Abstract
BackgroundThe cerebrospinal fluid tap test (CSF TT) is used for selecting shunt surgery candidates among patients with idiopathic normal pressure hydrocephalus (iNPH). We aimed to evaluate the predictive value of the CSF TT, by using the Hellström iNPH scale for shunted iNPH patients with a standardized method.MethodsOne hundred and sixteen shunt-operated iNPH patients were retrospectively included in this study. The gait and balance domains in the iNPH scale were used as outcome measures for the CSF TT and the total iNPH scale score as the postoperative outcome. A positive response to CSF TT was defined as a change of ≥ 5 points in the gait domain and ≥ 16 points in the balance domain. Differences between CSF TT responders and non-responders, sensitivity, specificity, positive and negative predictive values, accuracy, and correlations between changes from baseline to post CSF TT and from baseline to the postoperative follow-up, were calculated.ResultsIn the CSF TT there were 63.8% responders in the gait domain and correspondingly 44.3% in the balance domain. CSF TT responders had a significantly better postoperative outcome in the total scale score (gait P ≤ 0.001, balance P ≤ 0.012) and gait CSF TT responders improved more in gait (P ≤ 0.001) and balance CSF TT responders in balance (P ≤ 0.001). No differences between CSF TT gait or balance responders could be found in neuropsychological or urinary continence assessments postoperatively. The sensitivity and specificity of the CSF TT and the outcome of the total iNPH scale score postoperatively were 68.1% and 52.0% for gait and 47.8% and 68.0% for balance, respectively.ConclusionsThe CSF TT, with the Hellström iNPH scale as the outcome measure, has clear limitations in predicting postoperative results. The gait domain may be used to predict outcomes for gait, but the balance domain is too insensitive.
Highlights
Idiopathic normal pressure hydrocephalus is a condition that usually has slowly progressive symptoms
The cerebrospinal fluid (CSF) Cerebrospinal fluid tap test (TT) has mostly been associated with a high positive predictive value (PPV) and a low negative predictive value (NPV) meaning that potential shunt responders would be missed if the indication for surgery is based on a negative cerebrospinal fluid tap test (CSF TT) [7, 8]
Among the 116 individuals, 74 (63.8%) were CSF TT responders with a positive outcome (≥ 5 points) in the gait domain on the idiopathic normal pressure hydrocephalus (iNPH) scale
Summary
Idiopathic normal pressure hydrocephalus (iNPH) is a condition that usually has slowly progressive symptoms. The cerebrospinal tap test (CSF TT), which involves a lumbar puncture (LP) with removal of 30–50 ml CSF and clinical evaluation before and after the LP, is commonly used to predict patients who could benefit from a shunt insertion [4,5,6,7]. We use the Hellström iNPH scale [15] to evaluate outcome in the four domains gait, balance, neuropsychology and continence, after surgery. The Hellström iNPH scale is a standardized method that has rarely been used as an outcome measure in the evaluation of the CSF TT [8, 16]. The cerebrospinal fluid tap test (CSF TT) is used for selecting shunt surgery candidates among patients with idiopathic normal pressure hydrocephalus (iNPH). We aimed to evaluate the predictive value of the CSF TT, by using the Hellström iNPH scale for shunted iNPH patients with a standardized method
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