Choose the most likely condition in these scans of a 2 years old boy.
- Hydrocephalus due to aqueductal stenosis
- Communicating hydrocephalus
- Hydrocephalus due to Chiari malformation
- Dandy-Walker syndrome
- Chiari malformation without hydrocephalus
This is hydrocephalus due to Chiari malformation. The cerebellar tonsils can be seen herniating through the foramen magnum below the posterior arch of C1. There is an obstruction to the flow of CSF out of the 4th ventricle, and a resultant syrinx in the spinal cord.