ABPN Clinical Neurophysiology flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Alpha rhythm frequency

Posterior dominant rhythm of 8-13 Hz seen in relaxed wakefulness with eyes closed; attenuates with eye opening and is the principal marker of normal cortical reactivity.

N2 sleep spindles

Bursts of 11-16 Hz activity lasting at least 0.5 seconds, often with K-complexes; their presence defines stage N2 sleep in a 30-second epoch.

N3 delta criteria

Slow waves of 0.5-2 Hz with peak-to-peak amplitude greater than 75 microvolts occupying more than 20 percent of a 30-second scoring epoch.

Triphasic waves

Generalized 1.5-2.5 Hz anteriorly predominant complexes with a fronto-occipital lag, classically seen in metabolic encephalopathy such as hepatic or uremic failure.

Burst suppression pattern

High-amplitude generalized bursts alternating with attenuation below 10 microvolts lasting over one second; indicates severe cortical dysfunction or deep anesthesia.

PLEDs

Periodic lateralized epileptiform discharges at 0.5-2 Hz, often following acute stroke or herpes simplex encephalitis; may be ictal or interictal.

BETS artifact

Benign epileptiform transients of sleep are small sharp spikes in N1/N2 with broad field and no focal slowing; they are not epileptiform and require no treatment.

Seizure onset evolution

Rhythmic scalp EEG activity that changes in frequency, amplitude, and morphology over time, with a definable field and failure to attenuate with alerting.

Nerve conduction velocity formula

Conduction velocity in meters per second equals the distance between stimulation sites in millimeters divided by the latency difference in milliseconds.

Axonal loss pattern

Reduced compound muscle action potential amplitude with preserved distal latency and conduction velocity, reflecting loss of axons rather than myelin damage.

Demyelination NCS criteria

Conduction velocity below 75 percent of the lower limit of normal, distal latency above 130 percent of upper limit, or over 50 percent amplitude drop across a segment.

Conduction block

A greater than 50 percent drop in compound muscle action potential amplitude between proximal and distal stimulation sites, indicating focal demyelination along the nerve segment.

F-wave purpose

A late response reflecting proximal motor conduction; prolongation with normal distal studies suggests proximal demyelination such as Guillain-Barre syndrome or radiculopathy.

H-reflex localization

Tibial nerve reflex assessing S1 root conduction; absent in S1 radiculopathy and polyneuropathy, but typically normal in L5 root lesions.

Fibrillation potentials

Spontaneous brief motor unit discharges seen on needle EMG at rest, indicating active denervation; they appear weeks after nerve injury and precede reinnervation.

Myopathic motor units

Short-duration, low-amplitude, polyphasic motor unit potentials with early recruitment at low effort, reflecting loss of muscle fibers within motor units.

Neuropathic motor units

Long-duration, high-amplitude, often polyphasic motor unit potentials with reduced recruitment, reflecting chronic reinnervation by collateral sprouting.

VEP P100 wave

Positive occipital potential near 100 ms evoked by checkerboard pattern reversal; latency delay indicates optic nerve demyelination such as optic neuritis.

BAEP wave V

Vertex-positive peak generated near the inferior colliculus, normally around 5.5-6 ms; its latency and interpeak intervals assess brainstem auditory pathway integrity.

SSEP N20 response

Cortical potential near 20 ms after median nerve stimulation; bilateral absence after cardiac arrest strongly predicts poor neurologic outcome.

Central motor conduction time

Motor evoked potential latency from transcranial magnetic stimulation minus peripheral motor conduction latency; prolongation indicates central corticospinal tract dysfunction.

Evoked potential amplitude

Peak-to-peak voltage of the evoked response, which primarily reflects the number of conducting axons and is reduced by axonal loss or conduction block.

Evoked potential latency

Time from stimulus to response peak; prolongation chiefly reflects demyelination along the sensory or motor pathway being tested.

Apnea scoring definition

Cessation of airflow for at least 10 seconds; obstructive if respiratory effort persists, central if effort is absent, mixed if central onset becomes obstructive.

Hypopnea criteria

At least 30 percent reduction in airflow lasting 10 seconds or more, accompanied by a 3 percent oxygen desaturation or an arousal on polysomnography.

AHI severity thresholds

Apnea-hypopnea index of 5-15 is mild, 15-30 moderate, and above 30 severe obstructive sleep apnea; CPAP is first-line for moderate to severe disease.

MSLT narcolepsy criteria

Mean sleep latency under 8 minutes with at least two sleep-onset REM periods across five naps, in the absence of another cause of hypersomnolence.

REM sleep without atonia

Persistent chin EMG tone during REM sleep on polysomnography; the hallmark of REM sleep behavior disorder, linked to synucleinopathies.

Orthostatic hypotension

Systolic blood pressure fall of at least 20 mmHg or diastolic fall of at least 10 mmHg within 3 minutes of standing or head-up tilt.

QSART purpose

Quantitative sudomotor axon reflex test measures postganglionic sudomotor function by acetylcholine iontophoresis and sweat response, assessing small autonomic nerve fibers.

Tilt-table positive response

Reproduction of syncope or presyncope with hypotension, often with bradycardia in vasovagal syncope, during passive head-up tilt testing.

Sleep spindle frequency

Sleep spindles are 11-16 Hz bursts lasting at least 0.5 seconds, maximal over central regions, marking stage N2 sleep onset and stability.