Introduction
The sylvian aqueduct is the most common site of intraventricular blockage of the cerebro-spinal fluid. Clinical aspects, neuroradiological appearance, and treatment of hydrocephalus secondary to aqueductal stenosis are specific.

Hydrocephalus in aqueductal stenosis

The cerebral ventricles have been recognized since ancient medical history. Their true function started to be realized more than a thousand years later. Their anatomy and function are extremely important in the neurosurgical panorama. The literature was searched for articles and textbooks of different topics related to the history, anatomy, physiology, histology, embryology and surgical considerations of the brain ventricles. Herein, we summarize the literature about the cerebral ventricular system.

The ventricular system of the brain: a comprehensive review of its history, anatomy, histology, embryology, and surgical considerations

Management of hydrocephalus with insertion of ventriculoperitoneal (VP) shunt is associated with significant complications in both adult and pediatric patients. These may be more common in developing countries due to poor economic conditions and a dearth of available resources. We report a 6 years' experience with VP shunt insertion in pediatric patients from a developing country, focusing particularly on factors affecting shunt failure. Patients aged below 15 years, who had undergone insertion of VP shunts for hydrocephalus during the years 2006 to 2011, were included. A retrospective analysis of shunt survival was performed using Kaplan–Meier curves and Logrank (Cox–Mantel) test. Among the total 113 patients, the most common etiologies of hydrocephalus were congenital hydrocephalus (19.5 %), brain tumors (14.2 %), and postcranial surgery (13.3 %). Overall shunt failure at a mean follow-up of 11 months was 23 % with the median time to first shunt failure being 68 days. Shunt survival was worse in patients with meningitis (p = 0.024), aqueductal stenosis (p = 0.008), postcranial surgery hydrocephalus (p = 0.006), Caesarean mode of delivery (p = 0.036), congenital abnormalities (p = 0.031), and a past history of surgical excision of mass lesion (p = 0.044).Frequency of shunt failure was also significantly affected by the location of brain tumor (p = 0.015) and prematurity (p = 0.015). Premature infants still have a higher rate of shunt failure. Patients with meningitis, aqueductal stenosis, postcranial surgery hydrocephalus, congenital abnormalities, and a past history of surgical excision of mass lesion may have early shunt failure. However, the frequency of shunt failure that we observed (23 %) was much lower than that quoted earlier in the literature and this may be a consequence of rigorous periodic evaluation of patients with VP shunt in situ.

Analysis of factors affecting ventriculoperitoneal shunt survival in pediatric patients

Cerebrospinal fluid (CSF) is a dynamic compartment of the brain, constantly circulating through the ventricles and subarachnoid space. In recent years knowledge about CSF has expended due to numerous applications of phase-contrast magnetic resonance imaging (PC-MRI) in CSF flow evaluation, leading to the revision of former theories and new concepts about pathophysiology of CSF disorders, which are caused either by alterations in CSF production, absorption, or its hydrodynamics. Although alternative non-invasive techniques have emerged in recent years, PC-MRI is still a fundamental sequence that provides both qualitative and quantitative CSF assessment. PC-MRI is widely used to evaluate CSF hydrodynamics in normal pressure hydrocephalus (NPH), Chiari type I malformations (CMI), syringomyelia, and after neurosurgical procedures. In NPH precisely performed PC-MRI provides reliable clinical information useful for differential diagnosis and selection of patients benefiting from surgical operation. Patients with CMI show abnormalities in CSF dynamics within the subarachnoid space, which are pronounced even further if syringomyelia coexists. Another indication for PC-MRI may be assessment of post-surgical CSF flow normalisation. The aim of this review is to highlight the significance of CSF as a multifunctional entity, to outline both the physical and technical background of PC-MRI, and to state current applications of this technique, not only in the diagnosis of central nervous system disorders, but also in the further clinical monitoring and prognosis after treatment.

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Imaging of cerebrospinal fluid flow: fundamentals, techniques, and clinical applications of phase-contrast magnetic resonance imaging.

