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Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

Shunt age-related complications in adult patients with suspected shunt dysfunction

Acta Neurochir (2017) 159:1421–1428

Patients admitted for suspicion of shunt dysfunction (SD) often show unspecific symptoms and require timeconsuming, expensive and even invasive diagnostics involving significant radiation exposure. The purpose of this retrospective study was to analyse the current diagnostic procedures and to propose a process optimisation.

Method: As all patients admitted for suspicion of SD receive imaging studies, we searched for adult patients receiving neuroimaging in the period from January 2010 to July 2013, analysing referring diagnosis, clinical signs, products, diagnostic process and final diagnosis. Recursive partitioning was used to define time intervals for differentiating types of SD.

Results A total of 148 patients, aged 18–89 (mean, 54) years, were studied. Forty-two percent were referred by a hospital or rehabilitation centre, 30% by general practitioners and 24% were self-referrals. The admission diagnosis was in the majority “shunt dysfunction” only. Further differentiations were rarely made. An SD was confirmed in 46% of the patients. In 17%, the symptoms were based on another cause and in 37% they could not be clearly attributed to any specific disorder. Abdominal dislocations (2%) and shunt infections (5%) were found within the first 6 months. Over- (3%) and underdrainage (14%) were the most frequent complications during the first 4 years. Disconnections (13%) occurred generally 4 years or more after implantation. Only shunt obstruction (9%) showed no temporal pattern.

Conclusions: Symptoms of SD remain mostly unspecific. This study showed that the type of SD depends on the time interval from implantation.We propose a workup strategy for patients with SD based on the temporal profile.

Comparison of anti-siphon devices—how do they affect CSF dynamics in supine and upright posture?

Acta Neurochir (2017) 159:1389–1397

Three different types of anti-siphon devices (ASDs) have been developed to counteract siphoning induced overdrainage in upright posture. However, it is not known how the different ASDs affect CSF dynamics under the complex pressure environment seen in clinic due to postural changes. We investigated which ASDs can avoid overdrainage in upright posture best without leading to CSF accumulation.

Methods Three shunts each of the types Codman Hakim with SiphonGuard (flow-regulated), Miethke miniNAV with proSA (gravitational), and Medtronic Delta (membrane controlled) were tested. The shunts were compared on a novel in vitro setup that actively emulates the physiology of a shunted patient. This testing method allows determining the CSF drainage rates, resulting CSF volume, and intracranial pressure in the supine, sitting, and standing posture.

Results The flow-regulated ASDs avoided increased drainage by closing their primary flow path when drainage exceeded 1.39 ± 0.42 mL/min. However, with intraperitoneal pressure increased in standing posture, we observed reopening of the ASD in 3 out of 18 experiment repetitions. The adjustable gravitational ASDs allow independent opening pressures in horizontal and vertical orientation, but they did not provide constant drainage in upright posture (0.37 ± 0.03 mL/min and 0.26 ± 0.03 mL/min in sitting and standing posture, respectively). Consequently, adaptation to the individual patient is critical. The membrane-controlled ASDs stopped drainage in upright posture. This eliminates the risk of overdrainage, but leads to CSF accumulation up to the volume observed without shunting when the patient is upright.

Conclusions While all tested ASDs reduced overdrainage, their actual performance will depend on a patient’s specific needs because of the large variation in the way the ASDs influence CSF dynamics: while the flow-regulated shunts provide continuous drainage in upright posture, the gravitational ASDs allow and require additional adaptation, and the membrane-controlled ASDs show robust siphon prevention by a total stop of drainage.

Association between shunt-responsive idiopathic normal pressure hydrocephalus and alcohol

J Neurosurg 127:240–248, 2017

Idiopathic normal pressure hydrocephalus (iNPH) is characterized by ventriculomegaly, gait difficulty, incontinence, and dementia. The symptoms can be ameliorated by CSF drainage. The object of this study was to identify factors associated with shunt-responsive iNPH.

METHODS The authors reviewed the medical records of 529 patients who underwent shunt placement for iNPH at their institution between July 2001 and March 2015. Variables associated with shunt-responsive iNPH were identified using bivariate and multivariate analyses. Detailed alcohol consumption information was obtained for 328 patients and was used to examine the relationship between alcohol and shunt-responsive iNPH. A computerized patient registry from 2 academic medical centers was queried to determine the prevalence of alcohol abuse among 1665 iNPH patients.

