Evoked Potentials & Late Response Studies Flashcards
7 cards from real ABEM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Evoked Potentials & Late Response Studies flashcards as text
Following median nerve stimulation, which SSEP peak represents activation at the level of the brachial plexus (Erb's point)?
Answer: N9
N9 represents the nerve action potential volley arriving at the brachial plexus, recorded from the ipsilateral supraclavicular fossa (Erb's point).
What is the primary clinical application of brainstem auditory evoked potentials (BAEPs)?
Answer: Evaluating auditory pathway integrity and detecting acoustic neuromas or brainstem lesions
BAEPs evaluate conduction through the auditory pathway from the cochlea through the brainstem, making them sensitive for acoustic neuromas and demyelinating brainstem lesions.
In pattern-reversal visual evoked potentials (VEPs), the P100 wave is generated primarily by which structure?
Answer: Primary visual cortex (occipital cortex, V1)
The P100 is a positive deflection at approximately 100 ms recorded over the occipital scalp, reflecting activation of the primary visual cortex (V1).
A unilaterally delayed P100 latency with preserved amplitude on VEP testing is most characteristic of which condition?
Answer: Multiple sclerosis with a history of optic neuritis
Demyelination of the optic nerve from multiple sclerosis characteristically prolongs the P100 latency, often with preserved amplitude, reflecting slowed rather than lost conduction.
Which wave of the brainstem auditory evoked potential (BAEP) is generated by the distal cochlear nerve?
Answer: Wave I
Wave I is generated by the distal portion of the eighth cranial nerve (cochlear nerve), representing the most peripheral auditory generator in the BAEP series.
The I-V interpeak latency in BAEP studies primarily reflects conduction through which segment?
Answer: Brainstem conduction from the cochlear nerve (Wave I) to the inferior colliculus (Wave V)
The I-V interpeak latency measures conduction time through the brainstem from Wave I (cochlear nerve) to Wave V (inferior colliculus/lateral lemniscus).
In median nerve SSEPs, which peak represents the initial cortical response recorded over the contralateral scalp?
Answer: N20
N20 is the first cortical response recorded over the contralateral somatosensory cortex (C3' or C4'), representing thalamocortical activation reaching primary somatosensory cortex.