Effect of an Anti-Siphon Device on Shunting Procedure: Intraventricular Pressure During Posture Changes

Abstract

Intraventricular pressure (IVP) is closely related to the posture of patients who have had cerebrospinal fluid (CSF) shunting for hydrocephalus. An overdrainage of CSF through the shunt tube sometimes causes low pressure syndrome, and this syndrome sometimes influences the daily activity of the patient (LPS). The anti-siphon device (ASD) was designed to prevent LPS. We investigated IVP in patients with a CSF shunt with or without an ASD during posture changes. In this study, patients were divided into two groups: Group A consisted of patients with shunts with an ASD placed 10 cm below the level of the foramen of Monro (11 cases), and Group B consisted of patients with shunts without an ASD (6 cases). IVP was measured by inserting a 25 G needle attached to a transducer into the dome of the shunt device during changes of the patient’s posture (positional IVP monitoring). In the supine position, IVP was significantly lower in Group B than in Group A (Student’s t test, P < 0.05). In the semi-sitting (head raised 30°) and sitting or standing positions, the differences between Group B and Group A were greater than in the supine position (P < 0.001). In conclusion, an ASD was effective in restoring physiological pressure to patients in a sitting or standing position. Nevertheless, LPS was observed in only one patient in Group B (16.7%), and shunt malfunctions due to the adverse effects of an ASD were observed in two patients in Group A (18.2%). Adequate usage of ASDs in shunting must be considered as part of the important effort to prevent LPS.