Patients Treated with Vigabatrin Exhibit Central Visual Function Loss

Hilton, E J Roff; Cubbidge, Robert P; Hosking, Sarah; Betts, Tim; Comaish, Ian F.

doi:10.1046/j.1528-1157.2002.00502.x

Cited by 33 publications

(32 citation statements)

References 35 publications

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“…Some reports describe visual field constriction that may be more severe nasally (8,9), but central visual loss also may develop (10). In accordance with these observations, ophthalmoscopy can show optic nerve pallor, macular irregularities, and peripheral retinal abnormalities (9,11,12).…”

mentioning

confidence: 64%

Acute Vigabatrin Retinotoxicity in Albino Rats Depends on Light But Not GABA

Izumi¹,

Ishikawa

Benz³

et al. 2004

Epilepsia

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Summary:Purpose: Vigabatrin (VGB) is an irreversible inhibitor of γ -aminobutyric acid (GABA) transaminase. Its use as an antiepileptic drug (AED) has been limited because it causes retinal dysfunction, leading to visual field defects (VFDs). We performed this study to identify factors contributing to acute VGB retinotoxicity.Methods: In ex vivo experiments, Sprague-Dawley rat retinas were isolated and incubated with VGB or GABA in the presence or absence of light. In in vivo experiments, Sprague-Dawley rats were given intraperitoneal injections of VGB and then exposed to light or kept in the dark. The retinas were analyzed histologically by using both light and electron microscopy.Results: Incubating retinas with 50-500 µM VGB under 20,000 Lux white light for ≤20 h caused a characteristic time-and dose-dependent degeneration limited to the outer retina. Incubating retinas with 500 µM VGB in darkness for 20 h caused no damage. Five hundred micromolar GABA and 50 µM tiagabine were not toxic in the presence or absence of light. Sprague-Dawley rats exposed to an intense white light for 20 h after a 1,000-mg/kg intraperitoneal injection of VGB showed damage in the outer retina, whereas those kept in the dark did not.Conclusions: Direct exposure of the retina to VGB causes acute retinotoxicity that depends on light exposure rather than GABA accumulation.

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confidence: 64%

Acute Vigabatrin Retinotoxicity in Albino Rats Depends on Light But Not GABA

Izumi¹,

Ishikawa

Benz³

et al. 2004

Epilepsia

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“…First, a potential confounding should be noted-the AED may have influenced perceptual and cognitive functions of the patients [31], although the patients had discontinued medication for about 24 h in the present study. Second, some methodological issues about the ICA should be considered.…”

Section: Discussionmentioning

confidence: 96%

Impaired perceptual networks in temporal lobe epilepsy revealed by resting fMRI

et al. 2009

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Viewed as a neural network disorder, mesial temporal lobe epilepsy (mTLE) may cause widespread deficits in human brain functions. Impairments in cognitive functions such as memory and language have been well addressed, but perceptual deficits have only been considered in terms of behavioral data. Little imaging research on perceptual deficits in mTLE has been reported. The present study is expected to reveal impairments in the perceptual networks in patients with mTLE using fMRI. The fMRI-based independent component analysis (ICA) was applied to 33 patients with mTLE and 33 matched healthy controls. In light of the resting-state networks (RSNs) corresponding to the basal functions of visual, auditory, and sensorimotor systems, the ICA data of functional connectivity within these RSNs were compared between the patients and controls. Compared with the controls, the mTLE patients presented decreased functional connectivity within the regions of the auditory and sensorimotor networks, as well increased functional connectivity in the primary visual cortex and decreased functional connectivity in the bilateral MT+ areas of the visual network. Our neuroimaging results are in agreement with the previous findings that specific perceptual functions are impaired in mTLE. Furthermore, our findings in the visual network support the belief that the primary visual function is not impaired and that there may be deficits in the high-order visual function in mTLE. Our fMRI study may contribute to the understanding of neuropathophysiological mechanisms underlying perceptual impairments in mTLE.

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“…Patients with epilepsy usually have visual problems that can be attributable to the pathology itself or to the drugs used to control seizures (Hilton, Cubbidge, Hosking, Betts, & Comaish, 2002;Mirabella et al, 2007;Verrotti, Manco, Matricardi, Franzoni, & Chiarelli, 2007). However, many studies have related epilepsy to visual perception, but these studies used different methodologies and samples that were poorly described only as patients with epilepsy or partial epilepsy (Hilton et al, 2002; For example, Mirabela et al (2007) developed a study that investigated visual deficits in children, with seizuretype epileptic infants either taking no medicine, receiving vigabatrin (VGB), or taking other antiepileptic drugs.…”

Section: Introductionmentioning

confidence: 99%

“…However, many studies have related epilepsy to visual perception, but these studies used different methodologies and samples that were poorly described only as patients with epilepsy or partial epilepsy (Hilton et al, 2002; For example, Mirabela et al (2007) developed a study that investigated visual deficits in children, with seizuretype epileptic infants either taking no medicine, receiving vigabatrin (VGB), or taking other antiepileptic drugs. They measured contrast sensitivity (CS) using the sweep visual evoked potential method.…”

Section: Introductionmentioning

confidence: 99%

Visual contrast sensitivity in tonic-clonic epileptic patients.

Bezerra¹,

Alencar²,

Mousinho³

et al. 2011

Psychology & Neuroscience

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We measured the effects of epilepsy on visual contrast sensitivity to linear and vertical sine-wave gratings. Sixteen female adults, aged 21 to 50 years, comprised the sample in this study, including eight adults with generalized tonic-clonic seizure-type epilepsy and eight age-matched controls without epilepsy. Contrast threshold was measured using a temporal two-alternative forced-choice binocular psychophysical method at a distance of 150 cm from the stimuli, with a mean luminance of 40.1 cd/m 2 . A one-way analysis of variance (ANOVA) applied to the linear contrast threshold showed significant differences between groups (F[3,188] = 14.829; p < .05). Adults with epilepsy had higher contrast thresholds (1.45, 1.04, and 1.18 times for frequencies of 0.25, 2.0, and 8.0 cycles per degree of visual angle, respectively). The Tukey Honestly Significant Difference post hoc test showed significant differences (p < .05) for all of the tested spatial frequencies. The largest difference between groups was in the lowest spatial frequency. Therefore, epilepsy may cause more damage to the neural pathways that process low spatial frequencies. However, epilepsy probably alters both the magnocellular visual pathway, which processes low spatial frequencies, and the parvocellular visual pathway, which processes high spatial frequencies. The experimental group had lower visual contrast sensitivity to all tested spatial frequencies.

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Patients Treated with Vigabatrin Exhibit Central Visual Function Loss

Cited by 33 publications

References 35 publications

Acute Vigabatrin Retinotoxicity in Albino Rats Depends on Light But Not GABA

Acute Vigabatrin Retinotoxicity in Albino Rats Depends on Light But Not GABA

Impaired perceptual networks in temporal lobe epilepsy revealed by resting fMRI

Visual contrast sensitivity in tonic-clonic epileptic patients.

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