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Discrepancies between CT and EEG findings after acute cerebrovascular disease
M Knibestöl1, E Hägg, B Liliequist
1Department of Clinical Neurophysiology, University Hospital, Umeå, Sweden.
Insights
Electroencephalography (EEG) and CT scans after stroke revealed discrepancies. Abnormal EEG with normal CT may indicate internal carotid occlusion, warranting further investigation.
Area of Science:
- Neurology
- Neurophysiology
Background:
- Stroke is a leading cause of disability, and accurate diagnosis is crucial for effective treatment.
- Electroencephalography (EEG) and computed tomography (CT) are common neuroimaging modalities used in stroke assessment.
- Discordant findings between EEG and CT can complicate diagnosis and treatment planning.
Purpose of the Study:
- To evaluate the utility of combined EEG and CT in the early post-stroke period.
- To investigate the significance of discrepant findings between EEG and CT in stroke patients.
- To explore the potential of EEG in identifying surgically treatable conditions like internal carotid occlusion.
Main Methods:
- A cohort of 33 patients underwent combined EEG and brain CT examinations within the first two weeks post-stroke.
- Abnormalities in both EEG and CT were systematically recorded and compared.
- Specific attention was given to cases with normal CT findings but abnormal EEG results.
Main Results:
- CT was abnormal in 51% of patients, while EEG was abnormal in 72%.
- Conflicting results were observed in 17 patients (51%).
- Notably, 12 patients had normal CT but abnormal EEG, with 5 of these showing prominent unilateral EEG abnormalities.
Conclusions:
- EEG may provide valuable diagnostic information when CT findings are negative or inconclusive after stroke.
- A prominent unilateral EEG abnormality in the context of a normal CT scan should prompt further investigation for internal carotid occlusion.
- Consideration of angiography in such cases could lead to the identification of surgically treatable cerebrovascular conditions.
Abstract:
Combined EEG and brain CT examinations were performed in 33 patients during the 1st and 2nd week after stroke. CT was abnormal in 17 patients (51%) and EEG was abnormal in 24 patients (72%). In 17 patients CT and EEG showed conflicting results; in 5 patients with normal EEG findings CT was pathological, and 12 patients had normal CT but pathological EEG findings. In this latter group, there were 5 particularly interesting cases with normal CT and a prominent unilateral EEG abnormality. Recently patients with this combination of findings have been described where further investigations disclosed internal carotid occlusion, which could be treated surgically. It is suggested that EEG should be more extensively used when CT findings are negative after stroke, and if a major unilateral EEG abnormality is encountered in such cases, further investigations with angiography should be considered in order to exclude surgically treatable internal carotid occlusion.