Seizures & Spells (Granner) Flashcards
this type of neurons are the primary source of EEG signal and seizures in the human brain
large pyramidal neurons
in which cortical layers do pyramdial neurons reside?
layers 3-5
Which of the following statements regarding cortical neurophysiology is FALSE?
A. EPSPs depolarize the cell membrane.
B. IPSPs cause chloride channels to open.
C. EPSPs lead to the environment outside the cell becoming more positive.
D. IPSPs are created by the binding of GABA to its receptor.
E. As a general rule, seizures resut from too much glutamate and too little GABA.
C. When an EPSP excites the cell membrane, Na+ channels open and sodium enters the neuron, causing the intracellular environment to become more positive while the extracelllar environment becomes less positive.
type of generalized seizure that is a genetic condition caused by excessive excitability of the reciprocal thalamocortical circuit
Absence seizure.
*Sipla’s lecture on the thalamus, minute 46, is a good recap of the thalamocortical circuit.
I don’t really like the rubber band analogy in the notes, I’m gonna go with a merry-go-round. The merry-go-round is just sitting there, not moving, ready for someone to get on. This is analagous to “burst mode” of the thalamic relay neurons - they’re not passing any information to the cortex yet, thanks to inhibitory signals coming from the intralaminar thalamic cells, keeping them in check. But they’re sitting ready to at any moment. The intralaminar thalamic cells are the playground mom, who is keeping everything under control at the merry-go-round. As soon as her little preschooler gets on, inhibitory signals are lifted, and mom gently pushes and gets the merry-go-round going. Now the relay neurons are in “tonic mode” and they are passing the information up to the cortex. An absence seizure is when the big 6th grader suddenly runs over, grabs the bars with both hands, and yanks the merry-go-round as hard as he can, causing it to wildly spin and knocking all the little kids off. That’s an absence seizure.
What is the dormant basket cell hypothesis?
seizure theory that relates to a problem in the hippocampus, where the inhibitory interneurons that are normally controlling the sorting and passing of information through excitable pyramidal neurons are not functioning. This causes unopposed excitation of pyramidal neurons (prolonged depolarization) and a seizure can result.
*car anaology - the pyramidal cells are the gas pedal and the interneurons are the brakes that are no longer working
What is the mossy fiber sprouting hypothesis?
seizure theory that suggests that pyramidal neurons sprout dendritic fibers back upon their neighbors, resulting in excessive excitation in thehippocampus
*car analogy - gas pedal is overly sensitive
Which of the following is NOT an FDA-approved seizure treatment strategy in the US?
A. Inhibit excitation during partial seizures
B. Inhibit excitation during generalized seizures
C. Promote inhibition during partial seizures
D. Inhibit hyperpolarization of intralaminar thalamic neurons with a calcium antagonist during generalized seizures
E. Surgical resection for a partial seizure
F. Electrical modulation (cortical stimulation) during partial seizure
B. See slide 18.
True or False: All seizures result from some type of epilepsy.
False. It is important to rule out an acute, symptomatic (provoking) cause as the first order of business.
A ______ seizure is bilateral and synchronous at the onset whereas a ______ seizure arises from less than the whole brain, often from a discrete structure.
generalized; partial
a partial seizure is defined based on the preservation (simple) or not (complex) of consciousness, and when it secondarily generalizes, the end result is always a _________ seizure.
tonic-clonic
what are the two critera that define epilepsy?
2 or more unprovoked seizures OR single unprovoked seizure with >60% likelihood of recurrence.
All of the following are factors that lead to an increased risk of epilepsy EXCEPT:
A. A long febrile seizure
B. A focal febrile seizure
C. More than one febrile seizure within a single illness
D. Traumatic injury that results in a depressed skull fracture
E. Loss of consciousness or amnesia for more than 15 minutes
E. The cutoff for increased risk factor in this scenario would be 30 minutes or more.
True or False: An EEG is the gold standard for diagnosing epilepsy, because an abnormal EEG will prove the diganosis.
False. EEG is the most powerful tool for aiding in diagnosis, but a normal EEG does not exclued the diagnosis of epilepsy and an abnormal one does not prove it.
True or False: MRI has better resolution than CT for viewing the temboral lobes and is indicated for all patients with new onset unprovoked seizures.
True.
What is the appropriate progression of treatment when it comes to seizure medication?
- start with monotherapy\
- if that fails convert to second med after weaning off the first
- if that fails refer to epilepsy center for drug-resistant epilepsy –> multiple meds or surgery
