Slight elevation of baseline intracranial pressure after fluid infusion into CSF space in patients with hydrocephalus.
OBJECTIVE
To investigate the elevation of resting cerebrospinal fluid (CSF) pressure recorded after a CSF infusion test in patients with hydrocephalus.


METHODS
Fifty patients (30 men and 20 women, mean age 68 +/- 13 years) with ventriculomegaly and clinical symptoms of normal pressure hydrocephalus have been studied. Lumbar (56%) or intraventricular (44%) computerized infusion studies were performed to investigate the hydrodynamics of CSF. After infusion, the fall in ICP was recorded until a steady-state level was achieved and the difference between pre- and post-infusion resting ICP was calculated (DeltaICP).


RESULTS
A positive difference (>2 mm Hg) between post- and pre-infusion resting ICP was identified in 31 infusion tests (62%). The mean value of the difference was 6.7 with an SD of 3.5 mm Hg. The patients who demonstrated this phenomenon had a greater elastance coefficient (p>0.05); DeltaICP was positively correlated with age (R=0.27; p=0.03), with the size of the brain's ventricles (R=0.63, p=0.03) and inversely with the severity of clinical impairment (Stein-Langfitt score R=-0.61, p=0.02; normal pressure hydrocephalus score: R=0.54; p<0.05). DeltaICP was independent of the site of infusion (lumbar or ventricular).


CONCLUSIONS
In patients with a 'stiffer' brain, ICP returns to the resting level after the infusion test at a slightly higher level than before the test. The magnitude of this increase is greater when ventricles are more dilated and clinical symptoms are less severe.
Academic Neurosurgery Unit, University of Cambridge Cambridge, UK.
Magdalena
M
Kasprowicz
Zofia
Z
Czosnyka
Marek
M
Czosnyka
Shahan
S
Momjian
Henryk
H
Juniewicz
John D
JD
Pickard
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002555:Cerebrospinal Fluid / Q000502:physiology*; D002557:Cerebrospinal Fluid Shunts; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology*; D015918:Infusion Pumps, Implantable; D007427:Intracranial Pressure / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric