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Background: Fourth ventricular outlet obstruction is an infrequent but well-established cause of tetraventricular hydrocephalus characterized by marked dilatation of the ventricular system with ballooning of the foramina of Monro, Magendie, and Luschka. Multiple processes including inflammation, infection, hemorrhage, neoplasms, or congenital malformations are known to cause this pathological obstruction. However, true idiopathic fourth ventricular outlet obstruction is a rare phenomenon with only a limited number of cases reported in the literature. Case Description: A 61-year-old female presented with several months of unsteady gait, intermittent headaches, confusion, and episodes of urinary incontinence. Conventional magnetic resonance imaging demonstrated tetraventricular hydrocephalus without transependymal flow, but with ventral displacement of the brainstem and dorsal displacement of the cerebellum without an obvious obstructive lesion on pre- or post-contrast imaging prompting a diagnosis of normal pressure hydrocephalus. However, constructive interference in steady state (CISS) and half-Fourier acquisition single-shot turbo spin echo (HASTE) sequences followed by fluoroscopic dynamic cisternography suggested encystment of the fourth ventricle with thin margins of arachnoid membrane extending through the foramina of Luschka bilaterally into the pontocerebellar cistern. Operative intervention was pursued with resection of an identified arachnoid web. Postoperative imaging demonstrated marked reduction in the size of ventricular system, especially of the fourth ventricle. The patient's symptomatology resolved a few days after the procedure. Conclusion: Here, we describe an idiopathic case initially misdiagnosed as normal pressure hydrocephalus. The present case emphasizes the necessity of CISS sequences and fluoroscopic dynamic cisternography for suspected cases of fourth ventricular outlet obstruction as these diagnostic tests may guide surgical management and lead to superior patient outcomes. [ABSTRACT FROM AUTHOR]

Hypertensive encephalopathy is a life-threatening medical condition manifested by headache, confusion, seizures, and visual disturbance, and, if treatment is delayed, it may progress to coma and death [ 1 , 2 ] (Chester et al., Neurology 28:928–939, 1978 ; Vaughan and Delanty, Lancet 356:411–417, 2000 ). Involvement of the brainstem with or without supratentorial lesions has been reported and is termed hypertensive brainstem encephalopathy (HBE). Cases of HBE involving supratentorial deep gray and white matter are rare and extensive hyperintensity was predominantly seen in brainstem regions on fluid-attenuated inversion recovery and T2-weighted magnetic resonance images. We present radiologic findings of a patient with HBE involving deep supratentorial gray and white matter, causing tonsillar herniation and noncommunicating hydrocephalus by mass effect. [ABSTRACT FROM AUTHOR]

A biphasic model for noncommunicating hydrocephalus in patient-specific geometry is proposed. The model can take into account the nonlinear behavior of brain tissue under large deformation, the nonlinear variation of hydraulic conductivity with deformation, and contact with a rigid, impermeable skull using a recently developed algorithm. The model was capable of achieving over a 700 percent ventricular enlargement, which is much greater than in previous studies, primarily due to the use of an anatomically realistic skull recreated from magnetic resonance imaging rather than an artificial skull created by offsetting the outer surface of the cerebrum. The choice of softening or stiffening behavior of brain tissue, both having been demonstrated in previous experimental studies, was found to have a significant effect on the volume and shape of the deformed ventricle, and the consideration of the variation of the hydraulic conductivity with deformation had a modest effect on the deformed ventricle. The model predicts that noncommunicating hydrocephalus occurs for ventricular fluid pressure on the order of 1300 Pa. [ABSTRACT FROM AUTHOR]

Obstruction of the CSF circulation distal to the fourth ventricle is a rare cause of noncommunicating hydrocephalus. Endoscopic third ventriculostomy (ETV) represents one of the treatment options, but reports of results are rare. Between March 1997 and June 2008, 20 ETVs in 20 patients (mean 32.4 years, range 1 month–79 years) for noncommunicating hydrocephalus distal to the fourth ventricle were undertaken. All patients suffered from severe internal hydrocephalus and typical clinical symptoms. In addition to the standard ETV, a transaqueductal inspection of the posterior fossa with a flexible scope was performed. All patients were prospectively followed. An ETV was achieved in all patients. It was clinically successful in 15 of 20 patients (75%) with an improvement of 50% (three out of six) of the pediatric and of 83% (12 out of 14) of the adult population. A reduction of ventricle size was found in ten (50%). Five patients (25%) received ventriculoperitoneal shunting. A transaqueductal inspection of the posterior fossa cerebrospinal fluid (CSF) pathways was performed in 16. In the remaining four patients, no inspection with the flexible scope was done. One clinically silent fornix contusion and one CSF fistula which was treated conservatively occurred. There was no permanent morbidity. ETV is a successful treatment option in CSF pathway obstructions distal to the fourth ventricle. Although the success rate particularly of the pediatric population appears to be lower than with other indications of obstructive hydrocephalus, a relevant part of the patient population improves after ventriculostomy and shunting can be avoided. [ABSTRACT FROM AUTHOR]

Arachnoid cysts of the collicular cistern are rare. Two patients with this lesion are reported in whom the extent and location of the cyst were shown by computed tomography. The clinical and radiographic features of this lesion are summarized. [ABSTRACT FROM AUTHOR]

