Adverse effect of the Epley maneuver: Anterior canal crisis.

OBJECTIVE: In the Epley maneuver performed on patients with posterior semicircular canal-benign paroxysmal positional vertigo-canalolithiasis (P-BPPV-Can), an intense downbeat nystagmus and retropulsion rarely appear as soon as they reach the last upright sitting position. It is considered an anterior canal crisis that appears when the otoliths move to the ampullofugal direction in the anterior semicircular canal by changing head and body positions from the healthy-ear-down 135° head position (the third head position) to the upright sitting position (the fourth head position). This study aimed to determine the prevention of this anterior canal crisis. METHODS: The anterior canal crisis frequency was compared among the 178 cases that underwent general Epley maneuver (uncorrected Epley maneuver) and the 228 cases that underwent Epley maneuver (corrected Epley maneuver) by preventing head rotation beyond 135° to the healthy ear and the top of the head going down at the third head position. RESULTS: In 6% of patients with P-BPPV-Can who underwent the Epley maneuver, a transient mixed downbeat and torsional nystagmus to the affected ear and retropulsion were observed at the fourth head position (anterior canal crisis). The corrected Epley maneuver significantly reduced the incidence of unpredictable anterior canal crisis (p = 0.017). Additionally, there was no difference in the effect of the Epley maneuver the next day regardless of the anterior canal crisis appearance. CONCLUSION: Anterior canal crisis is an adverse effect of the Epley maneuver, and its prevention is important for safety. Avoiding head rotation beyond 135° to the healthy ear and/or the top of the head going down at the healthy-ear-down 135° head position is expected to reduce anterior canal crisis.

Evaluation of eye-related parameters and adverse events of rigid gas permeable contact lens and spectacles correction in infants with monocular aphakia after congenital cataract surgery: a retrospective clinical study.

BACKGROUND: Congenital cataract is currently one of the leading blindness-causing eye diseases in children. Surgical treatment only opens the visual pathway for children. The postoperative recovery of visual function is also dependent on effective optical correction and visual function training. In this study, we analyzed the changes in eye-related parameters, adverse events and the annual cost of rigid gas permeable contact lens (RGPCL) and spectacles correction in infants with monocular aphakia after congenital cataract surgery. METHODS: To analyze the postoperative visual acuity, strabismus, nystagmus, myopic shift, globe axial length growth, adverse events, patient adherence to patching, and annual cost for patients with unilateral congenital cataract who underwent cataract surgery. Rigid gas permeable contact lenses or spectacles were used to correct aphakia after congenital cataract. RESULTS: Of the 49 patients, 20 patients with unilateral aphakia who used RGPCL were in group 1. Group 2 comprised 14 patients with persistent fetal vasculature (PFV) who used RGPCL, and there were 15 patients with spectacles in group 3. In group 1, there were important improvements in visual acuity, strabismus and nystagmus. In groups 2 and 3, there were no significant improvements in visual acuity, strabismus or nystagmus. Patients with a good adherence to patching had better visual acuity after the operation than patients who did not, in groups 1 and 3. There were no significant differences in myopic shift or rate of globe axial length growth among the 3 groups. No patients in group 1 had ocular disease that affected visual acuity. The mean annual expenses of the RGPCL group was 3965 yuan, and the mean annual cost of spectacles was 1140 yuan to 2500 yuan. CONCLUSION: RGPCL is a safe and effective optical correction method for patients with monocular aphakia after congenital cataract surgery. Spectacles are not an ideal optical correction. Using RGPCL to correct patients with PFV, the final visual acuity improved, but the difference was not statistically significant. There were no improvements in strabismus or nystagmus in patients with PFV.

Congenital Cataract: Progress in Surgical Treatment and Postoperative Recovery of Visual Function.

