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NeuroPhysiology
Neurology
Question | Answer |
---|---|
EEGs are useful when: | Looking for evidence of epilepsy; determine if a shaking episode is epilepsy; detn whether someone is conscious; detecting absence of brain activity |
EEG: absence seizure | characteristic pattern which is diagnostic; intermittently occurs even when pt not having seizure |
NCSE: | ongoing seizure which has little if any movement assoc w/ it (most of these pts have PMH of seizure or brain injury) |
Pt w/single seizure: if sx of epileptiform discharges on EEG: | likely to have further seizures |
Pt w/single seizure: if MRI shows structural brain lesion: | more likely to have further seizures |
Pseudoseizure | Clinically resembles seizure; does not have EEG evidence of seizure, or respond to epilepsy meds |
EEG & coma | EEG can show presence & degree of coma or encephalopathy but not etiology |
EEG & brain death | Brain death = clinical dx based on neuro exam; if EEG is completely flat: no evidence of brain activity; useful adjunct to dx brain death; some pts who meet brain death criteria have EEG activity |
NCS | uses electrodes; record response to shock (amp & timing) |
EMG | uses needle; electrical activity observed during rest & activitation |
NCS & EMG interp: | very dependent on person performing & interpreting study |
NCS / EMG useful: | suspicion of peripheral nerve or mx injury; detect CTS; investigate polyneuropathy (sometimes suggest etiologies); investigate radiculopathy or mx dz |
Evoked potential studies | to study conduction of CNS pathways; electrodes on scalp; brain potentials recorded in response to stim |
Evoked potential studies: 3 kinds: | Visual; Brainstem (auditory); Somatosensory |
Evoked potential studies: useful to dx: | MS (VEP, SSEP), spinal cord diseases |
Visual evoked potential: optic neuritis: | After optic neuritis, the VEP will often remain abnormal indefinitely even after recovery of vision |
SSEP | record potentials from stimulus at wrist or ankle |