Understanding the complex pathophysiology of idiopathic intracranial hypertension and the evolving role of venous sinus stenting: a comprehensive review of the literature

Idiopathic intracranial hypertension (IIH) is a disease defined by elevated intracranial pressure without established etiology. Although there is now consensus on the definition of the disorder, its complex pathophysiology remains elusive. The most common clinical symptoms of IIH include headache and visual complaints. Many current theories regarding the etiology of IIH focus on increased secretion or decreased absorption of cerebrospinal fluid (CSF) and on cerebral venous outflow obstruction due to venous sinus stenosis. In addition, it has been postulated that obesity plays a role, given its prevalence in this population of patients. Several treatments, including optic nerve sheath fenestration, CSF diversion with ventriculoperitoneal or lumboperitoneal shunts, and more recently venous sinus stenting, have been described for medically refractory IIH. Despite the availability of these treatments, no guidelines or standard management algorithms exist for the treatment of this disorder. In this paper, the authors provide a review of the literature on IIH, its clinical presentation, pathophysiology, and evidence supporting treatment strategies, with a specific focus on the role of venous sinus stenting.

Reversible intracranial hypertension following treatment of an extracranial vascular malformation: case report

Pediatric hydrocephalus is a well-studied and still incompletely understood entity. One of the physiological means by which hydrocephalus and intracranial hypertension evolve is through perturbations to normal vascular dynamics. Here the authors report a unique case of an extracranial vascular anomaly resulting in persistently elevated intracranial pressures (ICPs) independent of CSF diversion in a patient with a Joubert syndrome-related disorder. The patient developed worsening intracranial hypertension after successful CSF diversion of Dandy-Walker malformation-associated hydrocephalus via endoscopic third ventriculostomy-choroid plexus cauterization (ETV/CPC). Vascular workup and imaging revealed an extracranial arteriovenous fistula of the superficial temporal artery at the site of a prior scalp intravenous catheter. Following microsurgical obliteration of the lesion, ICP normalized from > 30 cm H2O preoperatively to 11 cm H2O postoperatively. A repeat lumbar puncture at 4 months postoperatively again demonstrated normal pressure, and the patient remained asymptomatic for 9 months. Recurrent symptoms at 9 months were attributed to inadequate CSF diversion, and the patient underwent ventriculoperitoneal shunt placement. This is the first report of an extracranial-to-extracranial vascular anastomosis resulting in intracranial hypertension. This case report demonstrates the need to consider extracranial vascular anomalies as potential sources of persistently elevated ICP in the syndromic pediatric population.

Endoscopic third ventriculostomy and repeat endoscopic third ventriculostomy in pediatric patients: the Dutch experience

OBJECTIVE After endoscopic third ventriculostomy (ETV), some patients develop recurrent symptoms of hydrocephalus. The optimal treatment for these patients is not clear: repeat ETV (re-ETV) or CSF shunting. The goals of the study were to assess the effectiveness of re-ETV relative to initial ETV in pediatric patients and validate the ETV success score (ETVSS) for re-ETV. METHODS Retrospective data of 624 ETV and 93 re-ETV procedures were collected from 6 neurosurgical centers in the Netherlands (1998-2015). Multivariable Cox proportional hazards modeling was used to provide an adjusted estimate of the hazard ratio for re-ETV failure relative to ETV failure. The correlation coefficient between ETVSS and the chance of re-ETV success was calculated using Kendall's tau coefficient. Model discrimination was quantified using the c-statistic. The effects of intraoperative findings and management on re-ETV success were also analyzed. RESULTS The hazard ratio for re-ETV failure relative to ETV failure was 1.23 (95% CI 0.90-1.69; p = 0.20). At 6 months, the success rates for both ETV and re-ETV were 68%. ETVSS was significantly related to the chances of re-ETV success (τ = 0.37; 95% bias corrected and accelerated CI 0.21-0.52; p < 0.001). The c-statistic was 0.74 (95% CI 0.64-0.85). The presence of prepontine arachnoid membranes and use of an external ventricular drain (EVD) were negatively associated with treatment success, with ORs of 4.0 (95% CI 1.5-10.5) and 9.7 (95% CI 3.4-27.8), respectively. CONCLUSIONS Re-ETV seems to be as safe and effective as initial ETV. ETVSS adequately predicts the chance of successful re-ETV. The presence of prepontine arachnoid membranes and the use of EVD negatively influence the chance of success.

