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What is All of the following are true about Arnold-Chiari malformation except: and explain in detail?
Arnold-Chiari Malformation Type I Chiari malformation Type II Chiari malformation - Displacement of cerebellar tonsil into cervical canal - Associated with syringomyelia of cervical canal - Typically produces symptoms during adolescence or adult life - Not associated withhydrocephalus - Patients complain of recurrent headache, neck pain, urinary frequency, and progressive lower extremity spasticity - Lesion represents an anomaly of the hindbrain - Characterized by elongation of the 4th ventricle and kinking of the brainstem, with displacement of the inferior vermis, pons and medulla into the cervical canal. - Type II Chiari malformation is characterized by progressive hydrocephalus with a myelomeningocele. - Plain skull radiographs show a small posterior fossa and a widened cervical canalQ. - CT scanning with contrast and MRI display the cerebellar tonsils protruding downward into the cervical canal and the hindbrain abnormalities. - The anomaly is treated by surgical Decompression