HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shallo–Hoffmann, J. Articles by Tusa, R. J. Search for Related Content PubMed PubMed Citation Articles by Shallo–Hoffmann, J. Articles by Tusa, R. J.

The Incidence and Waveform Characteristics of Periodic Alternating Nystagmus in Congenital Nystagmus

¹ From the MRC Human Movement and Balance Unit, National Hospital, London, United Kingdom; and the ² Bascom Palmer Eye Institute, University of Miami, Florida.

PURPOSE. To investigate the incidence and waveform characteristics of periodic alternating nystagmus (PAN) in congenital nystagmus (CN).

METHODS. In a prospective study, 18 patients with CN without associated sensory defects agreed to undergo eye movement documentation using binocular infrared oculography. Two of the 18 had a diagnosis of suspected PAN before entering the study. The patients sat in a dimly lit room and viewed an LED (4 mm in diameter) located in the primary position, at a distance of 100 cm. During an 8-minute recording, patients were read a story of neutral interest to hold attention at a constant level. PAN was defined as a left-beating nystagmus, a transition phase, a right-beating nystagmus, and a final transition phase; the sequence was then repeated.

RESULTS. Seven of the 18 patients had PAN (median cycle: 223 seconds, range 180–307 seconds). The periodicity of the cycles for each adult patient was regular, although the phases within a cycle were often asymmetric. Six of the seven patients had an anomalous head posture (AHP), and in five the AHP was in only one direction. Except for one patient, the PAN waveforms had an increasing slow-phase velocity in at least one phase of the cycle; in the other phase they were linear.

CONCLUSIONS. The occurrence of PAN in CN is not as rare as previously thought and can be missed because of the long cycles and the use of only one AHP. The AHP was dependent on, and could be predicted from, the waveforms containing the longest foveation times. Although the waveforms and foveation times may differ among the phases of the PAN cycle, the periodicity of the cycle was usually regular and therefore predictable. Identification of PAN is essential in cases in which surgical treatment is considered for correction of AHPs.

This article has been cited by other articles:

				K. M. Cham, A. J. Anderson, and L. A. Abel Factors Influencing the Experience of Oscillopsia in Infantile Nystagmus Syndrome Invest. Ophthalmol. Vis. Sci., August 1, 2008; 49(8): 3424 - 3431. [Abstract] [Full Text] [PDF]

				K. M. Cham, A. J. Anderson, and L. A. Abel Task-Induced Stress and Motivation Decrease Foveation-Period Durations in Infantile Nystagmus Syndrome Invest. Ophthalmol. Vis. Sci., July 1, 2008; 49(7): 2977 - 2984. [Abstract] [Full Text] [PDF]

				D. Wiggins, J. M. Woodhouse, T. H. Margrain, C. M. Harris, and J. T. Erichsen Infantile Nystagmus Adapts to Visual Demand Invest. Ophthalmol. Vis. Sci., May 1, 2007; 48(5): 2089 - 2094. [Abstract] [Full Text] [PDF]

				Y.-Y. Huang, O. Rinner, P. Hedinger, S.-C. Liu, and S. C. F. Neuhauss Oculomotor Instabilities in Zebrafish Mutant belladonna: A Behavioral Model for Congenital Nystagmus Caused by Axonal Misrouting J. Neurosci., September 27, 2006; 26(39): 9873 - 9880. [Abstract] [Full Text] [PDF]

				R V Abadi and A Bjerre Motor and sensory characteristics of infantile nystagmus Br. J. Ophthalmol., October 1, 2002; 86(10): 1152 - 1160. [Abstract] [Full Text] [PDF]