M. MITCHELL, M.D. J. LAWTON SMITH, M.D. ROBERT M. QUENCER, M.D. Abstract A 18-ye~r-old hypertensive woman suddenly developed blurred vision, followed shortly by dizziness, difficulty walking with a tendency to veer to the left, and vertical diplopia. Examination 3 weeks later revealed a unique neuro-ophthalmologic motility pattern, which may be described as periodic alternating skew deviation. This previously unreported motility disturbance was associated with downbeat nystagmus in our ~tient, and a focal lesion at the level of the interstitial nucleus of Cajal was demonstrated on computed tomography. The spectrum of physiologically related motility patterns-including periodic alternating nystagmus, cyclic oculomotor paralysis, see-saw nystagmus, periodic alternating gaze deviation, "pingpong" gaze, and intermittent aperiodic alternating skew deviation-has been considered and is helpful in topical neuro-ophthalmologic diagnosis. We recently encountered a patient with a most unusual ocular motility pattern. To our knowledge, the clinical and radiographic features of periodic alternating skew deviation have not been previously reported in the literature. Case Report A 78-year-old, right-handed, hypertensive white woman suddenly developed bilateral blurring of vision while riding in her car. A few hours later she noted dizziness, difficulty walking with a tendency to veer to the left, and vertical diplopia. There were no other neurologic complaints. Her eye symptoms persisted, and she was referred to the Bascom Palmer Eye Institute through the courtesy of Dr. Kulvin 3 weeks later. Neuro-ophthalmologic examination on June 17, 1980, revealed a visual acuity of 20/25+2 in the right eye and 20/50+2 in the left eye. Her ocular motility pattern was unique and will be described in detail later. External eye examination was nor- From the Department of Ophthalmology, Basco.m Palmer Eye Institute, University of Miami School of MedICine, and the Department of Radiology, University of MiamI School of Medicine, Miami. Florida. March 1981 mal but for slight elastosis of the upper lids, and a twitch at the corner of her mouth when she blinked, due to aberrant regeneration of the left facial nerve, following an old Bell's palsy. The pupils were equal in size, reacted briskly to light, and there was no Marcus Gunn pupil. The visual fields were full. Slit lamp examination was normal for her age but for pseudo-exfoliation of the right lens capsule. Applanation tensions were 26 in the right eye and 20 in the left eye. Dilated fundus examination revealed normal discs, slight arteriolar narrowing in both eyes, and early cellophane maculopathy in the right eye. Facial sensation was intact. There was no facial weakness, and the other cranial nerves were intact. There were no abnormal movements of the tongue or palate. Her pulse was 66 and regular and the blood pressure was 145/80. Ocular motility examination revealed a comitant gross right hypertropia of over 25 prism diopters. However, after a period of 4-5 minutes, the right hypertropia abruptly cleared, and the eyes rapidly went through a transition phase during which screen and cover test elicited no vertical deviation at all. A left hypertropia of 8 prism diopters then abruptly appeared. The left hypertropia persisted for 40-50 seconds before disappearing and then promptly reverted to a right hypertropia. The versions were full throughout all phases and the deviation was comitant in both the right hypertropia and left hypertropia cycles. The transition periods when the eyes were essentially orthophoric on screen and cover test lasted no more than 10 seconds. We witnessed a number of the cycles, and the large right hypertropia consistently lasted 4-5 minutes, while the lesser left hypertropia lasted only 40-60 seconds. Optokinetic testing showed a decreased response in the right eye when targets were moved to her right, but a normal response in both eyes when targets were moved to her left. The vertical responses were normal to up targets and slightly diminished in the left eye only with down targets. We instructed the patient's husband as to how to document the phases of the deviation, and he carefully measured the periodicity