ABSTRACT
BACKGROUND: Describe an ictal EEG pattern of paradoxical lateralization in children with unilateral encephaloclastic hemispheric lesion acquired early in life. METHODS: Of 68 children who underwent hemispherectomy during 2003-2005, scalp video-EEG and brain MRI of six children with an ictal scalp EEG pattern discordant to the clinical and imaging data were reanalyzed. Medical charts were reviewed for clinical findings and seizure outcome. RESULTS: Age of seizure onset was 1 day-4 years. The destructive MRI lesion was an ischemic stroke in 2, a post-infectious encephalomalacia in 2, and a perinatal trauma and hemiconvulsive-hemiplegic syndrome in one patient each. Ictal EEG pattern was characterized by prominent ictal rhythms with either 3-7 Hz spike and wave complexes or beta frequency sharp waves (paroxysmal fast) over the unaffected (contralesional) hemisphere. Scalp video-EEG was discordant, however, other findings of motor deficits (hemiparesis; five severe, one mild), seizure semiology (4/6), interictal EEG abnormalities (3/6), and unilateral burden of MRI lesion guided the decision for hemispherectomy. After 12-39 months of post-surgery follow up, five of six patients were seizure free and one has brief staring spells. CONCLUSION: We describe a paradoxical lateralization of the EEG to the "good" hemisphere in children with unihemispheric encephaloclastic lesions. This EEG pattern is compatible with seizure free outcome after surgery, provided other clinical findings and tests are concordant with origin from the abnormal hemisphere.
Subject(s)
Brain Diseases/physiopathology , Electroencephalography , Epilepsy/physiopathology , Functional Laterality/physiology , Seizures/physiopathology , Adolescent , Age of Onset , Brain Diseases/complications , Child , Child, Preschool , Epilepsy/etiology , Epilepsy/surgery , Female , Follow-Up Studies , Humans , Infant , Infant, Newborn , Magnetic Resonance Imaging , Male , Neurosurgical Procedures , Paresis/etiology , Seizures/etiology , Treatment OutcomeABSTRACT
Malformations caused by abnormalities of cortical development (MCDs) as a group are now widely recognized as a key cause of medically refractory epilepsies, often leading to a consideration of surgical treatment. A practical classification scheme including histopathologic, imaging, and, if possible, clinical-electrographic features of the various different types of MCDs, will be important to the delineation of surgical strategies and anticipation of medical and surgical prognoses. A proposal of such a scheme with emphasis on the focal cortical dysplasias is given in the hopes that it will reopen the debate on the best way to classify these disorders.