A case of monocular nystagmus blockage syndrome and manifest-latent nystagmus

A 24-year-old man, left eye enucleated at the age of ten months, had jerk-right nystagmus with increasing amplitude in abduction and null position in near-extreme adduction. Under occlusion or in darkness, the nystagmus changed to jerk-left, the amplitude increased in adduction and null position was in abduction; as if his left eye had nystagmus blockage syndrome and he was seeing with this absent left eye! The difference between nystagmus blockage syndrome and latent nystagmus is discussed: nystagmus blockage syndrome is manifested by 'motor' maneuver of adduction and abduction, whereas latent nystagmus is induced with 'sensory' maneuver of occlusion. It suggests that nystagmus blockage syndrome and latent nystagmus may arise from different mechanisms despite their frequent concurrence.     

眼球震颤阻滞综合征的临床研究

眼球震颤阻滞综合征的特点为内斜视前先有眼球震颤,双侧外展神经假性麻痹以及当注视眼由内转位向外转位运动时,出现显性眼球震颤。本文结合临床资料就其发病率、临床表现、鉴别诊断和手术方法作了简要讨论。     

Pseudo-Monocular Nystagmus Associated with Duane’s Syndrome: Report of Two Cases

Abstract

Purpose: To present clinical findings and eye movement recordings of two children who had clinically apparent monocular nystagmus.

Methods: Full orthoptic and ophthalmological examination and eye movement recordings.

Results: An 8-year-old girl (patient 1) and a 13-month-old girl (patient 2) presented with right monocular nystagmus and right esotropia. A magnetic resonance imaging (MRI) scan of the brain obtained previously had been unremarkable for patient 2. Patient 1 had right amblyopia with visual acuity (VA) reduced to 20/400. Both patients had left abduction deficit and left palpebral fissure narrowing on adduction indicative of Duane’s retraction syndrome. Patient 2 also had mild enophthalmos. Both patients had constant horizontal nystagmus in the right eye and very fine nystagmus in the left eye, which could only be detected on video and eye movement recordings.

Conclusion: The existence of Duane’s syndrome in both patients was masking the presence of nystagmus in the left eye, highlighting that detailed examination in this case can eliminate the need for neuroimaging. Interestingly, the dominant eye of both patients was on the side which was affected by Duane’s syndrome, as there was less nystagmus in this eye.     

One-and-a-half syndrome. Type II: a case with rostral brain stem infarction

This article is about a patient who suddenly developed a right hemiparesis and stupor. Her neuro-ophthalmological examination revealed a left-sided ptosis and a combined vertical gaze palsy in addition to right esotropia, right conjugate gaze palsy, and abduction paralysis of the left eye on attempted gaze to the left with adduction nystagmus of the right eye. The horizontal eye movement disorder was similar to that in one-and-a-half syndrome, except for an abduction paralysis and an adduction nystagmus. MRI showed a rostral brain stem infarction on the left side. Left-sided ptosis and adduction paralysis were attributed to a left oculomotor fascicular involvement in the presence of a right hemiparesis. Right-sided esotropia and abduction paresis were consistent with a ‘pseudo-abducens palsy’, which has been reported in thalamo-mesencephalic lesions. Combined vertical gaze palsy is a classical finding of rostral brain stem infarction. Left-sided abduction paralysis with adduction nystagmus on the right side on attempted gaze to the left is thought to be due to involvement of the para-MLF on the left side and is called internuclear ophthalmoplegia of abduction (INO-abd). To our knowledge, this type of horizontal eye movement disorder has never been reported before with rostral brain stem infarction.     