Congenital cataract is a common cause of childhood low vision or blindness worldwide. Early surgery should be performed in sensitive vision development period to avoid vision deprivation in cases of strabismus and nystagmus development. Postoperative recovery of visual function is of great significance for these patients and should include proper postoperative aphakia correction by the application of a contact lens and secondary implantation of an intraocular lens (IOL). Patients should receive amblyopic training after surgery to improve their postoperative visual acuity. Although recent advances in surgery techniques and materials have brought better postoperative visual acuity and less complications, a few postoperative complications can still hamper vision condition and vision development, including posterior capsule opacification and secondary glaucoma. Surgery in early infancy are risk factors for these two complications. Life-long follow-up is essential for these patients. Further study will continue to address the surgery timing issue and methods that prevent postoperative complications.

Preventable visual impairment in children with nonprofound intellectual disability.

PURPOSE: To assess the preventable visual impairment in children with nonprofound intellectual disability (ID). 
 METHODS: A total of 215 children with IDs (90 Down syndrome [DS], 125 nonprofound ID) and 116 age- and sex-matched healthy subjects were enrolled in this study. All participants underwent ophthalmologic examinations including cycloplegic refraction measurements, ocular movement evaluation, screening for strabismus (Hirschberg, Krimsky, or prism cover test), slit-lamp biomicroscopy, funduscopy, and intraocular pressure measurements. All data were recorded for statistical analysis.
 RESULTS: Ocular findings in decreasing prevalence were as follows: refractive errors 55 (61.1%), strabismus 30 (33.2%), cataract 7 (7.8%), and nystagmus 7 (7.8%) in children with DS; refractive errors 57 (45.6%), strabismus 19 (15.2%), cataract 7 (6.4%), nystagmus 5 (4%), and glaucoma 1 (0.8%) in children with other ID; and refractive errors 13 (11.2%) and strabismus 4 (3.5%) in controls. Cataracts, glaucoma, and nystagmus were not observed in the control group. The most common ophthalmic findings in children with DS compared with other ID and controls were with hyperopia (p<0.03 and p<0.001, respectively) and esotropia (p<0.01 and p<0.01, respectively).
 CONCLUSION: The pediatric population with ID has a high prevalence of preventable visual impairments, refractive errors, strabismus, and cataracts. The prevalence of strabismus and refractive errors was more frequent in children with DS. The importance of further health screenings including ophthalmic examinations should be utilized to implement appropriate care management and improve quality of life.

Empleo de toxina botulínica en paciente con nistagmus congénito de tipo pendular / Use of botulinum toxin in a patient with pendular congenital nystagmus

Caso clínico: Se presenta el caso de un varón de 5 meses de edad, diagnosticado de nistagmus congénito y albinismo oculocutáneo. En la exploración inicial se evidenció un nistagmus horizontal pendular de gran amplitud sin posición de bloqueo ni períodos de fijación foveal. Se realizó una inyección de 2,5 UI de toxina botulínica en los músculos rectos horizontales de ambos ojos en dos sesiones separadas por 6 semanas permitiendo una disminución de la amplitud del nistagmus y un desarrollo inicial de la agudeza visual binocular de 4,8 ciclos/cm. Conclusión: Ante el diagnóstico de nistagmus horizontal en etapas precoces del desarrollo, de amplitud tal que impida períodos de fijación foveal, el empleo de toxina botulínica permite una disminución temporal en la amplitud del mismo y una mejoría de la agudeza visual con baja tasa de complicaciones. Ante la posibilidad descrita de mejoría espontánea de estos pacientes, especialmente durante el primer año de vida, son necesarios estudios con mayor tiempo de seguimiento para establecer la ventaja de este tratamiento a largo plazo(AU)

Case report: We report the case of a 5 month-old male diagnosed with congenital nystagmus and oculocutaneous albinism. The initial examination showed pendular horizontal nystagmus with high amplitude and without blocking position or foveal fixation periods. A 2.5 IU injection of botulinum toxin was administered in the horizontal rectus muscles of both eyes in two sessions separated by 6 weeks. This led to a decrease in amplitude of nystagmus and early development of binocular visual acuity of 4.8 cycles/cm. Conclusion: Faced with diagnosis of horizontal nystagmus in the early stages of development, and in order to avoid periods of foveal fixation, the use of botulinum toxin leads to a temporary reduction in its amplitude and an improvement in visual acuity with low complication rates. Given the possibility of spontaneous improvement described in these patients, studies are needed with longer follow-up to establish the advantage of long term treatment(AU)

[Pharmacological treatment of nystagmus]. / Medikamentöse Therapie des Nystagmus.

