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Epileptic negative myoclonus in herpes simplex virus encephalitis Volume 24, numéro 2, April 2022

Figure 1

(A) Brain MRI, DWI axial (Day 4) showing diffusion restriction in the left temporo-insular area (red circle). (B) Brain MRI, FLAIR axial (Day 12) showing hyperintensity in the left temporal and insular areas (red arrows) and a subtle hyperintensity in the left thalamus (red circle).

Figure 2

(A) EEG covering the left parasagittal derivation showing LPDs time-locked with the silent periods seen at EMG electrodes covering right biceps (BB1-BB2; pink color) and right triceps (TR1-TR2; blue color). EMG electrodes covering the left biceps (BB1-BB2; green color) and left triceps (TR1-TR2; orange color) do not show any interruption in tonic muscle activity. (B) EEG covering the left parasagittal derivation showing LPDs time-locked with the silent periods seen at EMG electrodes covering bilateral biceps and triceps. (C) Magnified view of the recording in (B) showing the relationship between the maximum negativity of the LPDs and the corresponding silent periods in left and right arms. The silent periods in the right biceps and triceps are more robust and longer compared to the left. (D) Back-averaged tracing of EEG (upper tracing in blue) and right arm EMG (lower tracing in orange) showing an approximate latency of 55-60 ms (obtained using BacAv, free online platform).