Hernández Palazón 2007.

Methods	Study design: randomized controlled trial (2 arms) Study duration: not reported Study setting: hospital, single centre, Spain
Participants	Adults undergoing elective supratentorial craniotomy for resection of brain tumours (n = 30) Inclusion criteria ASA I to III participants Exclusion criteria Inability to understand the pain scoring system Allergy to study drugs Long‐term opioid treatment Mean age, range (years) 44 (18 to 69) Numbers allocated to each arm Group intervention (n = 15) Group control (n = 15) Male gender Group intervention: 9/15 Group control: 8/15
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 0.25% bupivacaine with adrenaline 1:200,000 versus scalp block with saline, at the end of surgery Dosage 20 mL
Outcomes	Primary Morphine consumption in the first 24 hours postoperatively Secondary Time to requirement of rescue analgesia Pain as measured by the visual analogue score during the first 24 hours postoperatively (measured at 2, 4, 8, 12,16 and 24 hours) Sedation score Adverse events – nausea and vomiting, pruritis, respiratory depression
Notes	Paper published in Spanish only Paper published in Spanish only, translation software used but translation errors possible Funding No funding source reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Reported as randomized but method not reported
Allocation concealment (selection bias)	High risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Reported as double‐blinded but method or adequacy not reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Anaesthesiologist performing postoperative pain assessment did not participate in scalp block.
Incomplete outcome data (attrition bias) All outcomes	High risk	Losses to follow‐up and numbers included in final analysis were not reported.
Selective reporting (reporting bias)	Low risk	Outcomes reported as specified
Other bias	Unclear risk	Small study