Conditions for omitting invasive long-term monitoring before surgical resection in patients with temporal lobe epilepsy.

Abstract

The omission of invasive long-term monitoring before surgical resection in patients with epilepsy should be permitted only for those in whom the epileptogenic focus is presumed to localize unilaterally in the mesial aspect of the temporal lobe. The localization may well be confirmed through noninvasive measures. Retrospective analyses of data obtained from noninvasive investigations (scalp-recorded and sphenoidal EEGs, neuroimages, and electroclinical seizure manifestations) were carried out in 58 patients. The localization of their epileptogenic focus was subsequently confirmed by the implantation of both intracerebral and subdural electrodes; the focus had an amygdalohippocampal origin in 41 patients and a lateral temporal origin in 17 patients. From the comparison of noninvasive findings between these two groups, we propose the following indispensable conditions for omitting an invasive evaluation: 1. Appearance of focal epileptic discharges unilaterally in the sphenoidal lead observed during the simple phase of partial seizures, or unilateral discharges with predominancy in the sphenoidal lead during the early phase of complex partial seizures. 2. Interictal spikes on scalp-recorded EEGs localizing unilaterally in the anterior region of the temporal lobe, and if bilaterally independent, presenting with unilateral predominancy in a ratio of greater than 4:1. 3. Presence of autonomic signs in the initial phase of signal symptoms. 4. Neuroimaging findings in the mesial temporal region: elongated T2 on MRI and hippocampal atrophy, or a tumorous lesion. The lateralization conforms to interictal and ictal paroxysmal EEG findings. There were 8 patients with seizure of amygdalohippocampal origin who satisfied all the indispensable condition, but not a single patient with seizures of lateral temporal origin.(ABSTRACT TRUNCATED AT 250 WORDS)