Observations on the C.S.F. pressure during compression of the jugular veins.

It is often noted that the rise of C.S.F. pressure in response to compression of the jugular veins is variable and unpredictable. While doing routine lumbar punctures it was noticed that the amount of pressure rise seemed to depend on the side on which the patient was lying, and this report describes a study made to extend this observation. The subjects were I2 ward patients in whom there was no reason to suspect an abnormality of the circulation. of the C.S.F. or of the cerebral veins. Lumbar puncture was performed in the left lateral position with a wide gauge needle (17-I8 S.W.G. externally) and the pressure was recorded in a manometer of internal diameter about 2 mm. The patient rested until the pressure reached a steady reading. Compression was applied for 5 seconds by the fingers passed round the neck from behind and the pressure at the end of this time was recorded to the nearest 0.5 cm. The observation was repeated until a constant response was obtained. The patient was moved to the right lateral, and sometimes the sitting position and the measurement was repeated.