Overall, the majority of patients that underwent operations for intracranial cysts had good clinical and neuroimaging outcomes. No severe or permanent complications related to the treatments were observed.
A great deal of debate exists about what is the best choice of treatment for asymptomatic patients with intracranial cysts12,20,21)
. Generally, conservative treatment approaches are recommended for adult patients with asymptomatic cysts, whereas some authors advise more aggressive approaches for asymptomatic pediatric patients. There is substantial evidence indicating that there are critical developmental phases in childhood during which specific abilities are learned. Deprivation of stimuli that are important for the brain development during these critical periods can cause permanent deficits4,9,18)
. In several studies, intracranial cysts have been shown to cause functional deficits, metabolic deficits, or deficits in the perfusion of blood to the underlying cerebral tissues10,22,39,42,44,49)
. Therefore, the presence of intracranial cysts during childhood may impair optimal brain development during critical developmental periods. Intracranial cysts in children may not only cause acute symptoms in some patients, but also affect the developing brain in more subtle ways, which can ultimately lead to learning difficulties and behavioral problems. The series presented in this study included asymptomatic newborns with giant intracranial cysts or progressively enlarging cysts. In our opinion, it is important to consider these possible impairments when deciding whether to perform surgical decompressions of intracranial cysts in children because early decompression in a child may help to relieve the pressure on the underlying cerebral tissues and thus allow more normal brain development.
Most authors agree about the indications for treatment of symptomatic cysts19,37,51)
. In general, the more evident a symptom is, the sharper the indication is, which is followed by more satisfactory results. Neurological focalities usually respond favorably to treatment28)
. All patients with focal deficits improved in the series that was presented here, independent of cyst locations. Increased intracranial pressure, hydrocephalus, and mass effect are other clear indications for treatment.
The indications for treatment are debated far more in cysts with headaches or epilepsy8,15,27,45,47,48)
. This series included a few cases of patients with headaches (without increased intracranial pressure), and the results of treatment in these patients were not satisfactory. Headache remain a controversial indication for cyst surgery47)
and there is even skepticism about the effectiveness of cyst treatments48)
. Epilepsy is frequently associated with intracranial cysts15,25,33)
, but the seizure etiology remains unknown, and the coexistence of seizures and cysts may be incidental15,27,33,47)
. Thus, careful preoperative selections are mandatory.
The clinical improvements observed in our series seemed to parallel the postoperative reductions in cyst volumes, as the children who had the most pronounced volume reductions experienced better clinical improvements. Similar clinical correlations with neuroimaging have previously been described by other authors16,17,23,36)
. However, these results contrast with findings in adults that underwent surgeries to treat arachnoid cysts21)
. In these adults, clinical improvement seemed unrelated to the degrees of volume reductions. This difference between adults and children is likely due to the fact that many of the children underwent surgeries when their brains were still growing. Throughout childhood, the neurocranium is molded to fit the contents of the skull. Thus, intracranial cysts create surplus intracranial spaces by being present during skull growth. In adults, this extra volume may be too large for the relieved brain to fill even after successful cyst decompression. Therefore, in these situations, there would be residual fluid volumes. However, in children the growing brain may be able to fill in the vacant space left by the cyst. Therefore, surgical decompressions at early ages may prevent the mismatches between skull volumes and brain volumes that are often encountered after decompression in adults20)
The optimal treatment for arachnoid cysts in children has yet to be determined. The most common procedures are shunt placements and fenestrations of the cysts, but both procedures have drawbacks2,11,14)
. The shunt operation is a non-invasive, simple, and safe procedure compared to direct removal of cyst walls43)
. According to Punzo et al.38)
, shunt operations must be considered in the following cases : 1) when the non-communicative arachnoid cysts are accompanied by hydrocephalus and the basal cisterns are obstructed; 2) when neither mass effect nor hydrocephalus was confirmed on radiography; and 3) when long surgical times enhance the risks. However, the disadvantages of shunt operations are : 1) the arachnoid membranes are left to perform secretory and filtrating functions; 2) surgical vision is limited; and 3) there is a possibility of fatal slit ventricle syndrome due to infection, obstruction, or overdrainage of cerebrospinal fluid (CSF). Moreover, the postoperative outcomes are complicated by subdural hemorrhage and headache. For all of these reasons, shunt operations are now only performed in rare cases38,41)
Gradually, fenestrations have become the primary therapeutic option. In a large microsurgery series by Helland and Wester20,21)
, 82% of patients improved and 5% worsened; the rates of complications were 17% in adults and 6% in children; and additional surgeries were required in 7% of adults and 17% of children. Levy et al.28)
reported a microsurgery series of 50 patients and concluded that microsurgery was better than endoscopy because it offered better control of hemostasis with bipolar forceps and other standard instruments. Nevertheless, the complication rates in this study were not negligible : 10% of the patients suffered from meningoceles, 6% had nerve palsies, 6% had CSF leaks, 4% had subdural hematomas, and 2% had wound infections.
In the last 20 years, the rapid development of modern neuroendoscopic techniques had offered a new option for cyst fenestration. There are some authors that consider the current endoscopic success rates to be worse than those obtained with microsurgeries1,28)
. However, there are also several articles reporting that endoscopic results are better than microsurgical results37,46)
. Nowoslawska et al.35)
reported a series where microsurgeries and endoscopies were compared. This study found similar success rates with significantly shorter duration of hospitalization after endoscopies. Karabatsou et al.24)
obtained clinical and radiological improvements in 92% and 63% of cases, respectively, when using endoscopic neurosurgeries. These results can be compared with the clinical and radiological improvements of 72% and 79% of cases, respectively, reported by Levy et al.28)
In our study, clinical and radiological improvements were reported in 87.3% and 92.8% of cases, respectively, after endoscopic neurosurgeries, in 93.3% and 100% after open microsurgeries, and in 88.9% and 85.7% after shunt operations (). There were no statistical differences in clinical outcomes (p=0.710) or volume reductions (p=0.177) when the different surgeries were compared. Endoscopic neurosurgeries are less invasive than microsurgeries, and are at least as effective as open surgeries. Thus, given the advantages and complications of these surgical techniques, we suggest that endoscopic fenestration should be the first treatment attempted in children with intracranial cysts.
In this study, there seems to be little differences in surgical outcomes among the type of pathologies. However, given the surgical outcomes depending on the kind of cysts or mechanism of cyst growth could be different, prospective and large-sized study grouped according to pathologies of cysts should be investigated.