Purpose or Case Report: Chairi 1.5 malformation is different than usual Chair i1 malformation. Neuroisurgery treatment depends on certain specific measurements performed on MRI. Purpose of this presentation is to illustrate the method to perform these measurements.
Methods & Materials: When obex and cerbellar tonsils are below the foramen magnum, it is called Chiari 1.5 malformation. MRI performed on children with Chiari 1.5 malformation tereated at our tertiary care Children's hospital will be used for the purpose of illustration of various lines and measurements performed at skull base that are important in determining surgical approach. Various grades of pB-C2 line will be described. Various lines and angles at the skull base for diagnosis of basilar invagination will also be demonstated.
Results: Based on published paper by Ladner et al, when pB-C2 line measures 3 mm or more, the patients are more likely to have syrinx. These patients are morel ikely to get syrinx reduction and headache reduction after surgical treatment. Research by Bollo et al has demonstrated that clivo-axial angle of less than 125 dergrees is associated with increased risk of requiring occipito-cervical fusion in addition to posterior fossa decompression.
Conclusions: Diagnosis of Chiari 1.5 malformation and knowledge of how to perform its specific measurements are very important as this information is of immense value to the pediatric neurosurgeons.