What is Encephalitis?

Inflammation of the brain

a diffuse (wide spread/to become widely dispersed) infection involving the cerebral hemispheres & at times the pons & cerebellum

Fundamentals of EEG Technology vol 2, page 200

Usually caused by a virus.

measles, mumps, viral meningitis & herpes simplex,

mosquito-bourne virus such as western equine

or

slow virus such as SSPE (Subacute sclerosing panencephalitis) & Creutzfeldt-Jakob disease 

Fundamentals of EEG Technology vol 2, pg 200 & 202

Illness usually begins w/fever, headache & malaise.

These are followed by lethargy, which progresses to coma.

Fundamentals of EEG Technology vol 2, page 202

Excessive Slow Activity

(usually commensurate w/the clinical signs)

Seizures, if they occur, have correlated epileptiform activity

PLEDs may appear unilaterally or bilaterally between the 2nd & 5th day of the illness

Fundamentals o0f EEG Technology vol 2, pg 202

Focal Seizures

are also known as?

partial seizures

http://encyclopedia.thefreedictionary.com/focal+seizures

simple partial & complex partial

http://encyclopedia.thefreedictionary.com/focal+seizures

a larger seizure such as a complex partial seizure or a tonic-clonic seizure. When this occurs the simple partial seizure is usually called an aura

http://encyclopedia.thefreedictionary.com/focal+seizures

Temporal Lobe Epilepsy

http://encyclopedia.thefreedictionary.com/focal+seizures

periodic bursts of high-voltage sharp & slow wave or slow wave activity, each lasting 1-2sec & occurring periodically at an interval of 5 to 15sec. The bursts are stereotyped in appearance.

Fundamentals of EEG Technology vol 2, pg 202

from human to animal and from human to human

Fundamentals of EEG Technology vol 2, pg 202

it is used because the incubation period for these viruses is measured in years rather than days or weeks

Fundamentals of EEG Technology vol 2, pg 202

begins w/the clinical picture of a personality change followed by progressive dementia

Death occurs in 3 to 12months

Fundamentals of EEG Technology vol 2, pg 202

EEG shows slower than normal activity, w/loss of normal background

Fundamentals of EEG Technology vol 2, pg 202

SSPE

Subacute sclerosing panencephalitis (slow virus disease)

Fundamentals of EEG Technology vol 2, pg 202

bursts of moderate voltage biphasic & triphasic sharp waves

becoming increasing periodic, at intervals of 2 to 1 or less than 1 per sec.

The sharp waves may be slightly more prominent over one hemisphere

Fundamentals of EEG Technology vol 2, pg 202

bacteria & is almost always secondary to an infection elsewhere in the body, particularly the nasal sinuses, the mastoid air cells, or the teeth.

The lung is also a source of infection & brain abscesses are common in pt's w/cyanotic heart disease

Fundamentals of EEG Technology vol 2, pg 200

A brain abscess is most like a

________  ________,

where it is a space-occupying lesion & compresses the brain.

brain tumor.

(It causes headaches, alterations in consciousness & depending on location, focal neurological signs)

Fundamentals of EEG Technology vol 2, pg 200

The EEG is abnormal in nearly all pt's w/ brain abscess involving what hemispheres?

&

What do you generally see in the EEG?

the cerebral hemispheres

 &

usually there is focal, continuous, polymorphic delta activity.

Background rhythms usually are effected (i.e. voltage & frequency)

Fundamentals of EEG Technology vol 2, pg 200

a collection of pus, usually of bacterial origin, between the dura & the arachnoid

it has the shape & distribution of a subdural hematoma

since the infection is outside of the brain, disturbances of consciousness are more prominent than disturbances of focal neurological function - it is d/t increased intracranial pressure that compromises midbrain function

Fundamentals of EEG Technology vol 2, pg 200

is probably* the collective activity of many nerve cells in a small area under each electrode.

