Category: hydrocephalus

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Overdrainage shunt complications in idiopathic normal-pressure hydrocephalus and lumbar puncture opening pressure

Shunt complications of overdrainage

J Neurosurg 119:1498–1502, 2013

Management of idiopathic normal-pressure hydrocephalus (iNPH) is hard because the diagnosis is difficult and shunt surgery has high complication rates. An important complication is overdrainage, which often can be treated with adjustable–shunt valve manipulations but also may result in the need for subdural hematoma evacuation. The authors evaluated shunt surgery overdrainage complications in iNPH and their relationship to lumbar puncture opening pressure (LPOP).

Methods. The authors reviewed the charts of 164 consecutive patients with iNPH who underwent shunt surgery at their institution from 2005 to 2011. They noted age, sex, presenting symptoms, symptom duration, hypertension, body mass index (BMI), imaging findings of atrophy, white matter changes, entrapped sulci, LPOP, valve opening pressure (VOP) setting, number of valve adjustments, serious overdrainage (subdural hematoma requiring surgery), radiological overdrainage (subdural hematomas or hygroma seen on postoperative imaging), clinical overdrainage (sustained or postural headache), other complications, and improvements in gait, urine control, and memory.

Results. Eight patients (5%) developed subdural hematomas requiring surgery. All had an LPOP of greater than 160 mm H2O and an LPOP-VOP of greater than 40 mm H2O. Radiological overdrainage was more common in those with an LPOP of greater than 160 mm H2O than in those with an LPOP of less than 160 mm H2O (38% vs 21%, respectively; p = 0.024). The BMI was also significantly higher in those with an LPOP of greater than 160 mm H2O (median 30.2 vs 27.0, respectively; p = 0.005).

Conclusions. Serious overdrainage that caused subdural hematomas and also required surgery after shunting was related to LPOP and LPOP-VOP, which in turn were related to BMI. If this can be replicated, individuals with a high LPOP should have their VOP set close to the LPOP, or even higher. In doing this, perhaps overdrainage complications can be reduced.

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Assessment of intracranial dynamics in hydrocephalus: effects of viscoelasticity on the outcome of infusion tests

Assessment of intracranial dynamics in hydrocephalus- effects of viscoelasticity on the outcome of infusion tests

J Neurosurg 119:1511–1519, 2013

The treatment of hydrocephalus requires insight into the intracranial dynamics in the patient. Resistance to CSF outflow (R0) is a clinically obtainable parameter of intracranial fluid dynamics that quantifies the apparent resistance to CSF absorption. It is used as a criterion for the selection of shunt candidates and serves as an indicator of shunt performance. The R0 is obtained clinically by performing 1 of 3 infusion tests: constant flow, constant pressure, or bolus infusion. Among these, the bolus infusion method has the shortest examination times and provides the shortest time of exposure of patients to artificially increased intracranial pressure (ICP) levels. However, for unknown reasons, the bolus infusion method systematically underestimates the R0. Here, the authors have tested and verified the hypothesis that this underestimation is due to lack of accounting for viscoelasticity of the craniospinal space in the calculation of the R0.

Methods. The authors developed a phantom model of the human craniospinal space in order to reproduce in vivo pressure-volume (PV) relationships during infusion testing. The phantom model followed the Marmarou exponential PV equation and also included a viscoelastic response to volume changes. Parameters of intracranial fluid dynamics, such as the R0, could be controlled and set independently. In addition to the phantom model, the authors designed a computational framework for virtual infusion testing in which viscoelasticity can be turned on or off in a controlled manner. Constant flow, constant pressure, and bolus infusion tests were performed on the phantom model, as well as on the virtual computational platform, using standard clinical protocols. Values for the R0 were derived from each infusion test by using both a standard method based on the Marmarou PV equation and a novel method based on a system identification approach that takes into account viscoelastic behavior.

Results. Experiments with the phantom model confirmed clinical observations that both the constant flow and constant pressure infusion tests, but not the bolus infusion test, yield correct R0 values when they are determined with the standard method according to Marmarou. Equivalent results were obtained using the computational framework. When the novel system identification approach was used to determine the R0, all of the 3 infusion tests yielded correct values for the R0.

Conclusions. The authors’ investigations demonstrate that intracranial dynamics have a substantial viscoelastic component. When this viscoelastic component is taken into account in calculations, the R0, is no longer underestimated in the bolus infusion test.

