Clinical experience with a new pressure-adjustable shunt valve

Abstract

The pressure-adjustable valve system Codman Medos allows valve pressure adjustment in 18 steps between 30 and 200 mm H2O. A series of 90 patients, 15 children and 75 adults, who were shunted with this new programmable valve, is reported. Indication for shunt insertion were various types of hydrocephalus in 79 cases, malfunction of a medium pressure membrane valve shunt system in 9 cases and an arachnoid cyst and pseudotumour each in one case. The valve pressure was programmed prior to insertion to 200 mm H2O in the adults and according to age in children and was modified postoperatively according to the clinical course. Underdrainage with subdural fluid collections appearing in 5 patients could be managed by valve pressure adjustment alone in 2 cases. One malfunctioning of the valve mechanism was due to mechanical obstruction. At the time of follow-up, 7 to 29 months after operation, outcome was excellent in 64 patients, good with marked improvement but residual symptoms in 19 patients and unchanged in 7 patients. The possibility of adjusting the valve pressure to the patient's demands was frequently used in children and adult normal pressure hydrocephalus patients with satisfying clinical results.

Programmable valve represents an efficient and safe tool in the treatment of idiopathic normal-pressure hydrocephalus patients

“…The Codman Medos valve allows pressure adjustment in 18 steps between 30 and 200 mm H 2 O. A series of 90 patients was reported with satisfying clinical results 23 . Another retrospective study was published with 583 patients with hydrocephalus due to various causes who were shunted with Codman Hakim programmable valve 24 .…”

Guidelines for Management of Idiopathic Normal Pressure Hydrocephalus: Second Edition

“…44,51) However, the diagnostic value of the white matter evaluation by DTI has not been established.…”

“…Since the compliance of the brain is low in iNPH patients, readjustment of the pressure setting is very likely to be required multiple times. 51,57,67) A method to adjust the pressure setting based on the body size of the patient in a sitting position has been suggested. 43,44) Furthermore, there have been reports that the risk of postoperative complications can be minimized by gradually decreasing the pressure setting from high to lower values.…”

“…There is no established method for determining the initial postoperative valve pressure setting. The generally accepted method is to start with a high pressure setting and gradually lower the setting according to the clinical condition in order to prevent CSF overdrainage complications 7,8,18,26,51) (Recommendation grade B).…”

“…44) This method uses a higher initial pressure setting in order to compensate for the excessive decrease of ICP in the upright position. Other evidence in support of this algorithm include a study that showed symptomatic improvement in all subjects after setting a Sophy Valve } (Sophysa, Crown Point, Indiana, USA) at a high pressure, 26) and another study found that the final setting in more than 80% of patients using a 51) These studies, however, employed methods that are relatively invasive and difficult to use. In recent years, however, a quick and easy algorithm based on the patient's height and weight has been developed ( Table 7).…”