Neurosurgery and human immunodeficiency virus in the era of combination antiretroviral therapy: a review

Human immunodeficiency virus (HIV) is a global health problem. It renders the central nervous system susceptible to infectious and noninfectious diseases. HIV-positive individuals may present to neurosurgical services with brain lesions of unknown etiology. The differential diagnosis in these cases is broad, including opportunistic infections and malignancies, and investigation should be tailored accordingly. Opportunistic infections of the central nervous system can be complicated by hydrocephalus, and the management is pathogen dependent. Patients may also present to a neurosurgical service with conditions unrelated to their HIV status. This review outlines important conditions that cause brain lesions and hydrocephalus. It addresses the issues of diagnosis and intervention in HIV-positive patients in the era of combination antiretroviral therapy, while not ignoring the potential for opportunistic central nervous system infection in undiagnosed patients. The care of HIV-positive patients presenting to neurosurgical services requires a multidisciplinary approach, which is reflected in the authorship of this review, as well as in the guidance given.

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

OBJECTIVE 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 management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant

OBJECT Posthemorrhagic hydrocephalus (PHH) in the preterm infant remains a major neurological complication of prematurity. The authors first described insertion of a specially designed low-profile subcutaneous ventricular catheter reservoir for temporary management of hydrocephalus in 1983. This report presents the follow-up experience with the surgical management of PHH in this population and describes outcomes both in infants who were stable for permanent shunt insertion and those initially temporized with a ventricular reservoir (VR) prior to permanent ventriculoperitoneal (VP)/ventriculoatrial (VA) shunt placement. METHODS A retrospective review was undertaken of the medical records of all premature infants surgically treated for posthemorrhagic hydrocephalus (PHH) between 1997 and 2012 at Children's Hospital Los Angeles. RESULTS Over 14 years, 91 preterm infants with PHH were identified. Fifty neonates received temporizing measures via a VR that was serially tapped for varying time periods. For the remaining 41 premature infants, VP/VA shunt placement was the first procedure. Patients with a temporizing measure as their initial procedure had undergone CSF diversion significantly earlier in life than those who had permanent shunting as the initial procedure (29 vs 56 days after birth, p < 0.01). Of the infants with a VR as their initial procedure, 5/50 (10%) did not undergo subsequent VP/VA shunt placement. The number of shunt revisions and the rates of loculated hydrocephalus and shunt infection did not statistically differ between the 2 groups. CONCLUSIONS Patients with initial VR insertion as a temporizing measure received a CSF diversion procedure significantly earlier than those who received a permanent shunt as their initial procedure. Otherwise, the outcomes with regard to shunt revisions, loculated hydrocephalus, and shunt infection were not different for the 2 groups.

Transsutural distraction osteogenesis for 285 children with craniosynostosis: a single-institution experience