*Knowledge & understanding of how the potentials responsible for these wavy lines are generated is incomplete

Fundamentals of EEG Technology vol 1, pg 1

outer surface of the brain

Fundamentals of EEG Technology vol 1, pg 1

neurons

Fundamentals of EEG Technology vol 1, pg 1

ability to evaluate physiological disturbances of brain function not associated w/structural lesions

Fundamentals of EEG Technology vol 1, pg 5

Jacks into which the pins are inserted have either

__________________

or

__________________

identifications

numerical

or

anatomical

Fundamentals of EEG Technology vol 1, pg 9

a derivation

Fundamentals of EEG Technology vol 1, pg 9

The order in which the derivations are selected will determine the electroanatomical picture of the brain that will be displayed by the EEG instrument.

Such an arrangement of derivations is called?

a montage

Fundamentals of EEG Technology vol 1, pg 9

approximately one million times

Fundamentals of EEG Technology vol 1, pg 10

microvolts (μV) of input required to produce 1 millimeter (mm) of pen deflection at the output

Fundamentals of EEG Technology vol 1, pg 11

decimal system

Fundamentals of EEG Technology vol 1, pg 17

the centimeter

Fundamentals of EEG Technology vol 1, pg 17

seconds

Fundamentals of EEG Technology vol 1, pg 17

centimeters (cm) & millimeters (mm)

Fundamentals of EEG Technology vol 1, pg 17

it discharges to an area of lower charge

Fundamentals of EEG Technology vol 1, pg 27

like charges repel

if 2 paper balls are charge by contact with the same source, they will fly apart when placed next to each other

Fundamentals of EEG Technology vol 1, pg 27

unlike charges attract

Fundamentals of EEG Technology vol 1, pg 27

direct current (DC)

Fundamentals of EEG Technology vol 1, pg 28

alternating current (AC)

Fundamentals of EEG Technology vol 1, pg 28

1/60sec

Fundamentals of EEG Technology vol 1, pg 28

an atom

Fundamentals of EEG Technology vol 1, pg 31

a nucleus made up of protons & neutrons, surrounded by numerous orbiting electrons

Fundamentals of EEG Technology vol 1, pg 31

protons

Fundamentals of EEG Technology vol 1, pg 31

Hydrogen (H)

Fundamentals of EEG Technology vol 1, pg 31

uranium (U)

(92 electrons)

Fundamentals of EEG Technology vol 1, pg 33

when 2 or more elements are combined

Fundamentals of EEG Technology vol 1, pg 33

protons

Fundamentals of EEG Technology vol 1, pg 33

electrons

Fundamentals of EEG Technology vol 1, pg 33

conductors

Fundamentals of EEG Technology vol 1, pg 34

ampere (A)

the magnitude of current is determined by the rate, in time, of electron flow past a given point

Fundamentals of EEG Technology vol 1, pg 34

silver (Ag)

copper (Cu)

gold (Au)

platinum (Pt)

tin (Sn)

iron (Fe)

Fundamentals of EEG Technology vol 1, pg 35

ohm (Ω-Greek letter omega)

Fundamentals of EEG Technology vol 1, pg 35

Insulators are materials which, even when subjected to strong electrical forces, will not readily give up electron.

List insulators

glass

porcelain

rubber

many forms of plastic compounds

air (but if electrical force is very strong, current will flow through it & a spark will occur)

Fundamentals of EEG Technology vol 1, pg 35

volt (V)

Fundamentals of EEG Technology vol 1, pg 35

the ohm (R)

Fundamentals of EEG Technology vol 1, pg 35

the ampere (A)

Fundamentals of EEG Technology, vol 1, pg 35

Voltage (E) is equal to current (I) flowing in the circuit multiplied by resistance (R) in the circuit

E= I x R

if any 2 of the 3 variables are known, the other can be determined

I= E/R

the current (I) flowing in the circuit = the voltage (E) ÷ by the resistance (R)

R= E/I

the resistance (R) = the voltage (E) applied ÷ by the current (I)

