Revision surgery for Chiari malformation decompression.

Chiari malformations comprise four different hindbrain anomalies originally described by Hans Chiari, a professor of pathology at the German University in Prague. There are four basic Chiari malformations. The reasons for revision of Chiari malformation decompression may be for conservative or inadequate initial decompression or the development of postoperative complications. Another reason involves cases of both hindbrain herniation and syringomyelia in patients who have undergone adequate posterior fossa decompression without resolution of symptoms, signs, or radiological appearance of their syrinx cavity. Additionally, symptom recurrence has been reported in association with various types of dural grafts. Reoperation or revision surgery for patients with Chiari malformations is common and may not be due to technical error or inadequate decompression. The types of revision surgeries, their indications, and initial presentations will be reviewed.