Temporal plus epilepsy is a major determinant of temporal lobe surgery failures

Abstract

Reasons for failed temporal lobe epilepsy surgery remain unclear. Temporal plus epilepsy, characterized by a primary temporal lobe epileptogenic zone extending to neighboured regions, might account for a yet unknown proportion of these failures. In this study all patients from two epilepsy surgery programmes who fulfilled the following criteria were included: (i) operated from an anterior temporal lobectomy or disconnection between January 1990 and December 2001; (ii) magnetic resonance imaging normal or showing signs of hippocampal sclerosis; and (iii) postoperative follow-up ≥ 24 months for seizure-free patients. Patients were classified as suffering from unilateral temporal lobe epilepsy, bitemporal epilepsy or temporal plus epilepsy based on available presurgical data. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom over time. Predictors of seizure recurrence were investigated using Cox proportional hazards model. Of 168 patients included, 108 (63.7%) underwent stereoelectroencephalography, 131 (78%) had hippocampal sclerosis, 149 suffered from unilateral temporal lobe epilepsy (88.7%), one from bitemporal epilepsy (0.6%) and 18 (10.7%) from temporal plus epilepsy. The probability of Engel class I outcome at 10 years of follow-up was 67.3% (95% CI: 63.4-71.2) for the entire cohort, 74.5% (95% CI: 70.6-78.4) for unilateral temporal lobe epilepsy, and 14.8% (95% CI: 5.9-23.7) for temporal plus epilepsy. Multivariate analyses demonstrated four predictors of seizure relapse: temporal plus epilepsy (P < 0.001), postoperative hippocampal remnant (P = 0.001), past history of traumatic or infectious brain insult (P = 0.022), and secondary generalized tonic-clonic seizures (P = 0.023). Risk of temporal lobe surgery failure was 5.06 (95% CI: 2.36-10.382) greater in patients with temporal plus epilepsy than in those with unilateral temporal lobe epilepsy. Temporal plus epilepsy represents a hitherto unrecognized prominent cause of temporal lobe surgery failures. In patients with temporal plus epilepsy, anterior temporal lobectomy appears very unlikely to control seizures and should not be advised. Whether larger resection of temporal plus epileptogenic zones offers greater chance of seizure freedom remains to be investigated.

Auras in patients with temporal lobe epilepsy and mesial temporal sclerosis

“…Rational for excluding the patients who failed to respond to surgery was to have a very uniform group of patients who preoperatively had MRI-MTS and postoperatively responded well to the designed therapy with respect to seizure outcome. Response to appropriate treatment (i.e., standard anterior temporal lobectomy) was an indirect evidence for accuracy of the clinical diagnosis and also decreases the possibility of other variants of TLE such as temporal plus epilepsies [8], at least to some extent. We also investigated the potential clinical differences between patients with MTS and abdominal auras and those with MTS and non-mesial temporal auras (i.e., sensory, auditory or visual auras); to our knowledge, this comparison has never been done before.…”

Evaluating the Prognosis of Surgical Treatment in Atypical Temporal Lobe Epilepsy-A Study Based on Ictal Onset Patterns and Extratemporal Early Propagations on Stereo-Electroencephalography

“…According to the previous studies about surgical outcomes in TLE [6,21], our opinion was that prediction of seizure outcomes after surgery can be phased into two stages: the noninvasive stage and the invasive stage. As the ictal onset and EP are very difficult to distinguish, outcome prediction in the intracranial EEG stage is complicated among some patients.…”

“…The spectrum of TLE includes many subdivisions, from the focal mesiotemporal subtype, the temporopolar subtype, the mesiolateral subtype, the lateral subtype to the widely extended temporal plus epilepsy (TPE) subtype [5]. The patients with the EZs localized in the anterior temporal lobe may have better clinical outcomes after ALT, but those with TPE may not have [6].…”

Not all that glitters is gold: A guide to surgical trials in epilepsy

“…Obvious causes of surgical failure such as inaccurate localization of the epileptogenic zone or incomplete resection of the known epileptogenic cortex are intuitive explanations of ongoing postoperative seizures. This prevailing concept of inadequate resection is variably illustrated by works attributing seizure recurrence after TLE surgery to: (1) existing or developing sclerosis in the hippocampus contralateral to the current resection,48 (2) a remnant ipsilateral hippocampus,49 (3) temporal‐plus epilepsy defined by stereo‐EEG suggestion of epileptogenic zone extension to the insula, orbitofrontal region, operculum, or temporoparietal junctions,50 or (4) extension of the temporal epilepsy pathology to extratemporal components of the limbic network and the thalamus as suggested by functional or structural connectivity data 51, 52. Albeit variable in their “focus,” these hypotheses share one common concept: in addition to the hippocampus, the epilepsy in failed TLE surgery is also “somewhere in the brain” outside of the mesial temporal structures, and the implied path to improving outcomes is in refining localization tools, making the resections bigger, or withholding surgery if the epileptic network is too widespread.…”