Antiepileptic drugs management and long-term seizure outcome in post surgical mesial temporal lobe epilepsy with hippocampal sclerosis

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Summary

Surgery is the treatment of choice for refractory temporal lobe epilepsies, but unexpected seizure recurrences occur and the AEDs management strategy may be an implicated factor. We evaluated the AEDs management's role in the outcome of post surgical epilepsy patients with hippocampal sclerosis (HS).

Epileptic patients submitted to amigdalohippocampectomy due to HS in Engel class IA 12 months after surgery were selected. The following variables were studied: age, gender, time of post-surgical follow-up, present Engel class, number of antiepileptic AEDs before surgery and at the time of the interview, AED changes after surgery (stopped, increased, decreased, maintained), timing for AED changes after surgery and seizure recurrences.

Sixty-seven consecutive patients were studied (mean time of follow-up of 4.9 ± 2.8 years). Among these, 46.3% were tapering AEDs, 38.8% had not changed and 14.9% had increased AEDs. The global recurrence rate was 32.8%. Recurrence rates for patients tapering and not tapering AEDs were similar (34.2% and 31%, respectively). Fifteen patients tapered AEDs before 2 years and 20 at or 2 years after surgery, with similar recurrence rates (33% and 30%, respectively). All patients who recurred due to AED tapering and 66.7% of the patients who recurred with no AED reduction resumed the Engel class I.

This study suggests that in HS patients submitted to AHE who are seizure free during the first postsurgical year, AEDs tapering is achieved in a substantial percentage of patients. Tapering AEDs, independently of its timing, will induce seizure recurrence in about a third of patients. However, patients relapsing after tapering AEDs regain control after resuming therapy.

Introduction

Surgery is well recognized as the treatment of choice for refractory temporal lobe epilepsies (Wiebe et al., 2001), with short and long-term seizure remission rates higher than 85% (Pimentel et al., 2010), although with a better prognostic for medial temporal resections as compared to those in neocortical areas (Spencer et al., 2005). However, although the ultimate goal of surgery is the complete absence of seizures along with the total discontinuation of antiepileptic drugs (AEDs), the percentage of patients in this condition is not well known (Schmidt et al., 2004). Furthermore, somehow unexpectedly, seizure recurrence may occur in these elapsed periods of time. In what possible post surgery related factors are concerned, namely the role of AEDs strategy management, the literature is rather inconclusive (Schiller et al., 2003, Wieser and Häne, 2003, Wieser and Häne, 2004, Kim et al., 2005, Berg et al., 2006, Tanriverdi et al., 2008, Sperling et al., 2008, Kerling et al., 2009). One of the factors implicated may be due to their heterogeneity regarding the epileptogenic zone (EZ) location and type of pathology, rendering it difficult to achieve ultimate conclusions. Indeed, and to our best knowledge, only 4 of the studies of the last decade addressed exclusively the temporal lobe epilepsy (Schiller et al., 2003, Wieser and Häne, 2003, Wieser and Häne, 2004, Tanriverdi et al., 2008), and among them, only 1 (Wieser and Häne, 2004) addresses this issue with a homogeneous patient's population, respecting the aforementioned factors. Other related issues, such as the right time to start tapering AEDs, and the relation between tapering AEDs and seizure recurrence, remain controversial. Herein, with a different study design from the ones reported, we first aim to determine the long-term seizure outcome in a homogeneous population of post surgical epileptic patients and its relationship to AEDs tapering.

Section snippets

Materials and methods

Our Epilepsy Surgery Group of the Hospital de Santa Maria prospectively recruited and registered in a database a cohort of 164 surgical patients from 1998 to October 2009, in order to asses long-term seizure outcome. The great majority (127 patients) experienced temporal lobe resections. Among these, we included only those aged 18 years or older, who experienced selective amygdalohippocampectomies (AHE), either complete (non-dominant hemisphere) or of the anterior two-thirds (dominant

Results

Sixty-seven patients were eligible, 36 females and 31 males, with a mean (±S.D.) age of 43.6 ± 14.02 years (range 11.9–78.5 years; median 42.7) at the time of cross-section. Mean (±S.D.) time of post-surgery follow-up was 4.8 ± 2.9 years (range 1.1–13.2 years). At the time of the cross-section, 46.3% of the patients were tapering AEDs (31/67), 38.8% had not changed AEDs (26/67) and 14.9% had increased the dose of AEDs (10/67). Among the patients tapering AED, 32.2% had reached monotherapy (10/31)

Discussion

Our study addressed the role of the AEDs management strategy in the long term post surgery seizure outcome of a homogeneous adult patient population with HS who were seizure free for 1 year after surgery. It brings additional insights to the previously published data on the subject, generally addressing heterogeneous series regarding location of the EZ and type of pathology (Schiller et al., 2003, Wieser and Häne, 2003, Wieser and Häne, 2004, Kim et al., 2005, Berg et al., 2006, Tanriverdi et

Conclusions

Our study has some limitations. The sample was relatively small and we did not take into account potentially pre, intra and post surgery clinical and neurophysiological outcome factors in order to avoid too small subgroups. Also, dysplastic lesions associated with HS may have been included in the series of patients analysed. Furthermore, we may have misjudged some Engel classes’ subdivisions by using a telephone interview to collect patients’ data.

Despite these constraints, our study shows that

Disclosure

None of the authors has any conflict of interest to disclose.

References (15)

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