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KMID : 1001920090460040370
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Journal of Korean Neurosurgical Society
2009 Volume.46 No. 4 p.370 ~ p.377
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A Pressure Adjustment Protocol for Programmable Valves
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Kim Kyoung-Hun
Yeo In-Seoung
Lee Jin-Seok
Lee Hyung-Jin
Yang Ji-Ho
Lee Il-Woo
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Abstract
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Objective: There is no definite adjustment protocol for patients shunted with programmable valves. Therefore, we attempted to find an appropriate method to adjust the valve, initial valve-opening pressure, adjustment scale, adjustment time interval, and final valve-opening pressure of a programmable valve.
Methods: Seventy patients with hydrocephalus of various etiologies were shunted with programmable shunting devices (Micro Valve with RICKHAM® Reservoir). The most common initial diseases were subarachnoid hemorrhage (SAH) and head trauma. Sixty-six patients had a communicating type of hydrocephalus, and 4 had an obstructive type of hydrocephalus. Fifty-one patients had normal pressure-type hydrocephalus and 19 patients had high pressure-type hydrocephalus. We set the initial valve pressure to 10-30 mmH2O, which is lower than the preoperative lumbar tapping pressure or the intraoperative ventricular tapping pressure, conducted brain computerized tomographic (CT) scans every 2 to 3 weeks, correlated results with clinical symptoms, and reset valve-opening pressures.
Results: Initial valve-opening pressures varied from 30 to 180 mmH2O (mean, 102 ± 27.5 mmH2O). In high pressure-type hydrocephalus patients, we have set the initial valve-opening pressure from 100 to 180 mmH2O. We decreased the valve-opening pressure 20-30 mmH2O at every 2- or 3- week interval, until hydrocephalus-related symptoms improved and the size of the ventricle was normalized. There were 154 adjustments in 81 operations (mean, 1.9 times). In 19 high pressure-type patients, final valve-opening pressures were 30-160 mmH2O, and 16 (84%) patients’ symptoms had nearly improved completely. However, in 51 normal pressure-type patients, only 31 (61%) had improved. Surprisingly, in 22 of the 31 normal pressure-type improved patients, final valve-opening pressures were 30 mmH2O (16 patients) and 40 mmH2O (6 patients). Furthermore, when final valve-opening pressures were adjusted to 30 mmH2O, 14 patients symptom was improved just at the point. There were 18 (22%) major complications : 7 subdural hygroma, 6 shunt obstructions, and 5 shunt infections.
Conclusion: In normal pressure-type hydrocephalus, most patients improved when the final valve-opening pressure was 30 mmH2O. We suggest that all normal pressure-type hydrocephalus patients be shunted with programmable valves, and their initial valve-opening pressures set to 10-30 mmH2O below their preoperative cerebrospinal fluid (CSF) pressures. If final valve-opening pressures are lowered in 20 or 30 mmH2O scale at 2- or 3-week intervals, reaching a final pressure of 30 mmH2O, we believe that there is a low risk of overdrainage syndromes.
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KEYWORD
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Hydrocephalus, Programmable valve, Valve-opening pressure, Shunt
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