Abstract: A subarachnoid bolt for use in measuring intracranial pressure includes a lower bolt half and an upper bolt half which can be screwed to the lower bolt half. A tubular member extends downwardly from the lower bolt half and is adapted to be inserted into a hole formed in a patient's skull. In one embodiment, the bolt is securely held in place when the free end of a tubular element carried by the upper bolt half enters the tubular member and cams the lowermost end thereof radially outwardly when the two bolt halves are screwed together. In a second embodiment, a sleeve on the lower bolt half bulges outwardly against the walls of the hole when the two bolt halves are screwed together.

Abstract: A subarachnoid bolt for use in measuring intracranial pressure includes a lower bolt half and an upper bold half which can be screwed into the lower bolt half. A tubular member extends downwardly from the lower bolt half and is adapted to be inserted into a hole formed in a patient's skull. The bolt is securely held in place when the free end of a tubular element carried by the upper bolt half enters the tubular member and cams the lowermost end thereof radially outwardly when the two bolt halves are screwed together.