OBJECT Although distraction osteogenesis (DO) requires a secondary procedure in the surgical correction of craniosynostosis, it is relatively simple, requires less transfusion, results in a shorter intensive care unit stay, and is quite safe. Because of these positive factors, various DO techniques have been developed. However, there is disagreement regarding the superiority of DO. The authors reported on a new DO technique, transsutural DO (TSDO), 6 years ago that was performed in 23 patients over a period of 6 months, and it continues to be used at the present time. In this paper the authors report the results of TSDO performed in 285 patients with craniosynostosis over a period of 6 years at a single institution. METHODS TSDO consists of a simple suturectomy of the pathological suture followed by direct distraction of the suturectomy site only. Types of TSDO conducted included sagittal TSDO in 95 patients, bicoronal in 14, unilateral coronal in 57, lambdoid in 26, metopic in 13, multiple in 19, syndromic in 33, and secondary in 28. The mean age (± SD) of the patients was 19.4 ± 23.0 months, and mean follow-up was 39.5 ± 21.0 months. RESULTS The mean operating time was 115 ± 43 minutes, and mean anesthesia time was 218 ± 56 minutes. The mean transfusion volume of red blood cell components was 48 ± 58 ml, and mean transfusion volume of fresh-frozen plasma was 19 ± 35 ml. Total transfusion volume was significantly less in infants younger than 12 months of age and in children with lower lumbar puncture pressures (p < 0.05). Complications included 1 (0.4%) death from postoperative acute pneumonia after a distractor removal operation and 23 (8%) surgical morbidities comprising 10 revisions (3.5%) and 13 early removals of distracters (4.6%). CONCLUSIONS TSDO is a simple, effective, and safe method to use for treating all types of craniosynostosis. Some morbidity was experienced in this study, but it may be attributed to the learning curve of the technique.

Intrathecal baclofen trials: complications and positive yield in a pediatric cohort

OBJECT Intrathecal baclofen (ITB) is an effective management option for childhood hypertonia. Given the potential complications of implanted ITB pumps, trials of ITB are usually performed as part of the workup for ITB pumps. Two methods are used for ITB trials, lumbar puncture (LP) and catheter insertion into the intrathecal space. Little has been written to date on the number of positive trials and complications in trials. This study aimed to report the outcomes and complications in ITB trials for childhood hypertonia (dystonia, spastic, or mixed). METHODS A retrospective case notes review was conducted of all patients who underwent ITB trials at the Evelina London Children's Hospital between 2005 and 2012 (inclusive). Positive trials were defined as a reduction in Modified Ashworth Scale by a minimum of 1 point in at least 2 muscle groups and improvement reported by the caregivers in the areas of goals agreed upon between professionals and the families. RESULTS Our patient group comprised children with dystonia (n = 7), mixed spasticity/dystonia (n = 29), spasticity (n = 4), and pain (n = 1). A total of 47 trials were attempted in 41 children. Forty trials were successfully completed, with 39 being positive. Thirty-three were catheter trials, and 14 were LPs. The overall complication rate in the 47 attempted trials was 53%: 61% in catheter trials, and 36% in LP trials. This difference was not statistically significant. The most common complications were vomiting (n = 9) and CSF leak (n = 4). The most serious complication was meningitis (n = 1) in a catheter trial. No patients experienced a permanent injury. CONCLUSIONS There is a high risk of minor self-limiting complications with ITB trials, which needs to be factored into the decision process of progression to trials. The rate of positive trials in this study was 98%, of which 21% did not progress to pump implantation. While the authors would still advocate for ITB trials prior to ITB pump insertion to aid parental decision-making, this figure suggests that with good patient selection, ITB pumps could be placed without a preceding trial.

Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 2: Management of posthemorrhagic hydrocephalus in premature infants

OBJECT

The objective of this systematic review and analysis was to answer the following question: What are the optimal treatment strategies for posthemorrhagic hydrocephalus (PHH) in premature infants?

METHODS

Both the US National Library of Medicine and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words relevant to PHH. Two hundred thirteen abstracts were reviewed, after which 98 full-text publications that met inclusion criteria that had been determined a priori were selected and reviewed.

RESULTS

Following a review process and an evidentiary analysis, 68 full-text articles were accepted for the evidentiary table and 30 publications were rejected. The evidentiary table was assembled linking recommendations to strength of evidence (Classes I-III).

CONCLUSIONS

There are 7 recommendations for the management of PHH in infants. Three recommendations reached Level I strength, which represents the highest degree of clinical certainty. There were two Level II and two Level III recommendations for the management of PHH. Recommendation Concerning Surgical Temporizing Measures: I. Ventricular access devices (VADs), external ventricular drains (EVDs), ventriculosubgaleal (VSG) shunts, or lumbar punctures (LPs) are treatment options in the management of PHH. Clinical judgment is required.

