Two-Birds-One-Stone" Approach for Treating an Infant with Chiari I Malformation and Hydrocephalus: Is Cerebrospinal Fluid Diversion as Sole Treatment Enough?

BACKGROUND: Chiari I malformation (CIM) is a disorder characterized by caudal displacement of the cerebellar tonsils below the foramen magnum. It is often associated with syringomyelia and occasionally with hydrocephalus. CIM is commonly treated by posterior fossa decompression with or without removal of the posterior arch of C1 and duraplasty, but the treatment for infants with symptomatic CIM is not well established. We present a case of symptomatic CIM in an infant that was successfully treated with a ventriculoperitoneal shunt (VPS) and discuss the importance of the pathophysiology in management decisions. CASE DESCRIPTION: A 6-month-old male with a CIM and a cervicothoracic syrinx presented with stridor, lower cranial nerve dysfunction, and increased tone that worsened with crying. Magnetic resonance imaging studies revealed cerebellar tonsillar displacement extending to the level of C3-C4 with a syrinx extending from C4 to T4. In addition, there was compression of the cervicomedullary junction, fourth ventricular outflow obstruction, and obstructive hydrocephalus. The decision was made to place a ventriculoperitoneal shunt (VPS) instead of performing decompressive surgery as the initial treatment intervention. The infant had significant symptomatic relief at 6-, 9-, and 12-month follow-ups. Postoperative magnetic resonance imaging at 6-month follow-up revealed resolution of the syrinx and ventriculomegaly and ascent of the cerebellar tonsils. CONCLUSIONS: Ventriculoperitoneal shunting alone was successfully used to treat an infant with concurrent CIM, syrinx, and hydrocephalus. This case underscores not only the importance of hydrocephalus as the pathogenesis of CIM in some cases but also the possibility of avoiding the morbidity of decompressive surgery in infants.