Chiari malformation is a condition here the lowest part of the cerebellum herniates out of the skull and into the upper spinal canal. This can present with a range of symptoms from headache through to neurological impairment of the arms and legs due to the formation of a syrinx (cavity within the spinal cord). Most symptomatic malformations are treated with a foramen magnum decompression (posterior fossa decompression) and this is highly successful in the majority of cases. Occasionally, in more “complex” cases there may be evidence of instability necessitating fusion of the skull to the upper cervical spine (occipitocervical fusion). Assessment of a patient with Chiari Malformation involves a detailed history and examination followed by review of the MRI scan (+/- CT Scan). After this, an appropriate treatment plan can be made.