gms | German Medical Science

Objective: It is commonly believed that shunt or ETV failure is associated with symptoms and signs of raised intracranial pressure. If the are absent, especially in children with related developmental delay or behavioral problems, a shunt or ETV failure may remain undiagnosed or considered not relevant. In reality, children may suffer subclinical damage from uncompensated intracranial CSF dynamics. We report on the imaging features and ICP monitoring results of almost or totally asymptomatic patients in whom shunt blockage/ETV reclosure was confirmed.

Methods: Patients in our interdisciplinary hydrocephalus clinic were critically re-evaluated for treatment failure by careful clinical assessment, followed by high-resolution MRI imaging and/or computerized overnight ICP analysis or shunt infusion study. If the suspicion of shunt/ETV malfunction and uncompensated intracranial CSF dynamics could be substantiated, children underwent surgery.

Results: We identified 15 children with suspected treatment failure in absence of symptoms or signs of raised intracranial pressure. In 5 children with large ventricles or migrated shunt catheters, ICP overnight monitoring showed the same pathological and pathognomonic features of shunt malfunction (high baseline ICP >15 mmHg, peak ICP over 25 mmHg, RAP Index 0.6 at baseline or during vasogenic events) as we had found previously in symptomatic patients. In 5 children ICP recordings were normal. One child had a pathological and one a normal shunt infusion study, respectively. In 3 totally asymptomatic children post ETV, ICP recordings were pathological. In all children, who underwent surgery, a blocked shunt component or a closed ETV was found.

Conclusions: Asymptomatic treatment failure in hydrocephalic children seems to be more common the more thoroughly children are evaluated. A hallmark of the problem in non-gravity assisted shunt systems is the failure of ventricles to become significantly smaller after surgery or ventricular re-expansion. High resolution MRI can detect scarring around the shunt tip or ETV re-closure, which is not visible in CT scans and standard MRI. ICP overnight monitoring or shunt infusion studies are excellent diagnostic tools since shunt failure has characteristic patterns and highly pathological nocturnal ICP readings can occur in totally asymptomatic patients.