STRENGTH OF RECOMMENDATION

Level II, moderate degree of clinical certainty. Recommendation Concerning Surgical Temporizing Measures: II. The evidence demonstrates that VSG shunts reduce the need for daily CSF aspiration compared with VADs.

STRENGTH OF RECOMMENDATION

Level II, moderate degree of clinical certainty. Recommendation Concerning Routine Use of Serial Lumbar Puncture: The routine use of serial lumbar puncture is not recommended to reduce the need for shunt placement or to avoid the progression of hydrocephalus in premature infants.

STRENGTH OF RECOMMENDATION

Level I, high clinical certainty. Recommendation Concerning Nonsurgical Temporizing Agents: I. Intraventricular thrombolytic agents including tissue plasminogen activator (tPA), urokinase, or streptokinase are not recommended as methods to reduce the need for shunt placement in premature infants with PHH.

STRENGTH OF RECOMMENDATION

Level I, high clinical certainty. Recommendation Concerning Nonsurgical Temporizing Agents. II. Acetazolamide and furosemide are not recommended as methods to reduce the need for shunt placement in premature infants with PHH.

STRENGTH OF RECOMMENDATION

Level I, high clinical certainty. Recommendation Concerning Timing of Shunt Placement: There is insufficient evidence to recommend a specific weight or CSF parameter to direct the timing of shunt placement in premature infants with PHH. Clinical judgment is required.

STRENGTH OF RECOMMENDATION

Level III, unclear clinical certainty. Recommendation Concerning Endoscopic Third Ventriculostomy: There is insufficient evidence to recommend the use of endoscopic third ventriculostomy (ETV) in premature infants with posthemorrhagic hydrocephalus.

STRENGTH OF RECOMMENDATION

Level III, unclear clinical certainty.

Diagnostic accuracy of intraocular pressure measurement for the detection of raised intracranial pressure: meta-analysis: a systematic review

OBJECT

Because clinical examination and imaging may be unreliable indicators of intracranial hypertension, intraocular pressure (IOP) measurement has been proposed as a noninvasive method of diagnosis. The authors conducted a systematic review and meta-analysis to determine the correlation between IOP and intracranial pressure (ICP) and the diagnostic accuracy of IOP measurement for detection of intracranial hypertension.

METHODS

The authors searched bibliographic databases (Ovid MEDLINE, Ovid EMBASE, and the Cochrane Central Register of Controlled Trials) from 1950 to March 2013, references of included studies, and conference abstracts for studies comparing IOP and invasive ICP measurement. Two independent reviewers screened abstracts, reviewed full-text articles, and extracted data. Correlation coefficients, sensitivity, specificity, and positive and negative likelihood ratios were calculated using DerSimonian and Laird methods and bivariate random effects models. The I(2) statistic was used as a measure of heterogeneity.

RESULTS

Among 355 identified citations, 12 studies that enrolled 546 patients were included in the meta-analysis. The pooled correlation coefficient between IOP and ICP was 0.44 (95% CI 0.26-0.63, I(2) = 97.7%, p < 0.001). The summary sensitivity and specificity for IOP for diagnosing intracranial hypertension were 81% (95% CI 26%-98%, I(2) = 95.2%, p < 0.01) and 95% (95% CI 43%-100%, I(2) = 97.7%, p < 0.01), respectively. The summary positive and negative likelihood ratios were 14.8 (95% CI 0.5-417.7) and 0.2 (95% CI 0.02-1.7), respectively. When ICP and IOP measurements were taken within 1 hour of another, correlation between the measures improved.

CONCLUSIONS

Although a modest aggregate correlation was found between IOP and ICP, the pooled diagnostic accuracy suggests that IOP measurement may be of clinical utility in the detection of intracranial hypertension. Given the significant heterogeneity between included studies, further investigation is required prior to the adoption of IOP in the evaluation of intracranial hypertension into routine practice.