Can we safely monitor posterior fossa intracranial pressure? A cadaveric study.

BACKGROUND: measuring intracranial pressure (ICP) is considered the gold standard of care for brain injury. While supratentorial ICP monitoring has been adopted everywhere, posterior fossa ICP monitoring is rarely performed. In this study, we aimed to evaluate the feasibility of inserting ICP sensors into the posterior fossa of cadavers, to measure ICP in the posterior fossa.

METHODS: An ICP sensor was transcranially implanted into the posterior fossa of fifteen fresh adult cadavers. An extracranial point was defined in the retroauricular area 2 cm behind the tip of the mastoid process and 2 cm below the transverse sinus, in order to implant an ICP probe. The cranial cavity was opened and measures were taken of the distance that the ICP sensor had penetrated inside the posterior fossa, as well as the distance to nearby venous sinuses (lateral, transverse, sigmoid, inferior petrosal sinus, and jugular bulb). The cerebellar hemisphere was searched for any possible damage.

RESULTS: the selected extracranial point (2 cm behind the tip of the mastoid process and 2 cm below the transverse sinus) was a safe location. Intracranial structures such as the brainstem and the cerebellar hemisphere were not damaged. The implanted ICP probe was at least 2 cm away from the venous sinuses, which were not damaged.

CONCLUSION: ICP monitoring is safe and reliable at the described ICP probe placement site of the posterior fossa.