Abstracts

RATIONALE: The literature reports inconsistent findings regarding the effects of hemispherectomy on language development. We address two major issues in hemispherectomy and language research: 1)the effect of the side of resection, and 2)the relationship between linguistic outcome and clinical factors, such as age at onset, age at surgery and seizure history. We suggest that it is the integrity of the remaining hemisphere that determines linguistic prognosis and this can be defined by the pathological substrate (etiology) and variables related to it, such as post-operative seizure control and motor development. METHODS: We studied 42 children who had undergone hemispherectomy for intractable seizures at UCLA's Pediatric Epilepsy Surgery Program. Etiology was catalogued as cortical dysplasia (CD; n=19), infarct (n=12), and Rasmussen's encephalitis (n=11). Posoperative spoken language outcome was rated on the basis of free language samples from 0-no language to 6-fluent mature speaker. Motor development and post-operative seizure control were determined on the basis of parental reports. RESULTS: Better post-operative language scores were found in Rasmussen's patients compared with infarct and CD cases (p=0.003). Furthermore, language scores for all etiologies positively correlated with post-surgery motor performance (r=0.734, p=0.0002) and seizure control (r=0.132, p=0.02). Neither age at surgery nor seizure duration proved to be a significant predictor of language outcome. CONCLUSIONS: In predicting language after hemispherectomy, the integrity of the non-resected hemisphere seems to be a reliable index that integrates and accounts for a number of variables previously mentioned in the literature (such as age at onset/surgery and seizure history). Furthermore, our findings suggest that post-surgical motor development and seizure control may, indeed, be usable as indirect indices of the integrity of the remaining hemisphere, and thus may provide means by which we can further explore complex findings regarding language development following hemispherectomy.