Pathogenesis and treatment of intracranial arachnoid cysts in pediatric patients younger than 2 years of age.

Object: Arachnoid cysts can cause a variety of clinical signs and symptoms in infants. The authors sought to determine whether the clinical presentation of pediatric patients younger than 2 years old and harboring arachnoid cysts influenced the type of intervention that would be required.

Methods: A retrospective chart review was conducted for all patients younger than 2 years of age who had undergone craniotomy for fenestration of an arachnoid cyst at the Children's Hospital Los Angeles between 1995 and 2006. Forty-two patients were included in the study. The mean age was 10.4 months. The median follow-up time was 33 months. Clinical presentations were as follows: macrocephaly without ventriculomegaly (21 patients, 50%), hydrocephalus (six patients, 14%), and other symptoms (15 patients, 36%). After fenestration of the arachnoid cyst, 12 of 21 patients (57%) presenting with nonspecific macrocephaly required placement of a cystoperitoneal or ventriculoperitoneal shunt, compared with 1 of 15 patients (7%) presenting with other symptoms (p value = 0.0039). Five of six patients with hydrocephalus (83%) were shunt dependent following fenestration. Overall, 18 of 42 patients (43%) were shunt dependent after fenestration. Ten of these patients (55%) required revisions during the follow-up period.

Conclusions: Patients younger than 2 years of age and harboring an arachnoid cyst commonly present with macrocephaly. These patients are more likely to require shunts than are those presenting with other findings, such as seizures or incidental lesions. The development and expansion of arachnoid cysts may be related to aberrant cerebrospinalfluid dynamics, and these lesions may be a form fruste of hydrocephalus. Arachnoid cysts should be treatedwith craniotomy and cyst fenestration, taking into account the likelihood of perioperative shunt dependency.