RESULTS Bivariate analysis identified associations between shunt-responsive iNPH and gait difficulty (OR 4.59, 95% CI 2.32–9.09; p < 0.0001), dementia (OR 1.79, 95% CI 1.14–2.80; p = 0.01), incontinence (OR 1.77, 95% CI 1.13–2.76; p = 0.01), and alcohol use (OR 1.98, 95% CI 1.23–3.16; p = 0.03). Borderline significance was observed for hyperlipidemia (OR 1.56, 95% CI 0.99–2.45; p = 0.054), a family history of hyperlipidemia (OR 3.09, 95% CI 0.93–10.26, p = 0.054), and diabetes (OR 1.83, 95% CI 0.96–3.51; p = 0.064). Multivariate analysis identified associations with gait difficulty (OR 3.98, 95% CI 1.81–8.77; p = 0.0006) and alcohol (OR 1.94, 95% CI 1.10–3.39; p = 0.04). Increased alcohol intake correlated with greater improvement after CSF drainage. Alcohol abuse was 2.5 times more prevalent among iNPH patients than matched controls.

CONCLUSIONS Alcohol consumption is associated with the development of shunt-responsive iNPH.

 

Predictors of admission and shunt revision during emergency department visits for shunt-treated adult patients with idiopathic intracranial hypertension

J Neurosurg 127:233–239, 2017

Factors associated with emergency department admission and/or shunt revision for idiopathic intracranial hypertension (IIH) are unclear. In this study, the associations of several factors with emergency department admission and shunt revision for IIH were explored.

METHODS The authors performed a retrospective review of 31 patients (169 total emergency department visits) who presented to the emergency department for IIH-related symptoms between 2003 and 2015. Demographics, comorbidities, symptoms, IIH diagnosis and treatment history, ophthalmological examination, diagnostic lumbar puncture (LP), imaging findings, and data regarding admission and management decisions were collected. Multivariable general linear models regression analysis was performed to assess the predictive factors associated with admission and shunt revision.

RESULTS Thirty-one adult patients with a history of shunt placement for IIH visited the emergency department a total of 169 times for IIH-related symptoms, with a median of 3 visits (interquartile range 2–7 visits) per patient. Five patients had more than 10 emergency department visits. Baseline factors associated with admission included male sex (OR 10.47, 95% CI 2.13–51.56; p = 0.004) and performance of an LP (OR 3.10, 95% CI 1.31–7.31; p = 0.01). Contrastingly, older age at presentation (OR 0.94, 95% CI 0.90–0.99; p = 0.01), and a greater number of prior emergency department visits (OR 0.94, 95% CI 0.89–0.99; p = 0.02) were slightly protective against admission. The presence of papilledema (OR 11.62, 95% CI 3.20–42.16; p < 0.001), Caucasian race (OR 40.53, 95% CI 2.49–660.09 p = 0.009), and systemic hypertension (OR 7.73, 95% CI 1.11–53.62; p = 0.03) were independent risk factors for shunt revision. In addition, a greater number of prior emergency department visits (OR 0.86, 95% CI 0.77–0.96; p = 0.009) and older age at presentation (OR 0.93, 95% CI 0.87–0.99; p = 0.02) were slightly protective against shunt revision, while there was suggestive evidence that presence of a programmable shunt (OR 0.23, 95% CI 0.05–1.14; p = 0.07) was a protective factor against shunt revision. Of note, location of the proximal catheter in the ventricle or lumbar subarachnoid space was not significantly associated with admission or shunt revision in the multivariable analyses.

CONCLUSIONS The decision to admit a shunt-treated patient from the emergency department for symptoms related to IIH is challenging. Knowledge of factors associated with the need for admission and/or shunt revision is required. In this study, factors such as male sex, younger age at presentation, lower number of prior emergency department visits, and performance of a diagnostic LP were independent predictors of admission. In addition, papilledema was strongly predictive of the need for shunt revision, highlighting the importance of an ophthalmological examination for shunt-treated adults with IIH who present to the emergency department.

 

Cost-effectiveness analysis of shunt surgery for idiopathic normal pressure hydrocephalus

Acta Neurochir (2017) 159:995–1003

We showed that ventriculoperitoneal (VP) shunt and lumboperitoneal (LP) shunt surgeries are beneficial for patients with idiopathic normal pressure hydrocephalus (iNPH) in the Study of Idiopathic Normal Pressure Hydrocephalus on Neurological Improvement (SINPHONI; a multicenter prospective cohort study) and in SINPHONI-2 (a multicenter randomized trial). Although therapeutic efficacy is important, cost-effectiveness analysis is equally valuable.

Methods Using both a set of assumptions and using the data from SINPHONI and SINPHONI-2, we estimated the total cost of treatment for iNPH, which consists of medical expenses (e.g., operation fees) and costs to the long-term care insurance system (LCIS) in Japan. Regarding the natural course of iNPH patients, 10% or 20% of patients on each modified Rankin Scale (mRS) show aggravation (aggravation rate: 10% or 20%) every 3 months if the patients do not undergo shunt surgery, as described in a previous report. We performed cost-effectiveness analyses for the various scenarios, calculating the quality-adjusted life year (QALY) and the incremental cost-effective ratio (ICER). Then, based on the definition provided by a previous report, we assessed the cost-effectiveness of shunt surgery for iNPH.