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The Aqueduct of Sylvius: Applied 3-T Magnetic Resonance Imaging Anatomy and Morphometry With Neuroendoscopic Relevance

Aqueduct of Sylvius MRI morphometry

Neurosurgery 73[ONS Suppl 2]:ons132–ons140, 2013

The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendoscopic procedures. However, there is currently no clear and adequate description of the normal anatomy of the AqSylv.

OBJECTIVE: To study in detail hitherto unavailable normal magnetic resonance imaging morphometry and anatomic variants of the AqSylv.

METHODS: We retrospectively studied normal midsagittal T1-weighted 3-T magnetic resonance images in 100 patients. We measured widths of the AqSylv pars anterior, ampulla, and pars posterior; its narrowest point; and its length. We recorded angulation of the AqSylv relative to the third ventricle as multiple deviations of the long axis of the AqSylv from the Talairach bicommissural line. We statistically determined age- and sexrelated changes in AqSylv morphometry using the Pearson correlation coefficient. We measured angulation of the AqSylv relative to the fourth ventricle and correlated this to the cervicomedullary angle (a surrogate for head position).

RESULTS: Patients were 13 to 83 years of age (45% male, 55% female). Mean morphometrics were as follows: pars anterior width, 1.1 mm; ampulla width, 1.2 mm; pars posterior width, 1.4 mm; length, 14.1 mm; narrowest point, 0.9 mm; and angulation in relation to the third and fourth ventricles, 26 and 18, respectively. Age correlated positively with width and negatively with length of the AqSylv. There was no correlation between AqSylv alignment relative to the foramen magnum and the cervicomedullary angle.

CONCLUSION: Normative dimensions of the AqSylv in vivo are at variance with published cadaveric morphometrics. The AqSylv widens and shortens with cerebral involution. Awareness of these normal morphometrics is highly useful when stent placement is an option during aqueductoplasty. Reported data are valuable in guiding neuroendoscopic management of hydrocephalus and aqueductal stenosis.

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Hypertensive slit ventricle syndrome: pseudotumor cerebri with a malfunctioning shunt?

slit ventricles

J Neurosurg 119:1503–1510, 2013

Symptomatic shunt malfunction without ventricular enlargement is known as slit ventricle syndrome (SVS). Patients presenting with this syndrome are not a homogeneous group. Of the 5 different types classified by Rekate, Type 1 is caused by CSF overdrainage and is associated with low pressures; Types 2 and 3 are associated with shunt blockage and elevated CSF pressures; Type 4 is cephalocranial disproportion that increases brain parenchymal pressure but not CSF pressure; and Type 5 is headache unrelated to shunt function. The low and normal CSF pressure types are relatively well understood, but the high-pressure forms are more problematic. In the high-pressure forms of SVS it is said that the lack of ventricular dilation is related to a reduction in brain compliance analogous to idiopathic intracranial hypertension or pseudotumor cerebri. Despite this, there is little evidence in the literature to support this conjecture.

With this in mind, 3 cases of SVS associated with elevated CSF pressure are presented. The MR venogram findings and hemodynamics of these 3 cases are shown to be identical to those of pseudotumor cerebri. A literature review indicates that an underlying venous impairment may be functioning in the patients who re-present with small ventricles following shunt malfunction.

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Suboccipital endoscopic management of the entrapped fourth ventricle

Suboccipital endoscopic management of the entrapped fourth ventricle- technical note

Acta Neurochir (2013) 155:1957–1963

Entrapped fourth ventricle is the result of both inlet aqueduct and outlet fourth ventricular midline and lateral foraminae obstruction. It occurs as a sequalae of intracranial hemorrhagic or inflammatory disease condition. Usually it presents after previous shunting for communicating hydrocephalus with a period of improvement, after which manifestations of posterior fossa expanding process appear. The diagnosis of this rare condition is easy considering the patient past history and the recent clinical state, together with the midline CSF density of the dilated fourth ventricle in either the CT or MR images. The treatment options for this condition include open and endoscopic approaches together with the traditional ventricular to extracranial CSF diversionary procedures.

Objective The aim of the study was to adopt a procedure for treatment of entrapped fourth ventricle that carries the advantage of the minimally invasive technique thus avoiding the complications of the traditional opened and shunt surgeries as well as decreasing multiple procedures due to aqueduct restenosis or stent fall.

