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Introduction: Ventriculoatrial and ventriculopleural shunts (VPS) are alternatives to ventriculoperitoneal shunts for draining cerebrospinal fluid from patients with hydrocephalus. VPS has seldom been used because of the risk of respiratory insufficiency due to pneumothorax or pleural effusion. However, valves are currently available with anti-siphon devices for use with standard shunting systems to prevent the development of pleural effusion. The aim of this study was to analyze outcome after VPS in eight patients in whom we used the new valves for avoiding overdrainage of cerebrospinal fluid., Material and Method: Nine VPS procedures were performed in eight hydrocephalic patients between 1988 and 2000. We used differential pressure valves in eight procedures and a flow regulator valve in one. The externally adjustable Sophy valve was used in six cases. The indication for VPS was peritoneal adhesions in four cases, persistent ascites in two, ventriculoatrial valve obstruction in one, and infection of the peritoneal shunt (peritonitis) in one. The ninth case involved replacement of a previously obstructed valve., Results: After a follow-up period of 22 months all shunts were functioning well and the only patient with symptoms of hydrocephalus was the one who required valve replacement at six months. No surgical morbidity or mortality was observed, and only one patient developed transitory signs of excessive cerebrospinal fluid drainage, which was corrected by regulating the magnetic valve gradient. The death of one patient 36 months after surgery was unrelated to pleural drainage., Conclusions: Valves newly designed to prevent overdrainage of cerebrospinal fluid give satisfactory results, such that VPS should be considered as an alternative to peritoneal drainage.

The progression of congenital arachnoid cysts has seldom been documented. We report the case of a child who was diagnosed with arrested hydrocephalus at the age of 13 months. Neuroimaging studies performed when the girl was 22 months old showed the appearance of an arachnoid cyst in the right middle fossa, while the previously enlarged ventricles seemed to have decreased in size. To the best of our knowledge, the paradoxical expansion of an arachnoid pouch following a reduction in the size of the ventricular system has not previously been documented. We advance the hypothesis that the development of some cases of arachnoid cyst might be pathogenically related to impaired CSF dynamics associated with pre-existing hydrocephalus. We also briefly review the pertinent literature on the formation and evolution of congenital cerebral arachnoid cysts.

Two siblings presented with macrocephaly, psychomotor delay, and progressive dystonia. The initial diagnosis was of hydrocephalus and bilateral temporal cerebrospinal fluid collections. Following ventriculoperitoneal shunting, the patients showed only modest neurological improvement. Metabolic investigations performed later in the course of the disease disclosed increased levels of glutaric acid in the urine and decreased levels of serum carnitine, which were confirmatory of glutaric aciduria type 1. The association of macrocephaly, dystonia, and bilateral temporal arachnoid cysts, shown either by computed tomography or magnetic resonance imaging, seems to be diagnostic of glutaric aciduria type 1. The authors report these two cases as they think they might be of interest to neurosurgeons.

Complications of valve reservoirs or flushing devices are seldom reported as a cause of shunt malfunction. The authors document their experience in six cases of mechanical complications of shunting devices. Two cases presented with collapse and intracranial migration of the valve reservoir, a complication that has not been reported previously. In two cases, the plastic dome became disconnected from the metallic base of the reservoir. A fifth patient, with an integral shunt system, showed a fracture in the soldered join of the distal tube to the reservoir dome. The last patient had the valve reservoir partially collapsed by bone growth at the time of shunt revision.

Overdrainage of cerebrospinal fluid (CSF) is a well-known complication of shunting procedures. Several clinical manifestations of excessive drainage of CSF have been documented, such as subdural hematoma, subdural effusions, slit ventricles, isolated IV ventricle, etc. To the authors' knowledge, this is the first report of an arachnoid cyst due to the excessive function of a VP shunt.