Advance the needle a little further.

The ligamentum flavum often feels hard or gritty, especially in the elderly.

Often there is a distinct 'give' as the needle passes into the epidural space.

Withdraw the stylet. If blood is seen, you are in an epidural vein. Advance the needle further.

If CSF is seen, you are in the subarachnoid space (Fig 1).

If nothing is seen, replace the stylet and advance a little further.

Withdraw the stylet and check for CSF.