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Epilepsy Surgery
American Epilepsy Society
Epilepsy Care
Seizure
Epilepsy diagnosis
Medication trials
Imaging for pathology
Medical intractability
Surgical Consideration
Surgical workup
Surgery
American Epilepsy Society 2008
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Candidates for Epilepsy
Surgery
Persistent seizures despite appropriate pharmacological
treatment
Usually at least two drugs, appropriate to seizure
type, at adequate doses, with adequate compliance
Impairment of quality of life due to ongoing seizures
Loss of driving privileges, employment
opportunities, social/cultural stigma, dependence
on others, side effects of medications, under
achievement in school, memory deficit, attention
deficit, injuries, accidents
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Presurgical Evaluation
 History and Physical Exam
 Electroencephalography
 Imaging
 Presurgical Testing
 Neuropsychology Evaluation
 Comprehensive Patient Care Conference
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Imaging for Surgical
Candidates
MRI- with epilepsy protocols
• T1- inversion prepared, gradient-echo,
echoplanar, true inversion recovery image
• T-2- fast spin echo, FLAIR, 3D volume
acquisition
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Presurgical Evaluation- MRI
Right
hippocampal
sclerosis
(arrow)
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Presurgical Evaluation- MRI
Left mesial temporal sclerosis
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Presurgical Evaluation- PET/SPECT
 Functional Imaging
• PET
• hypometabolism interictally
• SPECT
• hypoperfusion interictally
• hyperperfusion ictally
• PET and/or SPECT may be coregistered
with MRI
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Presurgical EvaluationSISCOM
SISCOM
(SPECT with MRI
coregistration)
in a patient with
extratemporal
epilepsy
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Presurgical evaluation - fMRI
fMRI- language lateralization, hippocampus function,
epileptogenic focus assessment
Patient with left temporal
lobe epilepsy.
Left: Language mapping with
verb generation task activation in Broca’s and
Wernicke’s areas.
Right: Memory localization
with picture encoding task decreased activation in the
left hippocampus.
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Presurgical EvaluationMEG
 Magnetoencephalography (MEG)
Magnetic source localization of interictal epileptiform
discharges
Functional mapping
fMRI has a good spatial resolution but provides poor
temporal correlation, while EEG provides timed
waveforms with poor localization. MEG jointly
records these two signals providing spatially and
temporally correlated images.
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Testing for Surgical
Candidates
Visual fields
Formal testing if resection will endanger vision
Intracarotid Amobarbital Procedure (Wada)
Language dominance
Verbal memory
Prediction of postoperative decline
Phase II monitoring with intracranial electrodes if necessary
Subdural/depth electrodes
Identification of ictal onset and epileptogenic zone
Allows for cortical mapping if needed
Cortical mapping
Intraoperative (phase III) or during phase II monitoring
Identification of eloquent areas of cortex
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Neuropsychological Evaluation
for Surgical Candidates
Provides preoperative baseline
Predicts risk of cognitive decline with surgery
Testing includes:
IQ battery of tests
Language localization
Memory- verbal and visual localization
Visuospatial function
Attention/Executive
Motor- coordination and speed
Psych- expectations of surgery, coping skills, social support,
stability
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Comprehensive Patient Care Conference
for Surgical Candidates
 Epileptologist presents the patient
 Video-EEG studies are reviewed
 Semiology
 Interictal EEG morphology
 Ictal EEG morphology
 Neuroradiologist discusses imaging studies
 Neuropsychology results are examined
 Neurosurgeon delineates surgical options
 Discussion of risks/benefits/outcomes
 Group consensus
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Epilepsy Surgery
Phase II subdural electrodes for intracranial monitoring
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Types of Surgical Procedures
 Resective Surgery:
 Lesionectomy
 Selective amygdalohippocampectomy
 Corticectomy
 Lobectomy (e.g. temporal lobectomy)
 Multilobar resection
