The role of ictal or continuous epileptogenic discharges (I/CEDs), recorded during intraoperative electrocorticography (ECoG), in the planning of surgical resection for patients with cortical dysplastic lesions (CDyLs) and intractable partial seizures was evaluated at the Montreal Neurological Institute, the Epilepsy Surgery Program, Porto-Alegre, Brazil, and the Chonbuk National Hospital, Chonju, Korea. I/CEDs, consisting of repetitive electrographic seizures, repetitive bursting discharges, or continuous rhythmic spiking, were present in 23 of 34 patients (67%) with seizures associated with CDyLs, and in 1 of 40 (2.5%) whose partial epilepsy was associated with other types of structural leasions. A favorable surgical outcome was obtained in 75% of patients when the cortical dysplastic tissue showing I/CEDs was completely excised, whereas the outcome was poor if areas containing I/CEDs remained in situ. The authors advocate the removal as much as possible of the cortical dysplastic lesion that is visible and also those areas showing I/CEDs on acute ECoG. 
COMMENT. The extent of surgical excision for optimal seizure control in these patients was determined by the intraoperative electrocorticographic as well as visual identification of intrinsically epileptogenic dysplastic cortical tissue. Completeness of excision of tissue showing I/CEDs was important for seizure control. The authors found that dysplastic cortex was more epileptogenic than other structural lesions, and patients with cortical dysplasia have a greater tendency to intractable seizures and a higher incidence of status epilepticus than those with other lesions. Previous reports from Montreal have found status epilepticus in 30% of patients with cortical dysplasia compared to 3% with epilepsy caused by supratentorial tumors. Life-threatening focal status epilepticus due to occult cortical dysplasia, not revealed by MRI, was successfully treated by surgical excision in 4 patients (Desbiens R, Andermann F et al, 1993; see Progress in Pediatric Neurology II, 1994, p292).