title: Cerebrospinal Fluid Lumbar Tapping Utilization for Suspected Ventriculoperitoneal Shunt Under-Drainage Malfunctions.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Neurosurgery, Daejeon St. Mary's Hospital, College of Medicine (Nursing), The Catholic University of Korea, Daejeon, Korea.
authors.forename: Jong-Beom
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Daejeon St. Mary's Hospital, College of Medicine (Nursing), The Catholic University of Korea, Daejeon, Korea.
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Ahn
authors.affiliation: Department of Neurosurgery, Daejeon St. Mary's Hospital, College of Medicine (Nursing), The Catholic University of Korea, Daejeon, Korea.
authors.forename: Hong-Jae
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Daejeon St. Mary's Hospital, College of Medicine (Nursing), The Catholic University of Korea, Daejeon, Korea.
authors.forename: Ji-Ho
authors.initials: JH
authors.lastname: Yang
authors.affiliation: Department of Neurosurgery, Daejeon St. Mary's Hospital, College of Medicine (Nursing), The Catholic University of Korea, Daejeon, Korea.
authors.forename: Jin-Seok
authors.initials: JS
authors.lastname: Yi
authors.affiliation: Department of Neurosurgery, Daejeon St. Mary's Hospital, College of Medicine (Nursing), The Catholic University of Korea, Daejeon, Korea.
authors.forename: Il-Woo
authors.initials: IW
authors.lastname: Lee
keywords: Hydrocephalus; Lumbar tapping; Shunt malfunction; Under-drainage; Ventroculoperitoneal shunt