"It was first described in 1891 by Hans Chiari (1851-1916), an Austrian pathologist, based on the autopsies of children."
"The term Chiari 1 malformation should not be used when tonsillar descent is due to other causes, e.g., both idiopathic intracranial hypertension and spontaneous craniospinal hypotension (see acquired tonsillar ectopia)."
"Chiari 1.5 malformation (sometimes considered a variant of Chiari 1 malformation 4,16)"
Expected headings
"Terminiology"
"Associations"
"CT"
"MRI"
"Measurement"
"Ancillary features"
"If clinical features are present, they may include a headache and those associated with brainstem compression, syringomyelia, or scoliosis. Headaches are typically short-lasting ("
"abnormal skull base (e.g. short clivus)"
"cervical segmentation anomalies (e.g. Klippel-Feil syndrome)"
"The degree of tonsillar descent is determined by first drawing a line from the basion to the opisthion (anterior margin to the posterior margin of the foramen magnum); this defines the plane of the foramen magnum."