Practice Test Geeks(ABEM) American Board of Electrodiagnostic Medicine Practice Test
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Nerve Conduction Studies & Electromyography 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.

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  1. The blink reflex R1 response primarily assesses which pathway?

    Answer: Trigeminal sensory — facial motor via the pons (oligosynaptic)

    The R1 response is an oligosynaptic reflex traversing the trigeminal afferent and facial efferent within the pons.

  2. In a patient with suspected thoracic outlet syndrome, which NCS finding is most diagnostically helpful?

    Answer: Reduced medial antebrachial cutaneous SNAP

    Reduced medial antebrachial cutaneous SNAP amplitude reflects lower trunk/medial cord involvement characteristic of neurogenic thoracic outlet syndrome.

  3. Which feature distinguishes a fasciculation potential from a fibrillation potential on EMG?

    Answer: Fasciculations have the morphology of MUAPs and fire irregularly; fibrillations are small and fire regularly

    Fasciculations represent spontaneous discharge of entire motor units and have MUAP morphology with irregular firing; fibrillations are single muscle fiber potentials with regular firing.

  4. In Lambert-Eaton myasthenic syndrome (LEMS), high-frequency repetitive stimulation (50 Hz) or brief maximal voluntary contraction characteristically produces:

    Answer: Increment >100% in CMAP amplitude

    LEMS is a presynaptic disorder where high-frequency stimulation causes calcium accumulation and acetylcholine release, producing >100% CMAP increment.

  5. A patient has weakness and numbness in the lateral forearm after shoulder dislocation. Which nerve is most likely injured?

    Answer: Musculocutaneous nerve

    The musculocutaneous nerve innervates the biceps, coracobrachialis, and provides the lateral antebrachial cutaneous sensory nerve, commonly injured with shoulder dislocation.

  6. Electrodiagnostic criteria for Guillain-Barré syndrome (AIDP) classically include:

    Answer: Absent or prolonged F-waves, prolonged distal latencies, and reduced conduction velocities

    AIDP is a demyelinating polyradiculoneuropathy characterized by prolonged or absent F-waves, prolonged distal latencies, and reduced conduction velocities.

  7. On needle EMG, 'early recruitment' of motor units with small amplitude, short duration MUAPs is most consistent with:

    Answer: Myopathy

    Myopathies reduce the force output per motor unit, requiring early recruitment of many small MUAPs to generate adequate force.