Nystagmus can be associated with strong discomfort due to oscillopsia, blurry vision and dizziness. Since generally no curative treatment methods exist, studies focus on potential pharmaceuticals to dampen the nystagmus. An overview is given on which forms of nystagmus can be treated with what kind of pharmacological substances and their possible mechanism of nystagmus dampening. Controlled studies found gabapentin and memantine to be effective in acquired pendular nystagmus and early-onset idiopathic nystagmus, and an efficacy of 4-aminopyridine in downbeat nystagmus.

The critical period for surgical treatment of dense congenital bilateral cataracts.

INTRODUCTION: We examined the critical period for deprivation amblyopia in a cohort of patients with dense bilateral congenital cataracts to investigate the optimum timing for surgical treatment. METHODS: Thirty-seven infants with dense bilateral congenital cataracts that were extracted by 31 weeks of age were enrolled prospectively. Visual acuity outcome was assessed at >/=5 years of age. We statistically evaluated which of 4 models provided the best fit to the data: (1) no change in visual acuity outcome with delay in surgery, (2) linear decline of outcome with delay, (3) a bilinear model in which a critical age exists after which outcome depends on delay, and (4) a bilinear model in which a critical age exists before which outcome depends on delay. In addition, we reviewed medical records for associated adverse outcomes, including strabismus, nystagmus, secondary membrane formation, and glaucoma. RESULTS: A bilinear model with a critical age of 14 weeks fit the data better than a linear model (chi(2) = 14.7; p < 0.0006). During weeks 0-14, mean visual acuity decreased by 1 line with each 3 weeks' delay in surgery. From 14 to 31 weeks, visual acuity was independent the subject's age at surgery, averaging 20/80. Surgery after 4 weeks was associated with a greater prevalence of strabismus and nystagmus than surgery before 4 weeks, whereas surgery during the first 4 weeks was associated with a greater prevalence of secondary membrane formation and glaucoma. CONCLUSIONS: We did not find a latent period for the treatment of children with dense bilateral congenital cataracts. Deprivation amblyopia may be minimized with early surgery for bilateral cataracts.

Use of a visual guide to improve the quality of VOR responses evoked by high-velocity rotational stimuli.

High-velocity rotational stimuli have the potential to improve the diagnostic capabilities of clinical rotation testing by revealing nonlinear vestibulo-ocular reflex (VOR) responses that are indicative of asymmetric vestibular function. However, eye movements evoked by high-velocity rotations often are inconsistent over time and therefore do not yield reliable diagnostic measures. This study investigated whether use of a novel "visual guide" could improve the consistency and quality of VORs obtained during testing with pulse-step-sine (PSS) stimuli providing periodic high-velocity, horizontal-plane rotations with peak velocities up to 290 deg/s. The visual guide (narrow phosphorescent line spanning 180 degrees field of view) was mounted horizontally on the rotation chair at the subject's eye level. Eight healthy human subjects were tested either in complete darkness while performing an alerting task, or while viewing the visual guide in an otherwise dark room. We found that the visual guide improved the quality of VOR responses as shown by an increased proportion of slow-phase velocity data segments retained for analysis, by a decreased variance of the processed eye velocity data, and by a reduction of outlying VOR response measures. We also found that the visual guide did not induce visual suppression because VOR gain measures were not diminished.

Vestibular adaptation to centrifugation does not transfer across planes of head rotation.