of her complaint during the next 2 days. He confirmed that during those 2 days, the right eye was higher consistently 5 Periodic Alternating Skew Deviation for 4-5 minutes and the left eye was higher for periods of always less than 60 seconds. Dr. Noble David kindly performed a neurological examination on the patient on June 19, 2 days after presentation to our office. His examination confirmed aberrant regeneration of the left facial nerve, due to the old Bell's palsy. A slight snout reflex was present on the right. No palmar-mental or corneomandibular reflex was present. Rapid alternating movements were minimally slowed and a slight terminal tremor of the left hand was seen. Deep tendon reflexes were slightly decreased at the knees and ankles, and peripheral light touch, vibration, and pinprick were also slightly diminished. These subtle findings were felt to be within the normal range for her age. Computed tomography demonstrated a small nonenhancing midline area of diminished photon attenuation within the midbrain tegmentum. This was consistent with the level of interstitial nucleus of Cajal. There was no associated mass effect of hydrocephalus. The patient was treated with short courses of Tegretol, Dilantin, Clonopin, and Lioresal. She noted no subjective change in her complaints of blurred and double vision on any of these medications. She returned on August 12, 1980, and reported that she was spontaneously improving and that during the preceding 10 days, at times she had no double vision at all. The right hypertropia was now down to only 4 diopters, and the left hypertropia was less than 1 diopter. Only the dissociated downbeat nystagmus, greater in left eye, on left gaze remained. It was thought that this improvement was consistent with the clinical impression of a focal mesencephalic softening which had occurred 3 months earlier. However, the patient returned on August 26, 1980, and stated that 3 days earlier she had developed a headache and noted an abrupt worsening of her vision which had persisted since. Corrected acuity was 20/15-2 in her right eye and 20/30+2 in the left eye. The periodic alternating skew deviation had worsened since the previous follow-up, and the right hypertropia phase was now up to 11 diopters and the left hypertropia was as large as 6 diopters. Slight ptosis was present on the left. The pupils, fields, and discs were unchanged. Her blood pressure was 140/78. The downbeat nystagmus in left gaze was greater in amplitude than when seen 2 weeks earlier. It was thought that the patient's vertebrobasilar insufficiency was still clinically active, and she was referred to her internist for a course of anticoagulant therapy. Discussion Skew deviation is a vertical divergence of the eyes seen with posterior fossa lesions. I It has been classically associated with lesions of the brachium 6 pontls, but also has been described with k medulla, pons, and midbrain. I - 6 " Alternal w deviation" is a noncomitant fonn of skew . lion in which the right eye is hypertropic in 01 .,dd of gaze while the left eye is hypertropic in another field' of gaze.t . 4 "Paroxysmal skew deviation" is an intermittent variety of skew deviation that has been described with gliomas7and ischemia.3. 8 However, skew deviation with the cyclic or periodic variations seen in our patient has not been previously reported in the literature. . Ocular motility disorders that cycle over a penod of minutes include periodic alternating nystagmus,!! periodic alternating gaze deviation, to and cyclic oculomotor paralysisll . Periodic alternating nystagmus is an acquired horizontal jerk nystagmus in which the rapid phase is directed to the right for a period of 1-2 minutes, at which time the amplitude of nystagmus gradually decreases, and the rapid phase then changes to the left for about the same period of time. It has occasionally been associated with downbeat nystagmus,12 and lesions in the caudal brain stem have been demonstrated at autopsy.13 Periodic alternating gaze deviation lO is a rare gaze disturbance in which the eyes tonically deviate to the right for 1-3 minutes, and then slowly move into left gaze for 1-3 minutes with a cross-over time of 10-20 seconds. No pathologic documentation is available for this abnonnality, but the lesion is thought to be in the brain stem. to. 14 "Ping-pong" gaze is a tenn used to describe another fonn of periodic alternating gaze deviation. 