Epilepsy Surgery

Question 1

What is the irritative zone.

Answer 1

Interictal spikes on the EEG or MEG

Question 2

What is the symptomatic zone?

Answer 2

The area of cortex that, when activated by an epileptic discharge, reproduces the patient’s typical clinical symptoms.

Question 3

What is the ictal onset zone?

Answer 3

The area of cortex from which seizures can be objectively demonstrated to arise.

Question 4

What is the functional deficit zone?

Answer 4

The area that shows abnormal functioning during the inter ictal period and can be identified by clinical examination, functional neuroimaging, the WADA test, neuropsychology, etc

Question 5

What is the epileptogenic zone?

Answer 5

The area of cortex that is able to generate seizure and whose complete removal results in seizure freedom.

Question 6

What is the advantage of subdural grids over depth electrodes?

Answer 6

Ability to record functional information.

Question 7

Why is the combination of EEG and fMRI useful for investigation of the epileptic focus?

Answer 7

It is a noninvasive means of investigating the whole brain.

Question 8

What is required for EEG-fMRI to investigate the epileptic focus?

Answer 8

As long as epileptic discharge is present in scalp EEG.

Question 9

What is the mechanism of how EEG-fMRI works?

Answer 9

The method examines metabolic changes at the time of interictal activity, not at the time of seizures.

Question 10

What is the major complications of extratemporal epilepsy?

Answer 10

Hemiparesis, major visual field defects, and dysarthria

Question 11

What is the percentage of major complications in extratemporal epilepsy surgery?

Answer 11

6.5%

Question 12

What is the percentage of minor complications in extratemporal epilepsy surgery?

Answer 12

12%

Question 13

What are the common minor complications of extratemporal epilepsy surgery?

Answer 13

Visual defects, hemiparesis, and dysphasia

Question 14

What is the seizure-freedom rate after epilepsy surgery what percentage of patients?

Answer 14

30%

Question 15

What supplementary tests can increase success rate of seizure freedom when results are concordant with EEG findings?

Answer 15

PET, SISCOM, and intracranial recordings.

Question 16

What is SISCOM?

Answer 16

Subtraction ictal single photon emission computed tomography

Question 17

How do FDG-PET and SPECT improve surgical outcomes?

Answer 17

Detection of subtle structural alterations

Question 18

SISCOM has its best utility in what type of epilepsy?

Answer 18

Extratemporal lobe epilepsy

Question 19

What is a major complication of hemispherectomy?

Answer 19

23% require shunting

Question 20

What are the risk factors for possible shunting after hemispherectomy?

Answer 20

Prior brain surgery and anatomical as opposed to functional

Question 21

What is the percentage of shunts placed after 90 days?

Answer 21

27%

Question 22

What is the complication of death after hemispherectomy?

Answer 22

Less than 3%

Question 23

What is the percentage that remain ambulatory?

Answer 23

Greater than 80% of patients who previously walked

Question 24

How often do seizures arise from the opposite side from the hemisphectomy side?

Answer 24

Up to 30% in patients who had meningoencepalitis, trauma, or cortical dysplasia and in 10% in other etiologies. In about 5% of pets with bacterial meningitis

Question 25

Can magnetic source imaging (MSI or MEG) can be helpful for surgical planning?

Answer 25

10-15% of cases

Question 26

What are factors improve outcomes in stereotactic radio surgery for AVMs?

Answer 26

Small AVM size (<3 cm) , presenting with generalized tonic clinic seizures and epilepsy duration less than 6 months

Question 27

What is a poor prognostic factor for radioablation surgery with patients with AVMs?

Answer 27

Setting of hemorrhage

Question 28

In seizures from medial temporal lobe seizure onset is seen earlier with hippocampal depth electrodes or subdural strips?

Answer 28

Depth electrodes

Question 29

What are the advantages of stereo-EEG

Answer 29

Sampling EEG over larger networks but disadvantage of sampling large cortical areas

Question 30

What are the most common defects after dominant temporal lobe surgery?

Answer 30

Verbal memory deficits and confrontation naming deficits

Question 31

Surgical intervention thru the middle temporal gyrus or Sylvan fissure may cause fewer naming defects

Answer 31

Surgery thru the middle temporal gyrus may cause less naming defects.

Question 32

After a dominant temporal resection, usually impairment of verbal memory and difficulty with confrontation naming occurs, can some patients have a different outcome?

Answer 32

Yes, some may not have memory decline

Question 33

In non-dominant temporal lobe resection, what is the usual loss?

Answer 33

Facial recognition, especially famous faces

Question 34

MEG/MSI can adequately lateralization what function?

Answer 34

Language in 10-15% , but not memory

Question 35

What can be the benefits of early surgery in refractory focal seizures?

Answer 35

Reorganization of language and motor function

Question 36

In patients with bilateral temporal lobe seizures, is it possible to have a good seizure-free outcome with surgery?

Answer 36

Yes, if >80% of seizures arise from one side

Question 37

Can epilepsy surgery be performed if eloquent cortex is involved?

Answer 37

Yes

Question 38

What is the most frequent complication in a temporal lobe resection?

Answer 38

Visual field defect

Question 39

In LGS, what is the percentage of seizure freedom of drop attacks after corpus callosotomy?

Answer 39

As high as 80%

Question 40

What is disconnection syndrome?

Answer 40

Cognitive impairment due to loss of crossing fibers. Usually less 20% after cc.