伴有隐性眼球震颤弱视的遮盖治疗

目的：探讨遮盖疗法对伴有隐性眼球震颤弱视眼视力的治疗效果及眼球震颤的变化。方法：将隐性眼球震颤合并单眼弱视的52例患儿（52只眼），按弱视程度分为轻、中、重三组，采用全部遮盖及部分遮盖方法，每月复查一次视力、眼位、眼底及眼球震颤情况。视力提高到1.0后继续治疗3-6月。结果：52例中视力提高≥2行者48例（国际标准视力表），提高达1.0者22例。无论弱视眼视力提高≥2行，还是提高到1.0，眼球震颤无明显改变。结论：采用遮盖疗法可以提高伴有隐性眼球震颤弱视眼的视力，但视力提高后眼球震颤无明显改变。     

The effect of prolonged monocular occlusion on latent nystagmus in the treatment of amblyopia

We recorded eye movements in 5 patients with latent nystagmus (LN) before and after 2 days of occlusion of the better eye. The slow-phase speed of the nystagmus (SPS) was in general, before occlusion, lower when the better eye fixated but, after occlusion, lower when the worse eye fixated. However, the sum of SPS during right fixation and SPS during left fixation remained constant. Oscillopsia complaints gradually disappeared during the period of occlusion. These findings indicate that the difference between the SPS during fixation with the right eye and the SPS during fixation with the left eye in LN patients is caused by a compensatory drift that decreases LN during fixation with the better eye but increases LN during fixation with the worse eye. During occlusion, this compensatory drift changes its direction and magnitude slowly over days. Hence, occlusion of the better eye in children with amblyopia and LN should be prescribed only in days per week, not in hours per day.     

Nystagmus blockage syndrome in the unilaterally blind patient

Those patients who have reduced vision in one eye and a variable esotropia should be suspected of having the nystagmus blockage syndrome. Typically such patients will have a head turn in the direction of the good eye with a prefered medial fixation point. Careful examination will reveal a nystagmus with the preferred position as the null point. Also, any patient who repeatedly has a recurrent esotropia after surgery should be suspected of having the nystagmus blockage syndrome. It is important to perform a posterior fixation suture with a recession on the medial recti of both eyes and to alter the null point by recessing the medial rectus more than 3 mm and resecting the lateral rectus appropriately for the head turn at the same surgical procedure. The eye with poor vision also should have the lateral rectus resected.     

手术治疗伴有斜视的先天性冲动型眼球震颤

目的探讨先天性冲动型眼球震颤合并斜视的手术治疗方法及效果。方法回顾性分析行手术治疗的先天性冲动型眼球震颤伴有斜视11例,所有患者均根据中间带位置、代偿头位、斜视角度和注视眼的关系进行中间带的移位以及斜视的矫正。结果9例术后代偿头位完全改善,1例术后残留15°面转角,1例残留10°上斜视,所有患者原在位视力均提高两行以上。结论通过中间带移位及斜视度叠加矫正斜视,可以明显改善先天性冲动型眼球震颤的代偿头位及外观,并能提高第一眼位的双眼视力。     

Dissociated vertical deviation in a patient with Duane's retraction syndrome

Dissociated vertical deviation is a not uncommon strabismic syndrome characterized by upward deviation of an eye when occluded, with downward movement of the eye when occlusion is removed. Associated findings include latent nystagmus and horizontal strabismus. Duane's retraction syndrome is the clinical declaration of anomalous cranial nerve innervation characterized by a marked limitation or absence of abduction, variable limitation of adduction, narrowing of the palpebral fissure, and apparent globe retraction on attempted adduction. We report a patient with both dissociated vertical deviation and bilateral Duane's retraction syndrome, demonstrating that dissociated vertical deviation can occur with the anomalous neuroanatomic substrate present in Duane's retraction syndrome.     

Relationships among visual acuity demands, convergence, and nystagmus in patients with manifest/latent nystagmus.

