Residual Motor Control and Cortical Representations of Function Following Hemispherectomy: Effects of Etiology

Abstract

Fifteen posthemispherectomy children were examined to assess residual motor function of the paretic side using the 74-point Fugl-Meyer Assessment of Motor Recovery scale. The degree of residual motor control differed for upper and lower extremities, with hand function being most severely impaired. Posthemispherectomy motor outcomes also differed as a function of etiology: cortical dysplasia, perinatal infarct, and Rasmussen's encephalitis. Children whose intractable seizures resulted from perinatal middle cerebral artery stroke demonstrated the most spared motor function. To detect cortical areas that represented motor control of the hemiparetic side, we focused on voluntary control of the affected lower extremity. Seven of our patients were able to carry out a foot dorsiflexion paradigm during functional magnetic resonance imaging, and these results were compared with activations found in normal controls. All children showed activations in the sensorimotor network ipsilateral to the affected side. The perinatal infarct group demonstrated greater activity in the cingulate cortex, whereas the Rasmussen's encephalitis group had significant activations in the insula, suggesting etiology-specific differences in reorganization. These findings are discussed in the framework of our understanding of mechanisms of cortical plasticity in the injured brain and its relevance to neurologic rehabilitation. We suggest that imaging techniques are important tools in identifying cortical regions underlying functional reorganization. Furthermore, detection of such areas might become a basis for specific training promoting the optimal reorganization of cortical networks to enhance motor control.

Imaging motor imagery: Methodological issues related to expertise

“…These observations are consistent with the observation that every human movement has both a tonic and a phasic component [30]. Observations following hemispherectomy in both primates [31] and humans [32] suggest that the phasic component of voluntary finger movements is most closely associated with activation in primary motor cortex whereas the tonic component is most likely associated more strongly with activation in other cortical and subcortical regions. Thus the observations in Figure 1 suggest that KI is activating regions of cortex involved in the control of the tonic components of movement.…”

Case Report: Practicability of functionally based tractography of the optic radiation during presurgical epilepsy work up

“…In patients with focal epilepsy the determination of eloquent cortices can be further complicated by a commonly observed anatomical alteration of the eloquent cortex, which is driven by at least two interacting factors: (1) The epileptogenic lesion itself is identical with or forms a large part of the anatomical alteration. This has been observed in lesions which originate from an early disturbance in the individual's development, such as prenatal or infant cerebral insults [23,24], cortical malformations or developmental tumors [25,26]. (2) An anatomical alteration of the eloquent cortex was also observed in patients with epileptogenic lesions remote to the eloquent cortex [27], suggesting that the seizures, interictal cortical activity or other functional abnormality of the cortex lead to alteration of functional localization [28].…”

Reorganization of Sensorimotor Function after Functional Hemispherectomy Studied Using Near-Infrared Spectroscopy

“…In our experience, hemiplegia in children after hemispherectomy has a clinical presentation similar to that of individuals with a variety of conditions, such as cerebral palsy or stroke. At least 1 report describes that the distal muscles of the upper extremity often are more severely involved after this surgery [11]. …”