Assessment and cost comparison of sleep-deprived EEG, MRI and PET in the prediction of surgical treatment for epilepsy

Abstract

Our aim was to determine if less expensive interictal indices can predict which epilepsy patients may benefit from the more expensive comprehensive pre-surgical evaluation. Surgical treatment was determined based on the results of a comprehensive inpatient continuous video-EEG monitoring. This evaluation included three interictal tests, which were reviewed retrospectively-2 hour-sleep-deprived electroencephalogram (SDEEG), magnetic resonance imaging (MRI), and positron emission tomography (PET). Sixty-nine patients were evaluated with 35 patients having focal resection (33 temporal, two frontal). When two or more interictal tests were positive, 77% (27 /35) went to surgery, but when one test was positive 23% (8 /34) had surgery. When all tests were negative, only a single patient (1 /13 or 7.7%) had surgery, a frontal resection. The positive predictive value for any single interictal test was 68%, while it was higher for any combination of two positive tests (77-83%). PET was the most sensitive (0.86) single interictal test, compared to SDEEG (0.66) and MRI (0.66). The odds ratio for predicting surgical treatment for a positive PET, SDEEG, or MRI was 8.57, 4.01, and 4.01, respectively. MRI was three and PET was six times the cost of a SDEEG. The combination of SDEEG and MRI had the best cost/PPV ratio. Seventy-nine percent (11 /14) of the patients with three positive tests were seizure free following focal resection compared to 43% (9 /21) when less than three tests were positive ( P<or= 0.05). Interictal tests may predict which patients are most likely to benefit from comprehensive pre-surgical evaluation. Two or more positive tests are the most predictive. If all tests are negative, it is unlikely that the patient would qualify for surgical treatment. The combination of SDEEG and MRI may be more cost-effective as outpatient screening tools.

The Utility of Positron Emission Tomography in Epilepsy

“…However, PET was the most sensitive (86%) and had the highest proportion of true-positive and true-negative tests (72%), whereas the sensitivity and proportion of true-positive and true-negative tests were 66% and 67%, respectively, for both MRI and EEG. 21 The second study also reported a sensitivity of 86% for PET, which was higher than that of EEG (82%) but lower than MRI (90%). Additionally, multivariate analysis revealed that PET hypometabolism was a significant predictor of postoperative outcome (p = 0.02).…”

“…21,22,41,42 Two of these evaluated only patients with temporal lobe epilepsy, 41,42 whereas in the other studies, patients with temporal and extratemporal lobe epilepsy were included. 21,22 Two studies 21,42 evaluated the predictive utility of PET on surgical eligibility. PET could accurately predict surgical candidacy in 68% (PPV) of the patients, which was equivalent to that of MRI and EEG.…”

What is the role for EEG after sleep deprivation in the diagnosis of epilepsy? Issues, controversies, and future directions

“…Only a single study focused on the utility of SD EEG in predicting the feasibility of epilepsy surgery (DellaBadia et al, 2002). These authors showed that the combination SD EEG and MRI were the least expensive and the best predictors to select candidates for surgical treatment.…”

Clinical Spectrum, Seizure Outcomes, Correlation of Neuroradiology and Neuropathology, in Surgically Treated Epileptic Patients

“…[9] Epilepsi cerrahisinin başarı oranları epileptojenik odağı be- Literatürde de epilepsi cerrahisi adayı olan hastalarda benzer bir araştırma şeması önerilmektedir. [10,11] İnteriktal EEG epileptojenik odağı %80.9 oranında lokalize edebilirken, VEM'de en az üç özgün nöbet gözlenmesi son- [12] Bunun nedeninin de VEM sonuçları ile epileptojenik odağı tespit edilemeyen hasta sayısının az olmasına bağlı olduğu değerlendirilmiştir.…”

“…[11,17] Çalışmamızda ise PET sonucu epileptojenik odak ile uyumlu olanlar ile olmayanlar arasında ikinci yıl nöbet sonuçları açı-sından anlamlı fark saptanmamıştır.…”