Gravitational shunt valves in hydrocephalus to challenge the sequelae of over-drainage

Neurosurgical CSF Diversion in Idiopathic Intracranial Hypertension: A Narrative Review

“…Shunts may paradoxically cause complications due to over-drainage. Development of low-pressure symptom impacts on both VP and LP shunts though LP shunts are more severely affected due to the hydrostatic pressure effect of gravity on the fluid column within the neuroaxis in an upright position [ 58 ]. CSF leaks occurring around catheter insertion sites, particularly when shunts are inserted in an open technique, may further compound this [ 59 ].…”

“…In addition to the flow-regulated valves already discussed, standalone anti-siphon devices (ASD) exist, which can be installed in-line distal to the shunt valve [ 76 ]. Gravitational valves are a further alternative in which the siphon-reducing technology is integral to the valve mechanism itself and contained within the same housing [ 58 ]. Further to this, there exist programmable anti-siphon devices, which add a further level of complexity and versatility into the system.…”

Integrated understanding of hydrocephalus — a practical approach for a complex disease

“…This may be a very good parameter to adapt physiologic-like CSF drainage during shunt therapy for adjustment protocols adapting the drainage resistance in the valve system. The aim would then be to keep the percentile curves in order to avoid over-as well as under-drainage and keep a physiological pressure value which seems more relevant than a certain ventricle size [24,30]. Such a strategy if successfully applied would automatically avoid slit ventricle syndrome and its complications in the long run.…”

“…Complications such as malpositioning, obstruction, infection, and over-and under-drainage need full awareness for the treating pediatric neurosurgeon in order to find solutions to keep the complication rate as low as possible. Since pathophysiology of different types of hydrocephalus is so diverse as well as activity, age, height, growth, and anatomical circumstances are individually so heterogeneous, the adaptation of resistance in the valve system per case and over time seems to be still underestimated [24,30]. Moreover, underdrainage mostly exists when a shunt is somehow obstructed; over-drainage is a common problem infant and childhood hydrocephalus will develop over time, e.g., already when the patient gets in the upright position and the calvarial cavity get in a higher position compared to the peritoneum inducing hydrostatic force in the shunt.…”

“…This chronic problem needs to be addressed in the shunt system from early on to avoid long-term anatomical changes such as microcephaly or slit ventricles. Increased activity over time will further aggravate over-drainage in the developing child and needs adaptation, accordingly [30].…”