Читать книгу The Surgery of the Skull and Brain - Louis Bathe Rawling - Страница 85

This operation is strongly recommended by Keen on the ground that excellent drainage is supplied. A point is mapped out on the skull which lies 1¹⁄₄ inches behind the external auditory meatus and the same distance above Reid’s base-line. If the postero-lateral fontanelle be open a small trocar and cannula may be introduced at the upper angle of the space—thus avoiding the lateral sinus—and passed inwards in a direction towards the summit of the opposite ear. If the fontanelle be closed, a scalp-flap is framed and a bone-disk removed with a ¹⁄₄-¹⁄₂ inch diameter trephine. The dura should not be opened. The evacuating instrument is then introduced through the membrane in the same direction as before. In either case it should not be passed for a greater distance than 1¹⁄₂ inches, and, in all cases, the exploration should be of a progressive nature, that is to say, the trocar should be withdrawn once for each ¹⁄₂ inch of brain substance perforated. The escape of cerebro-spinal fluid must be regulated in the manner previously described.

If trephining has been necessitated, the bone-disk is not replaced, thus allowing of subsequent tappings through the trephine-hole, this gap now taking the place of a patent postero-lateral fontanelle.

Keen’s method of ventricular puncture presents many advantages over other methods, though still open to the objection that the actual central puncture is done blindly.