Out-of-plane head movements performed during fast rotation produce non-compensatory nystagmus, sensations of illusory motion, and often motion sickness. Adaptation to this cross-coupled Coriolis stimulus has previously been demonstrated for head turns made in the yaw (transverse) plane of motion, during supine head-on-axis rotation. An open question, however, is if adaptation to head movements in one plane of motion transfers to head movements performed in a new, unpracticed plane of motion. Evidence of transfer would imply the brain builds up a generalized model of the vestibular sensory-motor system, instead of learning a variety of individual input/output relations separately. To investigate, over two days 9 subjects performed pitch head turns (sagittal plane) while rotating, before and after a series of yaw head turns while rotating. A Control Group of 10 subjects performed only the pitch movements. The vestibulo-ocular reflex (VOR) and sensations of illusory motion were recorded in the dark for all movements. Upon comparing the two groups we failed to find any evidence of transfer from the yaw plane to the pitch plane, suggesting that adaptation to cross-coupled stimuli is specific to the particular plane of head movement. The findings have applications for the use of centrifugation as a possible countermeasure for long duration spaceflight. Adapting astronauts to unconstrained head movements while rotating will likely require exposure to head movements in all planes and directions.

Edaravone protects the vestibular periphery from free radical-induced toxicity in response to perilymphatic application of (+/-)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid.

Intracochlear infusion of (+/-)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) was performed with a syringe pump in guinea pigs, and peripheral vestibular dysfunction was induced. Animals were administered edaravone systemically or topically. In the systemic application group, animals were administered edaravone once a day for 7 days after AMPA infusion. In the topical application group, edaravone-soaked gelfoam was placed on the round window membrane just after, 12 h after or 24 h after AMPA infusion. Spontaneous nystagmus was observed after AMPA infusion. Immunohistochemistry for 4-hydroxy-2-nonenal (4-HNE), a marker of free radical-induced lipid peroxidation, was performed 24 h after AMPA infusion. In addition, caloric tests were performed to evaluate vestibular function 1 week after AMPA infusion. Animals in both groups showed decreased spontaneous nystagmus, but results were not significant. Animals treated topically with edaravone within 12 h of AMPA infusion showed normal morphology of the ampullar sensory epithelia of the lateral semicircular canals and showed a good response to the caloric tests. 4-HNE immunoreactivity in the sensory epithelia was very low in these animals. In contrast, untreated animals and animals treated with edaravone systemically or topically 24 h after AMPA infusion showed morphologic hair cell damage, reduced caloric response and remarkable 4-HNE immunoreactivity in the sensory epithelia. These results indicate that topical application of edaravone within 12 h after damage protects the vestibular periphery from free radical-induced toxicity in response to intracochlear infusion of AMPA.

Hyaluronate gel stapedotomy.

OBJECTIVE: To evaluate hearing results and postoperative dizziness after stapedotomy with application of sodium hyaluronate gel (HG) to the oval window niche during fenestration of the footplate. STUDY DESIGN: Case-control study comparing 27 stapedotomies with HG and 32 stapedotomies without HG. OUTCOME MEASURE: Preoperative and postoperative audiometric data, postoperative dizziness (vertigo or dysequilibrium), and nystagmus. RESULTS: Postoperative hearing results were not statistically different for the 2 groups. There were no cases of postoperative sensorineural hearing loss greater than 10 dB. Early postoperative dizziness (chi(2) = 4.08, P = 0.043) and nystagmus (chi(2) = 5.05, P = 0.024) were reduced in the HG group. CONCLUSIONS: HG stapedotomy is safe and effective and results in less early postoperative dizziness and nystagmus when compared with the standard technique of stapedotomy. The application of HG to the oval window niche to prevent blood from entering or perilymph from escaping the vestibule during fenestration of the stapes footplate may contribute to a quicker recovery in outpatient otosclerosis surgery.

Adaptations and deficits in the vestibulo-ocular reflex after third nerve palsy.

