Etezadi 2013.

Methods	Randomization: yes Participant blinding: unclear Provider blinding: no Assessor blinding: yes Dropouts: 0
Participants	Country: Iran ASA: I and II Gender: men and women Age range: 18–60 years Ambulatory surgery: no Surgical positioning: supine, lithotomy Number of participants: 250
Interventions	Drug 1: 5% lido, hyperbaric, variable dose (1.5–2 mL) Drug 2: 0.5% bupi, isobaric, variable dose (2.5–3 mL) Needle: 25 g sharp and pencil point
Outcomes	TNS
Notes	Follow‐up duration: 5 days Follow‐up method: in person, unclear after 48 hours ("visited") TNS therapy: NSAIDs TNS resolution: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "… randomization was achieved by a computer‐generated block of numbers and sealed envelope technique."
Allocation concealment (selection bias)	Unclear risk	Quote: "… randomization was achieved by a computer‐generated block of numbers and sealed envelope technique." Comment: did not specify allocation by sequentially numbered, sealed, opaque envelopes.
Participant blinding (performance bias and detection bias)	Low risk	Study was described as "double‐blind" but otherwise participant blinding was not addressed.
Provider blinding (performance bias)	High risk	Volumes of local anaesthetic were not the same for the 2 interventions, thus provider not blinded.
Assessor blinding (detection bias)	Low risk	Quote: "the symptoms of TNS… were observed by a neurosurgeon that was blinded to… the type of drug… used for spinal anesthesia."
Incomplete outcome data (attrition bias) All outcomes	Low risk	250 participants enrolled, data reported for 250 participants.
Selective reporting (reporting bias)	Unclear risk	Study protocol not available.