Fundamentals of EEG Technology, vol 1, pg 35

one one-millionth

(this is the commonest voltage measure in EEG)

Fundamentals of EEG Technology, vol 1, pg 37

this will effect impedance, reduce effective surface area & create an unstable battery effect, thus increasing noise at the amplifier input

Fundamentals of EEG Technology, vol 1, pg 132

wires may become fractured by mechanical stresses results will be massive noise artifact at the input to the amplifier

Fundamentals of EEG Technology, vol 1, pg 132

nasion (at the front of the head)

inion (at the back of the head)

if the location of the inion in not obvious-ask pt to tilt head backward

L & R preauricular

(felt as the depression at the root of the zygoma, just anterior to the tragus)

have the pt open mouth slightly

anterior: in front of

Fundamentals of EEG Technology, vol 1, pg 136

if it necessary to change the  placement of an electrode over 1 hemisphere, the corresponding electrode over the opposite hemisphere should be changed to maintain symmetry.

When repositioning involves a change of considerable distance, it may be better to add an electrode on the contralateral side, matching the displaced electrode.

Whenever electrodes are placed in locations other than those established by the ten-twenty system-diagrams, notations & measurements should be written on the EEG record to indicate the changes.

Fundamentals of EEG Technology, vol 1, pg 144

in practice you draw a line from auditory meatus to outer canthus 1/3 the distance out & 1cm directly above

Fundamentals of EEG Technology, vol 1, pg 144

Amplifiers used for EEG recording are

______________ amplifiers.

differential

 Each channel is a recording of the difference in voltage between the electrode selected for Input Terminal 1 & the voltage at the electrode selected  for Input Terminal 2 of the amplifier

Fundamentals of EEG Technology, vol 1, pg 146

it follows that 1 electrode is either more negative or more positive than the other electrode

Fundamentals of EEG Technology, vol 1, pg 146

0

Fundamentals of EEG Technology, vol 1, pg 146

Input 1 is more negative than Input 2

Fundamentals of EEG Technology, vol 1, pg 146

a single pair of electrodes inputting an amplifier (forms a derivation)

Fundamentals of EEG Technology, vol 1, pg 160

bipolar recording & referential recording

Fundamentals of EEG Technology, vol 1, pg 160

A1 & A2

L hemisphere derivations usually use A1 as a reference &

R hemisphere derivations use A2

Fundamentals of EEG Technology, vol 1, pg 164

downward

Fundamentals of EEG Technology, vol 1, pg 146

invalid

Fundamentals of EEG Technology, vol 1, pg 164

this occurs when the inferior midtemporal area of the brain is the focal region

Fundamentals of EEG Technology, vol 1, pg 164

it would be difficult to untangle the puzzle of phase reversals & to discover the real source of the activity, which appears in all channels but is local to one

Fundamentals of EEG Technology, vol 1, pg 164 & 165

Cz reference

Fundamentals of EEG Technology, vol 1, pg 165

because of glossokinetic potentials

Fundamentals of EEG Technology, vol 1, pg 165

tongue, like the eye is electrically charged,  & function like a dipole

(emedicine.com-eeg art)

~

the tip of the tongue is more negative than the root-these are charged like a battery

~

the tongue has a broad potential field that drops from frontal to occipital areas

(emedicine.com-eeg art)

~

the artifact produced by the tongue has a broad potential field that drops from frontal to occipital areas

~

mvt of the tongue can cause single or rhythmic slow waves that are seen predominantly in the temporal regions but can be seen in other areas

You can reproduce this art by asking pt to say "lilt", "light", "long", or "large"

~

Chewing & sucking can produce such art

~

The artifact may be monitored by placing an electrode on the cheek or near the mouth

Fundamentals of EEG Technology vol 1, pg 294

the base of the skull or high cervical (neck) point

this point may be very effective if there is no large signals in the occipital area or no activity is generated by neck muscles

Fundamentals of EEG Technology vol 1, pg 165