Methods Thirteen patients with symptomatic entrapped fourth ventricle underwent suboccipital endoscopic trans–fourth ventricular aqueductoplasty from May 2007 till November 2011. The Gabb endoscopic system was used and aqueductoplasty was performed using 3F Fogarty balloon followed by stent placement. Nine patients were females. The mean age was 3.6 years and the mean follow up period was 23 months. All cases had a previous one or two supratentorial VP shunt placement.

Results Short stent was used in eight patients. During the follow up, stent migration occurred in five of them. Three of these five patients developed posterior fossa compression manifestations due to aqueduct restenosis. Long stent from the aqueduct till the bur hole site for these three patients and the following five patients was used. All cases showed both clinical and radiologic improvement. Apart from the stent migration, no procedure-related complications were encountered.

Conclusion Endoscopic suboccipital paramedian aqueductoplasty with the use of a stent is a safe and effective surgical option that—in our opinion—should stand as the first line treatment for the entrapped fourth ventricle. Long stent is better used after aqueductoplasty to avoid the restenosis if no stent is used or stent fall after short stents. However, good case selection, familiarity with this fairly common endoscopic approach and longer follow-up is needed for obtaining an optimal result.

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Intraoperative Magnetic Resonance Ventriculography During Endoscopic Third Ventriculostomy

Usefulness of Intraoperative Magnetic Resonance Ventriculography During Endoscopic Third Ventriculostomy

Neurosurgery 73:730–738, 2013

Endoscopic third ventriculostomy (ETV) is the preferred method for the treatment of noncommunicating hydrocephalus. The different success rates of ETV indicate the difficulties in predicting the success of this procedure.

OBJECTIVE: To show the usefulness of intraoperative ventriculography performed by the low-field 0.15-T magnetic resonance imager Polestar N20 during ETV.

METHODS: The study was conducted in 11 patients with noncommunicating hydrocephalus caused by tumors or cysts of the third ventricle (n = 5), nontumoral stenosis of the sylvian aqueduct (n = 3), and fourth ventricle outlet obstruction (n = 3). Intraoperative magnetic resonance (iMR) ventriculography was performed before and after the ETV.

RESULTS: In each case, iMR-ventriculography was a safe procedure and determined the exact site of obstruction of cerebrospinal fluid flow. In all cases, iMR-ventriculography performed after ETV showed with the greatest accuracy the patency of the performed fenestrations, demonstrating in 9 patients good flow of the contrast from the third ventricle to the basal cisterns, restricted flow in 1 patient, and no flow in 1 patient. The results of ventriculography were consistent with the postoperative neurological status of operated-on patients. In 3 patients, the opinion of the surgeons about the patency of endoscopic fenestration, based on intraoperative observation of the third ventricle floor, was inconsistent with the results from iMR-ventriculography.

CONCLUSION: Low-field iMR-ventriculography is a safe procedure that can be successfully applied during ETV to determine the site of obstruction in hydrocephalus and the patency of performed ventricle fenestration.

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Low-pressure hydrocephalus: indication for custom-made catheters?

Low-pressure hydrocephalus- indication for custom-made catheters?

Acta Neurochir (2013) 155:1981–1985

Low-pressure hydrocephalus (LPH) is characterized by ventriculomegaly with persistent low intracranial pressure (ICP). Sub-zero drainage is needed for its management and multiple solutions have been described. Our aim is to report our experience with custom-made peritoneal catheters with larger inner diameter as an alternative treatment option.

Methods We made a retrospective review of all patients diagnosed with LPH and treated with custom-made peritoneal catheters at the Virgen del Rocío Pediatric Neurosurgical Unit. Catheters were coated with antibiotic or silver. The inner diameter of ventricular catheters was 1.4 mm; peritoneal catheters were larger than usual (1.9 mm inner diameter).

Results We identified four patients in whom five custommade peritoneal catheters were used over a 3-year period. There were two males and the mean age was 10 years (6 months–17 years). In all patients, placement of an EVD was necessary for sub-zero drainage, with maximum negative pressure of −8 cm H20. The mean time of maintenance of EVD was 102 days (10 days–1 year). Finally, three ventriculoperitoneal (VP) valveless systems, one with antigravitation device, and one Pro-GAV VP shunt were placed, all of them with larger custom-made peritoneal catheters. After a mean follow-up period of 2.3 years (6 months– 3 years), two patients are completely recovered, one patient is partially dependent for daily activities with good cognitive status, and the last one is a child who died due to his brain tumor.

