This 17-year-old boy with congenital left-sided hemiparesis had medically refractory seizures since the age of 3 years. The seizures started with a sudden inability to speak and a “sensation that the muscles of the left arm were tightened,” followed by version of the head and eyes to the left, clonic movements of the left arm, and sometimes bilateral convulsions. Neurologic examination showed an alert, cooperative boy with left hemiparesis and hemianopia. His left limbs were spastic, although he could perform some finger movements (Video S1). Electroencephalography (EEG) showed bilateral sharp waves predominating in the right fronto-centroparietal regions, associated with irregular delta waves. Ictal patterns consisted of bilateral rhythmic discharges preceded by right frontocentral delta waves and, occasionally, low-amplitude polyspikes in both rolandic regions. Structural magnetic resonance imaging (MRI) showed a large cortico-subcortical lesion in the right hemisphere (Fig. 1A) and a small wedge-shaped ischemic lesion in the contralateral (left) parietal region, which did not manifest clinically (Fig. 1B). Functional MRI (1.5 T Siemens scanner, echo planar imaging (EPI), repetition time (TR) 0.6 msec, echo time (TE) 60 msec, scan time 3 s, slice thickness 4 mm) was acquired in a block design, with each functional study consisting of 60 scans alternating six periods of rest and six periods of activation. Data were realigned, smoothed (full-width half-maximum [FWHM] = 8 mm) and analyzed using Statistical Parametric Mapping (SPM2), with an activation threshold of p < 0.0001 (uncorrected). Repetitive grasping with the right (nonparetic) hand elicited activation in the central (rolandic) region of the left (contralesional) hemisphere (Fig. 1C); grasping with the left (paretic) hand elicited activation of the central area in the right (affected) hemisphere, without any additional suprathreshold activation (Fig. 1E). Epilepsy surgery was performed at the age of 17 years. No changes in medication were made in the time around surgery; at that time, the patient had several seizures per day, with secondary generalization once per week. Electrical cortical stimulation of the rolandic cortex in the exposed right hemisphere consistently elicited motor activity in the left (paretic) hand and forearm with 4–6 mA and of the fingers of the paretic hand with 14 mA (Video S1). No motor activity was elicited with stimuli up to 14 mA in the other exposed cortical regions. Corticectomy was then performed, from the sylvian region to the midline, extending 8 cm from the frontal region until 5 mm anterior to Trolard's vein in the parietal region, thus including all aspects of the precentral and postcentral gyrus except for their most medial aspects. Following resection of this frontocentral “bloc,” the lateral ventricle was opened, disconnecting the corona radiata and then sectioning the body and the isthmus of the corpus callosum. This left the frontomesial cortex in place, yet completely disconnected. Therefore, the entire rolandic cortex (precentral and postcentral gyrus) was either removed or disconnected. Postoperatively, an immediate and significant improvement of motor functions in the paretic hand was observed: Already on the first postoperative day, the patient was able to extend the fingers of the paretic hand much more easily, and spasticity had markedly decreased (Video S1). Postoperative functional MRI (fMRI) (13 months postoperatively) during active movements of the paretic hand elicited activation in the “hand knob” area of the contralesional hemisphere (Fig. 1F). At follow-up 3 years after the operation, the patient is still seizure-free, and manual abilities remain improved. Mirror movements were now tested, and were present both during voluntary movements with the paretic hand and with the nonparetic hand (Video S1). Cognitive functions had been normal preoperatively, and no change was observed after the operation.
Figure 1. Preoperative and postoperative structural/functional MRI and schematic illustration of corticospinal projections. (A) Preoperative axial fluid-attenuated inversion recovery (FLAIR) MRI depicting the right-sided cortico-subcortical infarction. (B) Postoperative inversion-recovery MRI depicting the surgery (corticectomy [white arrowheads]; frontal and parietal leukotomies [white arrows]) as well as the small additional parietal lesion in the “contralesional” left hemisphere (black arrow). (C–F) Functional MRI during unimanual grasping movements [C, D: nonparetic hand (symbolized in gray); E, F: paretic hand (symbolized in orange); C, E: preoperative fMRI; D, F: postoperative fMRI]. (G) Preoperatively, the paretic hand (P) received projections from both hemispheres. The epileptic dysfunction is symbolized by lightning bolts over the affected hemisphere (gray circle = lesion). (H) Postoperatively (black dashed line = resection), the crossed projection from the affected hemisphere has been disconnected (gray dotted line), so that the paretic hand receives input only from the contralesional hemisphere.
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