Methods of measuring intracranial pressure via the fontanelle without puncture.

It is suggested that non-invasive techniques for measuring intracranial pressure should be suitable for use in the unsedated infant and should be capable of measuring pressure continuously. Methods described by other authors are reviewed. After investigation of 18 patients the technique relying upon the pulsation of the fontanelle described by Purin was rejected as being difficult to perform and applicable only in certain patients with large fontanelles. The technique of using a modified Schiotz tonometer was examined but rejected on grounds of inaccuracy, the need to perform the measurement with the infant in a vertical position, and the varying compressibility of the fontanelle. A method for indirectly estimating intracranial pressure using a modified aplanation principle is described, and a comparison of the pressures so measured and needle pressures is reported. The possible uses of a `fontanometer' using the aplanation principle are discussed and a preliminary report given of its use to monitor the changes of intracranial pressure caused by drugs.