Parietal Lobe Epilepsy: Surgical Treatment and Outcome

OBJECTIVE: Parietal lobe epilepsy(PLE) is neither common nor easily diagnosed because of its variable clinical features. To elucidate its characteristics and surgical outcome, the authors review their surgical experiences. METHODS: Between September 1994 and August 2001, 38 patients with parietal lobe epilepsy received surgical treatment at our Hospital. All patients underwent resection, mainly involving the parietal lobe. In most patients, preoperative evaluation included interictal and ictal electroencephalography, magnetic resonance image, positron emission tomography, and interictal and ictal single photon emission computed tomography. The male to female ratio was 23: 15. Age at surgery ranged from 4 to 38 years (median, 25). RESULTS: Preoperatively over 60% were considered not to be PLE, even though PLE was the most common (15/38, 39.8 %). The most common seizure type was complex partial seizure (26/38, 68.4%) rather than simple partial seizure (3/38, 7.9%). Invasive study was performed in 37 of the 38 patients. Monitoring duration was from 4 to 18 days (median, 8 days). Awake operations under regional anesthesia were performed in 20 patients (52.6%). Follow-up periods ranged from 14 to 81 months (mean, 50.7). Seizure disappeared in 15 (Engel's classification I, 39.5%), and rare seizure remained in 5 (Engel II, 13.2%). Thirteen patients showed a worthwhile improvement (Engel III, 34.2%) and 5 no worthwhile improvement (Engel IV, 13.2%). Pathologies were diverse, the most common being cortical dysplasia (94.3%). CONCLUSION: Since PLE is difficult to diagnose preoperatively, an invasive study covering the parietal lobe is mandatory, if PLE is suspected. Cortical dysplasia was the most common etiology, thus awake operation under regional anesthesia and intraoperative brain mapping is helpful during extensive resection in order to spare the eloquent cortex. Using this protocol, PLE can be controlled surgically with a satisfactory result and a reasonably low level of complications.

Intracranial Ictal Electroencephalographic Patterns in Parietal Lobe Epileptic Seizures : Correlation with Surgical Outcome

BACKGROUNDS: Parietal lobe epilepsy is uncommon and its intracranial ictal EEG findings have not been well elucidated. We investigated the ictal EEG patterns of epilepsy originating from the parietal lobe and its adjacent areas recorded by intracranial subdural electrode arrays. METHODS: The following intracranial ictal EEG patterns from twenty patients who underwent epilepsy surgery for medically intractable parietal lobe epilepsy were studied: 1) Anatomical ictal onset area [pure parietal (PP), combined parietal and extraparietal, such as fronto-parietal, temporo-parietal, etc. (EP)], 2) localization within the parietal lobe, 3) extent of the ictal onset zone, 4) the number of ictal onset zones, 5) frequency and waveform of ictal onset rhythms, and 6) type of spreading. RESULTS: Twelve patients (60%) were seizure-free (5 from PP, 7 from EP) and 8 were with persistent seizures (3 from PP, 5 from EP). Eight patients (40%) had ictal onset from PP and 12 were from EP. There were! Significant correlations with surgical outcome (p<0.05) in two variables: extent of ictal onset zone and type of spread. Patients with focal onset zones (n=9) showed better outcomes (eight are seizure-free) than those with wide ictal onset zones (4 out of 7 are seizure-free). Patients with slow spreading patterns showed better outcomes (12 from 16 are seizure-free) than those with fast spreading outcomes (all of them had persistent seizures). CONCLUSIONS: The extent of ictal onset zones correlates with surgical outcomes. The patterns of intracranial ictal EEG are helpful in predicting the surgical outcomes for parietal lobe epilepsy. (J Korean Neurol Assoc 19(5):478~484, 2001)