1. EPILEPSY SURGERY Nonlesional Localization-related Epilepsy
Sang Kun Lee
Department of Neurology
Seoul National University Hospital
Seoul, Korea

2. Pre-surgical evaluation and surgical outcome of 41
Seizure 2002; 11: 184–192
Pre-surgical evaluation and surgical outcome of 41
patients with non-lesional neocortical epilepsy
KEUN-SIK HONG, SANG KUN LEE‡, JOO-YONG KIM‡, DONG-SOO LEE§& CHUN-KEE CHUNG¶†
Department of Neurology, Inje University Ilsan Paik Hospital, Korea; ‡ Department of Neurology;
§ Nuclear Medicine; ¶ Neurosurgery, College of Medicine, Seoul National University, Korea

3. Presurgical evaluation and surgical outcome of 89 patients with non-lesional neocortical epilepsy

4. SURGICALLY REMEDIABLE EPILEPSY SYNDROMES
Nearly 40% of adults with partial epilepsy have medically refractory seizures.
The diagnostic yield of MRI in patients with MTS and lesional epilepsy has been confirmed.
Patients with MTLE and lesional epilepsy may be highly favorable candidates for epilepsy surgery.
A structural neuroimaging alteration almost invariably is a reliable indicator of the site of seizure onset.

5. DIAGNOSTIC ROLE OF NEUROIMAGING IN MEDIAL TLE
Hippocampal sclerosis can be easily found by MRI.
Cases without any abnormal findings exit but rare (Son YJ, 1999).
Diagnostic role in three types of medial TLE
Not prominent hippocampal sclerosis
Bilateral hippocampal sclerosis
Normal MRI findings

6. NONLESIONAL NEOCORTICAL EPILEPSY
The most frequent site of seizure onset is extratemporal, mainly frontal lobe.
Pathology: gliosis, focal cell loss, MCD, FCD or normal
Inherent difficulty in identifying the epileptogenic zone may lead to incomplete resection.
Only a minority of patients are rendered seizure-free after surgical treatment: An estimated 20 to 30% in previous series with extratemporal, mainly frontal lobe, experienced a seizure remission after a focal cortical resection (Cascino GD, 2004, 1992).

7. ROLE OF NEUROIMAGING TOOLS
FDG-PET has known to be frequently normal in patients with nonlesional localization-related epilepsy
Ictal SPECT with SISCOM analysis may be good in the localization of epileptogenic foci and in predicting surgical outcome (O’Brien TJ, 2000).
Need to delineate the roles of various diagnostic techniques

8. PURPOSE
To evaluate the surgical outcome of nonlesional neocortical epilepsy
To assess the diagnostic and prognostic roles of interictal and ictal scalp EEG, interictal FDG-PET, subtraction 99mTc-HMPAO SPECT, and invasive study

9. PATIENTS
89 non-lesional neocortical epilepsy patients (35 frontal lobe epilepsy, 31 neocortical temporal lobe epilepsy, 11 occipital lobe epilepsy, 11 parietal lobe epilepsy, and one with multifocal onset) who underwent focal neocortical resection and invasive study between December 1994 and July 2002
Follow-up for at least two years after surgery

10. PRESURGICAL EVALUATIONS
Interictal EEG
Video-EEG monitoring
Interictal and ictal SPECT: Visual and subtraction analysis
FDG-PET: Visual and SPM analysis
Invasive monitoring: Onset pattern and onset frequency

11. ANALYSIS
Assessing surgical outcome as a whole and according to the location of epileptogenic lobe
Diagnostic accuracy of presurgical evaluations in seizure free patients
Assessing the relationship between the results of presurgical evaluations and the surgical outcome
Assessing the relationship between the surgical outcome and the concordance of the presurgical evaluations

12. THE LOCATION OF EPILEPTOGENIC FOCI
SURGICAL OUTCOME AND
THE LOCATION OF EPILEPTOGENIC FOCI

13. SURGICAL OUTCOME AND THE LOCATION OF EPILEPTOGENIC FOCI
Seventy-one patients (80.0%) had good surgical outcome (Engel class 1-3) including 41 seizure free patients (46.1%).
The surgical outcome of FLE and PLE was less favorable than neocortical TLE and OLE but failed to reach statistical significance (P=0.428).

14. DEMOGRAPHIC DATA AND SURGICAL OUTCOME
Surgical outcome was not related with age at onset, age at surgery,
and duration of illness.

15. DIAGNOSTIC ACCURACY AND SURGICAL OUTCOME
Interictal EEG showed unifocal epileptiform discharges concordant to the resected lobe in 33 of 89 patients (37.1%) and 20 of 41 seizure free patients (48.8%).
FDG-PET had concordant focal hypometabolism in 35 of 79 patients (44.3%) and 22 of 39 seizure free patients (56.4%).
Subtraction SPECT had concordant focal hyperperfusion in 23 of 56 patients who underwent ictal and interictal SPECT. It was observed in 10 of 23 seizure free patients.
Ictal EEG correctly localized the epileptogenic lobe in 63 of 89 patients.

16. DIAGNOSTIC ACCURACY AND SURGICAL OUTCOME
The localization of FDG-PET and interictal EEG was significantly
related with seizure-free outcome
while the result of subtraction SPECT showed marginal significance.
Diagnostic sensitivity is highest in ictal EEG (selection bias?).

17. LOCALIZING VALUE OF INDIVIUAL MODALITIES IN
THE SEIZURE FREE PATIENTS (41 PATIENTS)
The localizing value of FDG-PET and ictal SPECT is higher
in neocortical TLE than in other epilepsies.

18. RESULTS OF INVASIVE STUDY AND SURGICAL OUTCOME
Focalizaiton of ictal onset and ictal onset frequency
in invasive studies were not related with surgical outcome.

