Mid Latency Potential

Question 1

What is a normal AMLR response (3)

Answer 1

1. 15ms-100ms
2. Repeatable wave
3. Interpretation is based on interaural differences (latency, amplitude and morphology)

Question 2

What are the advantages over ABR (3)

Answer 2

1. ABR requires sychronised neuraual firing
2. Not syncronising is required - can be used under anesthetic
3. Better on low frequencies

Question 3

What is the primary site of generations

Answer 3

Tests up to the auditory cortex

Question 4

What are the major troughs

Answer 4

Na (sub-cortical inferior colliculus)-Nb

Question 5

What are the major peaks

Answer 5

Pa (primary auditory cortex) -Pb

Question 6

What are the normal ranges for Pa waves

Answer 6

15-30 ms

Question 7

Clinical applications of AMLR (3)

Answer 7

1. Establish electrical thresholds
2. Monitoring cortical function (intra-operative)
3. Assesses 500-1kHz

Question 8

What is habituation

Answer 8

Inhibition in the presence over repetitive stimulation

Question 9

What are the disadvantages of MLR

Answer 9

Pb amplitude decreases with repetitive auditory stimulation - sensory gating

Question 10

Disorders related to MLR (6)

Answer 10

1. Alzheimers (abnormal Pb)
2. Autism (abnormal Pb)
3. Down Syndrome (Na)
4. Parkinson’s (abnormal Pb)
5. Stuttering (abnormal Pb)
6. CAPD - Abnormal MLR

Question 11

What are MLR measured in

Answer 11

Nano-volts

Question 12

AMLR generator sites

Answer 12

AMLR represent dendritic neural activity [versus axonal neural activity