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![▪ Nystagmus characteristics may change with gaze direction.
▪ Pendular nystagmus can become jerk nystagmus on side gaze.
▪ Jerk nystagmus can have a null point or null zone (gaze position in
which the intensity [frequency × amplitude] is diminished and the vision
improves), or it can decrease in intensity with gaze in the direction
opposite that of the fast-phase component.
▪ The abnormal head position that patients assume in order to reduce
nystagmus can be the most prominent manifestation of their condition.](https://image.slidesharecdn.com/far-childhoodnystagmus-241017054842-22052b74/75/Childhood-Nystagmus-AAO-Pediatric-and-Strabismus-5-2048.jpg)
Childhood Nystagmus AAO Pediatric and Strabismus
- 1. CHILDHOOD NYSTAGMUS Faradhillah A.Suryadi AAO READING SUBDIVISI PO 17-09-2024 Pembimbing : dr. Ratih Natasha Maharani, Sp.M(K), M.Kes
- 2. HIGHLIGHTS • Nystagmus isa sign, not a diagnosis, and requires an evaluation for the underlying cause. • Childhood nystagmus is often associated with visual sensory defects but can also result from neurologic abnormalities. • Treatment options for some forms of nystagmus include the use of prisms or eye muscle surgery.
- 3. INTRODUCTION Nystagmus is aninvoluntary, rhythmic oscillation of the eyes. It is a sign, not a diagnosis, and requires an evaluation. Nystagmus can be related to: • instability in the damping portion of the smooth pursuit system, which can be due to a motor defect that is compatible with relatively good vision • an ocular abnormality that is associated with poor vision or fusion • a neurologic abnormality
- 4. GENERAL FEATURES ▪ Theplane of nystagmus can be horizontal, vertical, torsional, or a combination of these. ▪ The condition is often characterized as either jerk nystagmus,which has a slow and a fast component, or pendular nystagmus,in which the eyes oscillate with equal velocity in each direction. ▪ Jerk nystagmus is described by the direction of its fast-phase component; for example, a right jerk nystagmus consists of a slow movement to the left, followed by a fast movement (jerk) to the right. Nystagmus is conjugate when its direction, frequency, and amplitude are the same in both eyes.
- 5. ▪ Nystagmus characteristicsmay change with gaze direction. ▪ Pendular nystagmus can become jerk nystagmus on side gaze. ▪ Jerk nystagmus can have a null point or null zone (gaze position in which the intensity [frequency × amplitude] is diminished and the vision improves), or it can decrease in intensity with gaze in the direction opposite that of the fast-phase component. ▪ The abnormal head position that patients assume in order to reduce nystagmus can be the most prominent manifestation of their condition.
- 6. TYPES OF CHILDHOODNYSTAGMUS INFANTILE NYSTAGMUS SYNDROME (INS) ➢binocular, conjugate nystagmus with several distinctive features ➢related to visual sensory defects or idiopathic ➢often recognized in the first few months of life ➢uniplanar and most often horizontal ➢When INS has a jerk waveform, it shows an exponential increase in velocity during the slow phase ➢A null point may be present, with a change in the direction of the nystagmus to the right or the left of the null point
- 7. ➢If the nullpoint is not in primary position, the patient may adopt an abnormal head position to improve vision by placing the eyes near the null point.This head position becomes more pronounced as the child approaches school age. ➢Head bobbing or movement may be present initially but commonly decreases with age if there is no progressive visual deficit.
- 11. ▪ INS worsenswith fixation and may worsen with illness or fatigue. ▪ Convergence damps (reduces the intensity of) the nystagmus.Thus, near visual acuity is often better than distance acuity in these patients. ▪ Children with INS overconverge to damp the nystagmus (nystagmus blockage syndrome), resulting in esotropia. ▪ INS can be confused with nystagmus blockage syndrome in which esotropia and nystagmus happen to coexist. ▪ Patients with this condition characteristically present with an esotropia that “eats up prism” as the strabismic deviation increases upon attempted measurement, and with nystagmus that is least apparent when the deviation is largest.
- 12. ▪ Approximately two-thirdsof INS patients exhibit a paradoxical inversion of the optokinetic nystagmus (OKN) response. ▪ Typically, when a patient with right jerk nystagmus views an optokinetic drum rotating to the patient’s left, the intensity of the right jerk nystagmus increases. ▪ The waveform is identical in INS whether it is related to visual sensory defects or is idiopathic. Given that the visual behavior of an infant with a central scotoma is not that different from that of an infant with normal visual acuity, all cases of INS should be presumed to be related to sensory issues and deserve a workup.
