Monitoring Neurological Injury by qEEG - Quantitative EEG Analysis Methods and Clinical Applications - page 177

1

Gamma

0

Rat #6 (NDS:59) Rat #1 (NDS:46)

1 Beta

0

Alpha

1

0

Theta

1

0

Delta

1 1

0 0

0 1 2 3 4

Figure 7.5 Subband information quantity (SIQ) of rat #1 (NDS: 46) and rat #6 (NDS: 59) for five
clinical bands: gamma ( 30 Hz), beta (16-30 Hz), alpha (8-15 Hz), theta (4-8 Hz), delta ( 4 Hz). > <

( From: [71]. © 2008 IEEE. Reprinted with permission.)

entropy subband analysis is analogous to how EEG is analyzed and interpreted by
looking for power in different spectral subbands ( δ , θ , α , β ).

7.4 Experimental Methods

The experiments reported in this chapter were carried out on rodents. Global
ischemic brain injury and hypothermic neuroprotection response were evaluated.
EEG recording was done using a conventional monitoring technique involving scalp
electrodes, signal amplification and acquisition, and eventual qEEG evaluation. In a
typical experiment, EEG epidural screw electrodes (Plastics One, Roanoke, Vir-
ginia) were implanted 1 week before the experiment. Two channels of EEGs were
recorded in the right and left parietal areas throughout the experiment using the
DI700 Windaq system. Using stereotactic guidance, electrodes were placed 2 mm
lateral to and 2 mm anterior or posterior to the bregma. A ground electrode was
placed 2 mm posterior to the lambda in the midline. Recording was continued
throughout the hypothermia treatment and during the rewarming periods and the
recovery hours. Serial 30-minute EEG recordings were also done in free-roaming,
unanesthetized rats at 24, 48, and 72 hours after return of spontaneous circulation
(ROSC). Two-channel EEG signals were recorded and analyzed.
After CA in humans and various animal models, several common EEG patterns
are seen that may be predictive of poor neurological recovery including generalized
EEG suppression, persistent burst suppression, generalized unreactive α or θ activ-