Elsevier

Epilepsy Research

Volume 55, Issue 3, August 2003, Pages 211-223
Epilepsy Research

Antiepileptic drug treatment before and after selective amygdalohippocampectomy

https://doi.org/10.1016/S0920-1211(03)00116-5Get rights and content

Abstract

Retrospectively, we analyzed pre and postoperative (po) AED treatment in relation to long-term annual seizure outcome in the Zurich selective amygdalohippocampectomy (AHE) series. In 376 patients (hippocampal sclerosis (“HS”), n: 185; other lesions (“lesional”), n: 191) with a follow-up of more than 1 year, in the last available outcome (lao), 60% were seizure- and aura-free (ILAE Class 1). During the year prior to surgery, in the “HS” group a mean of 2.3±0.8 AEDs were taken. The percentage of patients without AEDs increases to 36.1% in the po years 1–5 (po year 5: “HS” (n: 133) 27.8%; “lesional” (n: 111) 45.9%). In po years 7–11 this percentage is between 40 and 43% (po year 10: “HS” (n: 75) 29.3%; “lesional” (n: 65) 55.4%). In the ILAE Class 1a, at po year 5 63/85 (74.1%) patients have discontinued AED intake. At lao 36.2% of patients were off AEDs and additional 18.9% had a “substantial” reduction (i.e. from polytherapy to monotherapy, or a reduction of the existing monotherapy by at least 66% compared to the year before AHE). The relapse rate is similar for patients who were free of disabling seizures (a) for ≥1 year and without AEDs (17.1%), (b) immediately after surgery with or without AEDs (18.4%), and (c) had a “substantial” AED reduction over the entire follow-up period (18.9%). The rate of re-gained full seizure control, however, is significantly better for group (b) compared to (c) (77% versus 53%). 10.9% of patients showed the “running down phenomenon,” i.e. had seizures during the first po year, but then became seizure-free for 1 or more years. The percentage of patients free of “disabling” seizures, who did not follow the medical advice to discontinue/reduce AEDs, is about 30% after the 10th po year. In the 15th po year this figure is 4.2 times higher for “HS” versus “lesional” patients. We conclude that the time of discontinuation of AEDs after AHE should be tailored based on the results of the presurgical evaluation, the early po seizure outcome, the histopathological findings, the intraoperative ECoG findings and the po EEG. In an optimal constellation, “substantial” AED reduction with the goal of a monotherapy can be advised 1 year and discontinuation 2 years after surgery.

Introduction

While most surgically active epilepsy centers have reported and updated their seizure outcome data (King et al., 1986, Walczak et al., 1990, Rasmussen and Feindel, 1991, Luders et al., 1994, Vickrey et al., 1995), detailed studies on the antiepileptic drug (AED) treatment of surgically treated patients are relatively rare (Kuzniecky et al., 1992, Mathern et al., 1999, Schiller et al., 2000, Bien et al., 2001, van Veelen et al., 2001). Since AED medications affect seizure outcome as well as quality of life and disability, a comparison of pre to postoperative AED treatment remains central for the results of epilepsy surgery (Gilliam et al., 1999). We recently published the long-term seizure outcomes following selective amygdalohippocampectomy (AHE) performed at the University Hospital from 1975 to 1999 (Wieser et al., 2003). Here we complement the updated seizure outcome data with a study on the pre and postoperative AED treatment in relation to seizure outcome of this AHE series.

Section snippets

Patients and methods

Since 1975, a total of 468 patients underwent AHE in Zurich. Excluding patients with so-called “palliative” AHE (n: 43) and/or with normal histopathological findings (n: 31; in 16 patients only small tissue samples were obtained), and with a follow-up of less than 1 year (n: 18), 376 patients were included into this study. Patients with tumor recurrence or with re-operations due to insufficient seizure control (additional surgery with enlargement of the resection) were excluded from this study

Characteristics of patients

One hundred and eighty-five patients (49%) belonged to the “HS” group and 191 patients (51%) to the “lesional” group. As in the previously published long-term seizure outcome study (Wieser et al., 2003) there was no statistically significant difference with respect to gender (56% males and 44% females), side of AHE (52% had right AHE and 48% left AHE) and mean age at surgery (all patients 32±11; “HS” group 33±11; “lesional” 31±15 years) between these two AHE groups. The mean age at the first

Discussion

In the current study, a rigorous definition of seizure-freedom was achieved by using the new ILAE classification system with the Subclass 1a, i.e. seizure- and aura-free since surgery. A rigorous determination of the rate of seizure-free patients is extremely important because improvement of health related quality of life occurs primarily among patients who achieve complete seizure-freedom (Birbeck et al., 2002). The marked preoperative AED load, which is significantly higher in the “HS” group

Acknowledgements

H.-G.W. and A.H. contributed equally to the present work. We are indebted to the neurosurgeons Professor Gazi Yasargil (Department Neurosurgery, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA) and Professor Yasuhiro Yonekawa, and to Professor Adriano Aguzzi and Dr. A. Gooss for neuropathological re-evaluation of the tissue samples. We thank all members of the epileptology and neurosurgery group, in particular Drs. M. Hayek and D. Eschle, G. Frank, A.M.

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