The Relationship Between Intracranial Pressure and Age-Chasing Age-Related Reference Values.

BACKGROUND: No true reference values for intracranial pressure (ICP) in humans exist; current values are estimated from measurements in adults who undergo treatment in order to correct ICP. We report ICP values in a "pseudonormal" group of children and adults to examine if age affects ICP.

METHODS: We analyzed data from all nonshunted patients undergoing a 24-hour ICP monitoring as part of a diagnostic work-up and included patients with no subsequent suspicion of increased ICP and no need for pressure-relieving treatment with a minimum follow-up period of 3 years.

RESULTS: From February 2008 to November 2014, a 24-hour ICP monitoring was performed in 221 patients. Of these patients, 35 (14 children, 21 adults) met the inclusion criteria. Follow-up time to confirm absence of ICP-related disease was 3-9 years. Daytime ICP was 2.8 mmHg ± 2.2 in children and 1.9 mmHg ± 4.2 in adults (P = 0.39). Of 35 patients, 32 had higher nighttime ICP. The difference between daytime and nighttime ICP was similar in children (ΔICP = 5.8 mmHg ± 4.0, P < 0.0001) and adults (ΔICP = 6.1 mm Hg ± 3.3, P < 0.0001). ICP could be described as a decreasing function of age, with an ICP decrement of 0.69 mmHg per decade (P = 0.015).

CONCLUSIONS: We found similar differences in daytime and nighttime ICP between children and adults with no ICP-related disease. ICP seems to decrease with age across all ages. This has implications for therapeutic interventions (e.g., shunt valve selection or resistance in external ventricular drainage).