en Neurology Neurology case report case report <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="color:#0000ff;"><strong><em>Background</em></strong><em>:</em></span> Arachnoid cysts are congenital or acquired cerebrospinal fluid (CSF) filled intra arachnoidal lesions, included 1% of all infantile intracranial masses and were discovered incidentally in MRI or CT-scan. The vast majority of these lesions are generally asymptomatic but some patients with arachnoid cyst have headache, dizziness, seizure (or epilepsy), vestibular symptoms and cognitive impairment.<br> <span style="color:#0000ff;"><strong><em>Case Presentation</em></strong><em>:</em></span> We present a case of a 43-year-old woman who has late onset epilepsia partialis continua and had right spastic cerebral palsy due to huge arachnoid cyst. Surprisingly without any history of seizure, her first seizure presents with sustained seizures (epilepsia partialis continua) and occur in the middle age for the first time.<br> <span style="color:#0000ff;"><strong><em>Conclusion</em></strong><em>:</em></span> Most arachnoid cysts are asymptomatic and may not produce any symptoms throughout life. In our case, the late onset epilepsia partialis continua in the 5^th decade of life with probably a large arachnoid cyst without any history of seizure before that is unusual. Conservative approaches usually made for the management of arachnoid cysts as patients with these cysts usually maintain the vital neurological functions.</span></span> Arachnoid cyst, Epilepsia partialis continua, spastic cerebral palsy 464 466 http://caspjim.com/browse.php?a_code=A-10-1909-2&slc_lang=en&sid=1 Mohammad Javad Nasr nasrmjavad77@gmail.com 100319475328460031244 100319475328460031244 No Student Research Committee, Babol University of Medical Sciences, Babol, Iran Amir Hossein Zohrevand ahz59dr@gmail.com 100319475328460031245 100319475328460031245 No Department of Neurosurgery, School of Medicine, Babol University of Medical Sciences, Babol, Iran Ali Alizadeh Khatir alizade.ali83@yahoo.com 100319475328460031246 100319475328460031246 Yes Department of Neurology, School of Medicine, Babol University of Medical Sciences, Babol, Iran