Cerebrospinal Fluid Lumbar Tapping Utilization for Suspected Ventriculoperitoneal Shunt Under-Drainage Malfunctions

OBJECTIVE: The diagnosis of shunt malfunction can be challenging since neuroimaging results are not always correlated with clinical outcomes. The purpose of this study was to evaluate the efficacy of a simple, minimally invasive cerebrospinal fluid (CSF) lumbar tapping test that predicts shunt under-drainage in hydrocephalus patients. METHODS: We retrospectively reviewed the clinical and radiological features of 48 patients who underwent routine CSF lumbar tapping after ventriculoperitoneal shunt (VPS) operation using a programmable shunting device. We compared shunt valve opening pressure and CSF lumbar tapping pressure to check under-drainage. RESULTS: The mean pressure difference between valve opening pressure and CSF lumbar tapping pressure of all patients were 2.21±24.57 mmH₂O. The frequency of CSF lumbar tapping was 2.06±1.26 times. Eighty five times lumbar tapping of 41 patients showed that their VPS function was normal which was consistent with clinical improvement and decreased ventricle size on computed tomography scan. The mean pressure difference in these patients was −3.69±19.20 mmH₂O. The mean frequency of CSF lumbar tapping was 2.07±1.25 times. Fourteen cases of 10 patients revealed suspected VPS malfunction which were consistent with radiological results and clinical symptoms, defined as changes in ventricle size and no clinical improvement. The mean pressure difference was 38.07±23.58 mmH₂O. The mean frequency of CSF lumbar tapping was 1.44±1.01 times. Pressure difference greater than 35 mmH₂O was shown in 2.35% of the normal VPS function group (2 of 85) whereas it was shown in 64.29% of the suspected VPS malfunction group (9 of 14). The difference was statistically significant (p=0.000001). Among 10 patients with under-drainage, 5 patients underwent shunt revision. The causes of the shunt malfunction included 3 cases of proximal occlusion and 2 cases of distal obstruction and valve malfunction. CONCLUSION: Under-drainage of CSF should be suspected if CSF lumbar tapping pressure is 35 mmH₂O higher than the valve opening pressure and shunt malfunction evaluation or adjustment of the valve opening pressure should be made.

Clinical Experience with the Programmable Valve for Hydrocephalus Patients

OBJECTIVE: The goal of this study is to establish the value of the programmable valve system. METHODS: The authors conducted a single center retrospective study of 41 consecutive patients who had undergone ventriculoperitoneal shunt with programmable valve for hydrocephalus of various etiology from March 1999 to February 2002. RESULTS: In 10 patients(24%), valve pressure adjustment was required at least 3 times or more for the reason of underdrainage or overdrainage. The range of pressure reprogramming was 10 to 120mmH2O. The clinical symptoms improved in 37 patients(90%). The radiologic improvement was obtained in 88%. Shunt was minimally functioning in 3 cases without any clinical effect at the pressure of 30mmH2O. CONCLUSION: The programmable valve has been particularly useful in changing ventricular size for the correction of overdrainage or underdranage by the easy control of valve pressure without any invasive procedure. The authors' preference is to use the programmable valve system for all conditions.