BACKGROUND: We investigated the role convergence plays in nystagmus dampening, in particular, relationships among visual acuity demands, convergence, and nystagmus. Previously we showed that subjects with idiopathic infantile nystagmus exhibit a range of responses to acuity targets, one of which is nystagmus blockage syndrome. We report herein eye movement responses to acuity targets of patients with manifest/latent nystagmus. METHODS: Fourteen patients, 11 with latent or manifest latent nystagmus and 3 with combined manifest latent with infantile nystagmus, were asked to indicate the direction of the gap in Landolt C optotypes while their eye movements were recorded. RESULTS: The tested patients exhibited various responses to acuity demands: (1) dampening of nystagmus with convergence (i.e., nystagmus blockage syndrome) (5/14 patients), (2) changes in vergence without nystagmus dampening (2 patients), (3) decrease of nystagmus without convergence (2 patients), and (4) little change in nystagmus or vergence (5 patients). In nystagmus blockage syndrome the amount of convergence increased with acuity demands in two of five patients and the convergence duration in four of five patients; nystagmus dampening increased with acuity demands in one of five patients and the blockage duration in four of five patients. CONCLUSIONS: Many, but not all, patients with manifest/latent nystagmus, similar to those with infantile nystagmus, used convergence to dampen their nystagmus. The convergence response tended to increase with acuity demands, but the amount of dampening was idiosyncratic and not predictably related to the measured convergence across patients.     

Isolated Bilateral Abducens Nerve Palsies Due to Metastasis to the Clivus from Adenocarcinoma in the Lung

Objective: The term one-and-a-half syndrome, type II, was recently coined and has been applied to two somewhat different eye movement disorders: the loss of voluntary horizontal eye movements except for adduction in one eye (one patient with two lesions, one in the cerebral hemisphere and the other in the cavernous sinus) and the loss of all voluntary horizontal eye movements with adduction nystagmus in the right eye on attempted gaze to the left and preserved abduction in both eyes with the doll’s head maneuver (one patient with infarction of the midbrain). The justification of the term ‘one-and-a-half syndrome, type II’ is questioned. Design: Retrospective analysis of 9000 consecutive electro-oculographic recordings (EOG) with respect to combined abnormalities of conjugated horizontal eye movements to one side and abduction to the other. Results: Only one patient had loss of horizontal eye movements sparing adduction in one eye on clinical examination. In eight patients with clinically unilateral abduction paresis, EOG disclosed slowing of contraversive saccades. Another eight patients with clinically unrestricted horizontal eye movements had EOG-documented unilaterally slowed abduction saccades and slowing of contraversive saccades. Masseter reflex was abnormal in five patients and blink reflex in three. MRI performed in eight and CT in three of these patients failed to disclose acute lesions. Conclusions: The combination of a horizontal gaze paresis to one side and abduction paresis to the other is very rare, even if partial and subclinical forms are included. It occurs with single pontine or mesencephalic lesions or with two lesions at different sites, and can be caused by different mechanisms. Such an eye movement disorder does not constitute a new syndrome, as it entails neither a constellation of clinical findings due to an anatomically well-localized lesion, nor a consistent constellation of signs and symptoms due to a disease process.     

先天性特发性眼球震颤合并斜视的手术矫治

目的探讨先天性特发性眼球震颤合并斜视的手术矫治方法。方法根据中间带所处的位置、斜视性质与主导眼的关系,设计了八种类型的手术方法,并对资料完整的29例合并水平斜视的病例进行回顾性分析。结果所有患者主导眼原在位视力均提高二行以上,视力≥0.8者达48.3%。双眼正前方眼球无震颤或很轻微,头位消除,外观满意24例,占82.8%。术后眼位映光基本正位,在±5°以内26例,占89.6%。部分患者双眼视功能较术前有所改善。结论对合并水平斜视的先天性特发性眼球震颤按两大类八型设计手术治疗,效果满意。     

Clinical rationale for manifest congenital nystagmus surgery.

