Chapter 5 – Intracranial Pressure Monitors

Abstract

Intracranial pressure (ICP) can be measured by a monitor placed into one of the lateral ventricles; in the subarachnoid, subdural, or epidural spaces; or in the brain parenchyma.
ICP monitors should be placed in a patient’s nondominant hemisphere (e.g. right hemisphere in a right-handed person).
Kocher’s point is the external skin landmark most commonly used for insertion; at this point, the catheter trajectory to the frontal horn of the lateral ventricle avoids bridging veins, the superior sagittal sinus, and the motor strip. Kocher’s point is located 2 cm anterior to the coronal suture at the mid-pupillary line (2–3 cm lateral to midline). The coronal suture is approximately 11–12 cm from the base of the nose.
Alternative sites for placement include Keen’s point, which is located 2.5 cm posterior and superior to the top of the ear (posterior-parietal), a Frazier burr hole (occipital-parietal), and Dandy’s point (occipital).

Meghan Lewis and John Peter Gruen

Intracranial pressure (ICP) can be measured by a monitor placed into one of the lateral ventricles; in the subarachnoid, subdural, or epidural spaces; or in the brain parenchyma.

Figure 5.1 The intracranial pressure can be monitored via a catheter placed in one of the lateral ventricles, or with devices placed in the epidural, subdural, or subarachnoid spaces, or in the brain parenchyma.
ICP monitors should be placed in a patient’s nondominant hemisphere (e.g. right hemisphere in a right-handed person).
Kocher’s point is the external skin landmark most commonly used for insertion; at this point, the catheter trajectory to the frontal horn of the lateral ventricle avoids bridging veins, the superior sagittal sinus, and the motor strip. Kocher’s point is located 2 cm anterior to the coronal suture at the mid-pupillary line (2–3 cm lateral to midline). The coronal suture is approximately 11–12 cm from the base of the nose.

Figure 5.2 Anatomic landmarks for placement of an ICP monitor. Identification of the Kocher’s point (red X) for insertion of the ICP monitor: Mid-pupillary line, about 2 cm anterior to the coronal line.
Alternative sites for placement include Keen’s point, which is located 2.5 cm posterior and superior to the top of the ear (posterior-parietal), a Frazier burr hole (occipital-parietal), and Dandy’s point (occipital).

The Brain Trauma Foundation recommends management of severe traumatic brain injury (TBI) patients using information from ICP monitoring to reduce in-hospital and 2-week post-injury mortality.
Insertion of an ICP monitor may be performed in the emergency room, the operating room, or the intensive care unit.
Sterile technique should always be utilized for placement.
Avoid ICP placement if the INR is >1.5
Complications from ICP monitor placement include hemorrhage, infection, malposition or dislodgement, and cerebrospinal fluid (CSF) leakage.

An intraventricular catheter, also called external ventricular drain (EVD), is a flexible catheter inserted into one of the lateral ventricles.
An EVD can be used both to monitor ICPs and for therapeutic drainage of CSF.
A fluid coupled EVD is considered the gold standard for ICP monitoring, because it is the most accurate and can be recalibrated in situ. However, alternative methods of pressure transduction are commonly utilized in newer model EVDs.
Traditional EVDs permitted measurement of ICP only when the drain was closed; however, newer models allow simultaneous ICP monitoring and CSF drainage.

Microtransducers utilize fiber optic, strain gauge, or pneumatic sensors to continuously monitor ICPs. These are often placed into the desired space through a hollow screw, also called a “bolt.”
Microtransducers have a lower infection risk than EVDs; however, they do not allow for drainage of CSF.
Microtransducers are generally easier to place than EVDs, and can be positioned in several locations:
- Intraparenchymal
- Subarachnoid
- Subdural
- Epidural
- Intraventricular