Elaine Wyllie

Semiological seizure classification

Summary: We propose an epileptic seizure classification based exclusively on ictal semiology. In this semiological seizure classification (SSC), seizures are classified as follows:

Complications of invasive video-EEG monitoring with subdural grid electrodes

Objective: To evaluate the risk factors, type, and frequency of complications during video-EEG monitoring with subdural grid electrodes. Methods: The authors retrospectively reviewed the records of all patients who underwent invasive monitoring with subdural grid electrodes (n = 198 monitoring sessions on 187 patients; median age: 24 years; range: 1 to 50 years) at the Cleveland Clinic Foundation from 1980 to 1997. Results: From 1980 to 1997, the complication rate decreased (p = 0.003). In the last 5 years, 19/99 patients (19%) had complications, including two patients (2%) with permanent sequelae. In the last 3 years, the complication rate was 13.5% (n = 5/37) without permanent deficits. Overall, complications occurred during 52 monitoring sessions (26.3%): infection (n = 24; 12.1%), transient neurologic deficit (n = 22; 11.1%), epidural hematoma (n = 5; 2.5%), increased intracranial pressure (n = 5; 2.5%), and infarction (n = 3; 1.5%). One patient (0.5%) died during grid insertion. Complication occurrence was associated with greater number of grids/electrodes (p = 0.021/p = 0.052; especially >60 electrodes), longer duration of monitoring (p = 0.004; especially >10 days), older age of the patient (p = 0.005), left-sided grid insertion (p = 0.01), and burr holes in addition to the craniotomy (p = 0.022). No association with complications was found for number of seizures, IQ, anticonvulsants, or grid localization. Conclusions: Invasive monitoring with grid electrodes was associated with significant complications. Most of them were transient. Increased complication rates were related to left-sided grid insertion and longer monitoring with a greater number of electrodes (especially more than 60 electrodes). Improvements in grid technology, surgical technique, and postoperative care resulted in significant reductions in the complication rate.

A double-blind, randomized trial of topiramate as adjunctive therapy for partial-onset seizures in children

Objective: To evaluate the efficacy and safety of topiramate 6 mg/kg/day in children (age 2 to 16 years) as adjunctive therapy for uncontrolled partial-onset seizures with or without secondarily generalized seizures in a multicenter, randomized, double-blind, placebo-controlled trial. Methods: Patients with at least six partial-onset seizures during the 8-week baseline phase were treated with either topiramate (n = 41) or placebo (n = 45) for 16 weeks. Results: Topiramate-treated patients had a greater median percent reduction from baseline in average monthly partial-onset seizure rate than placebo-treated patients (33.1% versus 10.5%, p = 0.034), a greater proportion of treatment responders (i.e., patients with a ≥50% seizure rate reduction; 16 of 41 [39%] versus 9 of 45 [20%], p = 0.080), and patients with a ≥75% seizure rate reduction (7 of 41 [17%] versus 1 of 45 [2%], p = 0.019), and better parental global evaluations of improvement in seizure severity (p = 0.019). Emotional lability (12% versus 4%), fatigue (15% versus 7%), difficulty with concentration or attention (12% versus 2%), and forgetfulness/impaired memory (7% versus 0%) were more frequent among topiramate-treated than placebo-treated patients. Most treatment-emergent adverse events were mild or moderate in severity. No topiramate-treated patients discontinued the study due to adverse events. Conclusions: Topiramate was safe and effective in the treatment of partial-onset seizures in children.

Successful surgery for epilepsy due to early brain lesions despite generalized EEG findings

Objective: To understand the role of epilepsy surgery in children with generalized or bilateral findings on preoperative scalp EEG. Methods: From our pediatric epilepsy surgery series, we identified 50 patients in whom 30 to 100% of preoperative epileptiform discharges (ictal, interictal, or both) were generalized or contralateral to the side of surgery. Results: All patients had severe refractory epilepsy and an epileptogenic lesion on brain MRI. Ninety percent of the lesions were congenital, perinatal, or acquired during infancy, predominantly malformations of cortical development (44%) or cystic encephalomalacia (40%). Age at surgery was 0.2 to 24 (median 7.7) years. Surgeries were hemispherectomy (64%) or lobar or multilobar resection. At last follow-up (median 24.0 months), 72% of patients were seizure-free, 16% had marked improvement with only brief episodes of staring or tonic stiffening, and 12% were not improved. The rate of seizure-free outcome was not significantly associated with age at seizure onset or surgery, presence of hemiparesis or focal clinical features during seizures, type of lesion, or surgery type. Postoperative seizure-free rate did not differ from that in a comparison group of similar patients who matched the study group except for their high percentage (70 to 100%) of ipsilateral ictal and interictal epileptiform discharges on preoperative EEG. Conclusions: Epilepsy surgery may be successful for selected children and adolescents with a congenital or early-acquired brain lesion, despite abundant generalized or bilateral epileptiform discharges on EEG. The diffuse EEG expression may be due to an interaction between the early lesion and the developing brain.

Dystonic posturing in complex partial seizures of temporal lobe onset: A new lateralizing sign

We observed unilateral dystonic posturing of an arm or leg in 41 complex partial seizures (CPS) from 18 patients. In all cases this was contralateral to the ictal discharge. Unilateral automatisms occurred in 39 of 41 seizures on the side opposite the dystonic limb. Version occurred in 11 of the 41 CPS to the same side as the dystonic posturing and always followed the posturing. Subdural recordings of seven seizures showed ictal onset from the mesial basal temporal lobe. At the onset of dystonic posturing, maximum ictal activity was in the basal temporal lobe with minimal involvement of the cerebral convexity. Unilateral dystonic posturing occurs frequently in CPS of temporal lobe onset and is a lateralizing sign with a high degree of specificity. It probably reflects spread of the ictal discharge to basal ganglia structures.

