seizures Flashcards
what are seizure
an event characterised by abnormal excessive synchronous discharges of cerebral neurones
what is epilepsy
a chronic disorder characterised by seizures
what are convulsions
a condition in which muscles contract and relax quickly and cause uncontrolled shaking of the body. may occur during seizures
what is occurring in the brain during seizures
the feedback loops in the brain have an abnormal increase in action potentials firing by cells and the action potentials are spread
what are some of the possible causes of seizures
- excitatory glutamate receptors involved increase
- malfunctioning GABA secretion cells or receptors
what is happening with excitatory glutamate receptors
- overactivation of glutamate receptors as a result of increased release of decreased uptake of glutamate so there is a persistent activation of NMDA receptors
what stops glutamate uptake
astrocytes - if they don’t take up glutamate its is left in the synaptic cleft so there is increase firing causing seizures
what is happening is malfunctioning GABA (inhibitory) secretion
the inhibitory neurone function is altered or lost so there is less GABA in the brain which causes seizures
how is GABA secretion used as epilepsy treatment
eg valproic acid/ anti-convulsant - inhibit GABA transaminase which is an enzyme that metabolises GABA –> increases GABA levels in the brain –> less seizures
what conditions can cause seizures
- stokes
- infections
- trauma
- autoimmune
- tumours
- glucose, electrolyte disruption
- genetic, medications
what are difference manifestations of seizures
- abnormal motor response/ motor cortex
- abnormal sensory
- ANS
- psychological
pathway of seizures from GABA abnormalities
- initiation from trigger
- drive of feedback loop
- sudden transition by interneuronal connectivity
- inhibitory bolus produced
- post-inhibitory rebound - increases pyramidal cell spiking
- increase feedforward and feedback excitation
- seizure
