Comparison of noninvasive and direct measurements of intracranial pressure.

After creating "fontanelles" in infant rhesus monkeys, we measured intracranial pressure of these monkeys directly with an indwelling cannula and indirectly with a Ladd 1700 sensor. Values obtained with the Ladd sensor placed over the shaven fontanelle closely approximate directly measured pressure in acute experiments in these animals and in human cadavers. Application of the device is simple and application pressure need not always be the same for multiple determinations. The response time is 1.6 cm H2O/sec, which is adequate to record changes in intracranial pressure caused by changes in the partial pressure of CO2 in arterial blood.