Results In the first year after shunt surgery, the ICER of VP shunt varies from 29,934 to 40,742 USD (aggravation rate 10% and 20%, respectively) and the ICER of LP shunt varies from 58,346 to 80,392 USD (aggravation rate 10% and 20%, respectively), which indicates that the shunt surgery for iNPH is a cost-effective treatment. In the 2nd postoperative year, the cost to the LCIS will continue to decrease because of the lasting improvement of the symptoms due to the surgery. The total cost for iNPH patients will show a positive return on investment in as soon as 18 months (VP) and 21 months (LP), indicating that shunt surgery for iNPH is a cost-effective treatment.

Conclusions Because the total cost for iNPH patients will show a positive return on investment within 2 years, shunt surgery for iNPH is a cost-effective treatment and therefore recommended. The SINPHONI-2 study was registered with the University Hospital Medical Information Network Clinical Trials registry: UMIN000002730) SINPHONI was registered with ClinicalTrials.gov, no. NCT00221091.

Shunting of the over 80s in normal pressure hydrocephalus

Acta Neurochir (2017) 159:987–994

Idiopathic normal pressure hydrocephalus is predominantly a disease of the elderly. By its nature, many of those who present to clinic are in advanced old age with multiple comorbidities. Majority of patients treated are younger than 80 years old. We present the clinical outcomes and complication rates of patients over the age of 80 years at the time of operation, during the past 11 years at a single institution.

Methods Retrospective analysis of clinical records of all patients over the age of 80 years, who presented to our institution between 2006 and 2016.

Results were analysed for co-morbidities, immediate and delayed complications, change in mobility/cognitive function post shunting of hydrocephalus.

Results 39 patients (24 male, 15 female) met criteria. Mean [SD] age at the time of shunt insertion was 84 years (+/− 3.22) (range 80–94). No patients developed immediate CSF infection or sub-dural collection, or extended length of stay due to surgical or anaesthetic complications. There were no perioperative or anaesthetic complications. 4 patients required a delayed surgical revision to encourage greater CSF drainage. 3 patients went on to develop delayed subdural haematoma, 1 of which was associated with trauma, 2 through overdrainage. 1 patient experienced poor post-operative wound healing and subsequently underwent removal of shunt. Of the 34 patient followed up, 27 patients (79.4%) improved in their mobility. (64.7%) patients/families reported symptomatic improvement in their cognition and memory. 6 (17.7%) patients did not experience an improvement in either mobility or cognitive function.

Conclusions Our data supports the assertion that, with proper patient selection, shunting of the over 80s with iNPH is a safe and effective procedure.

Low-pressure Hydrocephalus in Children

Neurosurgery 80:439–447, 2017

Low-pressure hydrocephalus (LPH) is a rare phenomenon characterized by a clinical picture consistent with elevated intracranial pressure (ICP) and ventricular enlargement, but also a well-functioning shunt and low or negative ICP.

OBJECTIVE: To report our experience in evaluating this challenging problem. METHODS: Patients with LPH were identified from several sources, including institutional procedural databases and personal case logs. Electronic medical records were reviewed to collect demographic, clinical, surgical, and radiographic data to determine the presence of LPH. Each patient’s clinical course, including presentation, management, and outcome, is reported.

RESULTS: Thirty instances of LPH were identified in 29 patients. Eleven cases (37.9%) of LPH were after lumbar puncture (LP), and 19 cases (62.1%) occurred without any preceding spinal procedure. Among the post-LP patients, conservative measures alone were successful in 3 cases (27%); lumbar blood patch was successful in 2 cases (18%); and 6 cases (55%) required external cerebrospinal fluid (CSF) drainage. Of the spontaneous cases, 5 patients did not receive the full spectrum of treatment because of terminal prognosis. Of the remaining 14 patients, 11 (78.6%) required external CSF drainage. Post-LP patients required fewer days of external CSF drainage (median, 4 [range, 0-12] vs median, 11 [range, 0-90]) and had a shorter hospital stay (median, 2 [range, 2-16] vs median, 8 [range, 0-26]).

CONCLUSION: This study represents the largest series of LPH. Although its pathophysi-ology remains a mystery, there are a variety of management options. Multiple procedures and a protracted hospital stay are often required to successfully treat LPH.

 

Contrast-enhanced shunt series (“shuntography”) compare favorably to other shunt imaging modalities in detecting shunt occlusion

Acta Neurochir (2017) 159:63–70

Obstruction is a common cause of ventriculo-peritoneal shunt failure. Head computed tomography and plain x-ray examinations of shunt tubing (“shunt series”) are routinely used in patients readmitted for reemerging symptoms but are of limited value. The validity of shunt series can be improved by applying contrast agent into the system (contrast-enhanced shunt series, a.k.a. a “shuntogram” or “shuntography”). We hypothesized that contrast-enhanced shunt series have a high predictive value for shunt revision surgeries.

