PET evaluation of bilingual language compensation following early childhood brain damage

Predicting Language Outcome After Left Hemispherotomy: A Systematic Literature Review

Objective

Hemidecortication 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 before surgery. A systematic overview of potential predictors of language outcome after left hemidecortication in children is warranted.

Methods

In a systematic literature review, we analyzed 58 studies on language lateralization after congenital or postneonatally acquired left-hemispheric pathology, and on language outcome after left-sided hemidisconnection, such as hemispherotomy. Single-subject data were pooled to determine the distribution of lateralization across etiologies in congenital lesions and across age groups in acute postneonatal lesions. A hierarchical linear regression assessed the influence of age at surgery, lesion type, age at seizure onset, and presurgery language function on language outcome after left hemidecortication.

Results

In acute postneonatal lesions, younger age at injury was significantly associated with right-sided language lateralization (Cramér V = 0.458; p = 0.039). In patients with hemidecortication, age at surgery was not significantly associated with language outcome (Cramér V = -0.056; p = 0.584). Presurgical language function was the most powerful predictor for postsurgical language outcome (F _4,47 = 7.35, p < 0.0001), with good presurgical language bearing the risk of postsurgical deterioration. In congenital pathology, right-sided language lateralization was most frequent in pre-/perinatal stroke (Cramér V = 0.357; p < 0.0001).

Conclusions

We propose a presurgical decision algorithm with age, presurgical language function, language lateralization, and left-hemispheric structural pathology as decision points regarding surgery.

Model based prognosis of postoperative object naming in left temporal lobe epilepsy

Epilepsy surgery in the left temporal lobe is associated with a high risk of naming decline. In the present study, in 45 patients with left temporal lobe epilepsy (TLE) and confirmed left hemisphere language dominance, 13 (29%) patients demonstrated postoperative decrement >or=5 naming failures in the Boston Naming Test (BNT). Multivariate discriminant analysis with age at onset of epilepsy, age at first risk, age at operation and preoperative naming performance as predictors indicated that 12 (92%) patients with later naming decline could be identified preoperatively. Univariate group comparisons revealed that specifically patients with seizure onset later than 14 years without preceding risk factors (e.g., febrile seizures) are in danger of postoperative dysnomia. It is hypothesized, that there is a strong connection between stable naming performance and deviant intrahemispheric speech representation as a result of early brain damage and/or chronic seizures.

Evidence of cerebral reorganization following perinatal stroke demonstrated with fMRI and DTI tractography

A 44-year-old man with a left perinatal stroke and recurrent refractory epilepsy underwent functional MRI (fMRI) for motor and language mapping to determine if further epilepsy surgery could be performed without loss of language. Language was activated excessively in the right hemisphere, with only small areas of left hemisphere activation. This suggests bilateral language dominance acquired secondary to the perinatal stroke with the right hemisphere activation resulting from neonatal neuronal reorganization. Functional data were overlaid onto 3D diffusion tensor tractography, providing a unique image of the right hemisphere language recruitment.