Arachnoid cysts are non-neoplastic, intracranial cerebrospinal fluid (CSF)-filled spaces lined with arachnoid membranes. Large arachnoid cysts are often symptomatic because they compress surrounding structures; therefore, they must be treated surgically. As several surgical management options exist, we explore the best approach according to each major type of arachnoid cyst: middle cranial fossa cyst, suprasellar cyst, intrahemispheric cyst, and quadrigeminal cyst.

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Management of Arachnoid Cysts: A Comprehensive Review.

Endoscopic third ventriculostomy (ETV) is considered as a treatment of choice for obstructive hydrocephalus. It is indicated in hydrocephalus secondary to congenital aqueductal stenosis, posterior third ventricle tumor, cerebellar infarct, Dandy-Walker malformation, vein of Galen aneurism, syringomyelia with or without Chiari malformation type I, intraventricular hematoma, post infective, normal pressure hydrocephalus, myelomeningocele, multiloculated hydrocephalus, encephalocele, posterior fossa tumor and craniosynostosis. It is also indicated in block shunt or slit ventricle syndrome. Proper Pre-operative imaging for detailed assessment of the posterior communicating arteries distance from mid line, presence or absence of Liliequist membrane or other membranes, located in the prepontine cistern is useful. Measurement of lumbar elastance and resistance can predict patency of cranial subarachnoid space and complex hydrocephalus, which decides an ultimate outcome. Water jet dissection is an effective technique of ETV in thick floor. Ultrasonic contact probe can be useful in selected patients. Intra-operative ventriculo-stomography could help in confirming the adequacy of endoscopic procedure, thereby facilitating the need for shunt. Intraoperative observations of the patent aqueduct and prepontine cistern scarring are predictors of the risk of ETV failure. Such patients may be considered for shunt surgery. Magnetic resonance ventriculography and cine phase contrast magnetic resonance imaging are effective in assessing subarachnoid space and stoma patency after ETV. Proper case selection, post-operative care including monitoring of ICP and need for external ventricular drain, repeated lumbar puncture and CSF drainage, Ommaya reservoir in selected patients could help to increase success rate and reduce complications. Most of the complications develop in an early post-operative, but fatal complications can develop late which indicate an importance of long term follow up.

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Endoscopic third ventriculostomy.

Background  Microsurgical resection, stereotactic aspiration, endoscopically assisted microsurgical resection, and ventriculoperitoneal shunt have been the treatment options for colloid cysts of the third ventricle. Recently, an endoscopic approach has been recognized as an effective alternative to open surgery. There is suspicion about the long-term recurrence rate and about obtaining complete removal of cyst. Patients and Methods  This is a prospective study of 24 patients with colloid cyst who underwent endoscopic resection. Preoperative computed tomography (CT) scans revealed hydrocephalus in all the patients. Postoperative magnetic resonance imaging (MRI) was done in all cases. Results  Age ranged from 16 to 57 years. There were 16 male and 8 female patients. The diameter of the cyst varied from 14 to 24 mm. Operating time ranged from 90 to 156 minutes. Total resection was achieved in 21 patients. All patients with subtotal excision underwent coagulation of residual cyst wall. The follow-up period ranged from 6 to 78 months (mean, 37 months). None of the patients developed any symptoms at 26, 31, and 39 months of follow-up. Preoperative symptoms disappeared in all the patients except for memory disorders and seizures in one patient each. No residual cyst was observed on the postoperative MRIs in 21 patients. Hospital stay was 4 to 10 days (median, 6 days). No endoscopic operation was converted into an open resection. Conclusion  Endoscopic excision of a colloid cyst is an effective and safe alternate method. Although the follow-up time was short, residual cyst wall remained asymptomatic without any evidence of growth after subtotal excision and coagulation of wall.

Endoscopic management of colloid cysts.