19. CONCORDANCE OF PRESUGICAL EVALUATIONS AND SURGICAL OUTCOME (1)

20. CONCORDANCE OF PRESUGICAL EVALUATIONS AND SURGICAL OUTCOME (2)
Comparison of concordance between the good and poor outcome groups showed
that the concordance rate is higher in the seizure-free outcome.
Concordance with two or more results was significantly related with the
seizure free outcome.

21. COMPLEMENTARY ROLE OF FDG-PET AND ICTAL SPECT
IN THE SEIZURE FREE PATEITNS
The role of FDG-PET and ictal SPECT in the localization of the
epileptogenic lobe was complementary.
FDG-PET correctly localized the epileptogenic lobe in six patients with
non-localizing subtraction SPECT
while SPECT correctly localized in three with non-localizing PET.

22. DISCUSSION

23. ICTAL SCALP EEG
Ictal scalp EEG has serious limitations, frequently non-localizing and sometimes false localizing.
1. Very circumscribed focus
2. Rapid spreading
3. Widespread onset
4. Focus in the depths of sulcus or medial/inferior area of various lobes
There is a selection bias in the highest diagnostic sensitivity in this study because the patients with localized ictal scalp EEG can be recruited to the surgery.

24. The Clinical Usefulness of Ictal Surfacce EEG in Neocortical Epilepsy
Epilepsia 2000; 41:
The Clinical Usefulness of Ictal Surfacce EEG
in Neocortical Epilepsy
Sang Kun Lee, Joo-Yong Kim, Keun-Sik Hong, Hyun-Woo Nam, Sung-Ho Park, and
Chun-Kee Chung
Department of Neurology and Neurosurgery, Seoul National University College of Medicine,
Seoul, Korea

25. Localizing value of ictal scalp EEG of neocortical epilepsy,
based on the number of patients and the number of EEGs
Fifty-three (62%) patients had at least one localizable ictal EEG.
The number of localizable EEGs was 167 (42%).

26. Epileptic syndromes and localizing value of ictal scalp EEG
(based on the number of EEGs)
Localizable EEGs were observed more commonly in latTLE and OLE than in FLE and PLE.
(p<0.0001)

27. Epileptic syndromes and localizing value of ictal scalp EEG
(based on the number of patients)

28. FDG-PET
FDG-PET has been known to provide little information in the case of no detectable lesion on MRI (Swartz, 1989; Henry, 1991; Spencer 1994).
Useful in detecting even severe CD with normal MRI (Lee, 2001)
Our study demonstrate the usefulness of FDG-PET in non-lesional neocortical epilepsy for the localization and prediction of surgical outcome.
Most useful in neocortical TLE
False localization can be possible in pseudo lateral TLE (Lee, 2003)

29. Intracranial ictal onset zone in nonlesional lateral temporal lobe
Neurology 2003; 61:
Intracranial ictal onset zone in
nonlesional lateral temporal lobe
epilepsy on scalp ictal EEG
S.K.Lee, MD; C.H. Yun, MD; J.B., Oh, MD; H.W. Nam, MD; S.W. Jung, MD; J.C. Paeng, MD;
D.S. Lee, MD;C.K. Chung, MD; and G. Choe, MD

30. Patients with extratemporal epileptogenic foci
and falsely localizing FDG-PET and ictal SPECT

31. 18F-FDG PET in Localization of Frontal Lobe
J Nuc Med 2002; 43:
18F-FDG PET in Localization of Frontal Lobe
Epilepsy: Comparison of Visual and SPM Analysis
Yu Keyong Kim, MD; Dong Soo Lee, MD; Sang Kun Lee, MD; Chun Kee Chung, MD
June-Key Chang, MD; and Myung Chul Lee, MD
Department of Nuclear Medicine, Neurology, and Neurosurgery
College of Medicine, Seoul National University, Seoul, Korea

32. Sensitivities of MRI, FDG-PET by visual assessment and SPM analysis

33. ICTAL SPECT
Known to be useful in localization and predicting surgical outcome
Side by side visual analysis vs. subtraction analysis: Complementary?
Also complementary with FDG-PET
Concordance with other results is also important.

34. ICTAL SPECT IN NEOCORTICAL EPILEPSY: VISUAL AND SUBTRACTION ANALYSIS

35. ICTAL SPECT IN NEOCORTICAL EPILEPSY:
EPILEPTOGENIC LOBE

36. ICTAL SPECT IN NEOCORTICAL EPILEPSY:
INJECTION DELAY

37. CONCLUSION
Surgical treatment can be benefit in many patients with non-lesional neocortical epilepsy.
Other presurgical evaluations can correctly localize the epileptogenic lobe in these patients.
Results of presurgical evaluation including interictal EEG, FDG-PET, ictal SPECT, and concordance of these studies can be used in predicting surgical outcome.
Careful analysis of presurgical evaluation and implantation of intracranial electrodes based on the hypothesis derived from these results are mandatory.

38. REPOSITIONING OR ADDITION OF INTRACRANIAL ELECTRODES
REDUNDANT COMMENTS:
REPOSITIONING OR ADDITION OF
INTRACRANIAL ELECTRODES

39. Adding or repositioning intracranial electrodes during
J Neurosurg 2004; 100:
Adding or repositioning intracranial electrodes during
presurgical assessment of neocortical epilepsy:
electrographic seizure pattern and surgical outcome
SANG KUN LEE, M.D., KWANG-KI KIM, M.D., HYUNWOO NAM, M.D., JONG BAI OH, M.D.,
CHANG HO YUN, M.D., AND CHUN-KEE CHUNG M.D.
Department of Neurology and Neurosurgery, Seoul National University college of Medicine,
Seoul, Korea