Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 4 2 2019 08 18 e30 e30 Sepideh Paybast Neurology Department, BoualiSina Hospital, Qazvin University of Medical Sciences, Qazvin, Iran. Mohsen Koosha Neurosurgery Department, Imam Hossin Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Dina Motamedi Neurology Department Ghods Hospital, Kurdistan University of Medical Sciences, Sannandaj, Iran Arman Habibi Neurology Department, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran 2019 06 30 2019 07 10 Introduction: Chiari malformations are a group of congenital anomalies which involve the hindbrain and the cervical spinal canal. Case presentation: Here, we describe a patient who presented with acute diplopia and gait unsteadiness which was first deigned with Chiari malformation type-1. However due to progression of the ataxia the full neurologic evaluation was considered which established the diagnosis of spinocerebellar ataxia type 3 (Machado-Joseph-Disease). Conclusion: We aim to highlight the importance of careful examination in order to avoid misdiagnosis of even rare diseases. https://fem.tums.ac.ir/index.php/fem/article/view/206 https://fem.tums.ac.ir/index.php/fem/article/download/206/208