Pericerebral collections after shunting.

Nineteen pericerebral collections (18 subdural and 1 epidural) occurred in a series of 682 consecutive initial shunt insertions for hydrocephalus in children, performed between 1976 and 1984. No collections were observed in 358 reoperations performed in the same patients during the same period. The incidence rate of this complication is nearly four times higher after 2 years of age than in younger children (6.5% versus 1.7%). The rate is also higher, regardless of age, in noncommunicating than in communicating hydrocephalus. Pericerebral collections are observed with high- as well as low-closing pressure valves. Pericerebral collections after shunting were diagnosed in 80% of the cases less than 2 months after surgery. They were asymptomatic in nearly 60% of the cases but could become symptomatic later when they were not treated. At the onset at least, these pericerebral collections are compensated by the outflow of an equal quantity of intraventricular CSF so that ICP is only moderately elevated. Postshunt pericerebral collections may be the consequence of CSF loss at the time of surgery. In most cases, however, they are due to a CSF overdrainage by the valve. This overdrainage, together with the reversal of CSF flow in the highly resistant CSF pathways of hydrocephalus, establishes a pressure lower in the ventricles than in the subarachnoid space and tends to open up the subdural space. The treatment of postshunt subdural collections is the insertion of a simple tubing without valve between the subdural space and the peritoneum, the ventriculoperitoneal shunt being left in place. With this treatment, more than 80% of the collections disappeared or were improved.(ABSTRACT TRUNCATED AT 250 WORDS)