Methods: We retrospectively re-evaluated 107 contrast-enhanced shunt series and reviewed the patient histories. We defined outcome parameters for calculating the utility of a pathological contrast-enhanced shunt series in predicting revision surgery.

Results: Of 107 contrast-enhanced shunt series, 41 examinations were positive for obstruction, mainly of the ventricular (36.5 %) and the peritoneal catheter (48.8 %). Within 30 days, 35 successful revision surgeries and 3 revision surgeries without resolution of symptoms were performed. In two cases the shunt tubing was found to be patent. Sixty-six negative examinations resulted in two revision surgeries, in addition to ten surgeries not attempting to restore patency. After 30 days, the specificity of contrast-enhanced shunt series for shunt failure identification was calculated at 92.8 %, the sensitivity at 94.7 %, the positive predictive value at 87.8 %, and the negative predictive value at 97.0 %.

Conclusions: The contrast-enhanced shunt series method is a highly specific examination with a negative predictive value exceeding that of head computed tomography and plain shunt series. Compared to radionuclide marker studies, contrast-enhanced shunt series demonstrate better spatiotemporal resolution, enabling focused local surgical repair.

Walking assessment after lumbar puncture in normal-pressure hydrocephalus: a delayed improvement over 3 days

J Neurosur (126) 148-157, 2017

The determination of gait improvement after lumbar puncture (LP) in idiopathic normal-pressure hydrocephalus (iNPH) is crucial, but the best time for such an assessment is unclear. The authors determined the time course of improvement in walking after LP for single-task and dual-task walking in iNPH.

METHODS: In patients with iNPH, sequential recordings of gait velocity were obtained prior to LP (time point [TP]0), 1–8 hours after LP (TP1), 24 hours after LP (TP2), 48 hours after LP (TP3), and 72 hours after LP (TP4). Gait analysis was performed using a pressure-sensitive carpet (GAITRite) under 4 conditions: walking at preferred velocity (STPS), walking at maximal velocity (STMS), walking while performing serial 7 subtractions (dual-task walking with serial 7 [DTS7]), and walking while performing verbal fluency tasks (dual-task walking with verbal fluency [DTVF]).

RESULTS: Twenty-four patients with a mean age of 76.1 ± 7.8 years were included in this study. Objective responder status moderately coincided with the self-estimation of the patients with subjective high false-positive results (83%). The extent of improvement was greater for single-task walking than for dual-task walking (p < 0.05). Significant increases in walking speed were found at TP2 for STPS (p = 0.042) and DTVF (p = 0.046) and at TP3 for STPS (p = 0.035), DTS7 (p = 0.042), and DTVF (p = 0.044). Enlargement of the ventricles (Evans Index) positively correlated with early improvement. Gait improvement at TP3 correlated with the shunt response in 18 patients.

CONCLUSIONS: Quantitative gait assessment in iNPH is important due to the poor self-evaluation of the patients. The maximal increase in gait velocity can be observed 24–48 hours after the LP. This time point is also best to predict the response to shunting. For dual-task paradigms, maximal improvement appears to occur later (48 to 72 hours). Assessment of gait should be performed at Day 2 or 3 after LP.

Surgical treatment of long-standing overt ventriculomegaly in adults (LOVA)

Acta Neurochir (2017) 159:71–79

Longstanding overt ventriculomegaly in adults (LOVA) is characterised by chronic hydrocephalus presumed to begin during infancy, but arresting before becoming clinically detectable. Later in life clinical features of hydrocephalus ensue, typically in the 5th or 6th decades. Only a relatively small number of LOVA case series have been published, and ambiguity remains regarding optimal management. This case series describes a series of patients with LOVA treated successfully at a single neurosurgical institution using endoscopic third ventriculostomy (ETV).

Methods: A series of 14 patients were diagnosed with LOVA using established clinical and radiological criteria. All patients underwent an ETV and their clinical conditions were followed up for up to 5 years post-operatively.

Results: Fourteen patients (100 %) reported either improvement or halt of progression in their presenting symptoms 3 months after ETV; 93 % of patients (n = 13) did not require any further surgical intervention. One patient (7 %) reported deterioration in symptoms beyond 3 months post-operatively, which necessitated further surgery (ventriculoperitoneal shunt). These promising outcomes after ETV are mirrored in numerous other LOVA case series. Other works have analysed the value of CSF shunting procedures in LOVA, with mixed results. A direct, prospective comparison of outcomes after shunt procedures and ETV, with a specific focus on LOVA patients, is yet to be completed. A minority of patients fail to respond, or develop recurrence of symptoms, months or years after initial surgical intervention.

Conclusions: ETV is an attractive option for surgical treatment of LOVA. After surgical treatment for LOVA, long-term follow-up should be considered to screen for late recurrence of the condition.

