Kevin S King MD, Presenter: Nothing to Disclose

Angela Price MD, Abstract Co-Author: Nothing to Disclose

Zhiyue Jerry Wang PhD, Abstract Co-Author: Nothing to Disclose

Nancy Katherine Rollins MD, Abstract Co-Author: Nothing to Disclose

Patients with debilitating refractory seizures arising from one hemispheric disease are potential candidates for functional hemispherotomy. However, clinical predictors of potentially significant post-operative sensorimotor deficits and recovery of function are unreliable. Diffusion tensor imaging (DTI) can be used to study white matter plasticity. We studied changes in the corticospinal tracts (CST) in the brainstem by DTI before and/or after functional hemispherotomy to determine the association between integrity of the CST and sensorimotor function.  

There were 12 patients with medically intractable seizures who had undergone functional hemispherotomy at 0.7- 20 yrs of age and who had pre- and/or post-operative DTI. Etiology for the seizures was perinatal stroke in 5, cortical dysplasia in 4, chronic encephalitis in 2 and trauma in 1. DTI was done at 3T (b=1000, 2 mm3 voxels, 30 directions). Proprietary software was used to reconstruct the CST. The size and degree of symmetry of the CST at the level of the pons were correlated with sensorimotor deficits. This study was IRB-approved.  

Three patients had symmetric CST preoperatively; motor function was normal and symmetric. Loss of symmetry in the CST after surgery was associated with loss of motor function contralateral to the diseased hemisphere. Subsequent asymmetric increase in the size of the preserved CST was associated with improvement in motor function. Two subjects had asymmetric CST pre-operatively and had unilateral hemiplegia; post-operatively, the CST asymmetry was unchanged and patients had no significant loss of function. In the 7 patients with post- but no pre-operative DTI asymmetric CSTs were associated with dense hemiplegia contralateral to the hemispherotomy.  

In hemispherotomy candidates for treatment of intractable seizures, pre-operative symmetry of the corticospinal tracts (CST) as seen by DTI was associated with intact pre-operative motor function and predicted initial post-operative hemiplegia. Improvement in initial post-operative hemiplegia was associated with apparent compensatory enlargement of the CST ipsilateral to the intact hemisphere implying brain plasticity. Pre-operative asymmetry in the CST was associated with pre-existing hemiplegia which remained stable after surgery.  

DTI may be clinically useful in predicting hemiplegia after hemispherotomy for intractable seizures. 

King, K, Price, A, Wang, Z, Rollins, N,  DTI as a Predictor of Hemiplegia after Hemispherotomy for Intractable Seizures  .  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11016610.html