title: Disparity between adjusted and actual opening cerebrospinal fluid pressure in a patient with the Codman Hakim programmable valve: occult form of shunt failure due to head banging. Case report.
abstract: Although the Codman Hakim programmable valve (CHPV) system is popular, several problems arising from its design have been described. The authors report an additional cause of shunt failure associated with the use of the CHPV system. A 7-year-old girl who had previously undergone placement of a ventriculoperitoneal shunt with the CHPV system was admitted in a comatose state. Radiography did not demonstrate any breakage or change in the opening pressure of the valve. Manual pumping of the valve resulted in neurological improvement and shrinkage of the girl's ventricles. However, ventriculomegaly was again observed several hours later, and an emergency valve revision was performed. The manufacturer's examination of the extracted valve revealed a crack on the surface of the hard plastic housing covering the valve chamber, which appeared to be suggestive of some type of blunt trauma. In addition, the flat spring that transmitted resistance from the pressure control cam to the valve ball was deformed in such a manner that it caused excessive pressure against the valve ball. Because of this deformity, the actual opening pressure in this patient had reached a maximum level of 226 mm H2O instead of the adjusted pressure of 60 mm H2O. In patients with the CHPV system whose medical history is difficult to ascertain, the possibility of damage to the valve spring and the need for a prompt revision surgery should be considered. The authors conclude that placement of the CHPV system may be contraindicated in patients with a known habit of head banging.
authors.affiliation: Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan. kimitoshi@k8.dion.ne.jp
authors.forename: Kimitoshi
authors.initials: K
authors.lastname: Sato
authors.forename: Satoru
authors.initials: S
authors.lastname: Shimizu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Utsuki
authors.forename: Sachio
authors.initials: S
authors.lastname: Suzuki
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Oka
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Fujii
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging; D015170:Cerebrospinal Fluid Pressure; D002648:Child; D003128:Coma / Q000209:etiology; D020878:Device Removal; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D012086:Reoperation; D012984:Software; D019956:Stereotypic Movement Disorder / Q000150:complications*; D014057:Tomography, X-Ray Computed; D017287:Ventriculoperitoneal Shunt / Q000009:adverse effects*