Long-term outcome of nonsurgical candidates with medically refractory localization-related epilepsy
Selwa LM, Schmidt SL, Malow BA and Beydoun A;
Commented by , 28 Jan 2004
Background
In drug-refractory temporal lobe epilepsy with mesial temporal sclerosis (MTS), surgical removal of the epileptogenic zone leads to seizure remission in 70-80% of cases (1). In other types of localization-related epilepsies, surgical outcome is less favorable, with remission rates from 30 to 45% (2,3).
While many studies assessed seizure outcome after surgery, little attention has been given to evaluation of outcome in surgical candidates not found to be suitable for intervention. The outlook for these patients may not be as poor as it is generally believed.
Aim
To assess long-term outcome in patients with refractory localization-related epilepsy evaluated for possible epilepsy surgery but deemed to be inadequate for surgical intervention.
Methods
Patients evaluated for surgery but not ultimately offered surgical treatment at the University of Michigan from 1990 through 1998 were evaluated by means of a retrospective chart review and telephone survey with a self-rating questionnaire.
Changes in seizure frequency and type, neuroimaging data, ictal recordings, medication history and subjective changes in quality of life were investigated.
Results
Out of a total of 47 eligible patients, 34 could be evaluated. Most common reasons for ruling out surgery were diffuse or inadequately localizing ictal onsets (53%) and bilateral independent temporal ictal onset with normal or bilaterally abnormal imaging findings (38%).
Mean duration of follow-up after surgical evaluation was 4.4 years (range 1.2-9.6).
During follow-up, median seizure frequency decreased from 8 per month to 2 per month. Seven patients (21%) became seizure-free, with a mean remission of 2.5 years (range 1-5.5). Fifteen patients (44%) felt more or much more satisfied with their life.
No clear-cut predictors of outcome were found, although none of the 7 seizure-free patients had MTS on MRI, compared with 7 of 27 who continued to have seizures. Median seizure frequency at the time of surgical evaluation was 8.5 per month in patients who became seizure-free and 4.0 per month in those with continuing seizures.
Comments
This study highlights how little we know about long-term outcome – and, most importantly, outcome predictors - in patients with refractory epilepsy.
Clearly, the study has methodological limitations, due to its retrospective design and acquisition of follow-up data through a telephone survey. Nevertheless, a number of messages can be drawn from this interesting work:
- Most importantly, there is hope for those patients who are found to be inappropriate candidates for epilepsy surgery. Physicians should not give up in trying alternative medical treatments. Of the 7 patients who became seizure-free, 4 ascribed their remission to prescription of a new antiepileptic drug
- The data only apply to a subset of patients deemed to be unsuitable for surgical treatment. As such, these findings should not distract from the need to consider epilepsy surgery early, after failure on two or three drugs;
- Findings are consistent with evidence that MTS has a particularly poor outcome on medical treatment. Fortunately, MTS is associated with excellent outcomes after surgical resection, with seizure free rates < 80% (1). In the only controlled study that compared surgery with medical treatment in temporal lobe epilepsy (mainly MTS patients), only 8% of patients achieved seizure control with aggressive medication trials after one year (4).
- There is an urgent need for prospective studies to assess long-term outcome, and outcome predictors, in patients with localization-related epilepsy, whether managed by surgery or not.
References
1. Engel J Jr. Surgery for seizures. N Engl J Med 1996; 334; 647-652
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2. So NK, Olivier A, Andermann F et al. Results of surgical treatment in patients with bitemporal epileptiform abnormalities. Ann Neurol 1989; 25; 432-439
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3. Spencer SS. Long-term outcome after epilepsy surgery. Epilepsia 1996; 37; 807-813
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4. Wiebe S, Blume WT, Girvin JP, Eliasziw M. Effectiveness and Efficiency of Surgery for Temporal Lobe Epilepsy Study Group. A randomised, controlled trial of surgery for temporal lobe epilepsy.N Engl J Med 2001; 345; 311-318
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