Hydrocephalus is one of the commonest complications of tuberculous meningitis (TBM). It can be purely obstructive, purely communicating, or due to combinations of obstruction in addition to defective absorption of cerebrospinal fluid (CSF). Endoscopic third ventriculostomy (ETV) as an alternative to shunt procedures is an established treatment for obstructive hydrocephalus in TBM. ETV in TBM hydrocephalus can be technically very difficult, especially in acute stage of disease due to inflamed, thick, and opaque third ventricle floor. Water jet dissection can be helpful in thick and opaque ventricular floor patients, while simple blunt perforation is possible in thin and transparent floor. Lumbar peritoneal shunt is a better option for communicating hydrocephalus as compared to VP shunt or ETV. Intraoperative Doppler or neuronavigation can help in proper planning of the perforation to prevent neurovascular complications. Choroid plexus coagulation with ETV can improve success rate in infants. Results of ETV are better in good grade patients. Poor results are observed in cisternal exudates, thick and opaque third ventricle floor, acute phase, malnourished patients as compared to patients without cisternal exudates, thin and transparent third ventricle floor, chronic phase, well-nourished patients. Some of the patients, especially in poor grade, can show delayed recovery. Failure to improve after ETV can be due to blocked stoma, complex hydrocephalus, or vascular compromise. Repeated lumbar puncture can help faster normalization of the raised intracranial pressure after ETV in patients with temporary defect in CSF absorption, whereas lumbar peritoneal shunt is required in permanent defect. Repeat ETV is recommended if the stoma is blocked. ETV should be considered as treatment of choice in chronic phase of the disease in obstructive hydrocephalus.

Role of endoscopic third ventriculostomy in tuberculous meningitis with hydrocephalus.

There is wide racial difference in the prevalence of the absence of the plantaris tendon. This study was conducted to determine the prevalence of plantaris tendon in Indian population.The presence of the plantaris tendon was determined by ultrasound in 250 healthy volunteers using the standard technique.Out of 250 individuals 28 (11.2%) had absence of plantaris tendon either unilaterally or bilaterally. Unilateral absence of plantaris tendon was in 3.2%, bilateral absence in 4.8% and overall absence was in 8%. According to the hand and foot dominance the probability of finding right plantaris tendon in right dominant person was 92.3% and in left dominant is 89.7%. Height of the person also correlated significantly with tendon length.Plantaris tendon was absent in ∼11%, either unilaterally or bilaterally, in this cohort of Indian population. 

Assessment of prevalence and morphology of plantaris tendon in Indian population by ultrasound.


 Background: Intracranial pial arteriovenous fistulas (AVFs) are rare intracranial vascular malformation and their treatment is challenging because of high-flow pial supply of the lesion. We report a case of intracranial pial AVF with associated giant venous varices managed successfully by embolization.
 Case Description: A 25-year-old male presented with sudden onset headache and altered sensorium. Computed tomographic scan was suggestive of frontal lobar hematoma that had dissected into the third ventricle with associated intraventricular hemorrhage. Magnetic resonance imaging revealed presence of large vascular channels with the presence of multiple flow voids in bilateral frontal location. Digital subtraction angiography revealed pial fistula with arterial supply from hypertrophied left anterior cerebral artery. Treatment was done using combined coil and onyx embolization after careful analysis of angioarchitecture of the lesion using three-dimensional rotational angiogram cross-sectional reconstructions. Postprocedure angiogram revealed closure of fistula and giant varices.
 Conclusion: Pial AVFs with giant venous varix in adults are rare vascular malformation and understanding the angioarchitecture with exact identification of fistulous point is important to plan for surgical/endovascular management strategies. Combined strategy of embolization using coils and onyx is a safe option in such cases with giant varices.

Sonjjay Pande

Papers

Endoscopic third ventriculostomy.

Endoscopic management of colloid cysts.

Role of endoscopic third ventriculostomy in tuberculous meningitis with hydrocephalus.

Assessment of prevalence and morphology of plantaris tendon in Indian population by ultrasound.

Endovascular Management of Intracranial Pial Arteriovenous Fistula with Giant Venous Varix: Case Report and Review of Literature.