Conclusion The custom-made peritoneal catheters with larger inner diameter could be a good option for the management of this complex pathology.

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Gravity assisted vs. medium pressure valves for communicating hydrocephalus show similar valve-revision rates

Gravity assisted vs. medium pressure valves for communicating hydrocephalus show similar valve-revision rates

Acta Neurochir (2013) 155:1987–1991

Two common valve types used to treat hydrocephalus include gravity assisted valves (GAV) and medium pressure valves (MPV). Despite their different mechanism of action, differentiated surgical indications per type are not well defined. One could assume that due to a higher complexity of the GAV system, it may be more prone to valve-related malfunction. The purpose of this retrospective study was to compare the valve-related complication rates of GAV and MPV in patients with communicating hydrocephalus.

Method Patients aged 16 years or older undergoing their first shunt implantation using GAV or MPV were included. We recorded demographic data, implantation diagnosis, outcome, complications, valve type and valve adjustments. Symptoms were documented at discharge and follow-up. Valve-related malfunctions were distinguished from other shunt complications.

Results N =252 patients (range 16.6–88.4, mean 65.0 years, 116 male and 136 female) underwent shunt placement for the first time. N =122 GAV (48.4 %) and n =130 MPV were implanted (51.6 %) over a period of 5 years. The most frequent diagnoses were normal pressure hydrocephalus (NPH) in 86 cases (34.1 %) and posthemorrhagic hydrocephalus in 114 cases (45.2 %). About two thirds of patients were free of hydrocephalus-related symptoms at follow-up. N =66 subjects (26.2 %) underwent at least one shunt revision. N =29 revisions (11.5 %) were due to valve-related malfunction. Valve-related revisions were the main cause for revision in 18/37 cases (48.6 %) in the GAV group and in 11/29 (37.9 %) in the MPV group. Neither clinical improvement nor valve-related malfunctions were found to be statistically different among groups.

Conclusions Despite their technical differences, GAV and MPV show similar valve-related revision rates in the treatment of communicating hydrocephalus.

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Pathophysiology of shunt dysfunction in shunt treated hydrocephalus

Pathophysiology of shunt dysfunction in shunt

Acta Neurochir (2013) 155:1763–1772

We hypothesized that shunt dysfunction in the ventricular catheter and the shunt valve is caused by different cellular responses. We also hypothesized that the cellular responses depend on different pathophysiological mechanisms.

Methods Removed shunt material was collected. Macroscopic tissue in the catheters was paraffin-embedded and HE-stained. Valves were incubated with trypsin-EDTA in order to detach macroscopically invisible biomaterial, which was then cytospinned and HE-stained. Associated aetiological and surgical data were collected by reviewing patient files, and ventricular catheter position was examined using preoperative radiology (CT scans).

Results We examined eleven ventricular catheters and ten shunt valves. Catheters: 6/11 catheters contained intraluminal tissue consisting of vascularised glial tissue and inflammatory cells (macrophages/giant cells and a few eosinophils). Catheter adherence correlated with the presence of intraluminal tissue, and all tissue containing catheters had some degree of ventricle wall contact. All obstructed catheters contained intraluminal tissue, except one catheter that was dysfunctional because of lost ventricular contact. Valves: Regardless of intraoperative confirmation of valve obstruction, all ten valves contained an almost uniform cellular response of glial cells (most likely ependymal cells), macrophages/giant cells, and lymphomonocytic cells. Some degree of ventricle wall catheter contact was present in all examined valves with available radiology (9/10).

Conclusions The same cellular responses (i.e., glial cells and inflammatory cells) cause both catheter obstruction and valve obstruction. We propose two synergistic pathophysiological mechanisms. (1) Ventricle wall/parenchymal contact by the catheter causesmechanical irritation of the parenchyma including ependymal exfoliation. (2) The shunt material provokes an inflammatory reaction, either nonspecific or specific. In combination, these mechanisms cause obstructive tissue ingrowth (glial and inflammatory) in the catheter and clogging of the valve by exfoliated glial cells and reactive inflammatory cells.

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Comparison of the accuracy of ventricular catheter placement using freehand placement, ultrasonic guidance, and stereotactic neuronavigation

Stereotactic Ventricular Catheter Placement

J Neurosurg 119:66–70, 2013

The objective of this study was to compare the accuracy of 3 methods of ventricular catheter placement during CSF shunt operations: the freehand technique using surface anatomy, ultrasonic guidance, and stereotactic neuronavigation.

