Ventriculoatrial Shunting: An Escape Option in Patients with Idiopathic Normal Pressure Hydrocephalus Failing Ventriculoperitoneal Drainage

Background: Ventriculoperitoneal (VP) shunting is widely accepted as the gold-standard treatment for idiopathic normal pressure hydrocephalus (iNPH). However, a restricted group of patients experience only minimal or no improvement after the operation. In such cases, the question whether the diagnosis was incorrect or the shunt is malfunctioning remains unanswered. Methods: We retrospectively collected data on a 10-year series of VP-shunted patients with iNPH showing transient or minimal improvement of symptoms within 3 weeks from surgery. A full workup (including noninvasive diagnostic, cognitive, and invasive tests) was performed. After ruling out mechanical malfunction, we performed a tap test followed by a Katzman test 2 weeks later. The confirmed persistence of disturbance of cerebrospinal fluid dynamics was treated by shunt revision and, if found working, by its replacement into the atrial cavity. Results: Twenty patients were diagnosed with shunt insufficiency. At surgery, the distal end of the shunt was easily extruded and found working in all cases. It was then repositioned into the right atrium (the first 8 patients of the series also underwent failed contralateral abdominal replacement). Early postoperative clinical improvement was always confirmed. In 1 case, shunt overdrainage was corrected by valve upregulation. Conclusions: According to our experience, inadequate distal end placement of a shunt might be one of the reasons needing investigation in patients with iNPH failing improvement after surgery. In such situations, the conversion to a ventriculoatrial shunt proved to be a low-cost and successful treatment option