<prompt> Miller Fischer test is used for:Evaluating cognition in NPH.Severity of paralysis in GBS.Grading muscle involvement in ALS.Measuring disability in Multiple sclerosis.  <response>: Ans. A. Evaluating cognition in NPHEvaluating cognition in NPH. 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 30mL of cerebrospinal fluid CSF through a lumbar puncture, after which cognitive function is clinically reassessed. Clinical improvement showed a high predictive value for subsequent success with shunting. 