Withdrawal of shunt systems - clinical use of the programmable shunt system and its effect on hydrocephalus in children

Objects: The most important function of the programmable valve (PV) is to l imit the shunt-dependent flow of the cerebrospinal fluid by upgrading valve pressure. This activates the regular circulation of cerebrospinal fluid, w hich may make successful removal of the shunt possible once sufficient cere bral development has been achieved. The purpose of this paper is to indicat e the possibility of shunt removal using the programmable Medos and Sophy v alves (one programmable Sophy valve was specially designed for this situati on). Methods: Prior to regular use of the PV, removal of existing shunt sys tems was attempted in 57 children, since some systems malfunctioned and oth ers had abdominal tubes that were meanwhile too short as the children had g rown as they became older. Shunt removal was successfully achieved in only 18 patients (32%). However, in patients in whom PV valves were used, shunt removal was successful in 68 out of 114 patients (57%). This shows that the success rate of shunt removal becomes significantly higher when PV valves are used. The 68 cases in which PV valves were used and shunt removal was s uccessful were divided into three groups: A, B, and C. In group A (36 cases , 53%), the Medos valve was used for the initial PV shunt implantation and the pressure was gradually increased up to 200 mmH(2)O. The shunt systems w ere then withdrawn. Group B (29 cases, 43%) includes patients who experienc ed both the minor symptoms and ventricular enlargement attributable to incr eased valve pressure. The pressure was gradually upgraded by pumping severa l times and was maintained at close to 200 mmH(2)O. After 6-24 months' obse rvation shunt removal was performed, and in 21 out of 29 cases the outcome was good. However, the remaining 8 patients (12%) still had symptoms and re quired shunt reinsertion. The specially designed Sophy valves were then use d, which allowed the pressure to be set at above 200 mmH(2)O. The pressure was increased by degrees up to 400 mmH(2)O and kept at the same level for 6 -24 months. The shunt systems were then removed successfully. Although a hi gh pressure setting was required over a sustained period, a total of 29 pat ients (43%) were able to have their shunts removed. In group C (3 cases, 4% ), which included patients with aqueduct stenosis. the pressure was raised and thus allowed ventricle enlargement. Third ventriculostomy was performed under neuroendoscopy with the shunt pressure maintained at a high level. S hunt systems were removed successfully. Conclusions: This study showed that it is possible to remove the shunt systems in 50% or more of pediatric hyd rocephalus cases in which PV valves are used. This is achieved through care ful control of the valve pressure. Close observation is essential during th e period when the PV pressure is maintained at a high level, as well as 6-1 2 months after shunt removal.