<unk>  <unk>  is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull).<unk> s can cause headaches, difficulty swallowing, vomiting, dizziness, neck pain, unsteady gait, poor hand coordination, numbness and tingling of the hands and feet, and speech problems. Less often, people may experience ringing or buzzing in the ears, weakness, slow heart rhythm, or fast heart rhythm, curvature of the spine (scoliosis) related to spinal cord impairment, abnormal breathing, such as central sleep apnea, characterized by periods of breathing cessation during sleep, and, in severe cases, paralysis. This can sometimes lead to non-communicating hydrocephalus as a result of obstruction of cerebrospinal fluid (CSF) outflow. The cerebrospinal fluid outflow is caused by phase difference in outflow and influx of blood in the vasculature of the brain. The<unk>  is named for Austrian pathologist Hans<unk> . A type II<unk>  is also known as an Arnold–Chiari<unk>  in honor of<unk>  and German pathologist Julius Arnold.
Chiari malformation
Glial tumor
Central nervous system cyst
Dandy–Walker malformation
Arachnoid cyst
Subdural hygroma
Cavernous venous malformation
Meningism