The pressure measured by CSF manometry may be falsely elevated if the protein concentration is elevated. Miranda-Aguilar and Reymundo-Ponce determined a simple method to correct the observed pressure reading for the change in density caused by the increased protein concentration. The authors are from the Hospital Nacional Edgardo Rebagliati Martins-Es Salud and the Universidad Nacional Federico Villarreal in Lima, Peru.


NOTE: In Figure 4 the authors use 150 mg/dL as the protein concentration cutoff to use. In the abstract and text the value of 150 mg per cubic cm is used; this is comparable to 15,000 mg per dL (100 cubic cm). The first value seems more appropriate for CSF.


If the CSF protein concentration is < 150 mg/dL, then no correction is performed and the manometric reading is recorded as the CSF pressure.


If the CSF protein concentration is >= 150 mg/dL, then the following equation is used to obtain the "true" pressure reading:


corrected manometric CSF pressure in mm H2O =

= (manometric reading in mm H2O) + ((protein concentration in mg/dL) / 50) - 2


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