Fourth Ventricular Outlet Obstruction Research Articles

Acute Extradural Hematoma following Ventriculoperitoneal Shunt

Ventriculoperitoneal shunt, an extremely commonly performed neurosurgical procedure, can lead to rare life-threatening complications. The occurrence of extradural hematoma following internal diversion of cerebrospinal fluid is quite rare. We report a case of an 8-year-old girl who developed acute extradural hematoma following shunt for fourth ventricular outlet obstruction. Early diagnosis and management of this complication resulted in good outcome. We discuss the possible explanations for the development of hematoma as well as certain precautionary measures to be taken to avoid this catastrophic complication.

Endoscopic Transventricular Transaqueductal Magendie and Luschka Foraminoplasty for Hydrocephalus

Routinely, hydrocephalus related to fourth ventricular outlet obstruction (FVOO) has been managed with ventriculoperitoneal (VP) shunting or endoscopic third ventriculostomy (ETV). Few reports on Magendie foraminoplasty exist, and Luschka foraminoplasty has not been described. To present an alternative technique in the management of FVOO via an endoscopic transventricular transaqueductal Magendie and Luschka foraminoplasty and to discuss the indications, technique, findings, and outcomes. Between 1994 and 2011, all patients who underwent endoscopic Magendie and Luschka foraminoplasty were analyzed. A total of 33 Magendie (28) and/or Luschka (5) foraminoplasties were performed in 30 patients. Twenty-three were adult and 7 were pediatric patients. The etiology of the FVOO was divided into primary etiologies (congenital membrane in 5 and atresia in 2) and secondary causes (neurocysticercosis in 14 patients, bacterial meningitis in 9). Fifteen (50%) had previously failed procedures. Intraoperative findings that led to Magendie/Luschka foraminoplasty were ETV not feasible to perform, nonpatent basal subarachnoid space, or primary FVOO. Minor postoperative complications were seen in 3 patients. Only 26 patients had long-term follow-up; 17 (65.3%) of these had clinical improvement and did not require further procedures. Nine (34.7%) did not improve. Eight required another procedure (7 shunts, and 1 endoscopic procedure). One patient died. Flexible neuroendoscopic transventricular transforaminal Magendie and Luschka foraminoplasty is feasible and safe. These procedures may prove to be viable alternatives to standard ETV and VP shunt in appropriate patients. Adequate intraoperative assessment of ETV success is necessary to identify patients who will benefit.

Contrast ventriculo-cisternography: an auxiliary test for suspected fourth ventricular outlet obstruction

Fourth ventricular outlet obstruction (FVOO) causes obstructive hydrocephalus. Often, despite high-quality MRI sequences, differentiation between FVOO and communicating (absorptive) hydrocephalus is not easy. We describe our initial experience with five children with suspected FVOO that underwent CT ventriculography (CTV) or cisternography (CTC), to assist with this difficult diagnosis. Over 2.5 years, five children with suspected FVOO (5 months-7.5 years old) underwent CTV or CTC. Technical and clinical data were retrospectively collected. Four children had progressive macrocephaly, and one child had progressive ventriculomegaly. On CTV/CTC, four of five children showed communication between the ventricular system and spinal subarachnoid space or prepontine cistern, as evidenced by passage of contrast material. One child had a FVOO and therefore underwent an endoscopic third ventriculostomy, and is since, symptom and shunt free for 2.5 years. CT ventriculography in infants, and CT cisternography in elder children, may assist to differentiate between FVOO and communicating hydrocephalus. The importance of these tests is for children with MRI suggestive of FVOO related hydrocephalus, but with no clear demonstration of the obstruction site. The implication of this differentiation may be for deciding between treatment of hydrocephalus with a ventriculoperitoneal shunt or with an endoscopic third ventriculostomy.

EFFICACY OF ENDOSCOPIC THIRD VENTRICULOSTOMY IN FOURTH VENTRICULAR OUTLET OBSTRUCTION

Fourth ventricular outlet obstruction (FVOO), an uncommon cause of obstructive hydrocephalus, is most commonly associated with prior intraventricular hemorrhage or intraventricular infection in children. There have been few reports of FVOO in an adult population. Twenty-two patients with FVOO treated with endoscopic third ventriculostomy (ETV) were analyzed retrospectively. Of the 22 patients, 10 were younger than 2 years, 6 were between 2 and 18 years, and 6 were older than 18 years of age. Predisposing factors included tubercular meningitis (1 patient), ventriculitis (2 patients), and intraventricular hemorrhage (3 patients). Twelve patients (mostly >2 years of age) had no prior significant history. The third ventricular floor and the adhesions in the basal cisterns were individually graded (I-IV). An inflamed floor was encountered in 3 patients. ETV was successfully performed in 20 patients. Fourth ventricular exploration was carried out in 5 patients, with outlet membrane fenestration in 2 patients. The follow-up period was 1 to 8 years (mean, 4.2 years). The ETV failed in 7 patients, requiring shunt insertion. The overall success rate was 65%; 91% success was achieved in patients who were more than 2 years of age, whereas the procedure failed in all patients younger than 6 months of age. The cerebrospinal fluid yielded a positive bacterial culture (1 patient), antitubercular antibody (1 patient), anticysticercal antibody (1 patient), and cryptococcosis (1 patient). With a successful procedure, lateral ventricular size was reduced in all patients, whereas fourth ventricular size decreased in 12 patients. The extent of adhesions in the basal cisterns directly correlated with failure. None of the patients demonstrated isolated fourth ventricle on follow-up magnetic resonance imaging. In 4 of the 7 patients with failure, endoscopic exploration was performed, and a patent stoma was observed in all of these patients. ETV is a viable option for treatment of patients with FVOO. The high failure rate in infants younger than 6 months of age suggests that ventriculoperitoneal shunting is a favorable option in this age group, rather than ETV. Isolated fourth ventricle is uncommon after ETV in hydrocephalus attributable to FVOO.

Gardner's hydrodynamic theory of syringomyelia revisited.

Several theories have been put forth to explain the pathogenesis of syringomyelia, the formation of longitudinal, fluid-filled cavities within the spinal cord. Chief among them is Gardner's hydrodynamic theory, widely accepted for more than two decades. Gardner attributed the genesis of syringomyelia to craniospinal pressure differentials in the setting of fourth ventricular outlet obstruction; these differentials favor cerebrospinal fluid shifts from the fourth ventricle of the brain through the central canal of the spinal cord. Gardner's theory has been questioned, and several alternative theories of syringomyelia have been proposed. Physiological data and new information from magnetic resonance imaging support many of Gardner's concepts; however, a more comprehensive elucidation of the pathophysiologic mechanisms of syringomyelia requires incorporating facets of the other theories. We propose a unified theory of the pathogenesis of syringomyelia based on recent experience with magnetic resonance imaging, and on elements of other current theories.