Inferiorly Directed Posterior Cranial Vault Distraction for Treatment of Chiari Malformations

The authors present a case series of patients with Chiari I malformations treated with distraction osteogenesis of the posterior cranial vault, utilizing a vertical distraction vector for appropriate cranial vault expansion while mitigating the risks of scaphocephaly and cerebellar ptosis.

Patients with syndromic and nonsyndromic Chiari I malformations treated with vertical-vector distraction osteogenesis of the posterior cranial vault were identified from 2008 to 2014. Demographics, preoperative and postoperative clinical symptoms, and perioperative details were assessed. Long-term esthetic outcomes, complications, and symptomatic improvement were evaluated in conjunction with neurosurgery.

Nine patients were identified. Five had known syndromes, 2 likely had unidentified syndromes, and 2 were nonsyndromic. Seven had prior Chiari-related surgeries. Most presented with hydrocephalus, motor symptoms, and developmental delay. Operatively, 2 to 3 internal distraction fixators were applied such that the vector of distraction was along a cephalad-caudad axis. Devices were activated on postoperative day 5 and distracted 1 mm per day. Three postoperative complications were found within the first 3 months which included a dislodged distraction arm, a device extrusion, and a local cellulitis. No complications affected the clinical outcome. Radiographic follow-up showed good bone formation, decompression of the posterior fossa, improved cerebrospinal fluid flow, and no cerebellar ptosis. Neurological surveillance showed improvement in intracranial pressure, hydrocephalus, motor symptoms, and behavioral problems.

The authors have presented 9 patients with Chiari I malformations treated with distraction osteogenesis, along with a novel technique to safely and effectively expand the posterior fossa while minimizing the risk of cerebellar ptosis.

Level II (prognostic/risk studies).