Intracranial Pressure Assessments - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 375

In clinical studies as well as after experimental SAH, an increase
in intracranial pressure could be observed, which reached in rats
ICP levels of 50-90 mmHg comparable with normal rat mean
arterial blood pressure levels leading to an interruption of cerebral
perfusion ( 9-13 ). Over the years, different techniques and local-
izations (intraparenchymal, intraventricular, cisternal, sub- and
epidural) have been described to measure ICP and gain access to
CSF.
This chapter describes techniques for assessing intracranial
pressure in animals after SAH.
A variety of methods for clinical and experimental continuous
measurement of ICP have been described (sub- and epidural, intra-
parenchymal, cisternal, and ventricular). Ventricular cannulation
and ICP monitoring was developed around 1960 and remains gold
standard for CSF pressure measurement in patients ( 14 ).
Cannulation of the cisterna magna in experimental settings ( 15 ) as
well as intraparenchymal monitoring with fi beroptic devices ( 16,
17 ) showed also reliable ICP measurements. In experimental set-
tings, accurate and reliable ICP measurement results with minimal
damage to the brain are important and desirable.

2. Main
Considerations

2.1. Choice of ICP
Measuring Method

Three different methods to measure ICP in experimental settings
are described: ventricular, intraparenchymal, and cisternal moni-
toring. Comparisons of ventricular, intraparenchymal, and cisterna
magna ICP measurements revealed ICP oscillation with pulse pres-
sure and respiration in all three methods ( 18 ). ICP levels tended to
be slightly higher when measured intraparenchymally than intra-
ventricularly or cisternally (Table 1 ) ( 18 ). Although no signifi cant
differences ICP values were seen after SAH or trauma between
ventricular, fl uid-coupled catheter and intraparenchymal, fi beroptic
ICP measurements, intracisternal ICP recordings revealed differing

Table 1
Normal ICP values of rats measured intraventricular,
intraparenchymal or in the cisterna magna ( 18 )

Location ICP level (mmHg)

Intraventricular 8 ± 1.6

Intraparenchymal 11 ± 1.3

Cisterna magna 6 ± 0.9