Over-responsiveness to brain state changes and to transient sensory stimuli Seizure triggers: Sleep deprivation Stress Drugs or alcohol Menstrual cycle Nutritional deficiencies, low blood sugar Other meds Hyperventilation Flashing lights or sounds
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Drugs or alcohol
Nutritional deficiencies, low blood sugar
Flashing lights or sounds
(like from a video game or TV – 1991 Pokemon)
Associated with cortical or subcortical hyperexcitabilityWhat is Epilepsy
Numerous painters, writers, composers, leaders…The Sacred disease
'You are all healthy people, but you have no idea what joy that joy is which we epileptics experience the second before a seizure... I do not know whether this joy lasts for seconds or hours or months, but believe me, I would not exchange it for all the delights of this world.'
Many cases have no known cause.
Head injuries, such as MVA or fall.
Brain tumor or stroke
Arteriosclerosis (fatty plaque build-up)
Pre/natal brain injury (anoxia/hypoxia)
Infections-meningitis or encephalitis
Brain damage causes "scar" on brain. This is where a seizure starts. It is unknown why a scar starts a seizure.
Structural damage to brainEpilepsy Causes
3 cps spike and wave activity which may be precipitated by hyperventilation.
Hyperventilation is performed over a 3 minute period to induce absence seizures. Often bilateral slow waves are induced by hyperventilation.
NORMAL: Small evoked occipital potentials. Photic driving responses are time locked to each flash of light at same frequency or half the frequency (subharmonic). Photic driving responses begin and end simultaneously with the onset and cessation of photic stimulation.
Activity characterized by shape and frequency
Transients & background
x2 interhemispheric power asymmetry indicates abnormality
Assess severity & depth of coma
initial EEG more abnormal, more predictive at 24-48 hrs
Reactivity to sound & pain - somatosensory potentials
Cortical potentials are 500-1500 uV, but 5-50 uV at scalp
~1 billion neurons per electrodeTraumatic Brain Injury (TBI)
Images from http://www.neuro.mcg.edu/amurro/cnphys/
TBI: 1 in 400 people in USA
Leading cause of children's death and 60% of all traumatic deaths
1 No eye opening.
2 Eye opening to pain.
3 Eye opening to verbal command.
4 Eyes open spontaneously.
Best Verbal Response. (5)
1 No verbal response
2 Incomprehensible sounds.
3 Inappropriate words.
Best Motor Response. (6)
1 No motor response.
2 Extension to pain.
3 Flexion to pain.
4 Withdrawal from pain.
5 Localizing pain.
6 Obeys Commands to act.
HIGHER IS BETTER
GCS 13+ correlates with a mild brain injury,
9 to 12, moderate injury
8 or less, a severe TBI
E3V3M5 = GCS 11.Glasgow Coma Score (GCS)
At CBF 15 ml/100g/min, synaptic transmission ceases and EEG flattens.
Cellular integrity preserved (membrane ion pumps and ion gradients) until lower flows.
Loss of electrical activity is protective, reduces energy expenditure of cell.
Isoelectric -- CBF must be restored to avoid neurologic injury.
At 6 to 10 ml/100g/min, extracellular potassium concentrations increase and cell death follows
Detected and classified by EEG
Mild - isolated reduction in amplitude of fast activity
Moderate - amplitude reduction and concomitant slowing
Severe - loss of fast activity with predominant delta activity or isoelectricityCerebral Ischemia