The malformation can either be congenital or can develop over time due to a number of genetic diseases that affect connective tissue. It is often accompanied by hydrocephalus, syringomyelia, Ehlers-Danlos Syndrome and Marfan syndrome. The condition is usually diagnosed with a medical history, a neurological examination and finally an MRI. It is generally corrected with surgery to enlarge the opening at the base of the skull. This usually provides relief, but where the condition arises secondary to another condition, ongoing treatment is usually required.