Neuroimaging evaluation in refractory epilepsy

Abstract

Neuroimaging studies allow the assessment of functional and structural damage related to epileptogenic lesions and foci, and are helpful to select surgical treatment, conduct intraoperative neuronavigation techniques, predict surgical deficits and evaluate patient recovery.

Diagnosis of mesial temporal sclerosis: sensitivity, specificity and predictive values of the quantitative analysis of magnetic resonance imaging

“…MTS is the main cause of refractory epilepsy; regarding the final report of the institutional review board of epilepsy, MTS was diagnosed in 55.5% (25/45) of all epilepsy patients, which is related to reports in the literature. 2,9,10 The main imaging findings of MTS are decreases in the size of the hippocampus with signal alteration on T2-weighted sequences. 11–14 Conventional MRI, even with high-resolution thin sequences, has reported low predictive values with a sensitivity of 42% and specificity of 80% in the identification of hippocampal atrophy with a high proportion of false negatives; 2,11 they tend to improve in patients with moderate and severe MTS, where values have been reported of sensitivity up to 93% and specificity of 98%.…”

“…2,9,10 The main imaging findings of MTS are decreases in the size of the hippocampus with signal alteration on T2-weighted sequences. 11–14 Conventional MRI, even with high-resolution thin sequences, has reported low predictive values with a sensitivity of 42% and specificity of 80% in the identification of hippocampal atrophy with a high proportion of false negatives; 2,11 they tend to improve in patients with moderate and severe MTS, where values have been reported of sensitivity up to 93% and specificity of 98%. 13 Different factors associated with the technique and the patients mean that the qualitative analysis is susceptible to false negatives, even for expert neuroradiologists.…”

“…In 2013, the Pan American Health Organization estimated that close to 50 million people around the world had epilepsy. 1,2 Although the standard medical treatment of this syndrome is based on drug administration to control seizures, 30% of patients are refractory to this treatment. In temporal lobe epilepsy, resective surgery has been shown to be curative in 70% of cases, and approximately 25% of patients show a significant decline in seizures after surgical treatment.…”

“…[3][4][5][6][7][8] The main cause of refractory epilepsy is mesial temporal sclerosis (MTS), representing between 50% and 70% of cases and characterised, pathologically, by neuronal loss, atrophy and gliosis of the temporal structures. 2,9,10 The most common surgical procedure is the resection of the anterior region of the temporal lobe and the mesial structures. As such, a presurgical evaluation of the epileptogenic focus is of vital importance in order to avoid postoperative deficits in memory and language functions.…”

Nuclear Medicine Methods in Epilepsy

“…Başarısız cerrahi sonrası yeniden opere edilecek hastalarda özellikle de diğer görüntüleme yöntemlerinin arada kaldığı olgularda nöro-görüntüleme çalışmaları mutlak gereklidir (21,22). Ancak eğer MR bulguları ile iktal kafatası EEG bulguları uyumlu ise PET yeni bir veri sağlamazken MR'ı normal ve EEG bulguları karmaşık ise PET bulguları iyi cerrahi sonuç için yüksek prediktif değere sahiptir (23,24).…”