Manometer. Neurosurgeon inserts a small tube in the ventricle of brain (normal cavity in brain) other end is connected to a device which reads pressure.
In the ICU. A pressure monitor needs to be connected to the brain. This is performed by a neurosurgeon and monitored by special nurses in an ICU setting. Different monitoring devices can be used with either a tube directly into the brain or a pressure gauge sitting on the surface of the brain. More important is the balance of brain pressure to systemic blood pressure to be sure the brain is getting blood.