Journal of Neuro-Ophthalmology, June 1983, Volume 3, Issue 2

Periodic alternating nystagmus associated with periodic alternating skew deviation.

A 34-year-old man had both periodic alternating nystagmus and periodic alternating skew deviation. Neurologic examination and cranial computed tomography supported the diagnosis of cerebellar degeneration. Pathophysiologic mechanisms of these motility disturbances are discussed briefly. To our knowledge these two unusual eye movement abnormalities have not been reported previously in the same patient.

]. Clin. Neuro-ophthalrnol. 3: 115-117, 1983. Periodic Alternating Nystagmus Associated with Periodic Alternating Skew Deviation JAMES M. LEWIS, MD. LANNING B. KLINE, MD. Abstract A 34-year-old man had both periodic alternating nys­tagmus and periodic alternating skew deviation. Neu­rologic examination and cranial computed tomogra­phy supported the diagnosis of cerebellar degenera­tion. Pathophysiologic mechanisms of these motility disturbances are discussed briefly. To our knowledge these two unusual eye movement abnormalities have not been reported previously in the same patient. Periodic alternating nystagmus is a rare eye movement disorder in which spontaneous nystag­mus alternates in direction. It has been documented in four clinical settings: cerebellovestibular disease, severe bilateral visual loss, phenytoin toxicity, and congenitally. '-6 Periodic alternating skew deviation is a cyclic vertical divergence of the eyes which has been reported recently7 In this case, computed tomog­raphy (CT) revealed an area of decreased attenua­tion in the midbrain tegmentum consistent with an infarction. We report a patient who had both of these ocular motility disturbances. To our knowledge, the as­sociation of these disorders has not been described previously in the literature. Case Report A 34-year-old man was referred for evaluation of nystagmus. The patient reported that the nys­tagmus was discovered at age 5, but may have been present since birth. Strabismus procedures were performed at age 14 and 33 years, which neither diminished the nystagmus nor improved an inter­mittent left head tum. In addition, the patient reported increasing clumsiness and difficulty walk­ing for the past 10 years. There was no family history of ophthalmologic or neurologic disease. From the Department of Ophthalmology, Eye Foundation Hospital, University of Alabama School of Medicine, Birming­ham, Alabama. June 1983 Neuro-ophthalmologic testing revealed best-cor­rected vision of 20/300 in the right eye and 20/100 in the left eye. Pupils, color vision, visual fields, slit lamp examination, and fundi were normal. Applanation tensions were 16 mm Hg in each eye. In the primary position, the patient had a 5-prism diopter right esotropia. His periodic alternating nystagmus was characterized as follows: right beat­ing for 87 seconds gradually increasing and then decreasing in amplitude; 3-5 seconds of upbeat nystagmus; left beating nystagmus for 159 seconds gradually increasing and then decreasing in ampli­tude; and 3-5 seconds of upbeat nystagmus. The period was, therefore, approximately 256 seconds. The amplitude of the nystagmus increased with gaze in the direction of the fast component; gaze away decreased it. In addition, the patient had an alternating skew deviation such that during the phase of right beating nystagmus, he had a 30­prism diopter right hypertropia; during the phase of left beating nystagmus, he had a 45-prism diop­ters left hypertropia (Figs. la and Ib ). During the 5-second transition period of upbeat nystagmus, the patient had only a right esotropia. Extraocular movements were full throughout all phases and the vertical deviation was comitant during both the right hypertropia and left hypertropia cycles. Pre­ferring fixation with the left eye, on occasion the patient developed a left head tum during the left beating phase of his periodic alternating nystag­mus. At no time was the patient aware of diplopia or oscillopsia. Neurologic examination demonstrated mild dif­ficulty with finger-to-nose testing, and moderate truncal ataxia with a