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Show Journal of Clinical Neuro- ophtlwlmology 9( 3J: 169- 170, 1989. © 1989 Raven Press. Ltd.• New York Rhythmic Pupillary Oscillations Accompanying a Complete Third- Nerve Palsy James R. Keane, M. D. An automobile accident left a 26- year- old man in stupor with a complete right third- nerve palsy, Although fixed to light, the right pupil ( only) exhibited continual concentric oscillations, initially at 1 Hz but slowing to 0,3 Hz during 2 weeks' observation. The pathophysiologic characteristics of this unique movement are uncertain but may involve central parasympathetic nervous system dysfunction, Key Words: Parasympathetic nervous system- Pupillary oscillations- Third- nerve palsy, From the Department of Neurology, Los Angeles Countyl University of Southern California Medical Center. Los Angeles. California, Address correspondence and reprint requests to Dr. J. R. Keane, 1200 N. State Street, Los Angeles, CA 90033, U. s. A. This work was presented in part at the 1988 Internahonal Neuro- ophthalmology Congress, Vancouver, British Columbia, Canada. 169 The pupil normally exhibits continual, small, symmetric contractions, usually inapparent to the casual observer. Exaggeration of such pupillary unrest, sometimes called hippus, is a common and normal variation ( 1), The following case is unique in that dramatic, unilateral pupillary contractions, resembling very exaggerated pupillary unrest, occurred solely in an eye with a complete pupil- fixed- to- light thirdnerve palsy. CASE REPORT A 26- year- old man was found unconscious and in shock with fixed dilated pupils at the scene of an automobile accident. He was promptly resuscitated, and while his left pupil soon became reactive, the right pupil remained fixed to light. Two days after his injury, he was transferred to the Los Angeles County/ University of Southern California Medical Center. On admission, he was stuporous, febrile ( l03° F), and had complete paralysis of the right third nerve. His right pupil was 7 mm in diameter and fixed to light, whereas the left pupil was 4 mm and reacted briskly, Movements of the left eye were full; movement of the right eye was limited to full abduction. Visual acuity was symmetric in each eye at a distance but blurred at near in the right eye, Colors were perceived as equally saturated in both eyes and in both right and left visual fields, and visual fields were full to confrontation. No afferent pupillary defect was present. On admission, dramatic rhythmic concentric contractions of the right iris at a rate of lis were apparent. Pupillary constriction was clearly brisker than dilatation, and the movements ( recorded on serial motion pictures) were continuous and even persisted during sleep. The normal left pupil, on numerous observations using ophthalmoscopic 170 f. R. KEANE ------_._-------- DISCUSSION TABLE 1. Periodic pupillary phenomena magnification, did not partICIpate in the contractions. The pupil oscillations continued without interruption, gradually decreasing in frequency to 20/ min at the time of discharge. A computed axial tomography ( CAT) scan ( EMI 1010) was normal. A lumbar puncture, performed to evaluate his fever, showed hemorrhagic meningitis, probably sterile. He was discharged 2 weeks after the accident, still showing moderate confusion and a complete right third- nerve palsy with a continually oscillating pupil. He failed to return for outpatient follow- up observation, and attempts to locate him during the succeeding 9 years have been unavailing. L Thompson HS, Franceschetti AT, Thompson MT. Hippus, semantic and historic considerations of the word. Am IOphthalmol 1971; 71: 1116- 20. 2, Loewenfeld IR, Thompson HS. Oculomotor paresis with cyclic spasms, A critical review of the literature and a new case. Sun' 0l'hthalmol 1975; 20: 80- 124. 3, Shults WT, Hoyt WF, Behrens M, MacLean J, Saul RF, Corbett JJ, Ocular neuromyotonia, a clinical description of six patients. Arch 0l'hthallllt)/ 1986; 104: 1028- 34. 4. Lessell 5, Lessell 1M, Rizzo JF III. Ocular neuromyotonia after radiation therapy. Am J 0l'hthalmoI1986; 102: 766- 70. 5, Hallet M, Cogan DC. Episodic unilateral mydriasis in otherwise normal patients. Arch Ophthalmo/ 1970; 84: 13D- 6, 6, Lowl'nstein 0, Levine AS. Pupillographic studies. V. Peri · odic sympathetic spasm and relaxation and role of sympa · thetic nervous system in pupillary innervation. Arch Oph · thalmtl/ 1944; 31: 74- 94. 7. Thompson HS, Zackon DH, Czarnecki JSc. Tadpole · shaped pupils caused by segmental spasm of the iris dilator muscle. Alii J Ophthalmol 1983; 96: 467- 77. REFERENCES probably always begins within the 1st year of life. Neuromyotonia refers to involuntary, intermittent innervation of elements of a damaged ( most often by radiation) peripheral third nerve. This may Occur spontaneously or be induced by eye movement ( usually downward) ( 3,4). Again, this movement is not rhythmic, and a single episode lasts from 10 to 180 s. A third category of intermittent pupillary sphincter involvement, less well characterized and sometimes associated with migraine, is intermittent mydriasis. These highly variable episodes last minutes to weeks and probably encompass several clinical entities ( 5). Intermittent sympathetic nervous system pupillary abnormalities include cyclic sympathetic spasm ( 6) with concentric dilatation lasting 40- 60 s and " tadpole pupils," ( 7) in which the spasm is sectorial and persists about 60 s on average. None of these phenomena resemble the rhythmic pupil contractions of our patient. In his case, the quickness of contractions and the underlying third- nerve palsy suggest parasympathetic mediation of the pupil oscillations. The rhythmic quality and the dissociation of the transmitted oscillations and the blocked light reflex indicate an element of midbrain tegmental damage. Most likely, head trauma caused third- nerve traction that damaged the root entry zone as well as the ipsilateral midbrain tegmentum near the third- nerve nucleus. However, the absence of CAT scan abnormalities and follow- up observation and a lack of similar published cases mean that the physiologic characteristics of this unusual pupillary activity remain highly speculative. 6 7 2 3,4 5 Phenomena Reference Parasympathetic mediation cyclic oculomotor palsy neuromyotonia intermittent mydriasis Sympathetic mediation cyclic oculomotor spasm tadpole pupils Quicker contraction phases of this patient's pupillary movements suggest that the parasympathetically mediated pupillary sphincter was the active participant. The continuous rhythmic pupil movement implies a central pacemaker, presumably the same oscillation that drives normal pupillary unrest. Such movements were apparently amplified in the affected pupil and blocked from the opposite side. Absence of a pupillary efferent light response on the affected side requires an interruption of the light reflex arc while allowing transmission of the rhythmic oscillations. This unlikely sequence of events is postulated in the context of an isolated, seemingly peripheral third- nerve palsy without central nervous system long- tract findings or CAT scan abnormalities. Periodic pupillary movements are rare and little understood. Previously described movements have been intermittent rather than rhythmic, and I am unaware of previous reports of cases similar to this. Some periodic pupillary phenomena are listed in Table 1. The best known of periodic pupil contractions is cyclic oculomotor palsy ( 2). The pupil is always prominent in this intermittent innervation of a partially damaged third nerve, and in one patient, only the pupil was involved. These contractions are slow ( from 20 to 210 s), and the condition JClin Neuro- ophthalmol, Vol. 9, No, 3, 1989 |