Methods. This retrospective cohort study included all patients from a single institution who underwent a ventricular CSF shunting procedure in which a new ventricular catheter was placed between January 2005 and March 2010. Data abstracted for each patient included age, sex, diagnosis, method of ventricular catheter placement, site and side of ventricular catheter placement, Evans ratio, and bifrontal ventricular span. Postoperative radiographic studies were reviewed for accuracy of ventricular catheter placement. Medical records were also reviewed for evidence of shunt failure requiring revision through December 2011. Statistical analysis was then performed comparing the 3 methods of ventricular catheter placement and to determine risk factors for inaccurate placement.

Results. There were 249 patients included in the study; 170 ventricular catheters were freehand passed, 51 were placed using stereotactic neuronavigation, and 28 were placed under intraoperative ultrasonic guidance. There was a statistically significant difference between freehand catheters and stereotactic-guided catheters (p < 0.001), as well as between freehand catheters and ultrasound-guided catheters (p < 0.001). The only risk factor for inaccurate placement identified in this study was use of the freehand technique. The use of stereotactic neuronavigation and ultrasonic guidance reduced proximal shunt failure rates (p < 0.05) in comparison with a freehand technique.

Conclusions. Stereotactic- and ultrasound-guided ventricular catheter placements are significantly more accurate than freehand placement, and the use of these intraoperative guidance techniques reduced proximal shunt failure in this study.

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Role of Endoscopic Third Ventriculostomy and Ventriculoperitoneal Shunt in Idiopathic Normal Pressure Hydrocephalus: Preliminary Results of a Randomized Clinical Trial

Role_of_Endoscopic_Third_Ventriculostomy_and

Neurosurgery 72:845–854, 2013

Currently, the most common treatment for idiopathic normal pressure hydrocephalus (INPH) is a ventriculoperitoneal shunt (VPS), generally with programmable valve implantation. Endoscopic third ventriculostomy (ETV) is another treatment option, and it does not require prosthesis implantation.

OBJECTIVE: To compare the functional neurological outcome in patients after 12 months of treatment with INPH by using 2 different techniques: ETV or VPS.

METHODS: Randomized, parallel, open-label trial involving the study of 42 patients with INPH and a positive response to the tap test, from January 2009 to January 2012. ETV was performed with a rigid endoscope with a 30 lens (Minop, Aesculap), and VPS was performed with a fixed-pressure valve (PS Medical, Medtronic). The outcome was assessed 12 months after surgery. The neurological function outcomes were based on the results of 6 clinical scales: mini-mental, Berg balance, dynamic gait index, functional independence measure, timed up and go, and normal pressure hydrocephalus.

RESULTS: There was a statistically significant difference between the 2 groups after 12 months of follow-ups, and the VPS group showed better improvement results (ETV = 50%, VPS = 76.9%).

CONCLUSION: Compared with ETV, VPS is a superior method because it had better functional neurological outcomes 12 months after surgery.

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Is endoscopic third ventriculostomy superior to shunts in patients with non-communicating hydrocephalus?

ETV

Acta Neurochir (2013) 155:883–889

Endoscopic third ventriculostomy (ETV) and shunts are both utilized in the treatment of noncommunicating hydrocephalus. The objective of this study was to review the evidence comparing the effectiveness of these two techniques.

Methods The Cochrane Central Register of Controlled Trials (CENTRAL) and Medline databases were searched between 1990 and August 2012. We included all studies comparing the failure rate of patients with noncommunicating hydrocephalus treated with ETVand shunts. Two authors (HJM and FTR) appraised quality and extracted data independently.

Results Of 313 articles identified, 12 were selected for further review. Of these, 6 were included for qualitative analysis, and 5 for quantitative analysis (n=504). ETV was associated with a non-statistically significant reduction in failure using the random-effects model (OR 0.58, 95 % CI 0.29-1.13).

Conclusions Both ETV and shunts are associated with a relatively high failure rate. At present there is insufficient proof to unequivocally recommend one mode of treatment above the other. However, there is some evidence that ETV may confer long-term survival advantage over shunts in the treatment of non-communicating hydrocephalus, particularly in patients with certain aetiologies such as aqueductal stenosis. Prospective randomized controlled trials are currently underway and may provide more robust evidence to answer this important question and better guide future management.