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Types of Surgical Procedures
 Disconnective/Palliative Surgery:
 Hemispherectomy
 Anatomic
 Functional
 Corpus Callosotomy
 Multiple Subpial Transections
 Vagus Nerve Stimulator
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Surgical Treatment of
Epilepsy
MRI frameless stereotactic localization of focal cortical dysplasia at the
base of the central sulcus (center of cross hairs)
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Standard Temporal
Lobectomy
4.5 cm
Resection of the anterior temporal lobe (~4.5 cm on left side, ~5.5
cm on right side) followed by resection of mesial structures
(amygdala, hippocampus, parahippocampal gyrus)
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Selective
Amygdalohippocampectomy

Idea is to remove mesial structures
(hippocampus, amygdala, parahippocampal
gyrus) leaving lateral temporal cortex intact

Distinct surgical approaches include:
 Transsylvian
 Transcortical
 Subtemporal
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Transsylvian Selective
Amygdalohippocampectomy
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Functional hemispherectomy
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Functional hemispherectomy
Introduced by Rasmussen
Extensive cortical resection in temporal and
central cortex with disconnection of
residual frontal and occipital cortex by
transecting white matter fibers (not shown)
Perisylvian
Deafferentation
Transsylvian
Keyhole
Classic
(Rasmussen)
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R hemimegalencephaly in a 7month-old boy
Pre-op
Post-op
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Transsylvian functional
hemispherotomy (Schramm)
Transsylvian exposure and temporomesial resection
(uncoamygdalohippocampectomy)
Transventricular callosotomy and occipitoparietal mesial
disconnection
Frontobasal disconnection
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Corpus Callosotomy
Introduced by William P.
Van Wagenen in 1940
For intractable generalized
epilepsy
Particularly effective
against “drop attacks”
corpus callosum
pericallosal
artery
septum
pellucidum
Partial vs. complete
Spares the anterior
commissure, fornix
American Epilepsy Society 2008
callosotomy
(in progress)
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VNS Surgery
Electrodes are placed
around the left vagus nerve
and connected to the pulse
generator in the chest or
abdomen
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Clinical Trials
 Experimental Surgical Treatments Under Clinical
Trials
• Deep brain stimulation
• Responsive neurostimulation
• Gamma knife radiosurgery
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Head Trauma and Epilepsy
• Acute symptomatic seizures
• Usually within few days after head trauma
• Incidence is proportional to the severity of trauma
• Remote symptomatic seizures
• Seizure prevention in patients with traumatic brain
injury
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M
ar
y
h
Ci ead
Ci vili in
vil an ju
r
ia
n HI y (
HI (s HI
(m eve )
od re
Em
er )
b
at
LV oli
H c r S e)
w isk tro
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VH ut ct
o
w the rs
ith r
Ba
th apy
ct En er
e
a
As ria cep py
ce l m ha
Al pti en liti
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in s
m
ei
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M er' in
ul s gi
tip di tis
l e se
sc ase
le
ro
Al sis
co
ho
H
*M e l
ar roin
iju
a
No na
ris
k
ilit
Risk ratio
Risk Factors for Epilepsy
1000
580
100
10
1
0.1
29
20
4
16
7.3
2.3
0.7
10
4
2
4
3
3
1
0.4
LVH = left ventricular hypertrophy.
*Protective.
Hesdorffer DC, Verity CM. In: Engel J Jr, Pedley TA, eds. Epilepsy: A Comprehensive Textbook; vol 1.
Philadelphia, Pa: Lippincott-Raven Publishers; 1997:59-67.
Head Trauma and Epilepsy
 404 pts, severe head injury with cortical damage
randomized in < 24 hr: phenytoin vs. placebo.
 Seizures in one week: placebo 14%,
phenytoin 4%
 Once late seizure occurs, 86% recurrence.
 Recommend: Use prophylactic AED for 1-2 weeks
after severe head trauma, then stop. If late
seizures occur, treat with AED.
Temkin, NEJM 1990.
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Conclusion
 Many patients with medically-intractable epilepsy
are surgical candidates
 All patients with epilepsy should undergo epilepsy
protocol imaging
 Many modern epilepsy surgery options exist,
including resection, disconnection and palliation
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