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.

Management of Slit Ventricle Syndrome: A Single-Center Case Series of 32 Surgically Treated Patients.

OBJECTIVE: Slit ventricle syndrome (SVS) is an iatrogenic disease occurring in patients with ventriculoperitoneal shunt. This article reports the management modalities and results in a case series from a single center. METHODS: We reviewed a series 48 hospitalized patients with severe SVS whom we managed in a 10-year period. Thirty-seven patients harboring programmable valves (P-valves) first underwent attempts at valve reprogramming. This treatment produced no effect in 21 patients, who therefore required surgical treatment. Surgery was also required by 11 patients without P-valve. Accordingly, 32 patients had to be operatively treated by shunt externalization followed by valve replacement or endoscopic third ventriculostomy basing on intracranial pressure and ventricular size. The new valve was either ProGav Mietke (Aesculap) or Medos Codman (Integra), each equipped with its own antisiphon system. In selected cases, a programmable antisiphon system (ProSa Mietke) was used. RESULTS: Surgical mortality was 3% and major morbidity accounted for 6%. Complete resolution was obtained in 55% of cases, improvement in 32%, and no effect or worsening in 13%. Only 1 patient became shunt free after endoscopic third ventriculostomy. Medos and ProGrav provided comparable outcomes, whereas ProSa was determinant in selected cases. Pediatric age, uncomplicated shunt courses, and short SVS histories were significantly favorable indicators. CONCLUSIONS: SVS management remains problematic. However, this study individuated factors that may improve the outcome, such as wider use of P-valves to treat hydrocephalus, timely diagnosis of overdrainage, and earlier and more aggressive indications to manage SVS.

Slit Ventricle as a Neurosurgical Emergency: Case Report and Review of Literature.

BACKGROUND: Symptomatic slit ventricle is one of the most challenging complications of shunt surgery in children. Clinical signs and symptoms may appear with a wide range of intracranial pressure (ICP) values. We report the case of a 10-year-old girl, who did not present the classic clinical features of extremely elevated ICP, which was proven by multiple invasive ICP recordings, performed during shunt revisions. CASE DESCRIPTION: At the age of 6 months, the patient presented squeal for many hours, accompanied with sunset eyes, bulging anterior fontanel, and dilated ventricles of all 4 ventricles on computed tomography scan. Acute ventriculoperitoneal shunt insertion was performed with adjustable valve. During the following 9 years, she was regularly seen and medically treated for intermittent headache, with nausea and vomiting. From 9 years of age, she was hospitalized for severe (10/10 on the visual analog scale), unbearable headache, agitation, and screaming on multiple occasions. Altogether, we had to revise the shunt system 5 times throughout 1 year. Radiologic imaging always showed narrow ventricles. Ophthalmologic examination of the fundus never revealed signs of raised ICP. Perioperative monitoring of the ICP with intraparenchymal sensor showed unexpected high values of 40-45 mm Hg. However, repetitive shunt revisions were successful only temporarily because the symptoms always returned. Only bilateral shunting of the ventricular system was able to eliminate the symptoms permanently. CONCLUSIONS: Images of slit ventricle can be associated either with low or extremely high ICP needing urgent surgical consideration, including ICP monitoring. Bilateral shunt insertion can be effective treatment for slit ventricle syndrome.

Slit Ventricle Syndrome Leads to 10-Year History of Repetitive Transient Central Herniation Masquerading as Seizures: Hydrocephalus Case Report.

BACKGROUND: Slit-ventricle syndrome (SVS) is a recognized complication of ventricular shunt malfunction, resulting in cyclical symptoms without ventricular dilatation. We present a case of SVS with transient, repetitive, and progressive signs of brainstem herniation evidenced by pupillary dilatation, posturing, and unresponsiveness, with diffuse voltage attenuation on electroencephalogram (EEG). CASE DESCRIPTION: A 32-year-old female presented with a history of hydrocephalus and ventriculoperitoneal shunt placement at 9 months of age. She began experiencing significant headaches in college, later accompanied by stereotypical 5- to 25-minute episodes of unresponsiveness, posturing and pupillary dilatation, and failing anticonvulsant therapy. No neurosurgical evaluation was sought because of small ventricles on brain imaging. Episodes became progressively more frequent over a 10-year period, eventually occurring daily. On presentation, 5 clinical events were captured on EEG over 12 hours of monitoring. With each episode, she became unresponsive and hypertensive, with fixed, dilated pupils and flexor posturing. Between events, she was awake and alert, without confusion or postictal state. She had papilledema and limited extraocular movements, with normal pupils and vital signs. Computed tomography scanning showed small ventricles. A shunt tap revealed no flow. With each episode onset, an EEG revealed an abrupt background rhythm slowing to 2-3 Hz delta range without epileptiform discharges. Between events, EEGs displayed normal waveform activity. Emergent ventriculoperitoneal shunt revision resulted in no further episodes in a 4-year follow-up period. CONCLUSIONS: SVS can lead to severe intermittent brainstem herniation syndrome in the setting of shunt malfunction. Seizure diagnosis should be reserved for cases with proven functional shunt and EEG confirmation of epileptiform activity.