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Revision to an adjustable non-siphon control valve in low pressure hydrocephalus

Low pressure Hydrocephalus

Clinical Neurology and Neurosurgery 115 (2013) 175– 178

High intracranial compliance states requiring negative pressure drainage, otherwise known as low-pressure hydrocephalus syndromes, are rare conditions. The use of siphoning, enabled by revision to an adjustable shunt without an anti-siphon device, has been largely unexplored in low-pressure hydrocephalus.

Methods: Three patients with presumed normal pressure hydrocephalus (NPH) presented with unresolved symptoms, including urinary incontinence, disturbed gait, and cognitive dysfunction. Each was inadequately treated despite confirmed functioning Strata II valves (with built-in siphon control device) calibrated to the lowest pressure setting for maximum drainage. Surgical revision to Strata non-siphon control (NSC) valves was performed to allow for additional drainage via siphoning.

Results: Following revision to a shunt with a “siphoning” device, each patient achieved improved neurological function. Each differential pressure valve was initially set to a higher setting than with the Strata II valve. One of our patients experienced the formation of a subdural hematoma after shunt revision; resolution following adjustment of the valve to a higher setting suggests that siphoning may be of less importance to overdrainage syndromes when compared with valve opening pressure.

Conclusion: Our findings indicate that intermittent intracranial hypotension achieved by siphoning is effective in the treatment of a subset of patients presenting clinically with NPH. Direct conversion to a shunt system without an anti-siphon device allows reduction of ventricular size without the risk associated with external ventricular drainage (EVD). With conversion to the Strata NSC valve, our patients had sustained clinical improvement, even at higher valve settings.

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Theories of CSF dynamics and hydrocephalus

Theories of cerebrospinal fluid dynamics and hydrocephalus

J Neurosurg Pediatrics 11:170–177, 2013

According to the CSF bulk flow theory, hydrocephalus is caused by an imbalance between CSF formation and absorption, or a block at various locations in the major CSF pathway. New theories, however, have been proposed in which minor CSF pathways may play a significant role in the development of congenital hydrocephalus.

The authors review major contributions to the literature and analyze the evolution of theories of CSF dynamics in relation to hydrocephalus, dividing their development into 4 stages on the basis of historical trends. In Stage I (prior to 1950), 2 systems of classifying hydrocephalus were proposed, namely Dandy’s classifications of communicating and noncommunicating hydrocephalus and Russell’s nonobstructive and obstructive hydrocephalus. In Stage II (1950–1974), based on these theories of major CSF pathway dynamics, treatment focused on ventriculostomy as an alternative to reduction of CSF production by choroid plexus coagulation. In Stage III (1975–1999), some of the specific forms of hydrocephalus, especially in premature infants, were found to be unsuitable for ventriculostomy. In Stage IV (2000–2008), selection of treatment modalities evolved further, with a focus on analysis of the chronological changes in CSF dynamics and the differences in absorption pathways in the developing and mature brains.

The authors focus on “minor pathway hydrocephalus” in the immature brain, differentiating it from the conventional classification of obstructive and nonobstructive “major pathway hydrocephalus.”

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Poor Cognitive Outcome in Shunt-Responsive Idiopathic Normal Pressure Hydrocephalus

hydrocephalusNeurosurgery 72:1–8, 2013

Idiopathic normal pressure hydrocephalus (iNPH) causes cognitive decline that can be alleviated by shunting, but long-term outcome studies are scarce.

OBJECTIVE: To elucidate the long-term cognitive condition of shunt-responsive iNPH patients.

METHODS: The follow-up data (Kuopio University Hospital NPH Registry) of 146 patients diagnosed with iNPH by clinical and radiological examination, 24-hour intraventricular pressure monitoring, frontal cortical biopsy, and response to the shunt were analyzed for signs of dementia. The Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition, and specified memory disorder criteria were used. Median follow-up was 4.8 years.

