Functional relevance of abnormal fMRI activation pattern after unilateral schizencephaly

Abstract

Brain plasticity was investigated in a child with a hemiplegia due to unilateral schizencephaly involving the sensorimotor cortex. This focal lesion led to a dramatic functional reorganization of the undamaged hemisphere, as evidenced by the unusual pattern of fMRI activation during paretic finger movements. The functional relevance of the activation in the undamaged motor cortex was supported by the finding that TMS of this area yielded a response in the paretic hand, indicating that it controls both hands. However, this reorganization was not restricted to the primary motor cortex, but also concerned other structures involved in the control of movements, as shown by the activation of contralesional SMA and thalamus. In contrast, the fMRI activation in the damaged sensorimotor cortex during paretic hand movements appears functionally irrelevant.

Functional brain neuroimaging-guided repetitive transcranial magnetic stimulation in neurodevelopmental disorders: The case of a schizencephaly-related spastic dystonia

“…1A). As previously reported in other schizencephaly cases [4,5], these results suggest that the corticomotoneuronal tract to both hands originates from the non-affected motor cortex.Secondly, in order to precisely target rTMS, we performed functional magnetic resonance imaging (fMRI) with a block-designed motor paradigm to show sensorimotor regions involved in left hand and foot movements. The patient was instructed to alternate between left hand finger to thumb movements during activation periods (30 s) and resting-state periods (30 s), for a total imaging time of 6 min.…”

“…1A). As previously reported in other schizencephaly cases [4,5], these results suggest that the corticomotoneuronal tract to both hands originates from the non-affected motor cortex.…”

“…Schizencephaly, a disorder of cortical development, consists of a gray matter polymicrogyri-lined cleft of one cerebral hemisphere connecting extra-axial subarachnoid space and ventricle [4]. The patient was born after eight months pregnancy without reported complication.…”

“…It was suggested that ipsilateral cortico-spinal fibers for motor control are present during perinatal period, but they become rapidly non-functional during typical brain development because the contralateral motor pathway is enhanced [4]. In schizencephaly, a prenatal cortical lesion probably prevents formation of a typical contralateral pathway and thus ipsilateral cortico-spinal motor connections are strengthened in postnatal period.…”

Kortikale Reorganisation bei Kindern mit konnataler spastischer Hemiparese - eine funktionelle Magnetresonanztomographie-(fMRT-)Studie

“…Solche vermehrte ipsilaterale Aktivität bei Bewegung der paretischen Hand ist bei unterschiedlichen Läsionsformen wie bei Schizenzephalie und anderen frühen kortikalen Entwicklungsstörungen[8,22,23], bei PVL-Patienten[7], bei Patienten mit kortiko-subkortikalen Läsionen[9] und bei Patienten nach Hemisphärektomie[24] beschrieben worden. Demnach ist das Auftreten ipsilateraler Aktivität nicht auf einen bestimmten Schädigungszeitpunkt oder Schädigungsmechanismus beschränkt.…”