When do I need a lumbar puncture?
As a rule, a lumbar puncture is contraindicated when the intracranial pressure is increased, i.e. it should not be performed. For the following reason: When cerebrospinal fluid is drained from the cerebrospinal fluid space (the chamber surrounding the brain and spinal cord where the cerebrospinal fluid is located) of the spinal cord during a lumbar puncture, the brain shifts downwards towards the spinal cord. While this is not a problem in a healthy patient without increased intracranial pressure, the combination of increased intracranial pressure and lumbar puncture carries the risk of constriction of the brain stem by the brain pushing from above into the large cranial opening (foramen magnum). Such an incarceration is absolutely life-threatening, which explains the contraindication of a lumbar puncture in the case of increased intracranial pressure.The only exception to this rule is a suspected idiopathic intracranial hypertension (pseudotumor cerebri). However, even in this case, a CT scan must be taken before the lumbar puncture to ensure that the triggering of an incarceration by the lumbar puncture is practically ruled out.
What is an ICP probe?
An intracranial pressure probe is mainly used in cases of severe craniocerebral trauma or other diseases (e.g. tumor, pronounced stroke) with a significant increase in intracranial pressure for exact measurement and monitoring of the intracranial pressure. In this way, it is intended to detect at an early stage if the increased intracranial pressure causes a constriction of parts of the brain in the cerebellar tent (tentorium) or in the large cranial opening (foramen magnum). In addition, too high intracranial pressure can impair the blood flow in the brain.
To place a brain probe, a small hole (about 0.5 cm in diameter) is first drilled into the skull, through which the brain probe can then be inserted. Usually several probes are placed to measure the pressure in different compartments of the brain. Since the installation of a cerebral pressure probe is an invasive procedure and therefore carries a certain risk of infection, its use is reserved for particularly urgent cases, but sometimes it is unfortunately indispensable.