broad-based gait. Romberg's sign was negative. Cranial nerves, motor strength, sensory testing, and reflexes were all within normal limits. Plantar responses were flexor bilaterally. Cerebrospinal fluid analysis was unremarkable with normal IgG quantitation (9% of total protein) and no oligoclonal banding. Auditory and soma­tosensory evoked potentials were within normal limits. Cranial CT scanning, with detailed exami­nation of the posterior fossa, revealed mild cere­bellar atrophy (Fig. 2). The patient was treated with 115 Periodic Alternating Nystagmus ,(ot) Figures la and lb. Periodic alternating skew deviation during cycles of (a) left and (b) right hypertropia. Figure 2. Cranial CT scan demonstrates mild cerebellar atrophy with prominence of the cerebellar folia. courses of Valium, Dilantin, and Lioresal with no improvement in either eye movement abnormality. Discussion Periodic alternating nystagmus is a form of hor­izontal or horizontal-rotary jerk-type nystagmus which undergoes cyclic changes in amplitude and direction. Typically, each cycle lasts for 60-180 seconds, and between the right beating and left beating phases, there is a 5-15-second period dur­ing which the eyes remain steady. I, .3, 4, 6 Rarely, during this transition phase, upbeat or downbeat nystagmus has been observed and in one report periodic alternating nystagmus was combined with both upbeat and downbeat nystagmus (alternating windmill nystagmus),6, 8 Patients with periodic al­ternating nystagmus mayor may not have symp­toms of oscillopsia, blurred vision, unsteadiness, 116 or vertigo. Periodic alternating nystagm,us has be,en reported with other eye movement, disorders .m­cluding rebound nystagmus and penod alternatmg gaze,.3,9 It has been proposed that periodic, al~e~­nating nystagmus results from damage to mhlbl­tory projections from the archicerebellum to the vestibular nuclei, Alternating hyperexcitability of the vestibular nuclei on either side of the brainstem could produce a periodic shift of the null region as proposed by Daroff and Dell'Osso,1O Lioresal has been reported to abolish acquired periodic alter­nating nystagmus but has not been found effective in the congenital form,u, 12 Skew deviation is defined as any vertical diver­gence of the eyes due to disruption of supranuclear or vestibulo-ocular pathways.l.3 While signifying brain stem or cerebellar disease, skew deviation has no further localizing value. 14 The deviation may be comitant, laterally comitant, or noncomi­tant. "Alternating" has been applied to skew de­viation in describing three different motility dis­turbances, A noncomitant form of skew deviation has been termed alternating skew deviation, in which the hypertropia alternates on gaze to either side. 15 Slow alternating skew deviation appears to be a distinctive disorder in which one eye falls as the other rises. 16 Change in eye position takes 10-30 seconds and the new position is maintained for 30­60 seconds. It is accompanied by rotary nystagmus and elements of the dorsal midbrain syndrome. Postmortem examination in one patient revealed a lesion in the caudal diencephalon with extensive demyelination and periaqueductal spongiform de­generation. There was preservation of the vestib­ular nuclei, medial longitudinal fasciculi, oculo­motor and trochlear nuclei, and interstitial nuclei of Caja\. Periodic alternating skew deviation was reported in 1981 by Mitchell et a\.7 A 78-year-old hyperten­sive woman suddenly developed blurred vision, followed by dizziness, difficulty walking and with a tendency to veer to the left, and vertical diplopia. Examination 3 weeks later revealed the following motility pattern: for 4-5 minutes, the patient had a large right hypertropia of over 25-prism diopters. The eyes rapidly went through a transition phase lasting approximately 10 seconds during which she was orthophoric. This was followed by the appear­ance of a left hypertropia of 8-prism diopters which Journal of Clinical Neuro-ophthalmology lasted 40-50 seconds. The cycle would then recur regularly. Versions were full throughout all phases and the deviation was comitant in both