Shunt Over-drainage, Slit Ventricle Syndrome, Programmable Valves and Anti-Siphon Devices. A Narrative Review of a Multifactorial and Intractable Problem.

The current management strategy of hydrocephalus mainly involves the insertion of a ventriculoperitoneal shunt and is inherently related with a complication widely known as shunt over-drainage. Albeit this is a well-recognized complication, the true incidence and severity of this phenomenon remains undefined and most probably underdiagnosed, necessitating a more comprehensive pathophysiologic and therapeutic consideration. The slit ventricle syndrome is intimately related with the entity of shunt over-drainage, although who's the definition of the former is implicated by a lack of universally accepted inclusion criteria. Another point of controversy is related with the absence of widely accepted criteria that would be able to discriminate the existing differentiations between these two entities. This is reflected in the fact that there are many proposed, relevant, treatment protocols. The background for all this data is based on the uncertainty and ambiguity regarding the pathophysiological mechanisms that are implicated. Current efforts are centered on the implementation of precautionary measures, as well as on treatment of both of these entities. Currently, there are enough evidence that support the concept that prevention of siphoning via the use of gravitational valves or antisiphon devices is the most efficacious means contained in our current therapeutic armamentarium. We attempt to present an overview of this complex entity, emphasizing on the hydrodynamics of the cerebrospinal fluid circulation in conditions harboring a ventriculoperitoneal shunt, the effect of the siphoning effect and the role of programmable valves and anti-siphon devices in our effort to eliminate this phenomenon. Based on an extensive literature review and on expert opinion, we concluded that the insertion of an anti-siphon device (gravitational shunt valves) could reliably address the issue of over-drainage, when a patient assumes a vertical position. Besides that, there are ongoing prospective studies centered on the safety and efficacy of adjustable gravitational valves, whose results are of ultimate importance. It is of paramount importance to be recognized that, due to the complexity of the pathophysiology of shunted hydrocephalus, lifelong follow-up of patients with ventriculoperitoneal shunts is necessary.

Shunt overdrainage syndrome: review of the literature.

Shunt overdrainage in patients with hydrocephalus still represents a challenge for neurosurgeons, in part due to the lack of agreement or uniformity concerning the entity. Important problems exist relating to the real incidence of the entity, its definition, classification, and the pathophysiological theories behind the various treatment strategies proposed. Recent reports have suggested that the evidence about overdrainage and its consequences is not so robust as presumed. Consequently, the topic requires more detailed examination. In this review, we comment on all the main facets related with shunt overdrainage.

Shunt-dependent hydrocephalus: management style among members of the American Society of Pediatric Neurosurgeons.

OBJECTIVE The authors conducted a survey to evaluate differences in the understanding and management of shunt-dependent hydrocephalus among members of the American Society of Pediatric Neurosurgeons (ASPN). METHODS Surveys were sent to all 204 active ASPN members in September 2014. One hundred thirty responses were received, representing a 64% response rate. Respondents were asked 13 multiple-choice and free-response questions regarding 4 fundamental problems encountered in shunted-hydrocephalus management: shunt malfunction, chronic cerebrospinal fluid (CSF) overdrainage, chronic headaches, and slit ventricle syndrome (SVS). RESULTS Respondents agreed that shunt malfunction occurs most often as the result of ventricular catheter obstruction. Despite contrary evidence in the literature, most respondents (66%) also believed that choroid plexus is the tissue most often found in obstructed proximal catheters. However, free-text responses revealed that the respondents' understanding of the underlying pathophysiology of shunt obstruction was highly variable and included growth, migration, or adherence of choroid plexus, CSF debris, catheter position, inflammatory processes, and CSF overdrainage. Most respondents considered chronic CSF overdrainage to be a rare complication of shunting in their practice and reported wide variation in treatment protocols. Moreover, despite a lack of evidence in the literature, most respondents attributed chronic headaches in shunt patients to medical reasons (for example, migraines, tension). Accordingly, most respondents managed headaches with reassurance and/or referral to pain clinics. Lastly, there were variable opinions on the etiology of slit ventricle syndrome (SVS), which included early shunting, chronic overdrainage, and/or loss of brain compliance. Beyond shunt revision, respondents reported divergent SVS treatment preferences. CONCLUSIONS The survey shows that there is wide variability in the understanding and management of shunt-dependent hydrocephalus and its complications. Such discrepancies appear to be derived partly from inconsistent familiarity with existing literature but especially from a paucity of high-quality publications.

Craniocerebral disproportion: a topical review and proposal toward a new definition, diagnosis, and treatment protocol.

INTRODUCTION: At some point in their lives, patients previously shunted for hydrocephalus may experience chronic, debilitating headaches, despite the fact that their shunts are functioning properly. Previously published reports have suggested that a subset of these patients may be suffering from an iatrogenic craniocerebral disproportion (CCD) and, therefore, may benefit from procedures that expand the available intracranial space. A unified definition of this disorder, however, is lacking. DISCUSSION: Here, the authors chart the history (including historical terminology) of CCD, review its incidence, describe its signs, symptoms, and associated radiologic findings, and expound upon its pathophysiology. Next, a concise clinical definition of CCD based on the temporal correlation of headaches with the appearance of plateau waves on intracranial pressure (ICP) monitoring is proposed. The authors conclude with a discussion of the various therapeutic strategies employed previously to treat this disorder and present their individualized treatment strategy based upon the simultaneous utilization of ICP monitors and gradual external cranial vault expansion.

Analysis of therapeutic choices for slit ventricle syndrome after cyst-peritoneal shunting for temporal arachnoid cysts in children.

OBJECT: The goal in this study was to investigate early diagnostic evidence, optimal therapeutic strategies, and prophylactic methods for slit ventricle syndrome (SVS) in patients with temporal lobe arachnoid cysts who received cyst-peritoneal (CP) shunts. METHODS: Six cases of SVS in patients with temporal lobe arachnoid cysts who received CP shunts were treated by the senior authors in 2 institutions between January 2005 and January 2009. The radiological data, treatment process, and therapeutic results were reviewed retrospectively. RESULTS: There were 4 boys and 2 girls, whose mean age at presentation was 4 years and 1 month. The main clinical symptoms were severe headache, nausea, vomiting, and decreasing eyesight. Radiological studies showed normal or slightly smaller than normal ventricles, and arachnoid cysts that had shrunk dramatically. The most effective treatment for SVS was to replace the original shunts with devices that had a programmable valve, or if this was unsuccessful, to replace the original shunts with ventriculoperitoneal (VP) shunts. All symptoms in these patients disappeared, and the mean follow-up duration was 24 months. CONCLUSIONS: The SVS presents more often in patients with hydrocephalus who undergo VP shunting. However, it is also a serious complication in patients with arachnoid cysts who receive a CP shunt. The SVS is not a single condition; rather, different pathophysiological conditions can underlie this complicated syndrome. Because there are no striking morphological changes on radiological studies of the SVS in the patients with CP shunts, it is not easy for this syndrome to be diagnosed in time and treated rationally. Misdiagnosis and delayed treatment usually occur. The use of programmable shunts or VP shunts to replace the original shunt is an optimal therapeutic choice. The use of low-pressure shunts to treat arachnoid cysts should be abandoned unless dictated by specific indications.