15 In "pingpong" gaze the eyes briefly deviate far to the right, and then rapidly reverse direction and deviate conjugately to the left, with a periodicity of only several seconds. This disturbance has been described with cerebellarl5 and bilateral cerebral disease. 16 Periodic alternating gaze deviation is a horizontal alternating deviation, whereas the case was describe is a vertical alternating gaze disturbance. Cyclic oculomotor paralysis with cyclic spasmII. 20 is a disorder of the III nerve usually apparent at birth or shortly thereafter. It is characterized by oculomotor paresis, upon which superimposed oculomotor spasms occur at approximately 9O-second intervals. During the spasm, which usually lasts less than 30 seconds, the lid elevates, the pupil constricts, and the eye adducts. This spastic phase is followed by a paretic phase in which the eye returns to its abducted position with a ptotic lid and dilated pupil. Seesaw nystagmus17 is a torsional nystagmus with a disconjugate vertical vector from which it derives its name. It is thought to result from a lesion in the pathways between the caudal diencephalon and interstitial nucleus of Cajal, and Daroff'" pointed to the zona incerta as the location of the disturbance producing seesaw movements. Although our case did not have a significant torsional Journal of Clinical Neuro-ophthalmology component, and tilting of the patient's head to either shoulder produced little if any change in the pattern, the vertical character of our case might be somewhat analogous to a "slow motion" form of seesaw nystagmus. Shortly after encountering our patient, we mentioned her to Dr. Norman Schatz. He brought to our attention a report of three patients which is now in press and which is pertinent to this discussion. Dr. Corbett then kindly sent us a preprint of this paperl9 describing intermittent aperiodic alternating skew deviation. These patients had an unusual slowly alternating skew deviation, and each showed other elements of the sylvian aqueduct syndrome. Pathologic lid retraction, upgaze paresis, and retraction nystagmus were conspicuously absent in our patient. Autopsr examination in one of the cases of Corbett et al. I revealed a lesion in caudal diencephalon extending down toward the interstitial nucleus of Cajal. This observation led us to repeat the computed tomographic scan in our patient, previously reported as negative, with thin resolution cuts, and the smaIl focal midbrain lesion at level of interstitial nucleus of Cajal was then demonstrated. The computed tomographic differential diagnosis of this abnormal low density included neoplasm, multiple sclerosis, central pontine myelonolysis, and infarct. Although a brain stem neoplasm can result in an area of low density, the lack of mass effect on the quadrigeminal plate and interpeduncular cistern mitigated against that diagnosis. In multiple sclerosis, areas of low-density demyelinization are most frequently multiple, and may enhance during periods of acute exacerbation. None of those findings were present in our case. With central pontine myelinolysis, not only would the clinical presentation be entirely different than in our case, but the abnormal low-density area would be most prominent within the pons and not in the mesencephalon. A smaIl infarct of midbrain, then, is the most likely possibility. This explains the lack of mass effect and contrast enhancement, and certainly is most compatible with the abrupt onset of symptoms in an elderly hypertensive patient who gradually improved over the next 3 months, and then had intermittent and abrupt changes thereafter. The relationship of periodic alternating skew deviation to other neuro-ophthalmologic motility patterns is of great interest. One should emphasize that the word "alternating" refers to varying directions of gaze; that "intermittent" refers to variations in time without a recurring pattern; and that "periodic" should be used when the time variations adhere to a reproducible