Kaye Harper L, Gersner Roman, Boes Aaron D, Pascual-Leone Alvaro, Rotenberg Alexander
Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA.
Neuromodulation Program, Division of Pediatric Neurology, Department of Pediatrics, University of Iowa, Iowa City, IA, USA.
Epilepsy Behav. 2017 Oct;75:66-71. doi: 10.1016/j.yebeh.2017.07.013. Epub 2017 Aug 19.
Corticospinal connections may be bilateral at birth, but a predominantly unilateral and crossed pattern develops by the toddler years. Acquired injury can alter the normal development of laterality such that uncrossed corticospinal connections persist, particularly if the injury is early in life and involves the motor system. Whether other developmental insults, such as childhood epilepsy, affect the development of crossed laterality in the motor system is unknown, although this topic has relevance for understanding the broader impact of epilepsy on brain development. Accordingly, in a cohort of children with intractable focal epilepsy, we tested by neuronavigated transcranial magnetic stimulation (nTMS) whether childhood epilepsy is associated with persistent uncrossed corticospinal connections. Specifically, we hypothesized that in contrast to early-life neuroclastic corticospinal tract injury that induces preservation of uncrossed corticospinal connections in the contralesional hemisphere, uncrossed corticospinal connections will be preserved in the epileptic hemisphere where the corticospinal tract is intact, but overstimulated by ongoing seizures and epileptic interictal discharges. Motor cortex mapping was performed by nTMS as part of a clinical presurgical evaluation, and the analysis was limited to patients with radiographically intact motor cortices and corticospinal tracts. Given that foot motor cortex representation is often bilateral, we focused on the lateralization for the tibialis anterior muscle cortical motor representation and its relation to the seizure focus. We demonstrate preserved uncrossed corticospinal connections for the tibialis anterior region of the hemisphere affected by the epilepsy. These findings indicate a pathologically preserved immature motor lateralization in patients with epilepsy and suggest that developmental processes associated with hemispheric lateralization are affected by epilepsy.
皮质脊髓连接在出生时可能是双侧的，但在幼儿期会形成主要为单侧且交叉的模式。后天损伤可改变正常的偏侧性发育，使得未交叉的皮质脊髓连接持续存在，尤其是在生命早期发生损伤且累及运动系统时。尽管这个话题对于理解癫痫对大脑发育的更广泛影响具有重要意义，但其他发育性损伤，如儿童癫痫，是否会影响运动系统中交叉偏侧性的发育尚不清楚。因此，在一组患有顽固性局灶性癫痫的儿童中，我们通过神经导航经颅磁刺激（nTMS）测试儿童癫痫是否与持续存在的未交叉皮质脊髓连接有关。具体而言，我们假设，与早期导致对侧半球未交叉皮质脊髓连接保留的神经破坏性皮质脊髓束损伤不同，在皮质脊髓束完整但受到持续性癫痫发作和癫痫发作间期放电过度刺激的癫痫半球中，未交叉的皮质脊髓连接将得以保留。作为临床术前评估的一部分，通过nTMS进行运动皮层映射，分析仅限于影像学上运动皮层和皮质脊髓束完整的患者。鉴于足部运动皮层的代表区通常是双侧的，我们重点关注胫骨前肌皮质运动代表区的偏侧化及其与癫痫病灶的关系。我们证明，癫痫所累及半球的胫骨前区存在保留的未交叉皮质脊髓连接。这些发现表明癫痫患者存在病理性保留的未成熟运动偏侧化，并提示与半球偏侧化相关的发育过程受到癫痫的影响。