- 13. INS WITH VISUALSENSORY DEFECTS ▪ INS with visual sensory defects is associated with an early-onset, bilateral abnormality of the pregeniculate afferent visual pathway. ▪ Inadequate retinal image formation interferes with the normal development of the fixation reflex. ▪ If the visual deficit is present at birth, the resulting nystagmus becomes apparent in the first 3 months of life. ▪ Its severity is somewhat correlated with the degree of vision loss.The waveform of sensory nystagmus can be pendular or jerk.
- 14. ▪ Searching, slow,or wandering conjugate eye movements may also be observed ▪ Searching nystagmus is usually seen in children whose visual acuity is worse than 20/200 ▪ Pendular nystagmus typically occurs in patients with visual acuity better than 20/200 in at least 1 eye ▪ Jerk nystagmus is often associated with visual acuity between 20/60 and 20/100
- 16. IDIOPATHIC INFANTILE NYSTAGMUS(IIS) ▪ Idiopathic infantile nystagmus (IIS) is a form of INS that is not associated with visual dysfunction. ▪ Because the nystagmus waveform and clinical examination are almost identical to those of INS with visual sensory deficit, IIS should be considered a diagnosis of exclusion. ▪ Genetic testing for the gene FRMD7 can be performed to evaluate for X- linked INS, which can be mistaken for IIS.
- 17. CENTRAL VESTIBULAR INSTABILITYNYSTAGMUS ▪ Central vestibular instability nystagmus (also called periodic alternating nystagmus; PAN) is an unusual form of jerk nystagmus that can be congenital or acquired (the latter especially in those with cerebellar abnormalities or Arnold- Chiari malformation). ▪ The nystagmus periodically changes direction due to a shifting null point. ▪ The cycle begins with a typical jerk nystagmus, which slowly damps; this leads to a 10- to 20-second period of no nystagmus, followed by jerk nystagmus in the opposite direction.The cycle repeats every few minutes. ▪ Some children adopt an alternating head turn to take advantage of the changing null point.
- 19. FUSION MALDEVELOPMENT NYSTAGMUS SYNDROME(FMNS) ▪ Conjugate, horizontal jerk nystagmus and a marker of fusion maldevelopment, which occurs as a result of infantile-onset strabismus or decreased vision in 1 eye. ▪ When either eye is occluded, a conjugate jerk nystagmus develops.The fast- phase component is directed toward the uncovered eye: left jerk nystagmus occurs upon covering the right eye, and right jerk nystagmus upon covering the left.This is the only nystagmus that reverses direction depending on which eye is fixating.The nystagmus damps when the fixating eye is in adduction, so the preferred head turn also reverses direction with change of fixation (Fig 12-2). ▪ Amplitude, frequency, and velocity of the nystagmus can also vary depending on which eye is fixating.
- 21. ▪ Fusion orbinocular viewing damps FMNS, and disruption of fusion increases it. ▪ FMNS may manifest even when both eyes are open if only 1 eye is being used for viewing (eg, the other eye is suppressed or amblyopic). ▪ Electronystagmographic evaluation of both fully latent and manifest forms of FMNS shows similar waveforms, with a slow phase of constant or exponentially decreasing velocity. ▪ Like other hallmarks of infantile strabismus with which it is associated, FMNS becomes more prominent with age.
- 22. ACQUIRED NYSTAGMUS SPASMUS NUTANSSYNDROME ➢ idiopathic acquired nystagmus that manifests during the first 2 years of life, presenting as a triad of generally small-amplitude, high-frequency (“shimmering”), dysconjugate nystagmus; head nodding; and torticollis. ➢ The nystagmus is binocular but often asymmetric, sometimes appearing to be monocular. ➢ The plane of the nystagmus can be horizontal, vertical, or torsional; the nystagmus can vary with gaze position, and it is occasionally intermittent. ➢ The head nodding and torticollis appear to be compensatory movements that maximize vision.Typically, the abnormal head and eye movements diminish by 3–4 years of age. ➢ Spasmus nutans syndrome is a benign disorder in most cases, but there is a high incidence of associated strabismus, amblyopia, and developmental delay.
- 23. ▪ Spasmus nutans–likenystagmus has been seen with chiasmal or suprachiasmal tumors, hypomyelinating leukodystrophies (eg, Pelizaeus-Merzbacher disease) and retinal dystrophies such as cone dystrophy with supranormal rod response. ▪ Because the retina can appear normal despite abnormal function, electroretinography is part of the diagnostic evaluation. ▪ Neuroradiologic investigation is warranted when there is any evidence of optic nerve dysfunction or any sign of neurologic abnormality.