Hypothesis for intracranial hypertension in slit ventricle syndrome: new concept of capillary absorption laziness in the hydrocephalic patients with long-term shunts.

Many theories have been postulated to date regarding mechanisms involved in intracranial hypertension in patients with long-term, shunt-induced slit ventricle syndrome (SVS), but it still seems difficult to define this entity more clearly. Many hypotheses have attempted to explain the causes of SVS as chronic or intermittent catheter obstruction, brain compliance change, and ventricular herniation and distortion, but this theory does not explain clearly the reason why extraventricular pressure (EVP) is increased and intraventricular pressure (IVP) is low or frequently negative. The authors attempt to postulate a hypothesis by addressing new concept of capillary absorption laziness which results in dissociation of EVP with IVP. We, the authors, propose a concept of 'capillary absorption laziness', which is a tendency of the brain parenchymal extracellular fluid (ECF) not to be absorbed through the brain parenchymal capillary absorption system (BPCAS) that results from the bypass of ECF to shunt in the low or even negative ECF pressure and IVP. If this continues for a prolonged period, the tendency not to be absorbed through the BPCAS, even when the IVP and extracellular fluid pressures increases more than the intracranial pressure (ICP), may be established. This leads to situations of the brain such as parenchymal accumulation of the ECF which results in brain edema or swelling, and eventually distortion or herniation which can act as a functional obstruction and consequent dissociation between the IVP and EVP. Hypothesis of capillary absorption laziness may explain several common phenomena of the SVS such as low or even negative IVP in coexistence with high EVP and high ICP, and in these cases, we expect serious complications of SVS such as brain distortion and herniation. From this hypothesis we attempt to find new shunt management protocols to prevent long-term shunt induced complications.

Endoscopic management of complex hydrocephalus.

BACKGROUND: The management of complex hydrocephalus is challenging. There is no consensus of the best treatment for isolated fourth ventricles, arachnoid cysts, and multiloculated hydrocephalus, although the avoidance of multiple shunts is desirable. We reviewed our experience with the use of endoscopic techniques to simplify complex multicompartmental hydrocephalus to determine its efficacy and safety. METHODS: We performed a retrospective study of 114 consecutive adults and children undergoing endoscopic management of hydrocephalus by a single surgeon. The type of hydrocephalus and endoscopic procedure performed were recorded. The management algorithm for simplification of complex hydrocephalus is reviewed. All patients were followed up in the office or by telephone. RESULTS: A total of 143 endoscopic procedures were performed on 114 patients with a mean age of 4.4 years (4 weeks to 32 years). The endoscopic procedures performed included cyst fenestration, septum pellucidotomy, endoscopic third ventriculostomy, aqueductal plasty with and without stent, and removal of cystercicotic cysts. Twenty-two (19.3%) patients had planned staged endoscopic procedures. Mean follow up was 65 months (range 33-122 months). Eighty-two (72%) patients were reduced to 1 shunt, shunt independence was achieved in 32 (28%) patients, and only 8 (11%) patients required shunt revision in the follow-up period. CONCLUSIONS: Endoscopic simplification of complex hydrocephalus enables dependence on only a single shunt in the majority of patients, and a significant proportion achieve shunt independence. Endoscopic management should be considered before the placement of a second shunt, and some cases require staged endoscopic procedures to adequately communicate multicompartmental hydrocephalus.

Acute cranial decompression in Meckel-Gruber syndrome and slit-ventricle syndrome with craniocephalic disproportion.

Slit-ventricle syndrome (SVS) is characterized by headaches associated with subnormal ventricular size in patients with shunt-treated hydrocephalus. It commonly occurs in children who have had shunts placed at an early age and is diagnosed when computed tomography scans are carried out to investigate suspected shunt obstruction with an accompanying rise in intracranial pressure (ICP). Overdrainage of cerebrospinal fluid may additionally result in craniocephalic disproportion, potentially by dampening the normal expansile pulsations of the dura against the skull, which leads to craniostenosis. Management is controversial because many strategies have only short-term benefit, and surgical intervention is understandably often seen as a last resort.We present a case of a child with SVS and craniocephalic disproportion who was treated with urgent cranial expansion due to rising ICP. Intraoperative ICP monitoring demonstrates a rapid and sustained drop in ICP, and the patient made an uneventful return to his premorbid condition. We conclude that cranial vault expansion should be considered as an effective treatment for postshunt craniocephalic disproportion in patients with SVS.