Associations of intracranial pressure with brain biopsy, radiological findings, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus

Acta Neurochir (2017) 159: 51-61

It remains unclear how intracranial pressure (ICP) measures are associated with brain biopsies and radiological markers. Here, we aim to investigate associations between ICP and radiological findings, brain biopsies, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus (iNPH).

Method

In this study, we retrospectively analyzed data from 73 patients admitted with suspected iNPH to Kuopio University Hospital. Of these patients, 71% underwent shunt surgery. The NPH registry included data on clinical and radiological examinations, 24-h intraventricular pressure monitoring, and frontal cortical biopsy.

Results

The mean ICP and mean ICP pulse wave amplitude were not associated with the shunt response. Aggregations of Alzheimer’s disease (AD)-related proteins (amyloid-β, hyperphosphorylated tau) in frontal cortical biopsies were associated with a poor shunt response (P = 0.014). High mean ICP was associated with Evans’ index (EI; P = 0.025), disproportional sylvian and suprasylvian subarachnoid spaces (P = 0.014), and focally dilated sulci (P = 0.047). Interestingly, a high pulse wave amplitude was associated with AD-related biopsy findings (P = 0.032), but the mean ICP was not associated with the brain biopsy. The ICP was not associated with medial temporal lobe atrophy, temporal horn widths, or white matter changes. ICP B waves were associated with less atrophy of the medial temporal lobe (P = 0.018) and more severe disproportionality between the sylvian and suprasylvian subarachnoid spaces (P = 0.001).

Conclusions

The EI and disproportional sylvian and suprasylvian subarachnoid spaces were associated with mean ICP. Disproportionality was also associated with ICP B waves. These associations, although rather weak, with elevated ICP in 24-h measurements, support their value in iNPH diagnostics and suggest that these radiological markers are potentially related to the pathogenesis of iNPH. Interestingly, our results suggested that elevated pulse wave amplitude might be associated with brain amyloid accumulation.

Natural history of colloid cysts of the third ventricle

J Neurosurg 125:1420–1430, 2016

Colloid cysts are rare, histologically benign lesions that may result in obstructive hydrocephalus and death. Understanding the natural history of colloid cysts has been challenging given their low incidence and the small number of cases in most reported series. This has complicated efforts to establish reliable prognostic factors and surgical indications, particularly for asymptomatic patients with incidental lesions. Risk factors for obstructive hydrocephalus in the setting of colloid cysts remain poorly defined, and there are no grading scales on which to develop standard management strategies.

Methods The authors performed a single-center retrospective review of all cases of colloid cysts of the third ventricle treated over nearly 2 decades at Washington University. Univariate analysis was used to identify clinical, imaging, and anatomical factors associated with 2 outcome variables: symptomatic clinical status and presentation with obstructive hydrocephalus. A risk-prediction model was defined using bootstrapped logistic regression. Predictive factors were then combined into a simple 5-point clinical scale referred to as the Colloid Cyst Risk Score (CCRS), and this was evaluated with receiver-operator characteristics.

Results The study included 163 colloid cysts, more than half of which were discovered incidentally. More than half of the incidental cysts (58%) were followed with surveillance neuroimaging (mean follow-up 5.1 years). Five patients with incidental cysts (8.8%) progressed and underwent resection. No patient with an incidental, asymptomatic colloid cyst experienced acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly half (46.2%) of symptomatic patients presented with hydrocephalus. Eight patients (12.3%) presented acutely, and there were 2 deaths due to obstructive hydrocephalus and herniation. The authors identified several factors that were strongly correlated with the 2 outcome variables and defined third ventricle risk zones where colloid cysts can cause obstructive hydrocephalus. No patient with a lesion outside these risk zones presented with obstructive hydrocephalus. The CCRS had significant predictive capacity for symptomatic clinical status (area under the curve [AUC] 0.917) and obstructive hydrocephalus (AUC 0.845). A CCRS ≥ 4 was significantly associated with obstructive hydrocephalus (p < 0.0001, RR 19.4).

Conclusions Patients with incidentally discovered colloid cysts can experience both lesion enlargement and symptom progression or less commonly, contraction and symptom regression. Incidental lesions rarely cause acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly one-half of patients with symptomatic colloid cysts present with obstructive hydrocephalus, which has an associated 3.1% risk of death. The CCRS is a simple 5-point clinical tool that can be used to identify symptomatic lesions and stratify the risk of obstructive hydrocephalus. External validation of the CCRS will be necessary before objective surgical indications can be established. Surgical intervention should be considered for all patients with CCRS ≥ 4, as they represent the high-risk subgroup.

Does aqueductal stenosis influence the lumbar infusion test in normal-pressure hydrocephalus?

