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Attenuating actions of diazepam on the photomyoclonic reflex
1Neuropsychiatry Branch, National Institute of Mental Health, St. Elizabeth's Hospital, Washington, D.C. 20032.
Abstract:
The photomyoclonic reflex (PMR), consisting of a one- or two-component blink reflex associated with the flash electroretinogram (ERG), is sensitive to the acute effect of intravenously administered diazepam. In the 29% (two of seven) of normal volunteers who had a PMR, diazepam reduced it to a nonobservable level. Diazepam also had a significant attenuating effect on the a- and b-waves of the ERG; the magnitude of attenuation in normal volunteers, however, probably would not alter a clinical diagnosis based on ERG. These two findings together predict that individuals known to have a marked PMR may have the diagnostic risk associated with these specious artifacts reduced by receiving diazepam before clinical ERG studies are begun.
Insights
Diazepam effectively reduces the photomyoclonic reflex (PMR), a blink reflex variant seen during electroretinogram (ERG) testing. This intervention minimizes diagnostic artifacts in patients with a marked PMR, improving ERG study reliability.
Area of Science:
- Neuroscience
- Ophthalmology
- Pharmacology
Background:
- The photomyoclonic reflex (PMR) is a blink reflex variant observed during electroretinogram (ERG) testing.
- PMR can present as a diagnostic artifact in clinical ERG studies.
- Diazepam is known to affect neurological pathways involved in reflexes.
Purpose of the Study:
- To investigate the effect of diazepam on the photomyoclonic reflex (PMR).
- To assess the impact of diazepam on electroretinogram (ERG) waveform components.
- To determine if diazepam can mitigate diagnostic risks associated with PMR during ERG.
Main Methods:
- Normal volunteers with a photomyoclonic reflex (PMR) were administered intravenous diazepam.
- The effect of diazepam on the PMR was observed.
- The impact of diazepam on the a- and b-waves of the flash electroretinogram (ERG) was measured.
Main Results:
- Diazepam reduced the photomyoclonic reflex (PMR) to nonobservable levels in 29% of subjects.
- Diazepam significantly attenuated the a- and b-waves of the ERG.
- The degree of ERG attenuation by diazepam was unlikely to alter clinical diagnoses.
Conclusions:
- Diazepam effectively suppresses the photomyoclonic reflex (PMR).
- Pre-treatment with diazepam can reduce the risk of diagnostic errors caused by PMR in ERG studies.
- Diazepam administration is a potential strategy to improve the reliability of clinical ERG assessments in individuals with PMR.