Chiari Malformation Type Ii, also known as arnold-chiari malformation, is related to chiari malformation type i and chiari malformation type 4, and has symptoms including ataxia, muscle spasticity and opisthotonus. The drugs Polyestradiol phosphate and Estradiol have been mentioned in the context of this disorder. Affiliated tissues include spinal cord and cerebellum, and related phenotypes are agenesis of corpus callosum and nystagmus