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- 25. SEE-SAW NYSTAGMUS ▪ Unusualbut dramatic type of dysconjugate nystagmus that has both vertical and torsional components. ▪ If the 2 eyes are envisioned as being placed on an imaginary see-saw, 1 at either end, they “roll down the plank” as 1 end of the see-saw rises, with the high eye intorting and the low eye extorting. As the direction of the see-saw changes, so does that of the eye movement. Thus, the eyes make alternating movements of elevation and intorsion, followed by depression and extorsion. ▪ Often associated with rostral midbrain or suprasellar lesions, most often craniopharyngioma in children. ▪ Confrontation visual field testing may elicit a bitemporal defect. ▪ Neuroradiologic evaluation is necessary. ▪ A congenital form of see-saw nystagmus can be seen in disorders of decussation (usually associated with optic nerve hypoplasia and temporal visual field defects), such as those sometimes seen in Joubert syndrome.
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- 27. VERTICAL NYSTAGMUS ▪ Verticalnystagmus is uncommon. ▪ Congenital vertical nystagmus, often upbeat, can occur in infants with inherited retinal dystrophies (Video 12-6). ▪ Downbeat nystagmus (Video 12-7) can be part of a neurologic ataxia syndrome. ▪ When vertical nystagmus is acquired and associated ocular sensory defect has been ruled out, neurological workup is indicated, including investigation of structural abnormalities such as Arnold-Chiari malformations. ▪ Acquired vertical nystagmus can also be related to medications such as codeine, lithium, anxiolytics, and anticonvulsants.
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- 29. MONOCULAR NYSTAGMUS ▪ Monocularnystagmus has been reported to occur in severely amblyopic or blind eyes (Heimann- Bielschowsky phenomenon). ▪ The oscillations are pendular, chiefly vertical, slow, variable in amplitude, and irregular in frequency. https://www.youtube.com/watch?v=sbIYw4UZLlY
- 30. EVALUATION HISTORY ▪ Questions aboutthe pregnancy and birth because factors such as intrauterine exposure to infection, maternal use of drugs or alcohol, prematurity, and other prenatal or perinatal events can affect development of the visual system and contribute to nystagmus. Family history may aid diagnosis and provide prognostic information; many potential causes of INS are inherited. ▪ For children older than 3 months, parental observations regarding head tilts, head movements, gaze preference, and viewing distances can aid in functional assessment.
- 31. EVALUATION OCULAR EXAMINATION Visual acuity ▪The level of visual function does not help determine the cause of the nystagmus, especially in an infant. INS with visual sensory defects such as an isolated central scotoma can behave exactly like IIS. ▪ Because monocular occlusion can increase nystagmus intensity, particularly in cases of FMNS, monocular acuity should be tested with at least 1 of the following: • fogging, either with a fogging occluder, using >+5.00 diopters greater than the refractive error, or with translucent tape placed over the patient’s prescription glasses over the nontested eye) • polarizing lenses with a polarized chart • an occluder positioned several inches in front of the nontested eye
- 32. ▪ Binocular visualacuity is often better than monocular acuity and should be measured at distance and near fixation, with any desired head position permitted, to assess the child’s true functional vision. ▪ Near visual acuity is usually better than distance. Children with a distance acuity below 20/400 can sometimes read as well as at the 20/40 to 20/60 level at near fixation. ▪ In preverbal children, the optokinetic drum can be used to estimate visual acuity. If vertical rotation of an optokinetic drum elicits a vertical nystagmus superimposed on the child’s underlying nystagmus, the visual acuity is usually 20/400 or better. ▪ Preferential looking tests such as Teller Acuity Cards II can also be used; in patients with horizontal nystagmus, the responses can be more easily assessed with the cards held vertically.
- 33. Pupils ➢ Sluggish orabsent responses to light, or a relative afferent pupillary defect in asymmetric cases, indicate a bilateral anterior visual pathway abnormality such as optic nerve or retinal dysfunction. However, normal responses can be seen with some sensory abnormalities such as foveal hypoplasia and achromatopsia. ➢ The normal response to darkness is the immediate dilation of the pupil. If, instead of dilating, the pupils paradoxically constrict, optic nerve or retinal disease may be present.To test for a paradoxical pupil, the clinician can use a retinoscope from a distance to see the red reflex while turning the room light on and off.
- 34. Ocular motility ➢Nystagmus maybe associated with strabismus for a variety of reasons. ➢Early-onset strabismus may cause FMNS; convergence may be used to damp nystagmus; or poor vision may be the underlying cause of both the nystagmus and the strabismus.
- 35. Fundus ▪ Optic nervehypoplasia and foveal hypoplasia are common causes of congenital sensory nystagmus that may be diagnosed on fundus examination. ▪ Some types of retinal dystrophy may present with vascular attenuation or optic nerve head pallor; however, the fundus typically appears normal in an infant with Leber congenital amaurosis. ▪ If handheld optical coherence tomography is available,it can help the clinician rule out optic atrophy (eg, optic pathway glioma), foveal hypoplasia, or outer retinal changes; if electroretinography is available, it can help rule out Leber congenital amaurosis. ▪ If neither technology is available and vision is normal, genetic testing can reveal FRMD7- associated INS.