Ventriculo-cisternostomy is an established procedure for the treatment of noncommunicating hydrocephalus, if the underlying pathology cannot be removed. In cases in which the foramina of Monro and the proximal part of the third ventricle are obstructed, it is not possible to make a communication between the internal and external CSF-spaces by perforation of the floor of the third ventricle, the so-called third ventriculo-cisternostomy. For such cases the authors describe a new method of drainage of both lateral ventricles to the interpeduncular cistern. This new method has been used successfully in a case with obstructive hydrocephalus of both lateral ventricles, caused by a pilocytic astrocytoma of the optic chiasma and hypothalamus with obstruction of both foramina of Monro. [ABSTRACT FROM AUTHOR]

Abstract: We report a 47-year-old woman who manifested ocular motility disorder, bilateral pyramidal signs, and severe parkinsonism after a ventriculo-peritoneal shunt for non communicating hydrocephalus secondary to idiopathic aqueduct stenosis. The ocular motility disorder consisted of severe vertical gaze palsy and convergence retraction nystagmus. Parkinsonism included not only bradykinesia but also resting tremor and cogwheel rigidity. On the other hand, striatal uptake did not decrease in 18F-dihydroxyphenylalanine positron emission tomography, and anti-Parkinsonian drugs were not effective. 99mTc-ethyl cysteinate dimer bicisate single-photon emission computed tomography and F-18 fluorodeoxyglucose positron emission tomography revealed wide-ranged frontal cerebral cortical dysfunction due to midbrain dysfunction. Moreover, endoscopic third ventriculotomy markedly improved the clinical symptoms as well as the frontal cerebral cortical flow. A neural network formation known as the ‘cortico-basal ganglia loop,’ which intimately connects the frontal lobe with the basal ganglia, is possibly associated with the Parkinsonism observed in our patient. [Copyright &y& Elsevier]

OBJECTIVEAlthough endoscopic third ventriculostomy (ETV) for the treatment of hydrocephalus was introduced in 1923, the method was relegated to the sidelines in favor of extracranial techniques. Since the 1990s to the beginning of the current century, however, ETV has undergone a remarkable resurgence to become the first-line treatment for obstructive hydrocephalus, and for some groups, the procedure has been applied for communicating hydrocephalus as well. In the present study, the authors identified the top 50 cited ETV works. These articles represent works of significance that document current practices and provide guidance for future inquiry.METHODSThe top 50 cited articles pertaining to ETV were identified using bibliometric data obtained with the Harzing's Publish or Perish software search engine. These high-impact works were evaluated for publication properties including year, country of authorship, category, and journal.RESULTSThe top 50 works were cited an average of 141.02 times with a mean of 9.45 citations per year. Articles published in 2005 were the most numerous in the top 50 group. These top articles were most frequently published in the Journal of Neurosurgery: Pediatrics. Most of the articles were clinical studies reporting on patients in the pediatric age group. The country of most authorship was the US, although many other countries were among the top 50 works.CONCLUSIONSThe present report discusses the bibliometric analysis of the top 50 ETV articles. This list may be useful to those interested in the progress and current status of this procedure.

OBJECTIVE The pathophysiology of chronic noncommunicating hydrocephalus (ncHC) is poorly understood. This present study explored whether lessons about the pathophysiology of this clinical entity might be retrieved from results of overnight monitoring of pulsatile and static intracranial pressure (ICP) and ventricular infusion testing. METHODS The study cohort included adult patients (> 20 years of age) with chronic ncHC due to aqueductal stenosis in whom symptoms had lasted a minimum of 6 months. A reference cohort consisted of age- and sex-matched patients managed for communicating HC (cHC). Information about symptoms and clinical improvement following surgery was retrieved from a quality register, and results of overnight ICP recordings and ventricular infusion testing were retrieved from the hospital ICP database. RESULTS The cohort with ncHC consisted of 61 patients of whom 6 (10%) were managed conservatively, 34 (56%) by endoscopic third ventriculostomy (ETV), and 21 (34%) using ETV and subsequent shunt surgery. In patients responding to surgery, pulsatile ICP (mean ICP wave amplitude) was significantly increased to a similar magnitude in patients with ncHC and the reference cohort (cHC). Furthermore, intracranial compliance (ICC) was reduced in clinical responders. The results of ventricular infusion testing provided evidence that patients responding to ETV have impaired ventricular CSF absorption, while those requiring shunt placement after ETV present with impaired CSF absorption both in the intraventricular and extraventricular compartments. CONCLUSIONS The study may provide some lessons about the pathophysiology of chronic ncHC. First, increased pulsatile ICP and impaired ICC characterize patients with chronic ncHC who respond clinically to CSF diversion surgery, even though static ICP is not increased. Second, in patients responding clinically to ETV, impaired ventricular CSF absorption may be a key factor. Patients requiring shunt placement for clinical response appear to have both intraventricular and extraventricular CSF absorption failure. A subgroup of patients with ncHC due to aqueductal stenosis has normal ventricular CSF absorption and normal ICC and may not be in need of surgical CSF diversion.

Introduction: The purpose of this review is to describe the magnetic resonance imaging (MRI) findings in patients with noncommunicating hydrocephalus (NCH). Methods: We describe the technical aspects of MR sequences that are of use for the imaging of cerebrospinal fluid (CSF). Both the diagnosis of NCH and the follow-up after endoscopic third ventriculostomy (ETV) are discussed through clinical cases. Results: NCH is related to an obstacle hindering the CSF pathways. The combined use of anatomical and flow-sensitive MR sequences may help to characterize hydrocephalus. An imaging protocol is described at 1.5-T. Conclusions: The first step of the diagnostic work-up consists of the detection of an obstacle hindering CSF flow pathways using both constructive interference in steady state and flow-sensitive MR sequences. CSF volumetry and quantification of ventricular wall movement may also improve the diagnosis and follow-up of patients with NCH. [Copyright &y& Elsevier]