Aud 275 Niom

Front 1

Beta

Back 1

13-30 Hz
Seen as a drug affect
Predominately seen in frontal regions

Front 2

Alpha

Back 2

8-13 Hz
Seen in an awake, but relaxed/eyes closed patient
Predominately seen in occipital regions

Front 3

Theta

Back 3

4-8 Hz
Seen in an awake, but drowsy patient (Versed)

Front 4

Delta

Back 4

0.1-4 Hz
Seen in asleep patients (normal sleep or under anesthesia)

Front 5

EEG features

Back 5

Amplitude, frequency, symmetry.

Front 6

EEG is viewed as

Back 6

Raw data or in a power spectrum plot such as CSA or DSA.

Front 7

Electroencephalography

Back 7

Provides a quantitative measure of the spontaneous electrical activity of the brain (CNS). Obtained by surface electrodes on the scalp. Changes in this activity can signal negative changes to the structural and functional integrity of the neural pathways to which these generators belong.

Front 8

EEG recording settings

Back 8

Bandwidth:
Low-pass filter set to 1 Hz.
High-pass filter set to 30 Hz.
Time base:
5-10 seconds.

Front 9

Rational for IOM

Back 9

An effective way to monitor the patients functional integrity during surgery to ensure the patient woes up better than when they went into surgery.

Front 10

The four regions of the spine and the number of nerve roots associated with each

Back 10

Cervical - 8 nerve roots
Thoracic - 12 nerve roots
Lumbar - 5 nerve roots
Sacral - 5 nerve roots

Front 11

The importance of SSEPs and when they are collected

Back 11

To be able to monitor for changes. Should be taken before surgery.

Front 12

Impact of hypothermia on EEG

Back 12

Refers to body temperatures below 35°C. Reduction in frequency seen as body temperature is lowered, followed by amplitude reduction. Burst suppression begins at ~26°C. Isoelectricity seen in extreme hypothermia (< 20°C).

Front 13

Impact of hypercarbia on EEG

Back 13

Refers to increased levels of CO2 often due to hypoventilation. Reduction in EEG frequency secondary to decreased cerebral profusion.

Front 14

Impact of hypotension on EEG

Back 14

Refers to reduced blood pressure. Reduction in EEG frequency when cerebral perfusion pressure drops below 50 mmHg.

Front 15

EEG use for NIOM

Back 15

Monitor for affects of ischemia
–Carotid endarterectomy
–Aneurysm clipping
–Arteriovenous malformation resection
Determining depth of anesthesia

Front 16

Why monitor EMG

Back 16

Spontaneous EMG (sEMG) monitoring is used to protect both cranial and spinal nerves from injury due to
–excessive retraction
–manipulation that would cause mechanical, thermal or electrical irritation
–unintended dissection
This is the one modality where no response or a “quiet” recording is a good thing.

Front 17

When is EMG used?

Back 17

Anytime nerve or nerve roots are at risk. Anytime spinal cord is at risk.

Front 18

How is EMG tested?

Back 18

Needles are placed in muscle of interest in 1 of 2 recording paradigms:
Monopolar Recordings
–Active electrode placed in the belly of the muscle
–Reference electrode placed elsewhere (e.g., in the distal tendon, in contralateral cheek, etc.)
–Less specificity
Bipolar Recordings
–Both electrodes are placed in the belly of the muscle
–More specificity of muscle and associated nerve root
Need to ensure that both needles are placed in an orientation consistent with how the muscle contracts.

Front 19

Anesthetic consideration for EMG

Back 19

When utilizing EMG as a modality, it is critical to know if patient is pharmacologically ‘relaxed’ or not.
To determine level of relaxation, Train-of-Four (TOF) testing is completed
–Stimulation delivered to SSEP stim site (e.g., ulnar)
–Motor responses measured off of adjacent muscle (e.g., APB)
Number of measured twitches is an indicator of the depth of paralysis:
0/4 = full relaxation
4/4 = no paralysis

Front 20

When is sEMG monitored?

Back 20

During any surgeries when cranial nerves are at risk, such as:
–posterior fossa tumors (ANs, meningiomas)
–skull base tumors
–microvascular decompression

Front 21

Four functions of the nervous system

Back 21

•Gathers information (sensory)
•Transmits information to the processing area of the brain and spinal cord
•Processes that information
•Organizes response via muscles, glands, and organs (Motor)

Front 22

Role of the dorsal root of the spinal cord

Back 22

Carry messages to CNS

Front 23

Role of the ventral root of the spinal cord

Back 23

Carry messages to muscles and glands

Front 24

Longitudinal fissure

Back 24

Separates the right and left cerebral hemispheres

Front 25

Transverse fissure

Back 25

Separates the cerebral hemisphere from the cerebellum inferiorly

Front 26

Brocas area

Back 26

Anterior to the inferior region of the premotor cortex. Motor speech area for language production (left hemisphere)

Front 27

Wernicke's area

Back 27

Recognizing spoken words

Front 28

Midbrain

Back 28

–Rostral brainstem
–Contains cranial nerves III and IV
–Contains cerebral peduncles (the pyramidal motor tracts descending to the spinal cord)

Front 29

Pons

Back 29

–Between midbrain and medulla
–Contains cranial nerves V, VI, and VII

Front 30

Medulla

Back 30

–Caudal brainstem (blends into the spinal cord at the level of the foramen magnum)
–Contains cranial nerves VIII, IX, X, XI, XII
–Pyramidal motor tracts (MEP) cross over (decussate) to the opposite side of the brain at the junction of the caudal medulla in the brainstem and spinal cord
–Medial lemniscus sensory tract (SEP) cross over (decussate) to the opposite side of the brain at the level of the medulla.
•Note: Nucleus gracilis and nucleus cuneatus are part of this tract in the medulla. Nucleus gracilis receives sensory information from the lower extremities and nucleus cuneatus receives sensory information from the upper extremities.

Front 31

Cerebellum

Back 31

•The cerebellum is located dorsal to the pons and medulla separated by the fourth ventricle
•The cerebellum smoothes and coordinates body movements
•Maintains posture and equilibrium

Front 32

Spinal cord

Back 32

•The spinal cord begins at the foramen magnum at the base of the skull where the medulla ends
•The spinal cord terminates at the level of L1 or L2
•At the inferior end, the spinal cord tapers into the conus medullaris (the cone of the spinal cord)
•The conus medullaris then tapers into a long filament of connective tissue called the filum terminal
•The filum terminal attaches inferiorly to the coccyx. This anchors the spinal cord in place.

Front 33

Kyphosis

Back 33

A curvature in the saggital plane with anterior concavity (concavity toward the front) The spine had a thoracic and sacral kyphosis.

Front 34

Lordosis

Back 34

A curvature in the saggital plane with posterior concavity (concavity towards the back). The spine has a cervical and lumbar lordosis.

Front 35

Sensitivity

Back 35

True positive rate

Front 36

Specificity

Back 36

True negative rate

Front 37

Artifactual changes can happen due to

Back 37

Electrical noise, changes in anesthesia regime, interference from extraneous neurophysiological activity, equipment failure.

Front 38

Equipment that prevents monitoring

Back 38

Bovie: electrocautery device.
Cusa: debulge tumors by pulsating water at ultrasonic frequencies.

Front 39

Other noise producing equipment

Back 39

Bare hugger: patient warmer.
Cell saver: recycles patient blood lost during surgery.
Fluid warmers
Microscope
Surgeons head lights

Front 40

Artifacts

Back 40

Changes in anesthesia regime, blood pressure, and body temperature.