Surgery-epilepsy-introducefrom-NCBI

8/14/2019 Surgery-epilepsy-introducefrom-NCBI

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Epilepsy SurgeryEpilepsy Surgery

American Epilepsy Society


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Candidates for EpilepsyCandidates for Epilepsy

SurgerySurgery

Persistent seizures despite appropriate

pharmacological treatment (usually at

least two drugs at limits of tolerability) Impairment of quality of life due to

ongoing seizures


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Presurgical EvaluationPresurgical Evaluation

History and exam

MRI scan

Mesial Temporal Sclerosis (MTS), tumor, vascular

malformation, dysplasia Video/EEG monitoring with scalp EEG

interictal epileptiform discharges

ictal

Seizure semiology Ictal EEG discharge

Additional electrodes


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Figure 1aFigure 1a

Right hippocampalRight hippocampal

sclerosis (arrow)sclerosis (arrow)


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Figure 1bFigure 1b Figure 1cFigure 1c

Left mesial temporal sclerosisLeft mesial temporal sclerosis


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Functional Imaging

PET

hypometabolism interictally SPECT

hypoperfusion interictally

hyperperfusion ictally

subtraction and co-registration with MRI


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SISCOM Result in a patientSISCOM Result in a patient

with extratemporal epilepsywith extratemporal epilepsy


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Neuropsychological testing

Pre-operative baseline

Aid in localization Predicting risk of cognitive decline with surgery

Wada (intracarotid amobarbital) test

language

lateralization

Memory

prediction of postoperative decline


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Intracranial EEG when needed

Grids and strips, most commonly subdural

Parenchymal depth electrodes, especially forrecording from hipppocampus

Identification of ictal onset

Brain mapping

cortical stimulation SSEPs

Functional MRI


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Types of Surgical ProceduresTypes of Surgical Procedures

Resective Surgery: single seizure focus

in non-eloquent region.

Palliative Surgery: For drop attacks: corpus callosotomy

For Rasmussens encephalitis or hemimegalencephaly:

hemispherectomy


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Surgical Treatment of EpilepsySurgical Treatment of Epilepsy

Modified from McKhann G.M. and Howard M.A.: Epilepsy Surgery: Disease Treatment andModified from McKhann G.M. and Howard M.A.: Epilepsy Surgery: Disease Treatment and

Investigative Opportunity, inInvestigative Opportunity, in Diseases of the Nervous System: Clinical NeurobiologyDiseases of the Nervous System: Clinical Neurobiology, 2002., 2002.

CurativeCurative PalliativePalliative

PathologiesPathologies

MTS TLEMTS TLE Non-MTS TLENon-MTS TLE

LesionalLesional Frontal Lobe epilepsyFrontal Lobe epilepsy

- Low Grade Glioma- Low Grade Glioma SMA/cingulate epilepsySMA/cingulate epilepsy

- Cav. Malformation- Cav. Malformation Malformations of cortical developmentMalformations of cortical development

ProceduresProcedures

Lesionectomy HemispherectomyLesionectomy Hemispherectomy DisconnectionDisconnection

Lobectomy Topectomy (Callosotomy)Lobectomy Topectomy (Callosotomy)

MSTsMSTs

Figure 2Figure 2


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MRI frameless

stereotactic

localization of focal

cortical dysplasia atthe base of the

central sulcus

(center of cross

hairs).


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Functionalhemispherectomy:

extent of cortical

resections in temporaland central cortex

with disconnection of

residual frontal and

occipital cortex by

transecting white

matter fibers (notshown).


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Vagus Nerve StimulationVagus Nerve Stimulation

The vagus nervestimulator

(courtesy of

Cyberonics Inc.)

Reprinted with permission.Reprinted with permission.


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Percentage Change All SeizuresPercentage Change All Seizures

VNS Study Group, 1995

Handforth, et al., 1998

Results of two randomized, controlled trials in medicallyResults of two randomized, controlled trials in medically

refractory partial seizures.refractory partial seizures.


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Responder RatesResponder Rates

VNS Study Group, 1995

Handforth, et al., 1998

Responder rates from the randomized controlled trialsResponder rates from the randomized controlled trials


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Metaanalysis of AEDs and VNSMetaanalysis of AEDs and VNS

EfficacyEfficacy

Marson et al (1997)

0

1

2

3

4

5

6

7

8

Gabapentin

Lamotrig

ine

Topira

mate

Tia

gabine

Zonisam

ide

VNS

Oddsratiofor50%r

espond


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Epilepsy and Head InjuryEpilepsy and Head Injury

5% of all epilepsy may be attributed to head injury.

Most patients with early seizures after head injury

do not develop epilepsy.

With loss of consciousness: 2% develop epilepsy

With hospitalization: 7-15% develop epilepsy


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Risks to developing epilepsy: penetrating injury(up to 50%), early seizures, hemorrhage, lowscore in G.C.S., cortical lesion, volume lost,

depressed fx, metal fragments, loss ofconsciousness.

60% of epilepsy occurs in within 1 yr., 80% in 2yrs, 88% by 10 yrs.

Yablon, Arch Phys Med Rehab 1993.

Willmore, Epilepsy: A Comprehensive Text 1997.


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Mayo clinic study:

Severe injury (contusion, hematoma, focal deficit,

24 hr. of amnesia or LOC): 11.5% epilepsy (in 5

yr.)

Moderate injury (fracture, > 30 min LOC,

amnesia): 1.6%

Milder injury: no increased risk.

Severe injury and early seizure: 36%

Annegers., Neurology, 1980.


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Head Injury andHead Injury and

Prophylactic AEDsProphylactic AEDs

404 pts, severe head injury with cortical damagerandomized in < 24 hr: DPH vs. placebo.

Seizures in one week: placebo 14%,

phenytoin 4% Once late seizure occurs, 86% recurrence.

Recommend: Use prophylactic AED for 1-2 weeksafter severe head trauma, then stop. If late

seizures occur, treat with AED.

Temkin, NEJM 1990.

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