- 36. TREATMENT PRISMS ▪ The useof prisms can improve anomalous head positions by shifting the perceived object location toward the null point. ▪ For a patient with a left head turn and a null point in right gaze, the prism held before the right eye should be oriented base-in, and the prism held before the left eye oriented base-out.This shifts the retinal images to the patient’s left and the perceived object location to the right; objects in front of the patient are now imaged on the fovea when the patient is in right gaze, reducing the amount of head turn required to use the null point gaze position.
- 37. ▪ In patientswith binocular fusion, bilateral base-out prisms can improve vision by inducing convergence, which damps nystagmus (amounts are determined by trial and error). ▪ Prisms can be used as the sole treatment of nystagmus or as a trial to predict surgical success.With powers ranging up to 40 prism diopters, Press-On (Fresnel) prisms, inexpensive plastic pieces that can be cut and then applied to glasses, can be used for both purposes. ▪ Ground-in prisms cause less distortion and are preferred for patients who require only small amounts of prism.
- 38. TREATMENT SURGERY ▪ Extraocular musclesurgery for nystagmus may correct a stable anomalous head position by shifting the null point closer to the primary position; this is achieved with medial rectus recession in 1 eye and lateral rectus recession in the other (Anderson procedure) or a recession-resection procedure in both eyes (Kestenbaum procedure). ▪ Surgery can similarly alleviate compensatory head positions in adults with acquired nystagmus. ▪ Bilateral medial rectus recession can treat esotropia resulting from nystagmus blockage syndrome (using larger-than-normal recessions for the amount of esotropia, sometimes in combination with posterior fixation sutures).
- 39. ▪ In aKestenbaum or Anderson procedure, the eyes are rotated toward the direction of the head turn and away from the preferred gaze position, moving both eyes in the same direction. ▪ For patients with INS, a left head turn, and null point in right gaze, the eyes are surgically rotated to the left by recessing the right lateral and left medial rectus muscles and resecting the right medial and left lateral rectus muscles (exotropia surgery for the right eye and esotropia surgery for the left eye). ▪ The right-gaze effort, which damps nystagmus, now brings the eyes from this leftward-rotated position to primary position, instead of from primary position into right gaze; in other words, the null point has been shifted toward the primary position.
- 41. ▪ The totalamount of surgery for each eye (in millimeters) is equal in order to rotate each globe an equal amount. ▪ Nonaugmented numbers are sufficient for head turn that is less than 20°. For head turns of 30°, 40% augmentation is recommended; for turns of 45°, 60% augmentation is used. ▪ Augmentation may restrict motility, but this is usually necessary to achieve a satisfactory result.
- 43. ▪ For nystagmuspatients with strabismus, surgery to shift the null point is performed on the dominant eye; surgery on the nondominant eye is then adjusted to account for the strabismus. ▪ For example, a patient who is right-eye dominant with a right head turn and null point in left gaze would undergo right medial rectus recession and right lateral rectus resection.This would contribute to reducing the angle of an esodeviation or increasing the angle of an exodeviation. Surgery would then be performed on the nonpreferred eye to correct the residual or resultant deviation. Prisms can be used to estimate the target angle.
- 44. ▪ Other typesof nystagmus surgery are less widely practiced.The goal of recession of all 4 horizontal rectus muscles to a position posterior to the equator (8- to 10-mm recessions of medial rectus muscles and 10- to 12-mm recessions of lateral rectus muscles) is to improve vision. ▪ Simple 4-muscle tenotomy, in which the horizontal rectus muscles are disinserted and reattached without recession or resection, has produced similar results, improving recognition time and foveation time on electronystagmography, with modest improvements in visual acuity (approximately 1 line on average).
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- 46. ▪ Similarly, chin-upor chin-down positions may be ameliorated by use of a vertical prism (apex toward the null point) or surgery on vertical rectus or oblique muscles, rotating the eyes away from the preferred gaze position. ▪ For a chin-up, eyes-down position, the inferior rectus muscles are recessed and the superior rectus muscles resected, usually by 8–10 mm in each eye. Alternatively, the surgeon can combine weakening of a vertical rectus muscle and an oblique muscle in each eye. ▪ For a chin-up position, the inferior rectus and superior oblique muscles are weakened; for a chin- down position, the superior rectus and inferior oblique muscles are weakened. ▪ Improvement of head tilt in nystagmus has been reported with torsional surgery involving the oblique muscles or transposition of the vertical or horizontal rectus muscles. ▪ Although surgery for downbeat nystagmus can significantly improve head posture and central vision, it has a lower success rate than does surgery for horizontal nystagmus.