Appendix D: Diagnosis and Treatment Flowcharts

Nystagmus in infancy and childhood outlines the understanding, evaluation, and treatments of nystagmus in infancy and childhood. Aligning this condition with advanced concepts of developmental brain-eye diseases and summarizing novel treatment paradigms, the authors provide an authoritative resource for both clinicians and scientists in the care of infants and children with nystagmus. The chapters comprised here offer valuable coverage in all relevant areas related to nystagmus: algorithms for examination; descriptions of diagnostic techniques; medical, surgical, and alternative treatments of the visual system in infants and children; methodologies for investigation, including analysis software, models of the ocular motor system, and current hypotheses on the pathophysiology of ocular motor oscillations. Unlike earlier works on this topic, emphasis is placed on the motor mechanisms that cause the various types of nystagmus rather than the diagnosis or treatment of the afferent visual deficits that may accompany them. The study of each type of nystagmus using accurate eye-movement recordings serves as the foundation for differential diagnosis and treatment options. Each chapter summarizes the results of ocular motor research in a narrative manner, identifying the important ideas and observations that point to underlying neurophysiological mechanisms. Based on insights from the authors' combined 75 years of clinical experience, Nystagmus in Infancy and Childhood is a valuable clinical reference for ophthalmologists, neurologists, and other specialists in the treatment of this condition.

OUP UNCORRECTED PROOF – REVISES, 09/24/12, NEWGEN appendix d diagnosis and treatment flowcharts D.1 WAVEFORM-BASED DIAGNOSES 288 D.2 THERA PEUTICALLY EXPOITABLE WAVEFORM CHARACTERISTICS 288 D.3 CLINICALLY BASED DIAGNOSES AND LIMITATIONS 288 D.1 WAVEFORM-BASED DIAGNOSES Using eye-movement recordings, accurate, repeatable diagnoses can be made of infantile nystagmus syndrome (INS), fusion maldevelopment nystagmus syndrome (FMNS), the nystagmus blockage syndrome (NBS), the pendular nystagmus of the nucleus of the optic tract (NOT) associated with either INS or FMNS, and the spasmus nutans syndrome (SNS). If none can be identified, the nystagmus will be either vestibular nystagmus (VN) or another type of acquired nystagmus (AN). The flowcharts in this Appendix reflect the differential diagnosis material in Chapter 5 and the therapeutic material in Chapter 7. Using the flowchart in this chapter (Fig. D.1), eye-movement data provide the answers along each path to a nystagmus diagnosis. D.2 THERAPEUTICALLY EXPOITABLE WAVEFORM CHARACTERISTICS Using eye-movement recordings, the therapeutically exploitable characteristics of INS, FMNS, NBS, the pendular nystagmus of the nucleus of the NOT associated with either INS or FMNS, and SNS may be determined. 288 D.4 THERA PEUTICALLY EXPLOITABLE CLINICAL CHARACTERISTICS 288 D.5 ANALYSIS GRA PHS 293 Using the flowchart below (Fig. D.2), eye-movement data provide the answers along each path to a therapeutically appropriate therapy. D.3 CLINICALLY BASED DIAGNOSES AND LIMITATIONS Although it is possible to accurately diagnose and treat some cases of INS or FMNS based on clinical signs and examination alone, other cases the correct diagnosis will be problematic. Using the flowchart in Figure D.3, some diagnoses may be presumed while others remain doubtful. Nystagmus diagnosis from clinical examination alone is highly problematic and may result in the choice of an ineffective therapy. D.4 THERAPEUTICALLY EXPLOITABLE CLINICAL CHARACTERISTICS Some of the INS characteristics may be determined clinically to provide an indication of the therapy best suited for a patient (see Fig. D.4). Unlike the case when using waveform analysis, the improvements resulting from • 13_Hertle_Appendix_D.indd 288 9/24/2012 1:32:59 PM OUP UNCORRECTED PROOF – REVISES, 09/24/12, NEWGEN FIGURE D.1 Flowchart demonstrating how eye-movement data are used to arrive at a repeatable, definitive