[Corrected cerebrospinal fluid manometry by measurement of the density and its relation with its biochemical composition].
OBJECTIVE
We question the suitability of the usual methods for taking the pressure of cerebrospinal fluid (CSF). We suspect that the composition of CSF and, in consequence, its density have an important effect on its manometric value.


METHODS
We obtained 322 CSF samples, with known cytological and biochemical composition, density and manometric values. We corrected the manometric measurements and, for each case, we calculated the exact pressure exerted by the column of CSF from its density, which was already known. The working variable was set as the manometric error (ME) that resulted from: Abs (calculated pressure of the column of CSF from its density manometry) (absolute value of the difference).


RESULTS
It was found that protein concentration levels in CSF had an important effect on the ME of the CSF, especially in values above 150 mg/cm3, and this result is extrapolated from our ad hoc mathematical model: corrected manometry (mmH2O) = manometry (mmH2O) + [cerebrospinal fluid protein (mg/cm3) / 50] 2.


CONCLUSIONS
This model proved to be a suitable predictor of ME in our sample, with a= 0.005.
Miranda
H
H
Universidad Nacional Federico Villareal, Lima, Peru. helard-miranda@usa.net
Reymundo Ponce
R G
RG
D002555:Cerebrospinal Fluid / Q000737:chemistry*; D008365:Manometry