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Abstract
Objective To investigate the correlation between characteristics of lateralized periodic discharges (LPDs) and glucose metabolism measured by 18F-fluorodeoxyglucose (FDG)–PET.
Methods We retrospectively reviewed medical records to identify patients who underwent FDG-PET during EEG monitoring with LPDs present during the FDG uptake period. Two blinded board-certified neurophysiologists independently interpreted EEGs. FDG uptake was measured using standardized uptake value (SUV). Structural images were fused with PET images to aid with localization of SUV. Two PET readers independently measured maximum SUV. Relative SUV values were obtained by normalization of the maximum SUV to the SUV of pons (SUVRpons). LPD frequency was analyzed both as a categorical variable and as a continuous measure. Other secondary variables included duration, amplitude, presence of structural lesion, and “plus” EEG features such as rhythmic or fast sharp activity.
Results Nine patients were identified and 7 had a structural etiology for LPDs. Analysis using frequency as a categorical variable and continuous variable showed an association between increased LPD frequency and increased ipsilateral SUVRpons (p = 0.02). Metabolism associated with LPDs (0.5 Hz as a baseline) increased by a median of 100% at 1 Hz and for frequencies >1 Hz increased by a median of 309%. There were no statistically significant differences in SUVRpons for other factors including duration (p = 0.10), amplitude (p = 0.80), structural etiology (p = 0.55), or “plus” features such as rhythmic or fast sharp activity (p = 0.84).
Conclusions Metabolic activity increases monotonically with LPD frequency. LPD frequency should be a measure of interest when developing neuroprotection strategies in critical neurologic illness.
Glossary
- FDG=
- 18F-fluorodeoxyglucose;
- LPD=
- lateralized periodic discharge;
- ROI=
- region of interest;
- SUV=
- standardized uptake value;
- SUVmax=
- highest standardized uptake value;
- SUVR=
- relative standardized uptake value;
- SUVRcontra=
- relative standardized uptake value of the contralateral homologous region;
- SUVRpons=
- relative standardized uptake value of the pons
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received March 11, 2018.
- Accepted in final form November 14, 2018.
- © 2019 American Academy of Neurology
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