Although electronystagmography is most useful, especially in furthering our knowledge of nystagmus, simple clinical study is the first step to any understanding of nystagmus. Ophthalmologists should be aware that they may understand a good deal about nystagmus merely by studying visual acuity in their surgery. Testing visual acuity at distance with both eyes open will lead to the qualitative and quantitative diagnosis of compensatory abnormal head postures. Testing at distance with 1 eye covered will help to distinguish between the concordant head turn, one eye fixing in abduction and the other fixing in adduction (ABD + ADD) as manifest congenital nystagmus, and the discordant head turn in which each eye fixes in adduction (ADD + ADD), as is seen in manifest latent nystagmus, for which surgery is totally different. Pseudolatent nystagmus found in congenital nystagmus with exophoria can be differentiated from latent nystagmus. This illustrates de visu (with the naked eye) the "beauty" of the movement of blocking fusional convergence and the nature of the involved mechanisms with artificial divergence surgery. Testing at near will bring out the existence of blocking convergence. Depending on the results, the clinical rationale for surgery is thus made clear: horizontal, vertical, rotatory Kestenbaum-like surgery should be used in cases of abnormal head posture, whereas artificial divergence surgery is our most satisfactory armamentarium in cases of blocking convergence.     

Extended slow phase in latent/manifest latent nystagmus

PURPOSE: To investigate the slow phase in latent/manifest latent nystagmus (LMLN) by producing long eye-drift intervals devoid of fast phases (extended slow phases [ESPs]) and to relate ESP metrics to clinical findings. METHODS: Ten patients with LMLN had eye movements recorded while attending to paired visual and auditory cues presented to their left or right. Patients compared location of the visual target with that of the subsequently heard tone. The auditory cue and the comparison task directed attention away from vision and delayed the fast-phase onset to obtain ESPs. ESP metrics were analyzed with regard to patients' clinical characteristics. Five patients' data were further explored by isolating slow-phase components. RESULTS: All patients exhibited ESPs that resembled the usual slow phase but lasted two to three times longer. Five patients maintained alignment, whereas the other five made vergence movements. Greater eye velocity, excursion, and convergence during an ESP were associated with poor vision and large uncorrected esotropia. These metrics decreased when the viewing eye was in adduction, compared with primary position or abduction. Slow-phase components found in five patients consisted of a dominant decreasing-velocity or linear drift and a low-amplitude periodic oscillation. CONCLUSIONS: Shifting attention away from vision reliably delays the fast phase, revealing long intervals of slow phase, which can facilitate nystagmus investigation. ESP analysis in five patients with LMLN demonstrated two slow-phase components. ESP characteristics suggest that better ocular alignment is associated with improved stability in LMLN and provide metrics of eye drift that correlate with vision.     

Congenital mono-ophthalmia syndrome

Three patients affected by the congenital mono-ophthalmia syndrome were submitted to horizontal eye movements recording. The aim was to study the nystagmus and its characteristics, in order to give information that could explain signs and symptoms of the syndrome. Eye movements recording and analysis displayed a jerk nystagmus with a decreasing-velocity exponential slow phase, characteristic of a latent/manifest-latent nystagmus. The intensity of nystagmus decreased in adduction of the viewing eye, and increased in abduction in accordance with Alexander's law. The fast phase was toward the viewing eye. There was no reversal of the fast phase, nor an instability of gaze in the blind eye.     

Oscillopsia in "inverse latent" infantile nystagmus syndrome.

PURPOSE: A possibly unique individual with infantile nystagmus syndrome presented with incessant oscillopsia but good stereopsis when viewing binocularly; her nystagmus was greatly reduced with left eye occlusion. We have attempted to explain this and to identify an intervention that preserves binocular vision while maximizing perceptual stability. CASE REPORT AND METHODS: Eye movements were recorded and analyzed for duration of foveation (% time when the target was on or near the fovea and the eye was moving at < or = 4 degrees /sec) under different viewing conditions. Changes in foveation were compared with the patient's reports of her perceptual stability. RESULTS: In her right gaze null with her right eye fixating, foveation was 52.9%. This fell to 32.3% for the same eye in primary position and to 0.8% when viewing binocularly in primary position. When viewing binocularly oscillopsia was incessant; when viewing with her right eye vision was stable except in left gaze. Prism correction of her phoria greatly reduced her oscillopsia when viewing binocularly while preserving stereopsis; foveation went up to 33.7%. CONCLUSION: The patient's ability to maintain good foveation only when viewing with her right eye forces her to choose between stereopsis and stable vision. This may result from the rare combination of (1) requiring good foveation for oscillopsia suppression and (2) nystagmus deteriorating under the stress of maintaining binocularity. There may be many other infantile nystagmus syndrome patients who do not develop oscillopsia but may suffer sufficient asthenopia from a phoria to exacerbate their nystagmus.     

