De Andres 1994.

Methods	Prospective, randomized, double‐blind study
Participants	A total of 158 patients, ASA I and II, ranging in age from 20 to 40 years undergoing lower limb orthopaedic surgery
Interventions	Patients were randomly assigned to 2 groups (26 G Atraucan and 27 G Whitacre needles) for the realization of spinal anaesthesia
Outcomes	The primary outcome was: frequency and degree of PDPH. Secondary outcomes were: performance of the subarachnoid technique and intraoperative side effects.
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