Acta Neurochir (2016) 158:2305–2310

Late-onset idiopathic aqueductal stenosis may present with clinical features indistinct from idiopathic normal-pressure hydrocephalus (NPH). Moreover, aqueductal stenosis (AS) is not always detected by conventional magnetic resonance imaging (MRI). The aim of this study was to compare the hydrodynamic pattern among NPH patients according to the patency of the aqueduct.

Methods Fifty-six consecutive lumbar infusion tests were performed in patients with NPH syndrome. Precipitating causes of hydrocephalus were excluded, and aqueductal patency was examined through high-resolution, T2-weighted 3D MRI. Patients were classified into two groups: non-patent aqueduct and patent aqueduct. Mean values of pressure and pulse amplitude were obtained from basal and plateau stages of infusion studies.

Results Twelve of 56 patients with NPH-like symptoms presented with morphological AS (21.4 %). Patent aqueduct and non-patent aqueduct groups had similar values of mean opening lumbar pressure (8.2 vs. 8.1 mmHg), and mean opening pulse amplitude (3.1 vs. 2.9 mmHg). Mean pressure in the plateau stage (28.6 vs. 23.2 mmHg), and mean pulse amplitude in the plateau stage (12.5 vs. 10.6 mmHg) were higher in the patent aqueduct group. These differences were not statistically significant. Only Rout was significantly higher in the patent aqueduct group (13.6 vs. 10.1 mmHg/ml/min). One-third of NPH patients with AS presented Rout >12 mmHg/ ml/min.

Conclusions No differences in mean pressure or pulse amplitude during basal and plateau epochs of the lumbar infusion test in NPH patients were detected, regardless of aqueductal patency. However, Rout was significantly higher in patients with patent aqueduct.

One-year outcome in patients with idiopathic normal-pressure hydrocephalus: comparison of lumboperitoneal shunt to ventriculoperitoneal shunt

J Neurosurg 125:1483–1492, 2016

Idiopathic normal pressure hydrocephalus (iNPH) is treated with cerebrospinal fluid shunting, and implantation of a ventriculoperitoneal shunt (VPS) is the current standard treatment. The objective of this study was to compare the efficacy and safety of VPSs and lumboperitoneal shunts (LPSs) for patients with iNPH.

Methods The authors conducted a prospective multicenter study of LPS use for patients with iNPH. Eighty-three patients with iNPH (age 60 to 85 years) who presented with ventriculomegaly and high-convexity and medial subarachnoid space tightness on MR images were recruited from 20 neurological or neurosurgical centers in Japan between March 1, 2010, and October 19, 2011. The primary outcome was the modified Rankin Scale (mRS) score 1 year after surgery, and the secondary outcome included scores on the iNPH grading scale (iNPHGS). A previously conducted VPS cohort study with the same inclusion criteria and primary and secondary end points was used as a historical control.

Results: The proportion of patients who achieved a favorable outcome (i.e., improvement of at least 1 point in their mRS score) was 63% (95% CI 51%–73%) and was comparable to values reported with VPS implantation (69%, 95% CI 59%–78%). Using the iNPHGS, the 1-year improvement rate was 75% (95% CI 64%–84%) and was comparable to the rate found in the VPS study (77%, 95% CI 68%–84%). The proportion of patients experiencing serious adverse events (SAEs) and non-SAEs did not differ signi cantly between the groups at 1 year after surgery (SAEs: 19 [22%] of 87 LPS patients vs 15 [15%] of 100 VPS patients, p = 0.226; non-SAEs: 24 [27.6%] LPS patients vs 20 [20%] VPS patients, p = 0.223). However, shunt revisions were more common in LPS-treated patients than in VPS-treated patients (6 [7%] vs 1 [1%]).

Conclusions The efficacy and safety rates for LPSs with programmable valves are comparable to those for VPSs for the treatment of patients with iNPH. Despite the relatively high shunt failure rate, an LPS can be the treatment of choice because of its minimal invasiveness and avoidance of brain injury.

 

Hydrocephalus: an underrated long-term complication of microvascular decompression for trigeminal neuralgia

External lumbar drain- A pragmatic test for prediction of shunt outcomes in idiopathic normal pressure hydrocephalus

Acta Neurochir (2016) 158:2203–2206

Hydrocephalus is a common complication of posterior fossa surgery, but its real incidence after microvascular decompression (MVD) for idiopathic trigeminal neuralgia (TN) still remains unclear. The aim of this study was to focus on the potential association between MVD and hydrocephalus as a surgery-related complication.

Methods All patients who underwent MVD procedure for idiopathic TN at our institute between 2009 and 2014 were reviewed to search for early or late postoperative hydrocephalus.

Results There were 259 consecutive patients affected by idiopathic TN who underwent MVD procedure at our institution between 2009 and 2014 (113 men, 146 women; mean age 59 years, range 30–87 years; mean follow-up 40.92 months, range 8–48 months). Nine patients (3.47 %) developed communicating hydrocephalus after hospital discharge and underwent standard ventriculo-peritoneal shunt. No cases of acute hydrocephalus were noticed.

