A 20-year-old female presented with dysphasia and slight hemiparesis following a head trauma, who had a non-treated growing skull fracture which had remained asymptomatic for about 18 years, despite an encephalocele in the left parietal region. Neuroimaging demonstrated secondary brain damage and herniated brain resulting in gliosis. Electroencephalography revealed epileptic discharge in the affected region. Dural repair and cranioplasty resolved her neurological deficits. Early corrective surgery should be performed for growing skull fracture to prevent secondary brain damage.