[Prolonged ICP monitoring in children with sylvian fissure arachnoid cysts].

BACKGROUND

The decision making process for patients with sylvian fissure arachnoid cysts still represents a challenge for the neurosurgeon. A high proportion of the patients is indeed asymptomatic, in spite of neuroimaging signs of apparently increased intracranial pressure (ICP). The aim of the present study was to evaluate the usefulness of prolonged ICP recording in the preoperative work-out.

METHODS

Twelve children (11 M/1 F) harboring temporal arachnoid cysts were investigated (men age 6.3 years). According to Galassi classification they were subdivided into 3 groups. Group I included 3 patients with Type I cysts; group II comprised 6 children with Type II cysts; group III consisted of 3 children with Type III cysts. An extensible silicone microprocessor (Codman ), developed for continuous ICP recording, was implanted intraparenchymally, adjacent to the major extension of the cyst. The collected information was cable unloaded to a PC and stored. All the patients underwent a minimum of 48 hours to a maximum of 72 hours ICP continuous check. Ten mmHg was arbitrarily chosen as the upper normal limit of ICP in resting conditions and the patients were classified according to the percentile distribution of their ICP daily and nightly pressure values.

RESULTS

ICP recordings were in the normal range in all the 3 children with Type I cysts (49-86% <10 mmHg during the entire recording), in spite of the fact that 2 of them were apparently symptomatic. Three of the 6 children with a Type II temporal cyst had elevated ICP values (69-99% >10 mmHG), even though they had an incidental (1 case) or prenatal (2 cases) diagnosis. The remaining 3 patients had normal ICP values for more than 70% of the recording time period. Two of the 3 patients with type III temporal arachnoid cysts had almost constantly abnormal ICP values (95=99% >10 mmHg); conversely the third patient showed normal ICP values for more than 80% of the recording time period. Five patients were operated on; in 4 of them the surgical indication was based on ICP recordings (2 of the 3 children with a Type II cyst and increased ICP and the 2 patients with a Type III cyst and increased ICP). The last child, harboring a Type I cyst, was operated on under parents request, as a preventive measure. At a mean follow-up of 10.1 months all the patients operated on are in excellent clinical conditions; 1 of them (Type II cyst) initially submitted to craniotomy and cystic membrane excision needed a subdural-peritoneal shunt implant 3 months after surgery for the appearance of a symptomatic subdural hygroma on the side of the cyst. Postoperative CT showed signs of brain expansion in the 2 patients operated on for a Type III cyst, and in the patients operated on for a Type I cyst.

CONCLUSIONS

With the limit of the relatively small series here presented, prolonged ICP recording appeared to be an important preoperative tool to rule out the necessity of operating on children with Type I cysts. Furthermore, it was particularly useful in the decision-making process for children with Type III cysts. In cases of Type II lesions, the investigation resulted less discriminating, though the ICP monitoring contributed to find out those patients in whom surgery was indicated in spite of the absence of symptoms.