EEG Basics
International 10-20 system
> nasion & inion
> LORE system - left is odd, and right is even
How to place a routine EEG
- paper rule for 10-20 system
- mark w/ the pen the locations
- cotton swab to open the hair, place the gel, and place the paste, and last the sticker
> gel is nuprep (green); pasta is ten20
- start by middle back going to the front, then place the right, and after the left, and by last the ECG
- take the leads from near the machine, and follow to the end of the lead
- look at the monitor needs to turn green in machine
- last two leads are cardiac, one on each side of the thorax
- considerations
> can wrap the head, if the leads fall off; can wrap two times if needed
> can place the leads together near and distal, and place a wrap in all the cables
> eyelids leads are localized at sides
How to do a routine EEG
- calibrate the machine, and test impedance
- ask to open and close eyes
- ask orientation questions like the MMSE
- calm background sound to sleep, especially for kids
- photic stimulation, which does different photic frequencies, with eyes open and close
- channel test at the end
- remove leads with water
- considerations:
> all the modifications and patient positions should be described in the reading
Differences in home LTM EEG
- leads
> no eyelid leads or Fpz lead
> x1-x2 are ECG leads
> gel, paste, glue, and pressurized air
> to remove the leads you need the remover
- ground-ref: can be placed at any spot, usually on forehead
- RULL system: right lead is up, and left lead is low
- needs a backpack and a battery
- before patient leave, do a 30 minutes monitoring
- look at the machine, should be green, and blinking yellow
Cable length
- rEEG: 40 cm; home LTM EEG: 60 cmTypes of monitoring
- routine EEG (30 min)
- continuous EEG inpatient
- continuous EEG inpatient (EMU)
> look at LTM order about what to do
> CBC & BMP at arrival
> it is not a real admission, but it can be converted
- continuous EEG outpatient at home
Mechanism
- differential amplifier
- EEG is always relative
Montages
- channels; a mix of channels is called a chain
- average is used to look at where is coming the spike
- pediatric montages:
> double-banana peds
> reference peds
> trans peds
- adult montages:
> double-banana peds
> reference peds
> transversal (PFOT) peds
- other montages:
> bipolar montage
> common average reference montage