Neuro Diagnostics Flashcards
What is an electroencephalogram (EEG)?
Safe, painless recording of cortical electrical activity
8-16 electrodes applied to scalp
Stressors of EEG
Sleep deprivation
Hyperventilation
Indications for EEG
Seizure disorders (may be normal, they are episodic) Metabolic encephalopathy (distinguish focal from generalized slowing) Distinguish b/w cortical and subcortical Tumors (see focal slowing or spike discharges)
How to distinguish b/w cortical and subcortical on EEG
Cortical: see neglect, aphasia, hemianopia
Subcortical: see motor hemiparesis
Rhythms seen on EEG
Alpha: 8-12 Hz (normal awake adult)
Beta: >12 Hz
Theta: 4-8 Hz
Delta: 0-4 Hz
What does this EEG finding suggest: epileptiform activity
Seizures
What does this EEG finding suggest: focal discharges/spikes c/w focal problem
Tumor, infarct, scar tissue
What does this EEG finding suggest: generalized changes/slowing c/w metabolic disorders
Encephalopathy, anoxia
What does this EEG finding suggest: normal EEG with presence of seizure activity
Psychogenic seizures (inpt monitoring is helpful)
Contraindications to EEG
No major ones
What is an electromyogram (EMG)?
Clinical examination of the electrical activity of muscle fibers/ motor unit
Define location of problems affecting peripheral nerves
What can an EMG do?
Differentiate primary muscle conditions from muscle weakness caused by neurologic disorders
Technique for EMG
Needle electrodes inserted into skeletal muscle to record electrical potentials and look for abnormals (electrode on the needle detects electrical activity given off by muscles)
Makes graphs, sounds or numerical values
When to measure electrical activity with EMG
Needle insertion
Spontaneous activity at rest
Slight muscle contraction
Full muscle contraction
Indications for EMG
Lower motor neuron diseases (ALS)
NMJ disease (myasthenia gravis)
Muscle disease (myopathy)
Peripheral nerve disorders (carpal tunnel, peripheral neuropathies)
(alcohol neuropathy, brachial plexopathy, cervical spondylosis, denervation, guillain barre, nerve dysfunction, polymyositis)
What does an EMG show for myasthenia gravis (NMJ disease)?
Fatigability
What does EMG show for myopathy?
Decreased amplitude of motor response