Does F-18 FDG-PET substantially alter the surgical decision-making in drug-resistant partial epilepsy?
OBJECTIVE
There is a dearth of information on the critical utility of positron emission tomography (PET) in choosing candidates for epilepsy surgery especially in resource-poor countries where it is not freely available. This study aimed to critically analyze the utility of FDG-PET in the presurgical evaluation and surgical selection of patients with DRE based on the results obtained through its use in our comprehensive epilepsy program.


METHODS
From 2008 to 2012, 117 patients with drug-resistant epilepsy underwent F-18 fluoro-deoxy-glucose (FDG) PET in our center. We utilized their data to audit the utility of PET in choosing/deferring patients for surgery.


RESULTS
Of the 117 patients (age: 5-42years) who underwent F-18 FDG-PET, 64 had normal MRI, and 53 had lesions. Electroclinical data favored temporal ictal onset in 48 (41%), extratemporal in 60 (51.3%), and uncertain lobar localization in 9 (7.7%). The topography of PET hypometabolism was localizing in 53 (45.3%), lateralizing in 12 (10.3%), and 52 (44.4%) had either normal or discordant results. In the nonlesional group, focal hypometabolism was concordant to the area of ictal onset in 27 (41.5%) versus 38 (58.5%) in the lesional group (p=0.002). Greater concordance was noted in temporal lobe epilepsy (TLE) (78.0%) as compared to extratemporal epilepsy (ETPE) (28.6%) (p<0.001). Positron emission tomography was more concordant in patients with mesial temporal sclerosis than in those with other lesions (82.8% versus 50%) (p=0.033). Positron emission tomography helped in surgical decision-making in 68.8% of TLE and 23.3% of ETPE cases. Overall, 37 patients (31.6%) were directly selected for resective surgery based on PET results.


CONCLUSIONS
Positron emission tomography, when utilized judiciously, remained an ancillary tool in the surgical selection of one-third of patients with drug-resistant partial epilepsy, although its utility as an independent tool is not very promising.
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
Ramshekhar N
RN
Menon
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India. Electronic address: drashalatha@sctimst.ac.in.
Ashalatha
A
Radhakrishnan
Department of Nuclear Medicine and Imaging, Manipal Hospital, Bangalore, India.
Ramanathapuram
R
Parameswaran
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
Bejoy
B
Thomas
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
Chandrashekharan
C
Kesavadas
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
Mathew
M
Abraham
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
George
G
Vilanilam
R Madhavan Nayar Centre for Comprehensive Epilepsy Care, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India.
Sankara P
SP
Sarma
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003657:Decision Making; D000069279:Drug Resistant Epilepsy / Q000000981:diagnostic imaging* / Q000601:surgery; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D012640:Seizures / Q000000981:diagnostic imaging; D055815:Young Adult
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Cost-effectiveness; Drug-resistant; Epilepsy surgery; FDG-PET; Presurgical evaluation; Surgical outcome