OBJECTIVE: To analyze the vestibulo-ocular reflex (VOR) in patients with unilateral peripheral third nerve palsy. PARTICIPANTS AND METHODS: Ten patients and 15 healthy subjects were studied using magnetic search coils. Subjects made sinusoidal +/-10 degrees head-on-body rotations in yaw, pitch, and roll in darkness and during monocular viewing in light. RESULTS: Horizontal VOR and visually enhanced VOR (VVOR) gains of the paretic eye were decreased during both abduction and adduction. Vertical VOR and VVOR gains of the paretic eye were decreased during both elevation and depression. Dynamic and static torsional VOR and VVOR gains of the paretic eye were reduced during both excyclotorsion and incyclotorsion. Horizontal, vertical, and torsional VOR and VVOR gains were normal in the nonparetic eye. CONCLUSIONS: Adducting VOR gains were reduced as anticipated from medial rectus palsy. Abducting gains were also reduced; the reduction is attributed to an adaptive decrease in innervation to the lateral rectus to achieve symmetry of the horizontal VOR in the paretic eye. Torsional VOR gains were reduced during excyclotorsion from palsy of the inferior oblique muscle. Gains were also reduced during incyclotorsion, which can be explained by an adaptive decrease in innervation to the superior oblique to restore symmetry of the torsional VOR in the paretic eye. CLINICAL RELEVANCE: Monocular adaptation in the VOR of the paretic eye reduces asymmetrical movement of retinal images during head motion, prevents nystagmus, and reduces retinal image disparity.

Suppression of vestibular nystagmus by forced convergence in normal human subjects.

BACKGROUND: It has been suggested that the principal mechanism of nystagmus suppression in the nystagmus blockage syndrome is either adduction of the eye or convergence. We examined this issue using the nystagmus of the vestibulo-ocular reflex (VOR) as a model. METHODS: A motorized, computer-controlled rotary chair was used to produce VOR in darkness, using either sinusoidal or velocity step stimulation. Left eye position was monitored and horizontal slow-phase eye velocity was calculated. Subjects were cued to converge or perform other gaze tasks. RESULTS: Convergence suppressed nystagmus. With sinusoidal stimulation, nystagmus was nearly extinguished in extreme lateroversion, probably due to mechanical tethering of the eye. However, VOR gain suppression of 47% during convergence was observed even when the monitored eye was close to primary position. With velocity step stimulation, nystagmus was nearly extinguished at moderate angles of adduction. CONCLUSIONS: Convergence is sufficient to suppress nystagmus, without vision and without regard to whether the eye is adducted.

A dose-response analysis of the beneficial effects of the ACTH-(4-9) analogue, Org 2766, on behavioural recovery following unilateral labyrinthectomy in guinea-pig.

1. After removal of the peripheral vestibular receptors in one inner ear (unilateral labyrinthectomy, UL), oculo-motor and postural symptoms occur but disappear over time in a process of recovery known as vestibular compensation. 2. ACTH-(4-10), a fragment of the adrenocorticotrophic hormone (ACTH) molecule, which is devoid of corticotrophic activity, has been shown to enhance vestibular compensation. The present study investigated the effect of the ACTH-(4-9) analogue, Org 2766, on vestibular compensation in guinea-pig. Org 2766 is reported to be more potent behaviourally than ACTH-(4-10). 3. After UL, Org 2766 was delivered via an osmotic minipump implanted s.c. to 30 animals randomly assigned to one of five conditions: 1, 5, 10, 20 or 40 nmol kg-1 Org 2766, every 4 h for 52 h post-UL. Although infusion was continuous, in the present study the doses are expressed as nmol per 4 h in order to compare the results to a previous study in which animals received a discrete dose of ACTH-(4-10) at the end of each 4 h period. All animals were compared to saline controls (n = 6). 4. Three symptoms of UL, spontaneous ocular nystagmus, roll head tilt and yaw head tilt, were measured every 4 h for 52 h, beginning at 10 h post-UL. 5. Rates of infusion of 1, 5 and 10 nmol kg-1 accelerated spontaneous nystagmus compensation; 20 nmol kg-1 produced a significant decrease in the frequency of spontaneous nystagmus, as well as accelerating its compensation; 40 nmol kg-1 had no significant effect on spontaneous nystagmus compensation. 6. In comparison to the effects of Org 2766 on spontaneous nystagmus compensation, Org 2766 had little effect on the compensation of the postural symptoms, yaw head tilt and roll head tilt. Only 5 and 40 nmol kg-1 produced a significant change in postural compensation, and this was a reduction in the rate of roll head tilt compensation.7. At the optimal infusion rate of 20 nmol kg-1 every 4 h, Org 2766 produced a similar effect on spontaneous nystagmus compensation to that of ACTH-(4-10). However, Org 2766 was effective in accelerating spontaneous nystagmus compensation at much smaller doses per 4 h period than ACTH-(4-10). Org 2766 did not have the same effect on. postural compensation as it had on the compensation of spontaneous nystagmus.

