Programmable Shunting Systems: Correction of Liquor Circulation

K.E. Korostylev

Medicomilitary Academy, Chair of Field Surgery, Saint Petersburg, Russia

 

CSF shunting is an important method of hydrocephalus treatment. Its use allows to control hydrocephalus in the majority of patients against a background of minimum surgical intervention. Despite a positive effect of such interventions one of the main problems is correct choice of "pressure-velocity" parameters of implanted drainage systems with the purpose of obtaining an optimum liquor pressure and ventricle size after valve implantation. Hydraulic and mechanical discrepancy can be accompanied either by preservation of hypertension syndrome, manifesting itself in a constant size of ventricles and stability of clinical signs, or a hyperdrainage state (18% of cases in our study), represented by hypotension syndrome, orthostatic intracranial hypotension, craniostenosis, pneumocranium, syndrome of "slit-like" lateral ventricles with formation of subdural and epidural hematomas, subdural liquor accumulation. Such states can be treated only surgicaly, but repeated operations are characterized by a risk of inadequate choice of parameters. Furthermore, these complications are often accompanied by shunt contamination and seizures, pseudoperitoneal cysts, thromboembolism. Use of programmable shunting systems in hydrocephalus treatment allows to ensure atraumatic change of pressure within a wide range and with small intervals. It makes it possible to regulate parameters in compliance with clinical requirements of a patient. During 1995-2003 we managed to place such valves in 37 patients aged 1 month-48 years. Congenital hydrocephalus was watched in 65% of cases; the rest patient had hydrocephalus of inflammatory or traumatic etiology. Besides, there was 1 case with incurable thalamus tumor. Obstructive hydrocephalus was diagnosed in 62% of cases. We failed to determine a form of hydrocephalus in 1 patient. We preferred Codman-Medos programmable systems (Codman/Johnson&Johnson, USA; Medos S.A., Switzerland). The Sophy valve (Sophysa, France) was used in 4 cases. It is important to note, that adequate control after the first manipulation was achieved only in 4 patients. We changed valve parameters 2-15 times in the rest cases. Indications for such a change included hypotension (68% of cases) and hypertension (30% of cases) syndromes. Repeated programming was conditioned by changes of the valve system parameters after MRI-examination in 2 patients. While programming, we increased the inlet pressure in 70% of cases; it was reduced in all the rest cases. There were 177 manipulations, performed in 37 patients. Parameters were changed as follows: 11-15 times - 5 cases, 1-5 times - 26 patients, 5-10 times - the rest patients. Repeated changes of parameters were carried out both in one direction (gradual increase or decrease of pressure) and different directions (hampered determination of necessary pressure). The latter implied increase or decrease of parameters within high and then low ranges until necessary values were obtained. Parameters of the final pressure varied from 120 mm H2O up to 190 mm H2O. It was a rather big dispersion.

Use of programmable systems resulted in state stabilization in all 37 cases. One patient developed purulent meningitis, which demanded removal of the system and its reimplantation after arresting an inflammatory process. There was inflammation of a postoperative wound in one case. It was stopped by use of large doses of antibiotics and did not demand reoperation. Thus, programmable systems allow to ensure adequate liquor circulation.

In our opinion, use of the above systems has some advantages, consisting in exact adequate control of hydrocephalus, a reduced number of reoperations and complications (epilepsy, contamination), which are characterized by a higher risk of development against a background of hypo- or hyperdrainage. We stick to the opinion, that this valve can be used in the following cases: normal pressure hydrocephalus; hydrocephalus, operated several times; arachnoid and porencephalic cysts; liquorrhea. Disadvantages of the above systems include high cost, certain limitations and incidents (necessity of X-ray control, presence of a programmer, probability of deprogramming in MRI-examination).