抄録
One of the frequent causes of shunt impairment following ventriculoperitoneal (V-P) shunt is known to be obstruction of the peritoneal catheter. Expecting prolonged patency of peritoneal catheter, we devised additional slits in the peritoneal catheter of an Ames-Dow-Corning set and have been applying it clinically for several years. The incidence rate of postoperative abdominal catheter obstructions was 10% in the cases where additional slits were formed and 29% in cases that the original Ames' catheter was used. The usefulness of this additional slit formation technique for the prolongation of postoperative shunt patency was thus evidenced. On the other hand, however, several patients, among those shunted with peritoneal catheters having additional slits, complained of symptoms such as headache, vertigo, nausea, vomiting, ataxic gait, etc., accompanied by marked CSF hypotension. Changes in intraventricular CSF pressure were measured in 18 (mainly adult) post-shunt cases, including those in which complaints of CSF hypotension were seen, in changing body position from recumbency to sitting erect. Intraventricular pressure, as observed 10 minutes after sitting erect, ranged between -140 and -385 (-259 on the average) mmH2O. This marked CSF hypotension was considered to be caused by CSF overdrainage due to the siphon effect (reported by Portnoy et al.) and to a reduced flow resistance in the catheter having additional slits. Clinical symptoms seemed to have appeared only in excessively hypotensive cases. For the purpose of preventing CSF overdrainage due to the siphon effect in the erect body posture, we devised an apparatus, antisiphon ball valve (ABV), to be installed in the abdominal wall. This apparatus was installed in 7 cases in which excessive CSF hypotension was observed after V-P shunt. Postural changes in intraventricular CSF pressure before and after installation of ABV were observed in these cases. In 5 of them, CSF hypotension was improved after ABV installation and in 3 of the 5 cases clinical symptoms also were alleviated or disappeared. In 2 further cases, ABV was installed at the time of primary V-P shunting and, in them, CSF hypotension symptoms did not appear. In the 2 cases in which ABV installation was ineffective, inappropriate placement of ABV was considered to be the probable causative factor. Further improvements in the property of ABV and in the technique of its installation are being sought.
