Prediction of Contralateral Hand Function after Hemispherectomy for Refractory Epilepsies: Experience from 102 Pediatric Cases

Background/Purpose: Hemispherectomy usually leads to a complete loss of active grasping with the contralateral hand. Exceptions exist in congenital hemiparesis, apparently when a reorganization of motor functions into the contra-lesional hemisphere had taken place already preoperatively. We aimed to ameliorate the prediction of hand function after hemispherectomy.

Methods: Retrospective analysis of 102 patients (age at hemispherectomy: 0; 10–35 years; median 5.5).

Results: Preoperatively, 50 / 102 patients could grasp; this was preserved in 20/50. A complete loss of active grasping was observed when hand function was normal preoperatively (correct prediction in 3/3). The underlying brain lesion had occurred after the neonatal period (correct prediction in 7/7). A postoperatively preserved grasping was observed when TMS had demonstrated ipsilateral corticospinal projections from the contralesional hemisphere, but no crossed projections from the lesioned hemisphere (correct prediction in 11/12). Brainstem asymmetry > 4% in MRI → correct prediction in 15/22. Pyramidal tract asymmetry within the brainstem > 40% in MR diffusion tractography → correct prediction in 5/5. Prediction of postoperatively newly acquired hand function (5/52 patients) remains difficult.

Conclusion: These rules allow a relatively reliable prediction of hand function after hemispherectomy. Analysis of the brainstem using MRI and MR diffusion tractography (which, in clinical practice, can probably be replaced by qualitative analysis of color-coded fractional anisotropy maps) adds important information. In contrast to TMS or fMRI, these can be obtained also under sedation or anesthesia.