[The Codman Medos programmable shunt valve. Evaluation of 53 implantations in 50 patients]

Fifty three Codman Medos programmable valves were implanted in 50 patients (28 men and 22 women) aged 5 to 77 years, from April 1992 to February 1994. They presented with a hydrocephalus 43 times, an arachnoid cyst three times and a CSF leakage four times. The aims of this study were: a) to test the reliability of this equipment, in current use as well as its eventual advantages, inconveniences and restraints, b) to determine its best indications. Follow-up ranged from 12 to 36 months (average = 22 months). Five patients were lost for follow-up. One patient died from a post-operative sepsis. Four died from their disease. Infectious complications concerned 6 patients (11%). A radio-clinical overdrainage syndrome appeared in 9 patients with slit-ventricles, 5 of them associated with sub-dural collections. All these cases were treated with shunt reprogrammings. While 43 pressure settings over 53 were satisfactory in the immediate post-operative period, it appeared that only 38% of shunts had required one only setting when the study period was over. A certain number of pressure adjustments malfunctioned: 6 times, post-operative X-ray controls showed pressures significantly different from the figures which had been selected (difference from -30 mm H2O to + 70 mm H2O); pressure readjustments were effective and accurate for five of them, but one shunt had to be changed; 15 deprogrammings were detected during long term follow-up, 9 of them after MR1. Pressure programming was readjusted only on patients presenting with clinical signs, i-e mainly for those having a pressure difference > +/-30 mm H2O. As a conclusion, the authors consider that such a shunt can be very useful in some precise indications as: NPH, multioperated hydrocephalus, arachnoid and porencephalic cysts, some spontaneous or iatrogenic CSF leakages, temporary shunts necessitating a progressive withdrawal. Because of a) the cost of this equipment, b) the specific restraints (X-rays controls, programmer), and c) the specific incidents (spontaneous and/or post-MR1 deprogramming), it seems difficult to generalize indications to all cases of hydrocephalus. On the other hand, these shunts have the great advantage of simplifying the treatment of overdrainage by avoiding, in all cases, a reoperation for changing the shunt and/or removing a subdural hematoma. Consequent economies due to a significant diminution of the duration of hospitalisation, could justify an enlargement of indications.