nystagmus diagnosis. AN, acquired nystagmus; FMNS, fusion maldevelopment nystagmus syndrome; INS, infantile nystagmus syndrome; NBS, nystagmus blockage syndrome; NOT, nucleus of the optic tract; SNS, the spasmus nutans syndrome; VN, vestibular nystagmus. FIGURE D.2 Flowchart demonstrating how eye-movement data are used to determine therapeutically exploitable characteristics of infantile nystagmus syndrome (INS). The relevant therapies may be surgical or nonsurgical. Note that when the eXpanded nystagmus acuity function (NAFX) peak is high and the longest foveation domain (LFD) is broad, their values cannot be significantly increased and, therefore, no waveform foveation improvements are possible; only under these simultaneous conditions is nystagmus therapy precluded. BMR, bimedial recession; m, muscle; Rec, recession; R&R, recess and resect; Strab, strabismus; T&R, tenotomy and reatt achment. Nystagmus in Infancy and Childhood • 289 13_Hertle_Appendix_D.indd 289 9/24/2012 1:33:00 PM OUP UNCORRECTED PROOF – REVISES, 09/24/12, NEWGEN FIGURE D.3 Flowchart demonstrating how clinical observations and tests may be used to arrive at a nystagmus diagnosis. Note that, unlike when using waveform analysis, all paths do not lead to a defi nitive diagnosis and there is no reliable path to acquired nystagmus. AN, acquired nystagmus; FMNS, fusion maldevelopment nystagmus syndrome; INS, infantile nystagmus syndrome; NBS, nystagmus blockage syndrome; SNS, the spasmus nutans syndrome; VN, vestibular nystagmus. FIGURE D.4 Flowchart demonstrating how clinical observations and tests may be used to determine therapeutically exploitable characteristics of infantile nystagmus syndrome (INS). The relevant therapies may be surgical or nonsurgical. Note that when the peak is high and the range of high-visual acuity (Hi VA) gaze angles is broad, their values cannot be significantly increased and, therefore, no waveform foveation improvements are possible; only under these simultaneous conditions is nystagmus therapy precluded. BMR, bimedial recession; m, muscle; Rec, recession; R&R, recess and resect; Strab, strabismus; T&R, tenotomy and reattachment. 290 • DI AGNOSIS A N D TR E ATM ENT FLOWCH A RTS 13_Hertle_Appendix_D.indd 290 9/24/2012 1:33:00 PM OUP UNCORRECTED PROOF – REVISES, 09/24/12, NEWGEN FIGURE D.5 Plot of total millimeters of extraocular muscle surgery (recession plus resection) required to achieve the required amount of null (eXpanded nystagmus acuity function [NAFX] peak) shift ing in infantile nystagmus syndrome. FIGURE D.6 Plot of the estimated postt herapeutic improvement in the eXpanded nystagmus acuity function (NAFX) peak based on the pretherapeutic NAFX peak value. Nystagmus in Infancy and Childhood • 291 13_Hertle_Appendix_D.indd 291 9/24/2012 1:33:01 PM OUP UNCORRECTED PROOF – REVISES, 09/24/12, NEWGEN FIGURE D.7 Plot of the estimated postt herapeutic improvement in the longest foveation domain (LFD) based on the pretherapeutic LFD value. FIGURE D.8 Plot of the eXpanded nystagmus acuity function (NAFX) versus best-corrected visual acuity for patients of different ages. 292 • DI AGNOSIS A N D TR E ATM ENT FLOWCH A RTS 13_Hertle_Appendix_D.indd 292 9/24/2012 1:33:02 PM OUP UNCORRECTED PROOF – REVISES, 09/24/12, NEWGEN the indicated therapies cannot be estimated prior to therapy because acuity measures may not be correlated with INS foveation quality alone. Therapies chosen based solely on clinical observations and tests may not provide improvements in visual function. D.5 ANALYSIS GRAPHS and resections, pretherapeutic estimation of therapeutic improvements, postt herapeutic measurement of therapeutic improvements, and differentiation of the motor and sensory components of visual acuity. Individual work sheets may be copied and printed from the Companion Website (Appendix F, Section F.3) or downloaded from www.omlab.org. The graphs in Figures D.5 through D.8 are useful in the determination of surgical recessions Nystagmus in Infancy and Childhood • 293 13_Hertle_Appendix_D.indd 293 9/24/2012 1:33:05 PM