Surgery Can Be Effective for MRI-Negative Epilepsy
Last Updated: 2009-12-16 11:30:15 -0400 (Reuters Health)
Up to 43% of patients with epilepsy do not have lesions on MRI, Dr. Christian G. Bien, from the University of Bonn, Germany, and colleagues note. These patients can further be divided based on the presence or absence of histopathological lesions.
"Little is known as to why epileptogenic lesions are not always detected by preoperative MRI and what the epileptological characteristics...are" in patients without histopathological lesions, the authors state.
To investigate, they reviewed their data on 1192 patients with intractable focal epilepsy who were seen from 2000 to 2006 for presurgical evaluation. One hundred ninety (16%) had no visible lesions on MRI.
Twenty-nine (15%) patients without MRI lesions had surgery, such as tailored temporal lobe resection or selective amygdalohippocampectomy. Eleven of the 29 (38%) became seizure free. (Forty-five percent of patients with aura became seizure-free.).
Of the remaining 161 patients without lesions on MRI, only 120 were followed for this study. In this group, the seizure-free rate was 16% (p = 0.008).
Compared with MRI-negative patients, MRI-positive patients were more often offered surgery (73%) and were more likely to become seizure free after the operation (66%).
Nine MRI-negative surgery patients had histopathological lesions; in 8 cases, these lesions could be seen when MRI was reevaluated. Seven of these 9 patients were seizure free after surgery, compared with just 4 of the 20 MRI-negative patients without histopathological lesions (p = 0.003). Roughly three-fifths of this latter group had extensive epileptogenic areas.
"It is worthwhile to perform presurgical epileptological evaluation of patients with features compatible with monofocal epilepsy, even in the absence of a typically epileptogenic MRI lesion," the authors conclude. "Patients with concordant noninvasively obtained focus signs should have intracranial EEG and proceed to epilepsy surgery."
Arch Neurol 2009;66:1491-1499.
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