Lateralizing semiology predicts the seizure outcome after epilepsy surgery in the posterior cortex

Abstract

Compared with temporal or frontal resections, epilepsy surgery in the posterior cortex is rarely performed, and the literature concerning clinical predictors for the postoperative seizure outcome in this particular subgroup is sparse. The data of 42 patients with lesional focal epilepsies of the parieto-occipital lobe and the occipital border of the temporal lobe were evaluated retrospectively and related to the seizure outcome 2 years after epilepsy surgery. The investigated parameters included ictal semiology, pre- and postoperative EEG and neuroimaging, histological findings and demographic data. Postoperatively, seizure-free outcome was seen in: (i) 69% of patients with lateralizing auras, but only in 28% of patients without lateralizing auras (P = 0.01); and (ii) 57% of the patients with lateralizing seizures, but only in 17% of patients without lateralizing ictal semiology (P = 0.02). None of the patients with neither lateralizing auras nor lateralizing seizures achieved freedom from seizures (P < 0.01). The proportion of lateralizing seizures (P < 0.01) and auras (P = 0.02) in the total number of recorded seizures and auras was significantly related to the probability of a favourable surgical outcome. No patient with clinical lateralizing signs to the non-lesional hemisphere but 58% without such "false" lateralization achieved freedom from seizures (P = 0.02). The following parameters also proved to be predictive for a favourable seizure outcome: (i) tumoural aetiology; and (ii) absence of epileptiform discharges in the postoperative EEG. The presence and frequency of ictal semiology lateralizing to the lesional hemisphere and the absence of lateralizing signs to the non-lesional hemisphere are highly predictive of a favourable outcome after surgical treatment of epilepsy in the posterior cortex.

Presurgical seizure frequency and tumoral etiology predict the outcome after extratemporal epilepsy surgery

“…As in our study, a significant prognostic impact of the presurgical frequency of complex partial seizures in TLE was shown in only one other study [6]. A more favorable seizure outcome after tumor resections has been shown in extra temporal epilepsies [1,2] and temporal lobe epilepsies [4,7]. Resections of benign cortical tumors probably have the most favorable outcome regarding seizure freedom after surgery.…”

“…In 39 patients the epileptigenic lesion was located posterior (occipital, parietal or in the temporo-parieto-occipital border) and in 42 patients in the frontal cortex respectively. Detailed information about the patients' diagnostic results can be obtained elsewhere [2,8].…”

“…Conclusions Fewer than daily seizures prior to surgery and a tumoral etiology independently increase the likelihood of remaining seizure free two years after extratemporal epilepsy surgery. lobe and posterior cortical epilepsies respectively [2,8].…”

Cognitive changes after epilepsy surgery in the posterior cortex

“…Results of this analysis are reported elsewhere. 16 Magnetic resonance imaging using T 1 and T 2 weighted pulse sequences was available for every patient. In patients with lesions in the left hemisphere, speech dominance was tested by the Wada test 17 in five cases and/or cortical stimulation in seven.…”

Reliability of Seizure Semiology in Patients With 2 Seizure Foci

“…3,4 Lateralizing semiology has also been reported to predict favorable outcomes of epilepsy surgery. 5 However, these observations have been made mainly on patients with only 1 seizure focus. We have observed among our patients that clinical seizure semiology often appears to be indeterminate when there is more than 1 seizure focus.…”