Predicting language outcome after left hemisperotomy: A systematic literature review

Objective:Hemi-decortication is a therapeutic option in patients with drug-resistant structural epilepsy. If surgery is performed early enough in left-hemispheric pathology, the plasticity of the developing brain may enable the right hemisphere to take over language – if this has not occurred prior to surgery. A systematic overview of potential predictors of language outcome after left hemi-decortication in children is warranted.Methods:In a systematic literature review, we analysed 58 studies on language lateralization after congenital or post-neonatally acquired left-hemispheric pathology, and on language outcome after left-sided hemi-disconnection, such as hemispherotomy. Single-subject data was pooled to determine the distribution of lateralization across aetiologies in congenital lesions and across age groups in acute post-neonatal lesions. A hierarchical linear regression assessed the influence of age at surgery, lesion type, age at seizure onset, and pre-surgery language function on language outcome after left hemi-decortication.Results:(1) In acute post-neonatal lesions, younger age at injury was significantly associated with right-sided language lateralization (Cramér’s V = .458; p = .039). (2) In patients with hemi-decortication, age at surgery was not significantly associated with language outcome (Cramér’s V = -.056; p = .584). Pre-surgical language function was the most powerful predictor for post-surgical language outcome (F4,47 = 7.35, p < .0001), with good pre-surgical language bearing the risk of post-surgical deterioration. (3) In congenital pathology, right-sided language lateralization was most frequent in pre-/perinatal stroke (Cramér’s V = .357; p < .0001).Conclusions:We propose a pre-surgical decision algorithm with age, pre-surgical language function, language lateralization and left-hemispheric structural pathology as decision points regarding surgery.