Abstract

Background and Importance: Congenital encephalocele refers to the protrusion of CNS tissue through a skull defect. As a rare neural tube malformation, clinical evidence is particularly limited for large encephaloceles, and management is subject to ongoing discussions. Clinical Presentation: A 3-month-old boy presented with a left hemisphere herniation above the level of the Sylvian fissure into a congenital parietal encephalocele. No focal deficits were appreciated. We hypothesized that early prenatal damage due to protruding brain tissue may have resulted in unihemispheric motor control of both body sides. As such, surgical repair guided by intraoperative electrophysiology and plastic reconstruction was scheduled. Intraoperatively, bilateral and symmetric extremity response upon transcranial electric stimulation of the contra-lesional right hemisphere was detected, whereas no responses from direct cortical and subcortical stimulation of the herniated brain parenchyma were elicited. Complete resection of the herniated supra-insular hemisphere was provided, and no ischemic changes or new deficits occurred. At 24-month follow-up, the patient showed voluntary movements with both upper extremities and voluntary grasping with his left (non-paretic) hand, no mirror movements, no signs of spasticity, good eye contact, and could speak several words. Conclusions: Safe resection with excellent outcome can be provided even for large encephaloceles. Intraoperative electrophysiological findings aid in identifying the absence of cortico-spinal projections and appear helpful to avoid post-operative deficits.

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