Epilepsy Surgery in Infants

Purpose: We report 12 infants who had frontal (n = 3), temporal (n = 2), or temporoparieto‐occipital (n = 2) resection or functional hemispherectomies (n = 5) at age 2.5–29 (mean 15.3) months for catastrophic epilepsy due to focal cortical dysplasia (n = 5), Sturge‐Weber syndrome (n = 3), ganglioglioma (n = 3), or hemimegalencephaly (n = 1). Seizures began at 1 day to 14 months (mean, 4.0 months) after birth, occurred frequently (often many times per day, and were refractory to antiepileptic drugs. Patients were evaluated for surgery at 2.5–24 (mean 12.4) months of age. Seven patients had hemiparesis and eight had slowed cognitive development. Seizures were characterized by arrest or marked reduction of behavioral motor activity with unclear level of consciousness (n = 4, with temporal or temporoparietal EEG seizures), focal clonic activity (n = 3, with perirolandic EEG seizures), generalized tonic stiffening (n = 3, with temporoparieto‐occipital, parietal, or frontal EEG seizures), or infantile spasms and hypsarrhythmia (n = 2, with a frontal tumor or temporoparieto‐occipital cortical dysplasia).

Extraoperative cortical functional localization in patients with epilepsy

Functional localization prior to cortical resections for intractable seizures has usually been performed in the operating room in awake patients. Chronically placed subdural electrodes offer the possibility of performing such testing outside of the operating room and without the unavoidable stresses and time limitations of the surgical setting. The use of the technique is reviewed.

Supplementary motor seizures Clinical and electroencephalographic findings

The clinical and EEG features of 11 patients with seizures arising in the supplementary motor area (SMA) were reviewed. All patients underwent prolonged EEG with simultaneous video recording. Three patients had recordings and electrical stimulation of the SMA using subdural electrode arrays. All patients had preservation of consciousness during the seizure unless it became secondarily generalized. Tonic posturing of the extremities was present in all patients, and in seven it was present bilaterally. Adversive movements were not seen unless the seizure became secondarily generalized. Interictal and/or ictal abnormalities were present at or adjacent to the midline in ten patients. Seizures arising from the supplementary motor region are clinically distinct, and the diagnosis can almost always be verified with prolonged EEG/video recording.

Temporal lobe epilepsy due to hippocampal sclerosis in pediatric candidates for epilepsy surgery

Objective: To characterize the clinical, EEG, MRI, and histopathologic features and explore seizure outcome in pediatric candidates for epilepsy surgery who have temporal lobe epilepsy (TLE) caused by hippocampal sclerosis (HS). Methods: The authors studied 17 children (4 to 12 years of age) and 17 adolescents (13 to 20 years of age) who had anteromesial temporal resection between 1990 and 1998. Results: All patients had seizures characterized by decreased awareness and responsiveness. Automatisms were typically mild to moderate in children and moderate to marked in adolescents. Among adolescents, interictal spikes were almost exclusively unilateral anterior temporal, as opposed to children in whom anterior temporal spikes were associated with mid/posterior temporal, bilateral temporal, extratemporal, or generalized spikes in 60% of cases. MRI showed hippocampal sclerosis on the side of EEG seizure onset in all patients. Fifty-four percent of children and 56% of adolescents had significant asymmetry of total hippocampal volumes, whereas the remaining patients had only focal atrophy of the hippocampal head or body. Subtle MRI abnormalities of ipsilateral temporal neocortex were seen in all children and 60% of adolescents studied with FLAIR images. On histopathology, there was an unexpectedly high frequency of dual pathology with mild to moderate cortical dysplasia as well as HS, seen in 79% of children and adolescents. Seventy-eight percent of patients were free of seizures at follow-up (mean, 2.6 years). A tendency for lower seizure-free outcome was observed in patients with bilateral temporal interictal sharp waves or bilateral HS on MRI. The presence of dual pathology did not portend poor postsurgical outcome. Conclusions: TLE caused by HS similar to those in adults were seen in children as young as 4 years of age. Focal hippocampal atrophy seen on MRI often was not reflected in total hippocampal volumetry. Children may have an especially high frequency of dual pathology, with mild to moderate cortical dysplasia as well as HS, and MRI usually, but not always, predicts this finding. Postsurgical seizure outcome is similar to that in adult series.

The lateralizing significance of versive head and eye movements during epileptic seizures.

We studied 37 patients who had head and eye turning during 74 spontaneous epileptic seizures. Videotapes and EEGs were analyzed independently. Turning movements were classified without knowledge of EEG or clinical data as either versive (unquestionably forced and involuntary, resulting in sustained unnatural positioning) or nonversive (mild, unsustained, wandering, or seemingly voluntary). Videotape observations were then correlated with the EEG location of seizure onset. Contralateral versive head and eye movements occurred during 61 seizures in 27 patients, but ipsilateral versive movements did not occur. Nonversive lateral head and eye movements occurred ipsilaterally and contralaterally with equal frequency and were nonlocalizing, but versive movement was a reliable lateralizing sign.