Surgery of Epilepsy

Question 1

Epilepsy

Answer 1

epileptic seizures, non-epileptic syncopal episodes, psychogenic attacks
fits, faints, and funny turns

very common (5% chance of epileptic seizure)
75% of time can be controlled with meds = 25% potential surgery

Question 2

work up before surgery

Answer 2

investiations → history + exam; neuroimaging; EEG
neurology → neurophysiology → neurosurgery

Question 3

neuropsychology

Answer 3

seizures in temporal lobe can lead to memory deficits
if in speech dominant hemisphere, can cause verbal memory deficits

Question 4

Temporal lobe anatomy

Answer 4

hippocampus - most seizure prone area of brain
amygdala
parahippocampal gyrus
fusiform gyrus
inferior temporal gyrus
middle temporal gyrus
superior temporal gyrus

anterior choroidal artery runs along top of hippocampus - if damaged in surgery → paralysis
lots of vasculature in brain

Question 5

Imaging

Answer 5

CT - bone and blood
MRI - see scarring areas
PET scan - show abnormal metabolism
EEG - electrical activity

Question 6

MRI

Answer 6

useful in epilepsy
see grey matter and folds of brain - scarring
higher resolution MRI - segmentation to see into the gyri - deeper parts of grey matter

Question 7

EEG

Answer 7

electroencephalography
measure electrical activity in brain

difference in seizures on right vs left temporal lobe: dominant side (usually left hemisphere) has a bigger effect → larger seizure + more disabling

Question 8

invasive monitoring

Answer 8

surgical implant of electrodes to record brain activity

Question 9

epilepsy surgery

Answer 9

selective amygdalohippocampectomy
multiple subpial transection
awake craniotomy
removal of brain tumor
temporal lobectomy/resection

Question 10

selective amygdalohippocampectomy

Answer 10

slit in temporal lobe
remove parahippocampus and push the hippocampus into the space for easier removal

H.M. had both hippocampi removed

Question 11

awake craniotomy

Answer 11

intraoperative operation under local anesthesia
ensure the corrrect area by monitoring motor, sensory, language functions of patient

Question 12

multiple subpial transection

Answer 12

cut the fibres of the interneurons between the cortical regions
leave all descending tracts

Question 13

seizure

Answer 13

abnormal discharge of brain cells

epilepsy: enduring predisposition to having uncontrolled discharged of the brain

Question 14

new technologies

Answer 14

intra-operative MRI - when opening the head, the brain moves so the MRI provides an updated location of structures
fMRI
diffusion weighted imaging
LiTT

Question 15

fMRI

Answer 15

image regional blood flow that is related to activation of the brain with tasks
tasks result in change of regional cerebral blood flow
ex. moving both feet - region in front of central sulcus that will be supplied with blood; task will promote a change in the ratio of oxygenated-deoxygenated hemoglobin →increased oxygenated, decreased deoxygenated = increased signal
use blood oxygen level dependent (BOLD) signal → measure differences in magnetic susceptibility with T2* decay
measure hemodynamic response

Question 16

diffusion weighted imaging

Answer 16

motion of water molecule - hydrogen in living tissue is directional
white matter tracts that carry information from one area to another have barriers to diffusion = directional
diffusion anisotropy → diffusion is greater in the axis parallel to the orientation of nerve fibre; less in axis perpendicular to nerve fibre
move easily along long axis of fibres - myelin sheaths

corticospinal tract localization → generate tracts

Question 17

LiTT - laser interstitial thermo therapy

Answer 17

light amplification by stimulated emission of radiation
minimally invasive way to insert a laser catheter into brain → focal ablations without opening head
~60 degrees is optimal (avoid non-target tissues)
removing less tissue = less chance of success
2-3cm lesions