Conclusions Our study suggests that late communicating hydrocephalus may be an underrated potential long-term complication of MVD surgery.

 

Comparison of elevated intracranial pressure pulse amplitude and disproportionately enlarged subarachnoid space (DESH) for prediction of surgical results in suspected idiopathic normal pressure hydrocephalus

External lumbar drain- A pragmatic test for prediction of shunt outcomes in idiopathic normal pressure hydrocephalus

Acta Neurochir (2016) 158:2207–2213

To compare the prognostic value of pulse amplitude on intracranial pressure (ICP) monitoring and disproportionately enlarged subarachnoid space hydrocephalus (DESH) on magnetic resonance imaging (MRI) for predicting surgical benefit after shunt placement in idiopathic normal pressure hydrocephalus (iNPH).

Method Patients with suspected iNPH were prospectively recruited from a single centre. All patients received preoperative MRI and ICP monitoring. Patients were classified as shunt responders if they had an improvement of one point or more on the NPH score at 1 year post-surgery. The sensitivity, specificity, Youden index, and positive and negative predictive values of the two diagnostic methods were calculated.

Results Sixty-four of 89 patients clinically improved at 1 year post-surgery and were classed as shunt responders. Positive DESH findings had a sensitivity of 79.4 % and specificity of 80.8 % for predicting shunt responders. Fifty-five of 89 patients had positive DESH findings: 50 of these responded to VP shunt, giving a positive and negative predictive value of 90.9 % and 61.8 %, respectively. Fifty-seven of 89 patients had high ICP pulse amplitude. High ICP pulse amplitude had a sensitivity of 84.4 %, specificity of 88 %, positive predictive value of 94.7 % and negative predictive value of 61.8 % for predicting shunt responders.

Conclusions Both positive DESH findings and high ICP pulse amplitude support the diagnosis of iNPH and provide additional diagnostic value for predicting shunt-responsive patients; however, high ICP amplitude was more accurate than positive DESH findings, although it is an invasive test.

Endoscopic third ventriculostomy for treatment of adult hydrocephalus: long-term follow-up of 163 patients

ETV

Neurosurg Focus 41 (3):E3, 2016

The authors performed a retrospective chart review of all adult patients (age ≥ 18 years) with symptomatic hydrocephalus treated with ETV in Calgary, Canada, over a span of 20 years (1994–2014). Patients were dichotomized into a primary or secondary ETV cohort based on whether ETV was the initial treatment modality for the hydrocephalus or if other CSF diversion procedures had been previously attempted respectively. Primary outcomes were subjective patient-reported clinical improvement within 12 weeks of surgery and the need for any CSF diversion procedures after the initial ETV during the span of the study. Categorical and actuarial data analysis was done to compare the outcomes of the primary versus secondary ETV cohorts.

Results A total of 163 adult patients with symptomatic hydrocephalus treated with ETV were identified and followed over an average of 98.6 months (range 0.1–230.4 months). All patients presented with signs of intracranial hypertension or other neurological symptoms. The primary ETV group consisted of 112 patients, and the secondary ETV consisted of 51 patients who presented with failed ventriculoperitoneal (VP) shunts. After the initial ETV procedure, clinical improvement was reported more frequently by patients in the primary cohort (87%) relative to those in the secondary ETV cohort (65%, p = 0.001). Additionally, patients in the primary ETV group required fewer reoperations (p < 0.001), with cumulative ETV survival time favoring this primary ETV cohort over the course of the follow-up period (p < 0.001). Fifteen patients required repeat ETV, with all but one experiencing successful relief of symptoms. Patients in the secondary ETV cohort also had a higher incidence of complications, with one occurring in 8 patients (16%) compared with 2 in the primary ETV group (2%; p = 0.010), although most complications were minor.

Conclusions ETV is an effective long-term treatment for selected adult patients with hydrocephalus. The overall ETV success rate when it was the primary treatment modality for adult hydrocephalus was approximately 87%, and 99% of patients experience symptomatic improvement after 2 ETVs. Patients in whom VP shunt surgery fails prior to an ETV have a 22% relative risk of ETV failure and an almost eightfold complication rate, although mostly minor, when compared with patients who undergo a primary ETV. Most ETV failures occur within the first 7 months of surgery in patients treated with primary ETV, but the time to failure is more prolonged in patients who present with failed previous shunts.

