Arnold Chiari Malformation: the Otological Assessment as an Objective Criteria for Surgical Treatment

Inclusion criteria: * Chiari type I malformation proved at MRI or CT-scan with an indication of cranio cervical decompression. * Patients between 18 and 60 years old. * Patient should benefit of the national health care system * Agreement of the patient Inclusion criteria for healthy volunteers: * Between 18 and 60 years old. * Free of otologic pathology * Benefit of the national health care system * Agreement of the volunteers Exclusion criteria: * Acute hydrocephaly * Other type of Chiari disease (induced…) * Medical history of neurosurgery * Contraindication for MRI * Cophosis * Chronic otitis * Medical history of ontological surgery * Tympanic perforation * Disturbance of tonal audiometry with air bone more than 20dB in 4 frequencies with abolition of stapedial reflex * Pregnant women or nursing women * Protected adults by French laws Exclusion criteria for healthy volunteers: * Medical history of neurosurgery * Cophosis * Chronic otitis * Medical history of ontological surgery * Tympanic perforation * Disturbance of tonal audiometry with air bone more than 20dB in 4 frequencies with abolition of stapedial reflex * Pregnant women or nursing women * Medical history of Chiari malformation * Chronic headaches or neck pain * Protected adults by French laws