right and left hypertropia cycles. Cranial CT demonstrated an area compatible with an infarction at the level of the interstitial nucleus of Cajal. Therapeutic trial with various medications including Tegretol, Di­Iantin, Clonopin, and Lioresal had no effect on the periodic alternating skew deviation. Our patient is instructive for many reasons. First, periodic alternating nystagmus is uncommon and, therefore, may be missed clinically, as it was in our patient. Surgery is of no benefit in this type of congenital nystagmus. Second, to our knowledge there is only one previous report of upbeat nystag­mus occurring during the transition phase of pe­riodic alternating nystagmus 6 This occurred in a 54-year-old man with acquired periodic alternating nystagmus secondary to dense, bilateral vitreous hemorrhages. The vitreous hemorrhages were part of the patient's Terson's syndrome and the periodic alternating nystagmus resolved following bilateral vitrectomy. Third, this is the first instance of an association between periodic alternating nystag­mus and periodic alternating skew deviation. Whatever pathophysiologic mechanism is involved in these two eye movement disorders, in our pa­tient they were linked by a common "biologic clock." During the phase of right beating nystag­mus, the patient had a right hypertropia; during the phase of left beating nystagmus he had a left hypertropia. Fourth, our patient's periodic alter­nating nystagmus did not respond to Lioresal and this medication had no effect on his periodic alter­nating skew deviation. In our case, neurologic and CT findings would support the diagnosis of cerebellar degeneration. Presumably, our patient has involvement of cere­bellovestibular inhibitory pathways allowing si­multaneous expression of two unusual periodic eye movement abnormalities. References 1. Davis, D.G., and Smith, J.L Periodic alternating nystagmus. Am. J. Ophthalmol. 72: 757-762, 1971. June 1983 Lewis, Kline 2. Towle, P.A., and Romanul, F.: Periodic alternating nystagmus: First pathologically studied case. Neu­rology 20: 408, 1970. 3. Baloh, R.W., Honrubia, V., and Konrad, H.K.: Pe­riodic alternating nystagmus. Brain 99: 11-26, 1976. 4. Daroff, R.B., Troost, B.T., and Dell'Osso, L.F.: Nys­tagmus and related ocular oscillations. In Neuro­ophthalmology, J.5. Glaser, Ed. Harper & Row, Hag­erstown, Maryland, 1978, pp. 231-232. 5. Campbell, W.W.: Periodic alternating nystagmus in phenytoin intoxication. Arch. Neurol. 37: 178-180, 1980. 6. Cross, S.A., Smith, J.L., and Norton, E.WD.: Pe­riodic alternating nystagmus clearing after vitrec­tomy. J. Clin. Neuro-ophthalmol. 2: 5-11, 1982. 7. Mitchell, J.M., Smith, J.L., and Quencher, R.M.: Periodic alternating skew deviation. /. Clin. Neuro­ophthalmol. 1: 5-8, 1981. 8. Saunders, MD.: Alternating windmill nystagmus. In Neuro-ophtha/mology Symposium of The Univer­sity of Miami and The Bascom Palmer Eye Institute, Vol. 7, J.L. Smith and JS. Glaser, Eds C. V Mosby, St. Louis, 1973, pp. 133-136. 9. Kennard, c., Barger, G., and Hoyt, W.F.: The asso­ciation of periodic alternating nystagmus with pe­riodic alternating gaze. /. Clin. Neuro-ophthalmol. 1: 191-193, 1981. 10. Daroff, RD., Dell'Osso, L.F.: Periodic alternating nystagmus and the shifting null. Can. /. Otolaryngol. 3: 367-371, 1974. 11. Halmagyi, G.M., Rudge, P., Gresty, M.A., Leigh, R.J., and Zee, D.5.: Treatment of periodic alternating nystagmus. Ann. Neurol. 8: 609-611, 1980. 12. Plant, G.T.: Periodic alternating nystagmus in a case of hereditary ataxia and its treatment with baclofen. J. Neurol. Neurosurg. Psychiatry 45: 937-938, 1982. 13. Smith, J.L., David, N.j., and Klintworth, G.: Skew deviation. Neurology 14: 96-105, 1964. 14. Keane, J.R.: Ocular skew deviation. Arch. Neurol. 32: 185-190, 1975. IS. Keane, J.R.: Alternating skew deviation. Neurology 32: A96, 1982. 16. Corbett,).J., Schatz, N.J., Shults, W.T., Behrens, M., and Berry, R.G.: Slowly alternating skew deviation: Description of a pretectal syndrome in three pa­tients. Ann. Neurol. 10: 540-546, 1981. Write for reprints to: L.B. Kline, MD., 1720 University Boulevard, Birmingham, Alabama 35233. 117