Aggressive surgical management of patients with Chiari II malformation and brainstem dysfunction

Chiari II malformation represents a group of developmental abnormalities involving the caudal displacement of the cervicomedullary junction, pons, fourth ventricle, and medulla. This constellation of malformations is strongly associated with myelomeningocele (MM) and is a known cause of neurologic deterioration in older MM patients. We describe the evaluation and management of 4 adult MM patients who presented with brainstem compression and a retroflexed odontoid who were subject to aggressive surgical management including occipitocervical (OC) fusion with good clinical results.

Four MM patients who underwent OC fusion for new-onset brainstem dysfunction and myelopathy were identified in the practice of the principal investigator (D.W.P.) from 2003 to 2008.

The initial evaluation of these patients included consideration of other diagnoses, such as hydrocephalus due to shunt malfunction and tethered cord. These patients were treated with aggressive surgical management. In some cases, multiple surgeries were performed. All 4 patients were treated with cervical decompression and OC fixation and initially had good outcomes. No patients required transoral decompression. Three of the 4 had stable improvement at their last follow-up appointment (mean follow-up of 9 months).

Late deterioration in older MM patients may be secondary to brainstem or cervical spinal cord compression from ventral odontoid compression and Chiari II malformation, hydrocephalus, hydromyelia, or tethered cord. These patients may benefit from more than one surgery. Posterior decompression and OC fusion can avoid a morbid transoral odontoid resection, greatly improve patients' symptoms and prevent further neurologic decline.