Surgical treatment of MRI-negative temporal lobe epilepsy based on PET: a retrospective cohort study

Using retrospective and comparative methods, we aim to discuss the surgical treatment of magnetic resonance imaging (MRI)-negative temporal lobe epilepsy (TLE) presented with positive positron emission tomography (PET) results.

From the viewpoint of semiology, demography, surgical treatment and prognosis evaluation, we compared 19 MRI-negative, PET-positive TLE patients to 41 TLE with hippocampal sclerosis patients, and then statistically analyzed the differences between these 2 cohorts.

Under intraoperative electrocorticography monitoring, all patients underwent successful standard anterior temporal lobectomy. It appears that there is no significant difference between the surgical outcome of MRI-negative/PET-positive TLE (Engle class I: 68.4%, Engle class I + II: 84.2%) and TLE with hippocampal sclerosis (Engle class I: 68.3%, Engle class I + II: 80.5%). The analysis also shows that to some extent MRI-negative, PET-positive TLE might be distinct from TLE with hippocampal sclerosis as a clinical entity, i.e. the former is not a subtype of the latter. History of febrile convulsion and occurrence of secondary generalized tonic-clonic seizure may possibly differentiate them from each other.

Successful resective surgery of MRI-negative TLE based on PET can yield similar favorable results to TLE with hippocampal sclerosis. This study demonstrates that with reasonable presurgical workup, such TLE subtypes can be surgically treated without invasive intracranial electrode implantation.