Surgery for the treatment of vertical head posturing associated with infantile nystagmus syndrome: results in 24 patients

Background: The study of the clinical and electrophysiological effects of eye muscle surgery on patients with infantile nystagmus has broadened our knowledge of the disease and its interventions. Design: Prospective, comparative, interventional case series. Participants: Twenty‐four patients with a vertical head posture because of electrophysiologically diagnosed infantile nystagmus syndrome. The ages ranged from 2.5 to 38 years and follow up averaged 14.0 months. Methods: Thirteen patients with a chin‐down posture had a bilateral superior rectus recession, inferior oblique myectomy and a horizontal rectus recession or tenotomy. Those 11 with a chin‐up posture had a bilateral superior oblique tenectomy, inferior rectus recession and a horizontal rectus recession or tenotomy. Main Outcome Measures: Outcome measures included: demography, eye/systemic conditions and preoperative and postoperative; binocular, best optically corrected, null zone acuity, head posture, null zone foveation time and nystagmus waveform changes. Results: Associated conditions were strabismus in 66%, ametropia in 96%, amblyopia in 46% and optic nerve, foveal dysplasia or albinism in 54%. Null zone acuity increased at least 0.1 logMAR in 20 patients (P < 0.05 group mean change). Patients had significant (P < 0.05) improvements in degrees of head posture, average foveation time in milliseconds and infantile nystagmus syndrome waveform improvements. Conclusions: This study illustrates a successful surgical approach to treatment and provides expectations of ocular motor and visual results after vertical head posture surgery because of an eccentric gaze null in patients with infantile nystagmus syndrome.     

Eye movement baseline oscillation and variability of eye position during foveation in congenital nystagmus

Despite the inability to maintain steady fixation, congenital nystagmus does not necessarily reduce visual acuity, that can be achieved during the foveation periods. The duration of the foveation period, but also the cycle-to-cycle variability of eye position and velocity during foveations play an important role. A quantitative relationship that relates visual acuity with foveation time and cycle-to-cycle variability of eye position during foveation has been previously proposed. In many infrared-oculographic and electro-oculographic eye position recordings of our database, a sinusoidal-like oscillation of the baseline was observed, on which the nystagmus waveforms lay. This oscillation may contribute to increase cycle-to-cycle variability during foveations. The aim of this work is to extract the baseline oscillation from the recordings and to verify its relationship with eye position variability during foveation. On the basis of the observations, the baseline oscillation was assumed to be sinusoidal, and was estimated (using a least mean square technique) from eye movement signals recorded during fixation intervals, at different gaze positions, from 20 patients affected by congenital nystagmus with low visual acuity. The average baseline oscillation amplitude was 1.31°, while the average frequency was 0.34 Hz. Baseline oscillation amplitude was well correlated (with a coefficient of 0.66) to the standard deviations of eye-position during foveation, which in turn is connected to visual acuity.     

Acquired pendular nystagmus

A case of acquired pendular nystagmus is reported in a patient with multiple sclerosis. The nystagmus is vertical and monocular. The nystagmus is binocular after eye closure and is present only in primary position. During exacerbation of multiple sclerosis the pendular nystagmus disappears while bilateral internuclear ophthalmoplegia and rebound nystagmus are observed. On disappearance of internuclear ophthalmoplegia and rebound nystagmus, the pendular nystagmus reappeared.