pattern. The differential diagnosis between periodic alternating nystagmus, cyclic oculomotor paralysis, and seesaw nystagmus, as weIl as the other motility entities mentioned, is readily apparent from clinical examination. The patients reported by Corbett et March 1981 Mitchell, Smith, Quencer al.l\I as "intermittent aperiodic alternating skew deviation" were similar in some respects to our patient, but sufficient differences exist to warrant clinical differentiation. One point is that periodicity was striking in our case and was repeatedly confirmed by measurements over 2 days. However, there does appear to be some transition group, for our patient was also seen by Dr. Myles Behrens in New York 6 weeks after we first saw her and the cyclic or periodic phenomenon was decreasing at that time; we confirmed this when we saw her 8 weeks after the first visit and she was spontaneously improving. Another major point, however, was that the patients of Corbett et al. 19 showed other features of the sylvian aqueduct syndrome and indeed other neurologic manifestations, whereas our patient showed no features of the sylvian aqueduct syndrome, had no other complaints but for her eyes when we saw her, and had an essentially normal neurologic examination for her age. Finally, the paper by Corbett et al. 19 gives a very useful table differentiating the clinically important vertical anomalies of the eyes, and also lists skew deviation, seesaw nystagmus, monocular elevation paresis, ocular tilt reaction, dissociated vertical divergence, superior oblique myokymia, ocular counter rolling, and intermittent aperiodic alternating skew deviation. Cyclic oculomotor palsy and periodic alternating skew deviation should be added to this list. References 1. Smith, J.L., David, N.J., and Klintworth, G.: Skew deviation. Neurology 14: 96-105, 1964. 2. Keane, J.R.: Ocular skew deviation. Arch. Neurol. 32: 185-190,1975. 3. Walsh, F.B., and Hoyt, W.E.: Clinical Neuro-ophthalmology (3rd ed.). Williams & Wilkins, Baltimore, 1969, pp. 235-236. 4. Nashold, B.5., Jr., and Seaber, J.H.: Defects of ocular motility after stereotactic midbrain lesions in man. Arch. aphthalmol. 88: 245-248, 1972. 5. Wakusawa, S.: Sylvian aqueduct syndrome and mesencephalic skew deviation. lpn. f. Ophthalmol. 17: 154-165, 1973. 6. Trojanowski, J.Q., and Wray, S.H.: Vertical gaze ophthalmoplegia: Selective paralysis of downgaze. Neurology 30: 605-610, 1980. 7. Allerand, CD.: Paroxysmal skew deviation in association with a brain stem glioma. Neurology 12: 520523, 1962. 8. Fisher, CM.: Some neuro-ophthalmological observations. f. Neurol. Neurosurg. Psychiatry 30: 383392, 1967. 9. Davis, D.G., and Smith, J.L.: Periodic alternating nystagmus. Am. f. aphthalmol. 72: 757-762, 1971. 10. Goldberg, R.R., et al.: Periodic alternating gaze deviation with dissociation of head movement. Arch. aphthalmol. 73: 324-330, 1965. 11. Susac, J.O., and Smith, J.L.: Cyclic oculomotor paralysis. NeuroloKY 24: 24-27, 1974. 7 8 Periodic Alternating Skew Deviation 12. Keane, I.R.: Periodic alternating nystagmus with downward beating nystagmus. Arch. Neural. 30: 399-402, 1974. 13. Towle, P.A., and Romanul, F.: Periodic alternating nyst<lgmus: First p<lthologicdlly studied case. Neurology 20: 498, 1970. 14. Kestenb<lum, A: Clinical Methods ofNeuro-ophtha/mologic EX<lmindtion (2nd ed.) Grune & Stratton, New York, 1961, p. 383. IS. Senelick, R.C: "Ping-pong" gaze. Neurology 26: 532-535, 1976. 16. Stewart, J.D., Kirkham, T.H., <lnd Mithieson, G.: Periodic alternating gaze. Neurology 29: 222-224, 1979. 17. Smith, 1.L., and Mdrk, V.H.: See-saw nystagmus with suprasellar epidermoid tumor. Arch. Or'" mol. 62: 280, 1959. 18. Daroff, R.B.: See-saw nystagmus. Neurolo/" ,5: 874-877, 1965. 19. Corbett, J.J., et .II.: Intermittent aperiodic alt· r .lating skew deviation-Description of a pretectdl syndrome in three patients. Neurology (in press). 20. Loewenfeld, I.E., and Thompson, H.5.: Oculomotor paresis with cyclic spasms. A critical review of the literature and a new case. Surv. Ophthalmol. 20: 81124, 1975. Write for reprints to: J. Lawton Smith, M.D., Bascom Palmer Eye Institute, P.O. Box 016880, Miami, Florida 33101. Journal of Clinical Neuro-ophthalmology |
