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The original needles used for subarachnoid (spinal) anaesthesia were of the Quincke type, similar in appearance to a standard hypodermic needle with an angled cutting edge. A central removable stylet prevented skin, fat, ligament and dura from entry into the needle lumen during passage towards the subarachnoid space. Such blockage of the needle would prevent detection of CSF and either result in failure of location or multiple punctures of the dura with a much greater likelihood of post durai puncture headache. The technique therefore consisted of insertion of the needle in an appropriate spinal interspace and advancement of the needle, accompanied by (usually) several withdrawals of the stylet in order to detect the presence of CSF. Those of us brought up on this procedure continued to teach the same technique to trainees who were using the newer pencil-point needles.
Whilst watching a trainee hesitantly advance a 25 gauge Whitacre needle, remove the stylet, wait patiently for the emergence of CSF then with difficulty (aggravated by intention tremor) re-insert the stylet before another cautious advance, I began to consider whether it was really necessary to use the stylet. With an introducer needle in place the stylet does not really confer any further tensile strength to the spinal needle. The side-hole is well formed and...