RESULTS: At the end of follow-up, 117 (80%) of the 146 iNPH patients had cognitive decline and 67 (46%) had clinical dementia. The most common clinical diagnoses were Alzheimer disease and vascular dementia. In multivariate analysis of the 146 iNPH patients, memory deficit as a first symptom before shunt (odds ratio [OR] 18.3; 95% confidence interval [CI] 1.9–175), male sex (OR 3.29; 95% CI 1.11-9.73), age (OR 1.17 year; 95% CI 1.07-1.28), and follow-up time (OR 1.20 year; 95% CI 1.02-1.40) predicted dementia. Interestingly, 8 (5%) iNPH patients had dementia without any signs of other neurodegenerative diseases in clinical, neuroradiological, or brain biopsy evaluation. These patients initially presented a full triad of symptoms, with gait disturbance being the most frequent initial symptom followed by deterioration in cognition.

CONCLUSION: The novel findings were (a) a significant risk of dementia in iNPH initially responsive to cerebrospinal fluid shunt, (b) cognitive impairment most commonly due to iNPH-related dementia followed by concurrent degenerative brain disease, and (c) a subgroup with dementia related to iNPH without comorbidities.

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Shunting with gravitational valves—can adjustments end the era of revisions for overdrainage-related events?

overshunting with gravitational valves—can adjustments end the era of revisions for overdrainage-related events?

J Neurosurg 117:1197–1204, 2012

Overdrainage of CSF remains an unsolved problem in shunt therapy. The aim of the present study was to evaluate treatment options on overdrainage-related events enabled by the new generation of adjustable gravityassisted valves.

Methods. The authors retrospectively studied the clinical course of 250 consecutive adult patients with various etiologies of hydrocephalus after shunt insertion for different signs and symptoms of overdrainage. Primary and secondary overdrainage were differentiated. The authors correlated the incidence of overdrainage with etiology of hydrocephalus, opening valve pressure, and patient parameters such as weight and size. Depending on the severity of overdrainage, they elevated the opening pressure, and follow-up was performed until overdrainage was resolved.

Results. The authors found 39 cases (15.6%) involving overdrainage-related problems—23 primary and 16 secondary overdrainage. The median follow-up period in these 39 patients was 2.1 years. There was no correlation between the incidence of overdrainage and any of the following factors: sex, age, size, or weight of the patients. There was also no statistical significance among the different etiologies of hydrocephalus, with the exception of congenital hydrocephalus. All of the “complications” could be resolved by readjusting the opening pressure of the valve in one or multiple steps, avoiding further operations.

Conclusions. Modern adjustable and gravity-assisted valves enable surgeons to set the opening pressure relatively low to avoid underdrainage without significantly raising the incidence of overdrainage and to treat overdrainagerelated clinical and radiological complications without surgical intervention.

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Management of non-traumatic intraventricular hemorrhage

Neurosurg Rev (2012) 35:485–495

Intraventricular hemorrhage (IVH) is defined as the eruption of blood in the cerebral ventricular system and is mostly secondary to spontaneous intracerebral hemorrhage and aneurysmal and arteriovenous malformation rupture. IVH is a proven risk factor of increased mortality and poor functional outcome. Its seriousness is correlated not only with the amount of blood but also with the involvement of the third and fourth ventricles.

There are four mechanisms that explain the pathophysiology of this event: acute obstructive hydrocephalus, the mass effect exerted by the blood clot, the toxicity of bloodbreaking products on the adjacent brain parenchyma, and, lastly, the development of a chronic hydrocephalus. It is thus obvious that the clearance of blood from the ventricles should be a therapeutic goal.

In cases of acute hydrocephalus, external ventricular drainage is a mandatory step, but proven often insufficient. The concomitant use of intraventricular fibrinolytics such as recombinant tissue plasminogen activator or urokinase seems to be beneficial at least in the context of spontaneous intracerebral hemorrhage, in which their use is now accepted but not yet validated by a randomized trial. Given the potential neurotoxicity of these agents, further research is needed in order to identify the best treatment for intraventricular fibrinolysis (IVF).

The endoscopic retrieval of intraventricular blood was also described recently and seems to be as efficient as IVF, but its use is limited to specialized centers.

IVH represents a therapeutic challenge for neurosurgeons, neurologists, and intensivists. Thus, a better understanding of this dramatic event will help in better tailoring the treatment strategies.

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Diffusion tensor imaging in hydrocephalus—findings before and after shunt surgery

Acta Neurochir (2012) 154:1699–1706

To evaluate changes in diffusion tensor imaging (DTI)-derived parameters in patients with hydrocephalus (HC) before and several weeks after shunt surgery.

Methods Thirteen HC patients were examined with DTI before and after shunt surgery. In a combined region of interest and whole brain voxel-based analysis, different DTI parameters were compared with an age-matched control group.