Middle ear procaine injection before surgical labyrinthectomy reduces nystagmus.

A middle ear injection of 2% procaine (0.1 ml) was given to guinea-pigs 15-30 min before a surgical unilateral labyrinthectomy (UL) and the effects on spontaneous ocular nystagmus (SN) were observed. The pre-UL injection of procaine significantly reduced SN frequency compared to vehicle-injected controls or to animals receiving a post-UL injection of procaine. This result supports the hypothesis that the decrease in resting activity observed in vestibular nucleus neurones following UL may be due, at least in part, to Ca2+ influx due to injury-related glutamate release from vestibular nerve terminals.

Changes in nystagmus after simultaneous surgery for bilateral congenital cataracts.

The presence of nystagmus has been considered as an indicator of poor prognosis in infants with bilateral congenital cataracts. However, of the 10 infants with preoperative nystagmus reported in this study, after simultaneous surgery for bilateral congenital cataracts, 5 cases showed a resolution of nystagmus or reduction to latent nystagmus postoperatively. This study was carried out to clarify what factors resolved or reduced the preoperative nystagmus. Those 5 cases in whom nystagmus was ameliorated postoperatively were operated on within one month after the onset. Age of nystagmus onset, age at surgery or type of cataract did not affect this amelioration of nystagmus. In contrast, the 5 cases who had no postoperative change in nystagmus were operated on later than this period. Our results demonstrate that it is possible to resolve or reduce preoperative nystagmus in bilateral congenital cataracts by a simultaneous bilateral lens removal within one month after the onset of nystagmus.

Experimental research on antimotion sickness effects of Chinese medicine "pingandan" pills in cats.

Pingandan was a secret prescription for treatment of stomach upset, nausea and vomiting for emperors in the Qing Dynasty of China. This study was to compare the effects of Pingandan with those of scopolamine and dramamine on motion sickness (MS) and nystagmus. Fourteen cats were tested in a parallel swing (0.22 Hz, 3.9 m/S2) for 20 min, and then in a rotating chair (10 degrees/S2, 20 rpm) for 1-2 min. The effects of scopolamine 1 mg, dramamine 25 mg and three doses of Pingandan 50x, 30x, 10x of 0.45 g/kg were observed and compared to placebos. These drugs or placebos were administered to each cat 30-60 min prior to the tests. The post-rotary nystagmus and MS symptoms were recorded. The Suri's scale for MS severity, Latin square and double blind techniques were used. The interval between any two tests was 2-5 days. It was found that Pingandan 50x and scopolamine 1 mg were more effective than placebos in reducing MS symptoms (P less than 0.01) and suppressing slow phase velocity of nystagmus (P less than 0.05), while Pingandan 30x significantly reduced MS symptoms only (P less than 0.01). Pingandan 10x and dramamine 25 mg had no anti-MS effect. Chinese medicine Pingandan is an effective anti-MS drug.

Effect of ACTH-(4-10) on Bechterew's compensation in squirrel monkeys.

ACTH-(4-10), a fragment of the ACTH without hormonal action, has been known to have effects on learning and memory process. Recently, we have shown that ACTH-(4-10) had marked effects on the balance compensation process after unilateral labyrinthectomy in squirrel monkeys. In this study, we examined the effect of daily administration of ACTH-(4-10) following two-staged bilateral labyrinthectomy. When the locomotor balance function and the slow-phase eye velocity of the spontaneous nystagmus were analyzed, the ACTH-(4-10) groups compensated significantly faster than the control group (p less than 0.05).