module5.5 Flashcards
when given the name of an electrode, be able to describe it,
Metal discs (silver/gold/tin) (gold plated not pure gold) can be applied to patients with
electrolyte/paste/gel held on with tape/gauze or collodion.
Needles
A made of platinum alloy or stainless steel
Caps (with gel & blunt tip)
Disposable Sticker]
Nasopharyngeal Leads (NP leads
Clips (with gel)
Tympanic (very rare)
A to be used in conjunction with NPs
B record from inferior temporal lobe next to tympanic membrane
C inserted in external auditory meatus by a doctor
Sphenoidal
A very thin like thread that is passed thru a needle
B records from inferior anterior tip of temporal lobes (doesn’t touch brain)
C like NPs, these are also used on suspected temporal lobe epilepsy patients
D inserted through zygomatic arch below the sphenoidal bone & below brain
E made of platinum & used in LTMUs
F must be inserted by a physician, it is painful & it requires local anesthesia
Indwelling (depth)
A very thin, placed in substance of brain by a surgeon
B for evaluation of surgical treatment of epilepsy
C may be in for several days to weeks
Electrocorticographic
A also called wick, grid or strip electrodes
B used for surgical treatment of epilepsy in LTMU
C 4 to 64 platinum or steel balls in holder clamped to skull
D applied and manipulated by surgeon only (after skull has been opened)
Silver Silver Chloride (Ag-Ag Cl)
A silver electrodes are dipped in a sodium chloride solution (in non metallic
container) and are attached to positive pole of battery
Plastic or disposable electrodes to be used in place of metal disks.= Web or waffle electrodes have tiny holes in them that maximize surface area &
increase pt comfort
list the advantages and disadvantages of each of the application methods,
Collodion (clear glue)
1 Advantage: most secure application especially for long term recordings,
sweaty or uncooperative patients
2 Disadvantages: obnoxious smell (smell can cause headaches),
eye and breathing protection should be worn, room should have good ventilation,
takes a little longer to apply than paste & tape & it’s
highly flammable
Tape (electrodes can also be applied with gauze or cotton balls)
1 Advantages: faster to apply than collodion
no bad smell, not flammable & good ventilation not necessary
2 Disadvantage: not as secure as collodion
Needles
Advantages: quick to apply & no electrolyte gel
Disadvantages: can carry infection & are uncomfortable to the patient
Caps (with gel & blunt tip)
A Advantages: quickest application, good for kids, combative patients or cross
training
B Disadvantages: only measures circumference & it cannot be used if pt has scalp
lesions, bandages or stitch
Disposable Stickers
A Advantages: no glue or tape, no chance of spreading infection &
no clean up
B Disadvantages: can be expensive & does not work well on hair
Nasopharyngeal Leads (NP leads): Disadvantages: uncomfortable to the patient & can cause artifacts.
Silver Silver Chloride (Ag-Ag Cl)
B Advantages: best for recording DC potentials (slow potentials like respiration),
lower polarizing potentials are obtained, the electrodes remain stable during
prolonged recordings,
they are reversible (or non-polarized which means the Cl- can move in either
direction), they have a low half cell potential & low internal resistance
C Disadvantages 1) time consuming 2) must be properly chlorided & 3) can only be
used on 3 to 4 patients then they have to be re-coated
Plastic or disposable electrodes to be used in place of metal disks. +C Advantages: 1) Some plastic and disposable electrodes are compatible with MRIs
2) Because they are thrown away after every use, you don’t have to
worry about spreading infection
D Disadvantages: It is expensive and wasteful to throw electrodes away after one
use
state the most critical link in the whole recording chain,
Electrode application is the critical link in the whole recording process
describe the difference between AC impedance and DC resistance
name the recording site used when A1 and A2 are unable to be applied,
When electrodes cannot be applied to A1 & A2 due to small ear size or artifacts, the mastoid
location (behind each ear) can be used M1 & M2.
name the recording site used in place of NP leads
Nasopharyngeal Leads (NP leads)
A made of silver with a ball at the tip
B plugs into Pg1 and Pg2
C T1 and T2 can be used instead (picture on last page)
D records from anterior mesial surface of temporal lobe & the uncus & the anterior
describe the difference in impedance between needle and disc electrodes
Needles
A made of platinum alloy or stainless steel
B inserted horizontally with beveled edge up
C have higher scalp resistance due to smaller skin contact
D after use, should be soaked in bleach then, steam autoclaved
Metal discs (silver/gold/tin) (gold plated not pure gold) can be applied to patients with
electrolyte/paste/gel held on with tape/gauze or collodion.
discuss why two different metal electrodes cannot be used on one patient
when two different metals are introduced into one channel of the EEG machine, a small
galvanic potential and an electrical current will be produced and recorded on the EEG as an
artifact
