How is ICP monitored?
Ventriculostomy is the most common method of
meas-uring ICP. A catheter is placed through a burr hole and into the anterior
horn of a lateral ventricle.
Obliteration of the ventricle due to tumor or edema may create
technical difficulties inserting the catheter. Subdural bolts also serve to
measure ICP. These devices are placed via a twist drill hole in the calvarium
and a small hole in the dura. They are less invasive than a ventriculostomy and
provide only local pressure data instead of global information. Subdural bolts
can become infected and lack the potential to withdraw CSF for lowering ICP.
Proper positioning requires the bolt’s head to be aligned in the same plane as
underlying brain. Catheters or electronic transducers placed in the epidural
space can also be used for ICP monitoring. Lumbar subarachnoid catheters are
occasionally used. The accuracy of these devices is impaired by patient
positioning other than horizontal. Abrupt withdrawal of CSF through lum-bar
subarachnoid catheters risks brain herniation.