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document
Gabapentin but not vigabatrin is effective in the treatment of acquired nystagmus in multiple sclerosis : How valid is the GABAergic hypothesis ? Acquired nystagmus occurs frequently in patients with multiple sclerosis and is often the cause of illusory motion of the environment ( oscillopsia ) , and blurring of vision . Based primarily on the beneficial effect of gabapentin on acquired pendular nystagmus ( APN ) , a GABAergic mechanism in controlling nystagmus has been hypothesised . If increasing GABA concentrations in the CNS are critical for the treatment of nystagmus , then a selective GABAergic drug should be highly successful . However , as gabapentin is not a selective GABAergic agent , vigabatrin , a " pure " GABAergic medication , and gabapentin , were compared in a single blind cross over trial in eight patients with definite multiple sclerosis . Patients were randomly assigned to begin with gabapentin ( 1200 mg daily ) or vigabatrin ( 2000 mg daily ) . Neuro-ophthalmological and electro-oculographic ( EOG ) evaluations were performed four and three times , respectively . Treatment efficacy was based on improving visual acuity and EOG indices ( amplitude or frequency of nystagmus , or both ) by at least 50 % of pretreatment values . Three out of eight patients dropped out due to adverse effects . In the remaining five patients gabapentin improved symptomatic pendular or gaze evoked jerk nystagmus in four . Three patients decided to continue gabapentin therapy . Importantly , vigabatrin proved useful in only one out of five patients , suggesting that gabapentin effectiveness may be related to additional non-GABAergic mechanisms of action . Interaction with cerebral glutamate transmission by inhibition of NMDA receptor might be an alternative hypothesis for the therapeutic action of gabapentin .
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Intervention_Pharmacological
gabapentin ( 1200 mg daily ) or vigabatrin ( 2000 mg daily )
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Outcome_Other
efficacy
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Outcome_Physical
visual acuity
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Outcome_Physical
EOG indices ( amplitude or frequency of nystagmus , or both )
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Outcome_Adverse-effects
adverse effects
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Outcome_Physical
symptomatic pendular or gaze evoked jerk nystagmus
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Participant_Condition
acquired nystagmus
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Participant_Condition
multiple sclerosis
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Participant_Sample-size
eight
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Participant_Condition
definite multiple sclerosis
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Participant_Condition
dropped out due to adverse effects
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Participant_Sample-size
Three