Avoiding overdrainage with MBlue valve in pediatric hydrocephalus: efficiency, complications and valve survival.

PURPOSE Overdrainage is a significant long-term complication in shunted pediatric patients and remains difficult to prevent consistently. The MBlue valve is a novel programmable gravitational (AG) device designed to address this issue. This study aims to assess its performance in managing pediatric hydrocephalus. METHODS A retrospective review was conducted on children under 15 who received MBlue valves between April 2019 and October 2023 at La Fe University and Polytechnic Hospital. Data collected included demographics, hydrocephalus etiology, indications for MBlue implantation, pressure setting evolution, valve efficacy in overdrainage control, associated complications, and valve survival. RESULTS A total of 100 MBlue valves were implanted in 77 children (mean age: 5.77 ± 4.7 years; 44 males, 33 females). Mean follow-up was 36.92 months (range: 12–66). The most frequent etiology was posthemorrhagic hydrocephalus in preterm infants (29.9%), followed by tumor-related hydrocephalus (10.4%). MBlue was used for prevention in 32 cases (41.5%) and for treatment in 45 (58.5%). There were 197 pressure readjustments, with an overall trend toward increased settings; six cases required a setting of 40 cmH₂O. Overdrainage was prevented in 81.2% and successfully treated in 84.4% of cases, most commonly evidenced by radiological improvement. Complications included blockage of the adjustability mechanism in 38 of 78 tested valves (48.7%), with clinical impact in 20 cases (25.6%) and surgical replacement in 12 (15.4%). Age under 2 years was the only factor significantly associated with blockage. Spontaneous pressure changes occurred in 9 valves, 6 of which were linked to adjustability failure, requiring revision in 4. Seven additional valves showed obstruction with clinical deterioration, while only 3 cases involved catheter obstruction. Shunt survival rates at 1 and 3 years were 82% and 62%, respectively. Younger age at implantation was associated with higher rates of blockages of the adjustability mechanism and revisions. CONCLUSIONS The MBlue valve is effective in preventing and treating overdrainage in children, with high shunt survival and low incidence of catheter obstruction. Progressive pressure increases are often required, reflecting dynamic CSF physiology and the unpredictability of optimal settings. The main limitation is the frequent blockage of the adjustability mechanism, followed by spontaneous pressure changes and valve obstruction. Reducing fibrin deposition within the system may improve performance and longevity.