Benign extracerebral fluid collection in infancy as a risk factor for the development of de novo intracranial arachnoid cysts

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Intracranial arachnoid cysts are a relatively common benign intracranial pathology, accounting for as many as 0.75%–1% of nontraumatic CNS lesions. Although it has already been demonstrated that rupture of arachnoid cysts may lead to subdural hematomas/hygromas, no study to date has investigated benign extracerebral collection in infancy as a possible predisposing factor for further development of arachnoid cysts.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors performed a retrospective imaging and chart review of macrocephalic infants 12 months old or younger who were referred to neurosurgical care at OSF St. Francis Medical Center from 2003 to 2010, and who were diagnosed with benign extracerebral fluid collection in infancy on thin-slice (1-mm) head CT scans. Special attention was given to the investigation of risk factors for further development of de novo arachnoid cysts. Several epidemiological factors in the infants and mothers were analyzed, including gestational age at delivery, mode of delivery, mother's age at delivery, delivery complications, birth weight, age of macrocephaly development, degree of macrocephaly, family history of macrocephaly, prenatal and postnatal history of infection, fontanel status, presence of papilledema, previous history of head trauma, and smoking status. Imaging characteristics of the initial scans, such as location of subdural collection (frontal vs frontoparietal and frontotemporal) and presence of ventriculomegaly, were also evaluated. For those patients in whom arachnoid cysts were identified on subsequent CT scans, the size and location of the cysts were also analyzed.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The authors identified 44 children with benign extracerebral fluid collection in infancy. From this group, over a mean follow-up of 13 months (range 6–13 months), 18 children developed intracranial arachnoid cysts (a 40.9% incidence of de novo development of arachnoid cysts), with 27.8% presenting with bilateral cysts. In the multiple logistic regression analysis, infants who presented with an extracerebral collection restricted to the bilateral frontal region were more likely to develop intracranial arachnoid cysts (p = 0.035) than those with collections involving the frontotemporal and frontoparietal regions (odds ratio [OR] = 5.73). Additionally, children with benign extracerebral fluid collections and plagiocephaly were more likely to develop intracranial arachnoid cysts (p = 0.043) than those without plagiocephaly (OR = 4.96).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>This is the first report in the neurosurgical literature demonstrating that benign extracerebral fluid collections in infancy may constitute a significant risk factor for development of de novo arachnoid cysts. These findings support a 2-hit hypothesis for the development of arachnoid cysts, in which the combination of an embryological defect in arachnoid development followed by a second event leading to impairment of CSF fluid absorption in early childhood could lead to abnormal CSF dynamics and the consequent expansion of fluid collections in the intraarachnoid spaces.</jats:p></jats:sec>

Diverse arachnoid cyst morphology indicates different pathophysiological origins

“…A recent study presented a “2 hit” process for development of arachnoid cysts with both a congenital histological defect in the development of the arachnoid membrane and a later event of head trauma or hemorrhage [39,40]. This type of mechanism was not evident for the patients in our study, none of whom reported a complication during birth or early childhood and only a few of them reported head trauma.…”

Comparison of clinical and radiological manifestations and surgical outcomes of pediatric Chiari I malformations in different age groups

“…In addition, supporting evidence recently emerged from subjects regarding arachnoid cysts and subdural fluid collection [13]. These issues suggest that diseases related to disturbed CSF dynamics, such as Chiari I malformation, might present different clinical and radiological features and treatment outcomes in very young pediatric patients than in older patients.…”

Can Neonatal Hypoglycemia be Considered a Risk Factor for Development of Acquired Arachnoid Cysts?

“…ACs are intracranial extra-axial collections of CSF-like fluid. The reported prevalence is between 0.9 1 and 2.6% 10,11 in pediatric age and between 0.2 10-12 and 1.7% 2 in adults. Men are more frequently affected than women, approximate ratio is 2:1; this difference may be reduced by not considering temporal fossa cysts, which are more common in males.…”

“…Temporal fossa is the most frequent site for AC, followed by posterior cranial fossa, cerebral convexity, and suprasellar region. 1,2, [10][11][12][13] ACs are conventionally divided into primary and secondary/ acquired types. Primary ACs are congenital in nature and are intra-arachnoid lesions; secondary ones arise after trauma, hemorrhage, pre-or postnatal infections, and surgery, and these may demonstrate gliosis or other signs of inflammatory reaction and can contain xanthochromic, hemorrhagic, or proteinaceous fluid.…”