Longitudinal changes in photopic OPs occurring with vigabatrin treatment

Morong, Sharon; Westall, Carol A.; Nobile, R.; Buncic, J. Raymond; Logan, William J.; Panton, Carole M.; Abdolell, Mohamed

doi:10.1023/b:doop.0000005338.51554.e3

Cited by 21 publications

(16 citation statements)

References 22 publications

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“…Some of these electrophysiologic indicators are likely to reflect the changing retinal nontoxic GABA levels. 20,21 For example, oscillatory potentials decrease in amplitude during drug treatment but recover after discontinuation of the drug, unlike the decrease in flicker amplitude, which is less likely to recover. 22 Most children in the HSC longitudinal study do not show the form of retinal nerve fiber layer atrophy described in these 3 more advanced cases of retinal toxicity.…”

Section: Discussionmentioning

confidence: 99%

“…Because a variety of ERG parameters (amplitude and implicit time) change during vigabatrin treatment, the current studies are helping to clarify which of these changes represent nontoxic side effects and which correlate with drug toxicity. [20][21][22] Changes in oscillatory potential amplitude result, at least in part, from non-toxic changes. 22 Conversely, if the ERG, particularly the 30-Hz flicker response, decreases more than expected from intervisit variability, both the clinical assessment and the ERG are repeated within 3 months.…”

Section: Participants and Methodsmentioning

confidence: 99%

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Characteristic retinal atrophy with secondary “inverse” optic atrophy identifies vigabatrin toxicity in children

et al. 2004

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Objective-To describe the clinical pattern of retinal atrophy in children caused by the anticonvulsant vigabatrin. Design-An interventional case series report.Participants-One hundred thirty-eight patients, mainly infants, were evaluated regularly for evidence of possible vigabatrin toxicity in the Eye and Neurology clinics at the Hospital for Sick Children, Toronto. Conclusions-A recognizable and characteristic form of peripheral retinal atrophy and nasal or "inverse" optic disc atrophy can occur in a small number of children being treated with vigabatrin. The changes in superficial light reflexes of the retina in children facilitate the clinical recognition of nerve fiber layer atrophy. The macula is relatively spared, although superficial retinal light reflexes indicating wrinkling of the innermost retina suggest early macular toxicity as well. Because these changes are accompanied by electrophysiologic evidence of retinal dysfunction, discontinuation of vigabatrin should be strongly considered. Method-SequentialCorrespondence to J.

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Section: Discussionmentioning

confidence: 99%

Section: Participants and Methodsmentioning

confidence: 99%

Characteristic retinal atrophy with secondary “inverse” optic atrophy identifies vigabatrin toxicity in children

et al. 2004

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“…59 Numerous investigators have reported the prevalence in children to be well below that of adults, 91,96,98,99 suggesting a prevalence of approximately 20% in this younger population. The best data on infants 65,71,73,100 have established a prevalence of approximately 40%, with incidence of 16% as assessed by the highly sensitive electroretinogram (ERG) 30-Hz flicker amplitude. The prevalence of cone B-wave amplitude abnormalities, the other vigabatrin-specific ERG parameter that is sensitive and specific for the vigabatrin-induced defect, is about 20%, with an incidence of 4%.…”

Section: Prevalence Onset and Progression Of Vfd With Vigabatrinmentioning

confidence: 99%

Vigabatrin

2007

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Summary: Refractory epilepsies such as infantile spasms (IS) and complex partial seizures (CPS) can have a severe negative impact on the neurological integrity and quality of life of affected patients, in addition to drastically increasing their risk of premature mortality. Early identification of potentially effective pharmacotherapy agents is important. Vigabatrin has been shown to be a generally well tolerated and effective antiepileptic drug (AED) in a wide variety of seizure types affecting both children and adults, particularly those with IS and CPS. A bilateral, concentric constriction of the peripheral visual field characterizes the visual field defect (VFD) associated with vigabatrin, well characterized by numerous studies. This peripheral VFD presents in 30 -50% of patients with exposure of several years; however, most of these patients are asymptomatic. In well-controlled studies, the earliest onset in patients with CPS is 11 months and at 5 months in infants, with average onsets being more than 5 years and 1 year, respectively. Patients with a peripheral VFD retain an average 65°of lateral vision (normal, 90°). The fact that many patients never develop the vigabatrin-related peripheral VFD, despite long-term exposure at high doses, may support the hypothesis that the injury is an idiosyncratic adverse drug reaction (as opposed to a strict dose-or duration-dependent toxicity). Effective testing methods are available to aid in the early detection and management of the peripheral VFD. This article discusses issues of importance to clinical decision-making in the use of vigabatrin to assist the physician and patient in assessing the benefits of vigabatrin therapy and understanding the potential risks of the VFD and uncontrolled seizures.

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“…In adults, the amplitude of the electroretinogram (ERG) response to full-field 30-Hz flickering light has been reported to be a predictor of visual field defects [15,16] and to be correlated with the severity of the field defect [12]. Other photopic [6,12,[15][16][17][18][19][20][21][22][23][24][25] and scotopic [6,7,12,14,19,20,22] ERG response parameters have also been reported to be abnormal in VGB users. However, consistent association of any of these ERG abnormalities with visual deficits has not been established.…”

Section: Introductionmentioning

confidence: 99%

Electroretinographic (ERG) responses in pediatric patients using vigabatrin

et al. 2012

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The antiepileptic drug vigabatrin is known to cause retinal and visual dysfunction, particularly visual field defects, in some patients. Electroretinography (ERG) is used in an attempt to identify adverse effects of vigabatrin (VGB) in patients who are not candidates for conventional perimetry. We report data from 114 pediatric patients taking VGB referred for clinical evaluation; median age at test was 22.9 (2.4 to 266.1) months, and median duration of VGB use was 9.7 (0.3 to 140.7) months. Twenty-seven of them were tested longitudinally (3 to 12 ERG tests). ERG responses to full-field stimuli were recorded in scotopic and photopic conditions, and results were compared to responses from healthy control subjects. We found that abnormalities of photoreceptor and post-receptor ERG responses are frequent in these young patients. The most frequently abnormal scotopic parameter was post-receptor sensitivity, log σ, derived from the b-wave stimulus-response function; the most frequently abnormal photopic parameter was the implicit time of the OFF response (d-wave) to a long (150 ms) flash. Abnormal 30-Hz flicker response amplitude, previously reported to be a predictor of visual field loss, occurred infrequently. For the group as a whole, none of the ERG parameters changed significantly with increasing duration of VGB use. Four of the 27 patients tested longitudinally showed systematic worsening of log σ with duration of VGB use. In a subset of patients who underwent perimetry (N = 39), there was no significant association of any ERG parameter with visual field defects. We cannot determine whether the ERG abnormalities we found were due solely to the effects of VGB. We caution against over-reliance on the ERG to monitor pediatric patients for VGB toxicity and recommend further development of a reliable test of peripheral vision to supplant ERG testing.

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Longitudinal changes in photopic OPs occurring with vigabatrin treatment

Abstract: Early photopic OPs were disrupted more than the late OP, suggesting relative deficit in the ON (depolarizing) retinal pathways.

Cited by 21 publications

References 22 publications

Characteristic retinal atrophy with secondary “inverse” optic atrophy identifies vigabatrin toxicity in children

Characteristic retinal atrophy with secondary “inverse” optic atrophy identifies vigabatrin toxicity in children

Vigabatrin

Electroretinographic (ERG) responses in pediatric patients using vigabatrin

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