Lecture 17: Epilepsy Surgery Flashcards
What was Gowers (1800’s) definition of epilepsy?
“fits, faints, and funny turns”
What are “fits”?
epileptic seizures
What are “faints”?
non epileptic syncopal episodes
What are “funny turns”?
psychogenic attacks
non-epileptic events
How common is epilepsy?
very common!
chance of having an epileptic seizure in your life?? –> 5%
What are the chances of your seizures being controlled with medication?
75%
that leaves 25% uncontrolled and “potential” candidates for epilepsy surgery
What are the statistics of epilepsy in Canada?
1.5 million with an epileptic seizure
375,000 with intractable epilepsy
What are epilepsy surgery “work ups” or investigations?
history (semiology) and physical exam
neuro-imaging
EEG
other stuff
What is a standard anterior temporal lobectomy?
don’t take out whole lobe, only a part of it
How does the hippocampus relate to epilepsy?
most seizure prone area of the brain
What are the structures surrounding the hippocampus?
superior temporal gyrus
middle temporal gyrus
inferior temporal gyrus
fusiform gyrus
parahippocampal gyrus
hippocampus, amygdala
What is the internal architecture of the hippocampus?
CA 1
CA 2
CA 3
CA 4
granule cell layer
What does damage to the CA1 cause?
damage causes temporal lobe epilepsy
What will cutting the blood vessels during surgery cause?
cutting blood vessels can call stroke
What are types of imaging in a brain with epilepsy?
CT Scan (1970’s and 80’s)
MRI (mesial temporal sclerosis, cortical dysplasia)
EEG (right temporal seizure, left temporal seizure)
PET scan (won’t be metabolizing normally)
SISCOM (subtracted ictal SPECT co-registered with MRI)
What are methods of invasive monitoring?
depth electrodes (SEEG): little electrodes in the brain without opening up the brain
grid electrodes: big operation
What are types of epileptic surgery?
temporal lobectomy/resection
selective amygdalohippocampectomy
extra temporal resection
awake craniotomy
vagal nerve stimulation
LiTT (laser interstitial thermo therapy)
multiple subpial resection
What is an awake craniotomy?
intraoperative stimulation under local anesthesia
bipolar stimulation (Ojemman stimulator) as well as monopolar white matter stimulation
mapping: motor, sensory, langauge
What is the biological basis of fMRI?
fMRI is dependent on the blood oxygen level dependent (BOLD) signal
differences in magnetic susceptibility can be measured
What is the hemodynamic response?
signal change (condition-baseline) (0.2-3%)
can tell which part of the brain is responsible for which task
What is a language fMRI?
characterize areas of the brain that are responsible for speech
What is diffusion weighted imaging?
tractography
Brownian motion of water molecule
behavior of hydrogen
What is diffusion anisotrophy?
diffusion is greater in the axis parallel to the orientation of the nerve fibre
What is laser interstitial therapy (LiTT)?
a new treatment for epilepsy and other stuff
minimally invasive way to insert a catheter into the brain
need three things: energy source, medium, optical cavity
