Week 8 EP

Question 1

What is an Evoked Potential?

Answer 1

Electrical response recorded from the nervous system following a specific stimulation.

Question 2

What is the purpose of Evoked Potentials?

Answer 2

Evaluate the functional integrity of neural pathways and assist in both diagnostic evaluations and intraoperative monitoring to detect neurological dysfunction.

Question 3

What types of stimuli are used in Evoked Potentials?

Answer 3

Sensory (touch, auditory, visual) and Motor (direct cortical stimulation).

Question 4

Where are Evoked Potentials recorded from?

Answer 4

Scalp, spine, muscles.

Question 5

What do Evoked Potentials track?

Answer 5

The conduction time (latency) and signal strength (amplitude).

Question 6

What is the general methodology for Evoked Potentials?

Answer 6

Stimulation: A specific stimulus is delivered to activate neural pathways. Recording: Electrodes placed on scalp, spine, or muscles detect electrical responses. Analysis: Focuses on latency (time delay) and amplitude (signal strength) to assess nerve function.

Question 7

What does prolonged latency indicate?

Answer 7

Delayed neural response, which may indicate multiple sclerosis, spinal cord compression, or peripheral nerve damage.

Question 8

What does reduced amplitude indicate?

Answer 8

Decreased neural signal strength, which may indicate nerve damage, demyelination, or ischemia.

Question 9

What is the importance of clinical correlation in Evoked Potentials?

Answer 9

Must assess findings in context with patient symptoms, history, and other tests.

Question 10

How are Evoked Potentials used in intraoperative monitoring?

Answer 10

Used during surgery to track real-time changes and prevent nerve injury.

Question 11

What are SSEPs?

Answer 11

Somatosensory EPs that assess sensory pathways (brain, spine, nerves) and detect peripheral nerve damage.

Question 12

What is the clinical use of SSEPs?

Answer 12

Detects peripheral nerve damage (e.g. MS, spinal cord injury) and monitors spinal cord function during surgeries.

Question 13

What is the anesthesia effect on SSEPs?

Answer 13

↓ Amplitude, ↑ Latency with volatile agents/N₂O; TIVA preferred.

Question 14

What are MEPs?

Answer 14

Motor EPs that assess corticospinal motor pathways (voluntary movement).

Question 15

What is the clinical use of MEPs?

Answer 15

Diagnose motor neuron diseases, stroke recovery, and monitor motor function recovery after spinal cord or stroke.

Question 16

What is the anesthesia effect on MEPs?

Answer 16

Highly sensitive to volatiles & N2O = ↓ signal quality; TIVA preferred.

Question 17

What are BAEPs?

Answer 17

Brainstem Auditory EPs that assess auditory nerve & brainstem in response to sound.

Question 18

What is the clinical use of BAEPs?

Answer 18

Evaluate acoustic neuroma, MS, hearing issues, and anesthesia depth in high-risk patients.

Question 19

What is the anesthesia effect on BAEPs?

Answer 19

Least affected by anesthesia; deep inhalation may suppress waves.

Question 20

What are VEPs?

Answer 20

Visual EPs that assess visual pathway (eye to occipital cortex).

Question 21

What is the clinical use of VEPs?

Answer 21

Evaluate optic nerve disorders and tumors near the visual cortex.

Question 22

What is the anesthesia effect on VEPs?

Answer 22

Patients view a flashing light; responses are recorded from the occipital cortex.

Question 23

What is the effect of inhalational agents on EPs?

Answer 23

↓ Amplitude, ↑ Latency → depress EPs; avoid or limit to ≤ 0.5 MAC for SSEP.

Question 24

What is the effect of IV agents on EPs?

Answer 24

Preserves signal better → Preferred for all EPs; ideal for spinal, neurosurgical, and vascular procedures.

Question 25

What is the effect of muscle relaxants on EPs?

Answer 25

No effect on SSEPs/BAEPs; suppress MEP muscle responses → avoid/minimize use.

Question 26

What are the limitations of MEPs?

Answer 26

Most sensitive to anesthesia and muscle relaxants; hypothermia blunts waveforms.

Question 27

What factors affect the results of Evoked Potentials?

Answer 27

Age, sedation, and neuro disease.

Question 28

Why do Evoked Potentials matter?

Answer 28

Crucial for monitoring neural integrity in surgery, support diagnosis of neurologic disorders, and help prevent permanent nerve damage.

Question 29

Which evoked potential is most resistant to anesthetic suppression? A) Somatosensory Evoked Potentials (SSEPs) B) Motor Evoked Potentials (MEPs) C) Brainstem Auditory Evoked Potentials (BAEPs) D) Visual Evoked Potentials (VEPs)

Answer 29

Answer: C Rationale: BAEPs originate in the brainstem, which is more resistant to anesthetic suppression than cortical pathways.

Question 30

Which of the following best describes evoked potentials? A) Spontaneous electrical activity monitoring of the brain B) Electrical responses recorded from the nervous system after a stimulus C) Continuous monitoring of heart rate variability D) A method to measure cerebrospinal fluid pressure

Answer 30

Answer: B Rationale: Evoked potentials (EPs) measure the nervous system’s response to external stimuli, such as electrical, auditory, or visual inputs. They differ from spontaneous brain activity, which is measured by EEG.

Question 31

During neurosurgical procedures, a sudden loss of Somatosensory Evoked Potentials (SSEPs) may indicate: A) Adequate depth of anesthesia B) Ischemic injury to the spinal cord or brain C) An increase in muscle activity D) A decrease in cerebrospinal fluid (CSF) pressure

Answer 31

Answer: B Rationale: A sudden loss or significant decrease in SSEP amplitude suggests reduced blood flow or neural damage, requiring immediate surgical intervention.

Question 32

Which type of evoked potential evaluates the integrity of the sensory pathways from the periphery to the brain? A) Brainstem Auditory Evoked Potentials (BAEPs) B) Visual Evoked Potentials (VEPs) C) Somatosensory Evoked Potentials (SSEPs) D) Motor Evoked Potentials (MEPs)

Answer 32

Answer: C Rationale: SSEPs evaluate the function of the sensory pathways by stimulating peripheral nerves and recording the response at the brain and spinal cord.

Question 33

Which anesthetic management strategy is preferred when using Motor Evoked Potentials (MEPs)? A) High-dose volatile agents with deep neuromuscular blockade B) Total intravenous anesthesia (TIVA) with minimal neuromuscular blockade C) Only spinal anesthesia D) No anesthesia to allow patient movement

Answer 33

Answer: B Rationale: MEPs require intact motor pathways, so neuromuscular blockade should be minimized. TIVA (propofol and remifentanil) preserves MEP signals better than volatile agents.

Question 34

What is the primary reason Visual Evoked Potentials (VEPs) are not commonly used to assess depth of anesthesia? A) They are too resistant to anesthetic effects B) They are highly sensitive to anesthetics and easily suppressed C) They do not measure brain activity D) They require invasive procedures to record

Answer 34

Answer: B Rationale: VEPs are extremely sensitive to anesthetics, making them unreliable for routine intraoperative monitoring.