CSF tap test

{{Short description|Medical test}}

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| name = CSF tap test

| image = File:Wikipedian getting a lumbar puncture (2006).jpg|

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| caption = Lumbar puncture

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|purpose = test to decide shunting of cerebrospinal fluid

| synonyms = Lumbar tap test

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The CSF tap test, sometimes lumbar tap test or Miller Fisher Test, is a medical test that is used to decide whether shunting of cerebrospinal fluid (CSF) would be helpful in a patient with suspected normal pressure hydrocephalus (NPH). The test involves removing 30–50 ml of CSF through a lumbar puncture, after which motor and cognitive function is clinically reassessed.{{Cite journal |last1=Virhammar |first1=J. |last2=Cesarini |first2=K. G. |last3=Laurell |first3=K. |date=2011-07-30 |title=The CSF tap test in normal pressure hydrocephalus: evaluation time, reliability and the influence of pain |url=http://dx.doi.org/10.1111/j.1468-1331.2011.03486.x |journal=European Journal of Neurology |volume=19 |issue=2 |pages=271–276 |doi=10.1111/j.1468-1331.2011.03486.x |pmid=21801282 |s2cid=22058194 |issn=1351-5101}} The name "Fisher test" is after C. Miller Fisher, a Canadian neurologist working in Boston, Massachusetts, who described the test.{{cite book|vauthors=Collins LG, Rovner BN, Marenberg MM|veditors=Arenson C, Busby-Whitehead J, Brummel-Smith K, O'Brien JG, Palmer MH, Reichel W|title=Reichel's care of the elderly : clinical aspects of aging.|date=2009|publisher=Cambridge University Press|location=Cambridge|isbn=9780521869294|page=180|edition=6th |chapter-url=https://books.google.com/books?id=74FPjVwzGDUC&dq=%22fisher%20test%22%20NPH&pg=PA180|chapter=Evaluation and Management of Dementia}}

Clinical improvement showed a high predictive value for subsequent success with shunting. A "negative" test has a very low predictive accuracy, as many patients may improve after a shunt in spite of lack of improvement after CSF removal.{{cite journal |last1=Wikkelsø, C., Hellström, P., Klinge, P. M., Tans, J. T. J., & European iNPH Multicentre Study Group |author-link3=Petra Klinge|title=The European iNPH Multicentre Study on the predictive values of resistance to CSF outflow and the CSF Tap Test in patients with idiopathic normal pressure hydrocephalus |journal=Journal of Neurology, Neurosurgery, and Psychiatry |date=2013 |volume=84 |issue=5 |pages=562–568 |doi=10.1136/jnnp-2012-303314 |pmid=23250963|s2cid=6335882 }}