Choi 2009.

Methods	Study design: randomized controlled trial (2 arms) Study duration: not reported Study setting: hospital, single centre, China
Participants	Adults undergoing elective craniotomy (n = 32) Inclusion criteria Adults undergoing elective craniotomy Exclusion criteria Inability to understand the pain scoring system Allergy to study drugs Mean age, range (years) 44 (18 to 70) Numbers allocated to each arm Group intervention (n = 16) Group control (n = 16) Male gender Group intervention: 5/16 Group control: 4/16
Interventions	Technique and timing Scalp block of the following nerves: Supraorbital and supratrochlear Zygomaticotemporal Auriculotemporal Postauricular branches of the greater auricular Greater, lesser, and third occipital nerves with 0.75% ropivacaine versus scalp block with saline, at the end of surgery Dosage 2 to 3 mL per nerve
Outcomes	Primary Pain as measured by the VAS (0 to 100 mm) during the first 48 hours postoperatively (at 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours and 48 hours) Secondary Time to requirement of rescue analgesia Total amount of rescue analgesia required Heart rate and blood pressure
Notes	Published in Chinese only Paper published in Chinese only, translator used but translation errors possible Funding None
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer‐generated randomization table was used.
Allocation concealment (selection bias)	High risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not reported
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up. All participants were included in the final analysis.
Selective reporting (reporting bias)	Low risk	Outcomes reported as specified
Other bias	Unclear risk	Small study