We studied 23 patients with clinically defined mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), 25 oligosymptomatic or asymptomatic maternal relatives, and 50 mitochondrial disease control subjects for the presence of a previously reported heteroplasmic point mutation at nt 3,243 in the transfer RNA(Leu(UUR)) gene of mitochondrial DNA. We found a high concordance between clinical diagnosis of MELAS and transfer RNA(Leu(UUR)) mutation, which was present in 21 of the 23 patients with MELAS, all 11 oligosymptomatic and 12 of 14 asymptomatic relatives, but in only five of 50 patients without MELAS. The proportion of mutant genomes in muscle ranged from 56 to 95% and was significantly higher in the patients with MELAS than in their oligosymptomatic or asymptomatic relatives. In subjects in whom both muscle and blood were studied, the percentage of mutations was significantly lower in blood and was not detected in three of 12 asymptomatic relatives. The activities of complexes I + III, II + III, and IV were decreased in muscle biopsies harboring the mutation, but there was no clear correlation between percentage of mutant mitochondrial DNAs and severity of the biochemical defect.

Summary:Purpose: To identify factors that predict the outcome in seizure control after frontal lobe epilepsy surgery (FLES). FLES is the second most frequent type of epilepsy surgery, but the results are generally not as good as those after anterior temporal lobectomy.Methods: Our cohort consisted of 68 consecutive patients whose first epilepsy surgery involving the frontal lobe occurred between 1987 and 1994. Clinical history and results of imaging and electroencephalographic studies were reviewed in detail. Excellent outcome was defined as being seizure free or having only nondisabling seizures at last follow up.Results: Forty of the 68 patients (58.8%) had an excellent outcome; none of the patients with a history of childhood febrile seizures had an excellent outcome, whereas outcome was excellent in 63% of those without that history (p 5 0.01). The other significant presurgical factor was the presence of a potentially epileptogenic lesion in the frontal lobe on neuroimaging (excellent outcome in 72% when present versus 41% when absent, p 5 0.001). The only significant postsurgical factor was early postoperative seizure control in the first year (excellent outcome in 96% with early control versus 25% without, p 5

Summary:Purpose: To determine whether a focal ␤-frequency discharge at seizure onset on scalp EEG predicts outcome of frontal lobe epilepsy (FLE) surgery.Methods: We identified 54 consecutive patients with intractable FLE who underwent epilepsy surgery between December 1987 and December 1996. A blind review of EEGs and magnetic resonance images (MRIs) was performed. Lesional epilepsy is defined as presence of an underlying structural abnormality on MRI.Results: Overall, 28 (52%) patients were seizure free, with a mean follow-up of 46.5 months. Presence of a focal ␤-frequency discharge at seizure onset on scalp EEG predicted seizure-free outcome in lesional (p ‫ס‬ 0.02) and nonlesional (p ‫ס‬ 0.01) epilepsy patients. At least 90% of patients who had either lesional or nonlesional epilepsy were seizure free if scalp EEG revealed a focal ␤ discharge at ictal onset. Moreover, logistic regression analysis showed that focal ictal ␤ pattern and completeness of lesion resection were independently predictive of seizure-free outcome. Ictal onset with lateralized EEG activity of any kind and postresection electrocorticographic spikes did not predict surgical outcome (p > 0.05).Conclusions: Only about 25% of FLE surgical patients have a focal ␤-frequency discharge at seizure onset on scalp EEG. However, its presence is highly predictive of excellent postsurgical seizure control in either lesional or nonlesional FLE surgical patients.

Summary:Purpose: To determine the factors associated with changes in seizure control during the postsurgical course of epilepsy surgery patients.Methods: Evaluation of patients after consecutive temporal and frontal resection whose seizure frequency was scored for each year of postsurgical follow-up. In each cohort, patients with a change in their seizure control after the first postsurgical year were compared with control subjects to determine factors that may be responsible for the change.Results: Thirty-three (15%) of 214 temporal lobectomy versus 12 (20%) of 59 frontal resection patients experienced a change in seizure control (p > 0.05). Ten (5%) of 214 temporal lobectomy versus nine (15%) of 59 frontal resection patients experienced an improvement in seizure control (p = 0.009), but 23 ( I 1%) of 214 temporal lobectomy versus three (5%) of 59 frontal resection patients had a worsening in seizure control (p > 0.05). In temporal lobectomy patients, preoperative unilateral temporal epileptiform discharges were associated with improvement (p = 0.03), whereas older age at surgery was associated with worsening of seizure control (p = 0.007). In frontal resection patients, presence of a congenital central nervous system (CNS) anomaly was associated with late improvement in seizure control (p = 0.006).Conclusion: During the postsurgical course, an improvement in seizure control is more common after frontal resection than after temporal lobectomy. Factors associated with improvement are the presence of a congenital CNS abnormality in frontal resection patients, and the occurrence of preoperative unilateral epileptiform discharges in temporal lobectomy patients. Older age at temporal lobectomy may be associated with greater risk of worsening seizure control.