Hydrocephalus: cerebral aquaporin-4 and computational modeling

Aquaporin-4 channels

Neurosurg Focus 41 (3):E8, 2016

Aquaporin-4 (AQP4) channels play an important role in brain water homeostasis. Water transport across plasma membranes has a critical role in brain water exchange of the normal and the diseased brain. AQP4 channels are implicated in the pathophysiology of hydrocephalus, a disease of water imbalance that leads to CSF accumulation in the ventricular system. Many molecular aspects of fluid exchange during hydrocephalus have yet to be firmly elucidated, but review of the literature suggests that modulation of AQP4 channel activity is a potentially attractive future pharmaceutical therapy. Drug therapy targeting AQP channels may enable control over water exchange to remove excess CSF through a molecular intervention instead of by mechanical shunting.

This article is a review of a vast body of literature on the current understanding of AQP4 channels in relation to hydrocephalus, details regarding molecular aspects of AQP4 channels, possible drug development strategies, and limitations. Advances in medical imaging and computational modeling of CSF dynamics in the setting of hydrocephalus are summarized.

Algorithmic developments in computational modeling continue to deepen the understanding of the hydrocephalus disease process and display promising potential benefit as a tool for physicians to evaluate patients with hydrocephalus.

Fractional anisotropy in patients with disproportionately enlarged subarachnoid space hydrocephalus

Fractional anisotropy in patients with disproportionately enlarged subarachnoid space hydrocephalus

Acta Neurochir (2016) 158:1495–1500

Disproportionately enlarged subarachnoid space hydrocephalus (DESH) findings on MRI were described as a prognostic factor for responsiveness to the treatment of idiopathic normal pressure hydrocephalus (iNPH). Our premise is that DESH could be associated with compression of the cerebral white matter. Microstructural changes can be identified using diffusion tensor imaging (DTI), specifically fractional anisotropy (FA). The aim of this study is to compare FA in iNPH patients with and without DESH and healthy controls.

Methods: We analysed 1.5-T MRI scans of patients fulfilling the criteria of probable or possible iNPH and positive supplementary tests before and after surgery (ventriculo-peritoneal shunt). FA was measured in the anterior and posterior limb of the internal capsule (PLIC) and in the corpus callosum. Patients were divided into the DESH and non-DESH group. These data were also compared to FA values in the control group.

Results: Twenty-seven patients and 24 healthy controls were enrolled. DESH was present in 15 patients and lacking in 12. Twenty-three iNPH patients were shunt responders (85.2 %), and 4 were non-responders (14.8 %). All patients in the DESH group were shunt responders. In the non-DESH group, eight patients were responders (66.7 %). A significant difference between the DESH and non-DESH group was found in the FA of the PLIC. The mean value of FA in the PLIC was 0.72 in the DESH group and 0.66 in the non-DESH group. After the surgery FA decreased in both groups. In the DESH iNPH group FA PLIC decreased to 0.65 and in the non-DESH iNPH group to 0.60. In the healthy controls, the mean FA in the PLIC was 0.58.

Conclusion: DESH on MRI scans is related to a higher FA in the PLIC with a decrease after the surgery. It reflects a more severe compression of the white matter than in non-DESH patients or healthy volunteers. DESH patients had better outcome than non-DESH patients. This study confirmed the importance of DESH as a supportive sign for iNPH.

Defining a Standardized Approach for the Bedside Insertion of Temporal Horn External Ventricular Drains

Standardized Approach for the Bedside Insertion of Temporal Horn External Ventricular Drains

Neurosurgery 79:296–304, 2016

A trapped temporal horn can be emergently decompressed by inserting a bedside temporal horn external ventricular drain (tEVD). However, no standardized method for this procedure has been described.

OBJECTIVE: To identify methods for bedside tEVD insertion, and determine the safest, most accurate, and most easily standardized approach.

METHODS: Volumetric images of 20 patients with trapped temporal horns were analyzed. Three tEVD approaches (perpendicular, lateral, and medial) were defined, along with standardized insertion points and external landmarks for trajectory guidance. Predicted success in penetrating the temporal horn, skin-to-temporal horn entrance distance, temporal horn distance traversed, and trajectory target error and accuracy were evaluated; data were compared with independent sample t tests.

RESULTS: Nineteen of 20 cases were analyzed; 13 had critical temporal horn entrapment. Penetration was achieved in 100% of perpendicular and 84% (16/19) of lateral and medial approaches (92% [12/13] of critical entrapments). In 19 patients, trajectory error was not significantly different among approaches. The perpendicular approach had significantly more accuracy than the lateral (P = .01) and medial (P = .002) approaches. The lateral approach afforded significantly more traversable distance than the perpendicular approach (P = .009). In cases with critical entrapment, the perpendicular approach had significantly less error (P = .02) and significantly better accuracy (P = .02) than the medial approach. The perpendicular approach trended toward more accuracy than the lateral approach (P = .06).

CONCLUSION: The perpendicular approach appears to be the easiest, safest, and most reliable approach tested. We recommend conducting bedside tEVD placement only in patients with a critically dilated temporal horn who are clinically deteriorating at a rate that prohibits other procedures.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain

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