Hypercapnic Alteration of Visual Evoked Responses in Acute Cerebral Infarction

Klassen, Arthur C.; Heaney, Lois M.; Lee, Myoung C.; Torres, Fernando

doi:10.1001/archneur.1979.00500460061008

Cited by 13 publications

(3 citation statements)

References 8 publications

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“…For P100 of VEPs, an amplitude difference of ≥50% between the two hemispheres is considered significant (7). Only one report of a single case regards the relation between visual seizures and VEPs.…”

Section: Discussionmentioning

confidence: 99%

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Hyperglycemia with Occipital Seizures: Images and Visual Evoked Potentials

Wang¹,

Hsieh

Chen³

et al. 2005

Epilepsia

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Summary:Purpose: Hyperglycemia may rarely be seen with visual seizures. Observation of both visual evoked potentials (VEPs) and magnetic resonance imaging (MRI) in visual status epilepticus (SE) has not been reported. We describe acute and follow-up VEP and MRI findings of a patient with hyperglycemia-related visual SE of occipital origin.Methods: In a 59-year-old diabetic woman, complex visual hallucinations and illusions developed with ≤10 seizures per hour as an initial manifestation of nonketotic hyperglycemia.Results: Neurologic examination revealed ictal nystagmus to the right and continuous right hemianopsia. Ictal electroencephalography (EEG) and Tc-99m hexamethylpropylene amine oxime (HMPAO) single-photon emission computed tomography (SPECT) revealed an epileptogenic focus in the left occipital lobe. MRI with fluid-attenuated inversion recovery showed focal subcortical hypointensity and gyral hyperintensity. Followup MRI showed only minimal gyral hyperintensity at 6 months. The P100 amplitude of VEP was significantly higher at the right occipital area during SE, but slightly higher on the left after the patient had been seizure free for 6 months.Conclusions: Occipital seizures and hemianopsia can be caused by hyperglycemia and may be accompanied by special MRI and VEP findings. Key Words: Nonketotic hyperglycemia-Hemianopsia-Visual evoked potentialsMagnetic resonance imaging.Nonketotic hyperglycemia (NKH) is a clinical syndrome consisting of severe hyperglycemia, hyperosmolality, and intracellular dehydration without ketoacidosis. Only a few cases of NKH-related occipital visual seizures have been reported (1-4).Partial status epilepticus (SE) can be defined as (a) >30 min of abnormal neurologic function at the time of EEG, and (b) at least two discrete EEG seizures or continuous rapid (≥1.5 Hz) epileptiform discharges (5).Observation of both visual evoked potential (VEP) and magnetic resonance imaging (MRI) abnormalities in hyperglycemia-related visual SE has never been reported. We describe immediate and follow-up VEP and MRI findings of a patient with visual SE due to NKH.

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Section: Discussionmentioning

confidence: 99%

“…B: The P100 amplitude was slightly higher on the left side (O1) when the patient was seizure free for 6 months and with no hemianopsia. (7). Only one report of a single case regards the relation between visual seizures and VEPs.…”

Section: Discussionmentioning

confidence: 99%

Hyperglycemia with Occipital Seizures: Images and Visual Evoked Potentials

Wang¹,

Hsieh

Chen³

et al. 2005

Epilepsia

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“…VEPs are used extensively for assessing visual pathways. They can be used to distinguish normal brain from ischemic brain [ 9 10 ]. The range of disorders that may affect VEPs is vast, including multiple sclerosis, trauma, tumors, and stroke [ 11 ].…”

Section: Discussionmentioning

confidence: 99%

Visual Evoked Potential Using Head-Mounted Display Versus Cathode Ray Tube: A Pilot Study

Choi

Kim

et al. 2016

Ann Rehabil Med

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ObjectiveTo present a new stimulation method based on the use of a head-mounted display (HMD) during pattern reversal visual evoked potential (PR-VEP) testing and to compare variables of HMD to those of conventional cathode ray tube (CRT).MethodsTwenty-three normal subjects without visual problems were recruited. PR-VEPs were generated using CRT or HMD stimuli. VEP outcome measures included latencies (N75, P100, and N145) and peak-to-peak amplitudes (N75–P100 and P100–N145). Subjective discomfort associated with HMD was determined using a self-administered questionnaire.ResultsPR-VEPs generated by HMD stimuli showed typical triphasic waveforms, the components of which were found to be correlated with those obtained using conventional CRT stimuli. Self-administered discomfort questionnaires revealed that HMD was more comfortable in some aspects. It allowed subjects to concentrate better than CRT.ConclusionThe described HMD stimulation can be used as an alternative to the standard CRT stimulation for PR-VEPs. PR-VEP testing using HMD has potential applications in clinical practice and visual system research because HMD can be used on a wider range of subjects compared to CRT.

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Left-right asymmetry of visual evoked potentials in brain-damaged patients: A mathematical model and experimental results

et al. 1995

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The left-right asymmetry in the potential amplitude on the scalp was studied in poststroke patients by using flash visual evoked potential (VEP) and a numerical two-dimensional model of the head. The left-right asymmetry of the VEP was measured in three patients after thrombosis, in one after hemorrhage, and in one healthy subject. The numerical model used computed tomography images to define the different compartments of the head. The volume conductor equation for the potential distribution created by a dipole source in the occipital region was solved numerically with use of a finite volume method. Left-right asymmetry was calculated with several values of conductivity of the damaged region. The experimental results revealed a negative asymmetry in the three patients after thrombosis (i.e., the potential amplitude over the ischemic hemisphere was smaller than that over the intact hemisphere), whereas, in the patient after hemorrhage, a positive asymmetry was found. Nonsignificant left-right asymmetry was found in the healthy subject. The numerical model revealed that the electrical conductivity of the damaged tissue has a major effect on the left-right asymmetry. Negative asymmetry, such as that found for patients after thrombosis, was obtained when the conductivity of the damaged region was greater than that of the brain, whereas positive asymmetry (hemorrhage patient) was obtained when that conductivity was smaller than that of the brain. This finding indicates that the left-right asymmetry in the scalp VEP of patients after brain damage may be a result of changes in the conductivity of the volume conductor (the ischemic region) between the source and the electrodes.

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Hypercapnic Alteration of Visual Evoked Responses in Acute Cerebral Infarction

Cited by 13 publications

References 8 publications

Hyperglycemia with Occipital Seizures: Images and Visual Evoked Potentials

Hyperglycemia with Occipital Seizures: Images and Visual Evoked Potentials

Visual Evoked Potential Using Head-Mounted Display Versus Cathode Ray Tube: A Pilot Study

Left-right asymmetry of visual evoked potentials in brain-damaged patients: A mathematical model and experimental results

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