Results Alteration of DTI parameters in HC patients and changes after shunt surgery are regionally different. HC patients show an increase in fractional anisotropy values based on increases in parallel diffusivity in the corticospinal tract. On the other hand, reduced fractional anisotropy values are found in the corpus callosum of HC patients. Following shunt surgery, all DTI parameters showed a trend towards normalization, yet differences to healthy control subjects remained.

Conclusion Our results show that DTI parameter changes are regionally dependent and need a careful interpretation of the underlying diffusivities to serve as a diagnostic or follow-up measure in patients with hydrocephalus.

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Assessment of a Quick Reference Table Algorithm for Determining Initial Postoperative Pressure Settings of Programmable Pressure Valves in Patients With Idiopathic Normal Pressure Hydrocephalus: SINPHONI Subanalysis

Neurosurgery 71:722–728, 2012 

Management of overdrainage complications in shunted patients with idiopathic normal pressure hydrocephalus (INPH) remains a difficult task despite the use of programmable pressure valves.

OBJECTIVE: To assess the usefulness of a quick reference table (QRT) algorithm for achieving a suitable initial programmable pressure valve setting in INPH patients who participated in the Study for INPH on Neurological Improvement (SINPHONI).

METHODS: One hundred registered patients diagnosed with probable INPH were treated with ventriculoperitoneal shunts using Codman-Hakim programmable valves (CHPVs). In this series, the initial CHPV setting was decided prospectively according to the QRT algorithm. Shunt effectiveness, complications, and the number of CHPV readjustments during follow-up periods were investigated.

RESULTS: Eighty patients were considered better than shunt responders (more than 1 point improvement in modified Rankin Scale at any follow-up period). Readjustments of CHPVs within 3 months after treatment with ventriculoperitoneal shunt were performed 56 times in 44 cases (44%, 0.56 times/patient). Low-pressure headache occurred in 9 patients, all of whom improved by readjustment alone. Nontraumatic subdural fluid collections and chronic subdural hematomas occurred in 15 cases (15%); however, most of the cases were subclinical and improved after CHPV readjustments alone. Burr hole irrigation was necessary in only 1 case.

CONCLUSION: Use of the QRT algorithm was associated with a decrease in postoperative CHPV readjustments and serious overdrainage complications during the followup period. The QRT algorithm is an easy, safe, and effective method for determining the initial CHPV pressure setting in INPH patients.

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Efficacy and Safety of Endoscopic Transventricular Lamina Terminalis Fenestration for Hydrocephalus

Neurosurgery 71:464–473, 2012 DOI: 10.1227/NEU.0b013e31825b1e8d

Endoscopic third ventriculostomy (ETV) has become the procedure of choice in the treatment of obstructive hydrocephalus. In certain cases, standard ETV might not be technically possible or may engender significant risk.

OBJECTIVE: To present an alternative through the lamina terminalis (LT) by a transventricular, transforaminal approach with flexible neuroendoscopy and to discuss the indications, technique, neuroendoscopic findings, and outcomes.

METHODS: Between 1994 and 2010, all patients who underwent endoscopic LT fenestration as an alternative to ETV were analyzed and prospectively followed up. The decision to perform an LT fenestration was made intraoperatively.

RESULTS: Twenty-five patients, ranging in age from 7 months to 76 years (mean, 28.1 years), underwent endoscopic LT fenestration. Patients had obstructive hydrocephalus secondary to neurocysticercosis (11 patients), neoplasms (6 patients), congenital aqueductal stenosis (3 patients), and other (5 patients). Thirteen patients (52%) had had at least 1 ventriculoperitoneal shunt that malfunctioned; 6 patients (24%) had undergone a previous endoscopic procedure. Intraoperative findings that led to an LT fenestration were the following: ETV not feasible to perform, basal subarachnoid space not sufficient, or adhesions in the third ventricle. No perioperative complications occurred. The mean follow-up period was 63.76 months. Overall, 19 patients (76%) had resolutions of symptoms, had no evidence of ventriculomegaly, and did not require another procedure. Six (24%) required a ventriculoperitoneal shunt.

CONCLUSION: Endoscopic transventricular transforaminal LT fenestration with flexible neuroendoscopy is feasible with a low incidence of complications. It is a good alternative to standard ETV. Adequate intraoperative assessment of ETV success is necessary to identify patients who will benefit.

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