Clinical assessment of noninvasive intracranial pressure absolute value measurement method

Objective: To assess prospectively the accuracy and precision of a method for noninvasive intracranial pressure (ICP) measurement compared with invasive gold standard CSF pressure measurement. Methods: Included were 62 neurologic patients (37 idiopathic intracranial hypertension, 20 multiple sclerosis, 1 Guillain-Barre syndrome, 1 polyneuropathy, and 3 hydrocephalus). The average age was 40 +/- 12 years. All patients had lumbar puncture indicated as a diagnostic procedure. ICP was measured using a noninvasive ICP measurement method, which is based on a two-depth high-resolution transcranial Doppler insonation of the ophthalmic artery (OA). The OA is being used as a natural pair of scales, in which the intracranial segment of the OA is compressed by ICP and the extracranial segment of the OA is compressed by extracranial pressure (Pe) applied to the orbit. The blood flow parameters in both OA segments are approximately the same in the scales balance case when Pe = ICP. All patients had simultaneous recording of noninvasive ICP values and invasive gold standard CSF pressure values. Results: Analysis of the 72 simultaneous paired recordings of noninvasive ICP and the gold standard CSF pressure showed good accuracy for the noninvasive method as indicated by the low mean systematic error (0.12 mm Hg; confidence level [CL] 0.98). The method also showed high precision as indicated by the low SD of the paired recordings (2.19 mm Hg; CL 0.98). The method does not need calibration. Conclusion: The proposed noninvasive ICP measurement method is precise and accurate compared with gold standard CSF pressure measured via lumbar puncture. Neurology (R) 2012;78:1684-1691